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Linux 上 5 个最好 CAD 软件
|
||||
======
|
||||
|
||||
[计算机辅助设计 (CAD)][1] 是很多工程流程的必不可少的部分。CAD 用于建筑、汽车零部件设计、航天飞机研究、航空、桥梁施工、室内设计，甚至服装和珠宝设计等专业领域。
|
||||
|
||||
在 Linux 上并不原生支持一些专业级 CAD 软件，如 SolidWorks 和 Autodesk AutoCAD。因此，今天，我们将看看排名靠前的 Linux 上可用的 CAD 软件。预知详情，请看下文。
|
||||
|
||||
### Linux 可用的最好的 CAD 软件
|
||||
|
||||
![CAD Software for Linux][2]
|
||||
|
||||
在我们查看这份 Linux 的 CAD 软件列表前，你应该记住一件事，在这里不是所有的应用程序都是开源软件。我们也将包含一些非自由和开源软件的 CAD 软件来帮助普通的 Linux 用户。
|
||||
|
||||
我们为基于 Ubuntu 的 Linux 发行版提供了安装操作指南。对于其它发行版，你可以检查相应的网站来了解安装程序步骤。
|
||||
|
||||
该列表没有任何特殊顺序。在第一顺位的 CAD 应用程序不能认为比在第三顺位的好，以此类推。
|
||||
|
||||
#### 1、FreeCAD
|
||||
|
||||
对于 3D 建模，FreeCAD 是一个极好的选择，它是自由 (免费和自由) 和开源软件。FreeCAD 坚持以构建机械工程和产品设计为目标。FreeCAD 是多平台的，可用于 Windows、Mac OS X+ 以及 Linux。
|
||||
|
||||
![freecad][3]
|
||||
|
||||
尽管 FreeCAD 已经是很多 Linux 用户的选择，应该注意到，FreeCAD 仍然是 0.17 版本，因此，不适用于重要的部署。但是最近开发加速了。
|
||||
|
||||
- [FreeCAD][4]
|
||||
|
||||
FreeCAD 并不专注于 direct-2D 绘图和真实形状的动画，但是它对机械工程相关的设计极好。FreeCAD 的 0.15 版本在 Ubuntu 存储库中可用。你可以通过运行下面的命令安装。
|
||||
|
||||
```
|
||||
sudo apt install freecad
|
||||
```
|
||||
|
||||
为获取新的每日构建（目前 0.17），打开一个终端（`ctrl+alt+t`），并逐个运行下面的命令。
|
||||
|
||||
```
|
||||
sudo add-apt-repository ppa:freecad-maintainers/freecad-daily
|
||||
sudo apt update
|
||||
sudo apt install freecad-daily
|
||||
```
|
||||
|
||||
#### 2、LibreCAD
|
||||
|
||||
LibreCAD 是一个自由开源的、2D CAD 解决方案。一般来说，CAD 是一个资源密集型任务，如果你有一个相当普通的硬件，那么我建议你使用 LibreCAD ，因为它在资源使用方面真的轻量化。LibreCAD 是几何图形结构方面的一个极好的候选者。
|
||||
|
||||
![librecad][5]
|
||||
|
||||
作为一个 2D 工具，LibreCAD 是好的，但是它不能在 3D 模型和渲染上工作。它有时可能不稳定，但是，它有一个可靠的自动保存，它不会让你的工作浪费。
|
||||
|
||||
- [LibreCAD][6]
|
||||
|
||||
你可以通过运行下面的命令安装 LibreCAD。
|
||||
|
||||
```
|
||||
sudo apt install librecad
|
||||
```
|
||||
|
||||
#### 3、OpenSCAD
|
||||
|
||||
OpenSCAD 是一个自由的 3D CAD 软件。OpenSCAD 非常轻量和灵活。OpenSCAD 不是交互式的。你需要‘编程’模型，OpenSCAD 来解释这些代码来渲染一个可视化模型。在某种意义上说，它是一个编译器。你不能直接绘制模型，而是描述模型。
|
||||
|
||||
![openscad][7]
|
||||
|
||||
OpenSCAD 是这个列表上最复杂的工具，但是，一旦你了解它，它将提供一个令人愉快的工作经历。
|
||||
|
||||
- [OpenSCAD][8]
|
||||
|
||||
你可以使用下面的命令来安装 OpenSCAD。
|
||||
|
||||
```
|
||||
sudo apt-get install openscad
|
||||
```
|
||||
|
||||
#### 4、BRL-CAD
|
||||
|
||||
BRL-CAD 是最老的 CAD 工具之一。它也深受 Linux/UNIX 用户喜爱，因为它与模块化和自由的 *nix 哲学相一致。
|
||||
|
||||
![BRL-CAD rendering by Sean][9]
|
||||
|
||||
BRL-CAD 始于 1979 年，并且，它仍然在积极开发。现在，BRL-CAD 不是 AutoCAD，但是对于像热穿透和弹道穿透等等的运输研究仍然是一个极好的选择。BRL-CAD 构成 CSG 的基础，而不是边界表示。在选择 BRL-CAD 时，你可能需要记住这一点。你可以从它的官方网站下载 BRL-CAD 。
|
||||
|
||||
- [BRL-CAD][10]
|
||||
|
||||
#### 5、DraftSight (非开源)
|
||||
|
||||
如果你习惯在 AutoCAD 上作业。那么，DraftSight 将是完美的替代。
|
||||
|
||||
DraftSight 是一个在 Linux 上可用的极好的 CAD 工具。它有相当类似于 AutoCAD 的工作流，这使得迁移更容易。它甚至提供一种类似的外观和感觉。DrafSight 也兼容 AutoCAD 的 .dwg 文件格式。 但是，DrafSight 是一个 2D CAD 软件。截至当前，它不支持 3D CAD 。
|
||||
|
||||
![draftsight][11]
|
||||
|
||||
尽管 DrafSight 是一款起价 149 美元的商业软件。在 [DraftSight 网站][12]上可获得一个免费版本。你可以下载 .deb 软件包，并在基于 Ubuntu 的发行版上安装它。为了开始使用 DraftSight ，你需要使用你的电子邮件 ID 来注册你的免费版本。
|
||||
|
||||
- [DraftSight][12]
|
||||
|
||||
#### 荣誉提名
|
||||
|
||||
* 随着云计算技术的巨大发展，像 [OnShape][13] 的云 CAD 解决方案已经变得日渐流行。
|
||||
* [SolveSpace][14] 是另一个值得一提的开源软件项目。它支持 3D 模型。
|
||||
* 西门子 NX 是一个在 Windows、Mac OS 及 Linux 上可用的工业级 CAD 解决方案，但是它贵得离谱，所以，在这个列表中被忽略。
|
||||
* 接下来，你有 [LeoCAD][15]，它是一个 CAD 软件，在软件中你使用乐高积木来构建东西。你使用这些信息做些什么取决于你。
|
||||
|
||||
### 我对 Linux 上的 CAD 的看法
|
||||
|
||||
尽管在 Linux 上游戏变得流行，我总是告诉我的铁杆游戏朋友坚持使用 Windows。类似地，如果你是一名在你是课程中使用 CAD 的工科学生，我建议你使用学校规定的软件 (AutoCAD、SolidEdge、Catia)，这些软件通常只在 Windows 上运行。
|
||||
|
||||
对于高级专业人士来说，当我们讨论行业标准时，这些工具根本达不到标准。
|
||||
|
||||
对于想在 WINE 中运行 AutoCAD 的那些人来说，尽管一些较旧版本的 AutoCAD 可以安装在 WINE 上，它们根本不执行工作，小故障和崩溃严重损害这些体验。
|
||||
|
||||
话虽如此，我高度尊重上述列表中软件的开发者的工作。他们丰富了 FOSS 世界。很高兴看到像 FreeCAD 一样的软件在近些年中加速开发速度。
|
||||
|
||||
好了，今天到此为止。使用下面的评论区与我们分享你的想法，不用忘记分享这篇文章。谢谢。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/cad-software-linux/
|
||||
|
||||
作者：[Aquil Roshan][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[robsean](https://github.com/robsean)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://itsfoss.com/author/aquil/
|
||||
[1]:https://en.wikipedia.org/wiki/Computer-aided_design
|
||||
[2]:https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/08/cad-software-linux.jpeg
|
||||
[3]:https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/07/freecad.jpg
|
||||
[4]:https://www.freecadweb.org/
|
||||
[5]:https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/07/librecad.jpg
|
||||
[6]:https://librecad.org/
|
||||
[7]:https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/07/openscad.jpg
|
||||
[8]:http://www.openscad.org/
|
||||
[9]:https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/07/brlcad.jpg
|
||||
[10]:https://brlcad.org/
|
||||
[11]:https://i1.wp.com/itsfoss.com/wp-content/uploads/2018/07/draftsight.jpg
|
||||
[12]:https://www.draftsight2018.com/
|
||||
[13]:https://www.onshape.com/
|
||||
[14]:http://solvespace.com/index.pl
|
||||
[15]:https://www.leocad.org/
|
||||
244
published/20190402 Manage your daily schedule with Git.md
Normal file
244
published/20190402 Manage your daily schedule with Git.md
Normal file
@ -0,0 +1,244 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (wxy)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-11320-1.html)
|
||||
[#]: subject: (Manage your daily schedule with Git)
|
||||
[#]: via: (https://opensource.com/article/19/4/calendar-git)
|
||||
[#]: author: (Seth Kenlon https://opensource.com/users/seth)
|
||||
|
||||
用 Git 管理你的每日行程
|
||||
======
|
||||
|
||||
> 像源代码一样对待时间并在 Git 的帮助下维护你的日历。
|
||||
|
||||
|
||||
|
||||
[Git][2] 是一个少有的能将如此多的现代计算封装到一个程序之中的应用程序，它可以用作许多其他应用程序的计算引擎。虽然它以跟踪软件开发中的源代码更改而闻名，但它还有许多其他用途，可以让你的生活更轻松、更有条理。在这个 Git 系列中，我们将分享七种鲜为人知的使用 Git 的方法。
|
||||
|
||||
今天，我们将使用 Git 来跟踪你的日历。
|
||||
|
||||
### 使用 Git 跟踪你的日程安排
|
||||
|
||||
如果时间本身只是可以管理和版本控制的源代码呢？虽然证明或反驳这种理论可能超出了本文的范围，但在 Git 的帮助下，你可以将时间视为源代码并管理你的日程安排。
|
||||
|
||||
日历的卫冕冠军是 [CalDAV][3] 协议，它支撑了如 [NextCloud][4] 这样的流行的开源及闭源的日历应用程序。CalDAV 没什么问题（评论者，请注意），但它并不适合所有人，除此之外，它还有一种不同于单一文化的鼓舞人心的东西。
|
||||
|
||||
因为我对大量使用 GUI 的 CalDAV 客户端没有兴趣（如果你正在寻找一个好的终端 CalDAV 查看器，请参阅 [khal][5]），我开始研究基于文本的替代方案。基于文本的日历具有在[明文][6]中工作的所有常见好处。它很轻巧，非常便携，只要它结构化，就很容易解析和美化（无论*美丽*对你意味着什么）。
|
||||
|
||||
最重要的是，它正是 Git 旨在管理的内容。
|
||||
|
||||
### Org 模式不是一种可怕的方式
|
||||
|
||||
如果你没有对你的明文添加结构，它很快就会陷入一种天马行空般的混乱，变成恶魔才能懂的符号。幸运的是，有一种用于日历的标记语法，它包含在令人尊敬的生产力 Emacs 模式 —— [Org 模式][7] 中（承认吧，你其实一直想开始使用它）。
|
||||
|
||||
许多人没有意识到 Org 模式的惊人之处在于[你不需要知道甚至不需要使用 Emacs][8]来利用 Org 模式建立的约定。如果你使用 Emacs，你会得到许多很棒的功能，但是如果 Emacs 对你来说太难了，那么你可以实现一个基于 Git 的 Org 模式的日历系统，而不需要安装 Emacs。
|
||||
|
||||
关于 Org 模式你唯一需要知道的部分是它的语法。Org 模式的语法维护成本低、直观。使用 Org 模式而不是 GUI 日历应用程序进行日历记录的最大区别在于工作流程：你可以创建一个任务列表，然后每天分配一个任务，而不是转到日历并查找要安排任务的日期。
|
||||
|
||||
组织模式中的列表使用星号（`*`）作为项目符号。这是我的游戏任务列表：
|
||||
|
||||
```
|
||||
* Gaming
|
||||
** Build Stardrifter character
|
||||
** Read Stardrifter rules
|
||||
** Stardrifter playtest
|
||||
|
||||
** Blue Planet @ Mike's
|
||||
|
||||
** Run Rappan Athuk
|
||||
*** Purchase hard copy
|
||||
*** Skim Rappan Athuk
|
||||
*** Build Rappan Athuk maps in maptool
|
||||
*** Sort Rappan Athuk tokens
|
||||
```
|
||||
|
||||
如果你熟悉 [CommonMark][9] 或 Markdown，你会注意到，Org 模式不是使用空格来创建子任务，而是更明确地使用了其它项目符号。无论你的使用背景和列表是什么，这都是一种构建列表的直观且简单的方法，它显然与 Emacs 没有内在联系（尽管使用 Emacs 为你提供了快捷方式，因此你可以快速地重新排列列表）。
|
||||
|
||||
要将列表转换为日历中的计划任务或事件，请返回并添加关键字 `SCHEDULED` 和（可选）`:CATEGORY:`。
|
||||
|
||||
```
|
||||
* Gaming
|
||||
:CATEGORY: Game
|
||||
** Build Stardrifter character
|
||||
SCHEDULED: <2019-03-22 18:00-19:00>
|
||||
** Read Stardrifter rules
|
||||
SCHEDULED: <2019-03-22 19:00-21:00>
|
||||
** Stardrifter playtest
|
||||
SCHEDULED: <2019-03-25 0900-1300>
|
||||
** Blue Planet @ Mike's
|
||||
SCHEDULED: <2019-03-18 18:00-23:00 +1w>
|
||||
|
||||
and so on...
|
||||
```
|
||||
|
||||
`SCHEDULED` 关键字将该条目标记为你希望收到通知的事件，并且可选的 `:CATEGORY:` 关键字是一个可供你自己使用的任意标记系统（在 Emacs 中，你可以根据类别对条目使用颜色代码）。
|
||||
|
||||
对于重复事件，你可以使用符号（如`+1w`）创建每周事件或 `+2w` 以进行每两周一次的事件，依此类推。
|
||||
|
||||
所有可用于 Org 模式的花哨标记都[记录于文档][10]，所以不要犹豫，找到更多技巧来让它满足你的需求。
|
||||
|
||||
### 放进 Git
|
||||
|
||||
如果没有 Git，你的 Org 模式的日程安排只不过是本地计算机上的文件。这是 21 世纪，所以你至少需要可以在手机上使用你的日历，即便不是在你所有的个人电脑上。你可以使用 Git 为自己和他人发布日历。
|
||||
|
||||
首先，为 `.org` 文件创建一个目录。我将我的存储在 `~/cal` 中。
|
||||
|
||||
```
|
||||
$ mkdir ~/cal
|
||||
```
|
||||
|
||||
转到你的目录并使其成为 Git 存储库：
|
||||
|
||||
```
|
||||
$ cd cal
|
||||
$ git init
|
||||
```
|
||||
|
||||
将 `.org` 文件移动到你本地的 Git 存储库。在实践中，我为每个类别维护一个 `.org` 文件。
|
||||
|
||||
```
|
||||
$ mv ~/*.org ~/cal
|
||||
$ ls
|
||||
Game.org Meal.org Seth.org Work.org
|
||||
```
|
||||
|
||||
暂存并提交你的文件：
|
||||
|
||||
```
|
||||
$ git add *.org
|
||||
$ git commit -m 'cal init'
|
||||
```
|
||||
|
||||
### 创建一个 Git 远程源
|
||||
|
||||
要在任何地方提供日历，你必须在互联网上拥有 Git 存储库。你的日历是纯文本，因此任何 Git 存储库都可以。你可以将日历放在 [GitLab][11] 或任何其他公共 Git 托管服务（甚至是专有服务）上，只要你的主机允许，你甚至可以将该存储库标记为私有库。如果你不想将日历发布到你无法控制的服务器，则可以自行托管 Git 存储库，或者为单个用户使用裸存储库，或者使用 [Gitolite][12] 或 [Gitea][13] 等前端服务。
|
||||
|
||||
为了简单起见，我将假设一个自托管的 Git 裸存储库。你可以使用 Git 命令在任何具有 SSH 访问权限的服务器上创建一个远程裸存储库：
|
||||
|
||||
```
|
||||
$ ssh -p 22122 [seth@example.com][14]
|
||||
[remote]$ mkdir cal.git
|
||||
[remote]$ cd cal.git
|
||||
[remote]$ git init --bare
|
||||
[remote]$ exit
|
||||
```
|
||||
|
||||
这个裸存储库可以作为你日历在互联网上的家。
|
||||
|
||||
将其设置为本地 Git 存储库（在你的计算机上，而不是你的服务器上）的远程源：
|
||||
|
||||
```
|
||||
$ git remote add origin seth@example.com:/home/seth/cal.git
|
||||
```
|
||||
|
||||
然后推送你的日历到该服务器：
|
||||
|
||||
```
|
||||
$ git push -u origin HEAD
|
||||
```
|
||||
|
||||
将你的日历放在 Git 存储库中，就可以在任何运行 Git 的设备上使用它。这意味着你可以对计划进行更新和更改，并将更改推送到上游，以便在任何地方进行更新。
|
||||
|
||||
我使用这种方法使我的日历在我的工作笔记本电脑和家庭工作站之间保持同步。由于我每天大部分时间都在使用 Emacs，因此能够在 Emacs 中查看和编辑我的日历是一个很大的便利。对于大多数使用移动设备的人来说也是如此，因此下一步是在移动设备上设置 Org 模式的日历系统。
|
||||
|
||||
### 移动设备上的 Git
|
||||
|
||||
由于你的日历数据是纯文本的，严格来说，你可以在任何可以读取文本文件的设备上“使用”它。这是这个系统之美的一部分；你永远不会缺少原始数据。但是，要按照你希望的现代日历的工作方式将日历集成到移动设备上，你需要两个组件：移动设备上的 Git 客户端和 Org 模式查看器。
|
||||
|
||||
#### 移动设备上的 Git 客户端
|
||||
|
||||
[MGit][15] 是 Android 上的优秀 Git 客户端。同样，iOS 也有 Git 客户端。
|
||||
|
||||
一旦安装了 MGit（或类似的 Git 客户端），你必须克隆日历存储库，以便在你的手机上有副本。要从移动设备访问服务器，必须设置 SSH 密钥进行身份验证。MGit 可以为你生成和存储密钥，你必须将其添加到服务器的 `~/.ssh/authorized_keys` 文件或托管的 Git 的帐户设置中的 SSH 密钥中。
|
||||
|
||||
你必须手动执行此操作。MGit 没有登录你的服务器或托管的 Git 帐户的界面。如果你不这样做，你的移动设备将无法访问你的服务器以访问你的日历数据。
|
||||
|
||||
我是通过将我在 MGit 中生成的密钥文件通过 [KDE Connect][16] 复制到我的笔记本电脑来实现的（但你可以通过蓝牙、SD 卡读卡器或 USB 电缆进行相同操作，具体取决于你访问手机上的数据的首选方法）。 我用这个命令将密钥（一个名为 `calkey` 的文件）复制到我的服务器：
|
||||
|
||||
```
|
||||
$ cat calkey | ssh seth@example.com "cat >> /home/seth/.ssh/authorized_keys"
|
||||
```
|
||||
|
||||
你可能有不同的方法，但如果你曾经将服务器设置为无密码登录，这是完全相同的过程。如果你使用的是 GitLab 等托管的 Git 服务，则必须将密钥文件的内容复制并粘贴到用户帐户的 SSH 密钥面板中。
|
||||
|
||||
![Adding key file data to GitLab][17]
|
||||
|
||||
完成后，你的移动设备可以向你的服务器授权，但仍需要知道在哪里查找你的日历数据。不同的应用程序可能使用不同的表示法，但 MGit 使用普通的旧式 Git-over-SSH。这意味着如果你使用的是非标准 SSH 端口，则必须指定要使用的 SSH 端口：
|
||||
|
||||
```
|
||||
$ git clone ssh://seth@example.com:22122//home/seth/git/cal.git
|
||||
```
|
||||
|
||||
![Specifying SSH port in MGit][18]
|
||||
|
||||
如果你使用其他应用程序，它可能会使用不同的语法，允许你在特殊字段中提供端口，或删除 `ssh://` 前缀。如果遇到问题，请参阅应用程序文档。
|
||||
|
||||
将存储库克隆到手机。
|
||||
|
||||
![Cloned repositories][19]
|
||||
|
||||
很少有 Git 应用程序设置为自动更新存储库。有一些应用程序可以用来自动拉取，或者你可以设置 Git 钩子来推送服务器的更新 —— 但我不会在这里讨论这些。目前，在对日历进行更新后，请务必在 MGit 中手动提取新更改（或者如果在手机上更改了事件，请将更改推送到服务器）。
|
||||
|
||||
![MGit push/pull settings][20]
|
||||
|
||||
#### 移动设备上的日历
|
||||
|
||||
有一些应用程序可以为移动设备上的 Org 模式提供前端。[Orgzly][21] 是一个很棒的开源 Android 应用程序，它为 Org 模式的从 Agenda 模式到 TODO 列表的大多数功能提供了一个界面。安装并启动它。
|
||||
|
||||
从主菜单中，选择“设置同步存储库”，然后选择包含日历文件的目录（即，从服务器克隆的 Git 存储库）。
|
||||
|
||||
给 Orgzly 一点时间来导入数据，然后使用 Orgzly 的[汉堡包][22]菜单选择日程视图。
|
||||
|
||||
![Orgzly's agenda view][23]
|
||||
|
||||
在 Orgzly 的“设置提醒”菜单中，你可以选择在手机上触发通知的事件类型。你可以获得 `SCHEDULED` 任务，`DEADLINE` 任务或任何分配了事件时间的任何通知。如果你将手机用作任务管理器，那么你将永远不会错过 Org 模式和 Orgzly 的活动。
|
||||
|
||||
![Orgzly notification][24]
|
||||
|
||||
Orgzly 不仅仅是一个解析器。你可以编辑和更新事件，甚至标记事件为 `DONE`。
|
||||
|
||||
![Orgzly to-do list][25]
|
||||
|
||||
### 专为你而设计
|
||||
|
||||
关于使用 Org 模式和 Git 的重要一点是，这两个应用程序都非常灵活，并且你可以自定义它们的工作方式和内容，以便它们能够适应你的需求。如果本文中的内容是对你如何组织生活或管理每周时间表的冒犯，但你喜欢此提案提供的其他部分，那么请丢弃你不喜欢的部分。如果需要，你可以在 Emacs 中使用 Org 模式，或者你可以将其用作日历标记。你可以将手机设置为在一天结束时从计算机上拉取 Git 数据，而不是从互联网上的服务器上，或者你可以将计算机配置为在手机插入时同步日历，或者你可以每天管理它，就像你把你工作日所需的所有东西都装到你的手机上一样。这取决于你，而这是关于 Git、Org 模式和开源的最重要的事情。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/calendar-git
|
||||
|
||||
作者：[Seth Kenlon][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[wxy](https://github.com/wxy)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/seth
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/web-design-monitor-website.png?itok=yUK7_qR0 (website design image)
|
||||
[2]: https://git-scm.com/
|
||||
[3]: https://tools.ietf.org/html/rfc4791
|
||||
[4]: http://nextcloud.com
|
||||
[5]: https://github.com/pimutils/khal
|
||||
[6]: https://plaintextproject.online/
|
||||
[7]: https://orgmode.org
|
||||
[8]: https://opensource.com/article/19/1/productivity-tool-org-mode
|
||||
[9]: https://commonmark.org/
|
||||
[10]: https://orgmode.org/manual/
|
||||
[11]: http://gitlab.com
|
||||
[12]: http://gitolite.com/gitolite/index.html
|
||||
[13]: https://gitea.io/en-us/
|
||||
[14]: mailto:seth@example.com
|
||||
[15]: https://f-droid.org/en/packages/com.manichord.mgit
|
||||
[16]: https://community.kde.org/KDEConnect
|
||||
[17]: https://opensource.com/sites/default/files/uploads/gitlab-add-key.jpg (Adding key file data to GitLab)
|
||||
[18]: https://opensource.com/sites/default/files/uploads/mgit-0.jpg (Specifying SSH port in MGit)
|
||||
[19]: https://opensource.com/sites/default/files/uploads/mgit-1.jpg (Cloned repositories)
|
||||
[20]: https://opensource.com/sites/default/files/uploads/mgit-2.jpg (MGit push/pull settings)
|
||||
[21]: https://f-droid.org/en/packages/com.orgzly/
|
||||
[22]: https://en.wikipedia.org/wiki/Hamburger_button
|
||||
[23]: https://opensource.com/sites/default/files/uploads/orgzly-agenda.jpg (Orgzly's agenda view)
|
||||
[24]: https://opensource.com/sites/default/files/uploads/orgzly-cal-notify.jpg (Orgzly notification)
|
||||
[25]: https://opensource.com/sites/default/files/uploads/orgzly-cal-todo.jpg (Orgzly to-do list)
|
||||
@ -0,0 +1,305 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (MjSeven)
|
||||
[#]: reviewer: (wxy)
|
||||
[#]: publisher: (wxy)
|
||||
[#]: url: (https://linux.cn/article-11317-1.html)
|
||||
[#]: subject: (Learn object-oriented programming with Python)
|
||||
[#]: via: (https://opensource.com/article/19/7/get-modular-python-classes)
|
||||
[#]: author: (Seth Kenlon https://opensource.com/users/seth)
|
||||
|
||||
使用 Python 学习面对对象的编程
|
||||
======
|
||||
|
||||
> 使用 Python 类使你的代码变得更加模块化。
|
||||
|
||||
|
||||
|
||||
在我上一篇文章中，我解释了如何通过使用函数、创建模块或者两者一起来[使 Python 代码更加模块化][2]。函数对于避免重复多次使用的代码非常有用，而模块可以确保你在不同的项目中复用代码。但是模块化还有另一种方法：类。
|
||||
|
||||
如果你已经听过<ruby>面对对象编程<rt>object-oriented programming</rt></ruby>（OOP）这个术语，那么你可能会对类的用途有一些概念。程序员倾向于将类视为一个虚拟对象，有时与物理世界中的某些东西直接相关，有时则作为某种编程概念的表现形式。无论哪种表示，当你想要在程序中为你或程序的其他部分创建“对象”时，你都可以创建一个类来交互。
|
||||
|
||||
### 没有类的模板
|
||||
|
||||
假设你正在编写一个以幻想世界为背景的游戏，并且你需要这个应用程序能够涌现出各种坏蛋来给玩家的生活带来一些刺激。了解了很多关于函数的知识后，你可能会认为这听起来像是函数的一个教科书案例：需要经常重复的代码，但是在调用时可以考虑变量而只编写一次。
|
||||
|
||||
下面一个纯粹基于函数的敌人生成器实现的例子：
|
||||
|
||||
```
|
||||
#!/usr/bin/env python3
|
||||
|
||||
import random
|
||||
|
||||
def enemy(ancestry,gear):
|
||||
enemy=ancestry
|
||||
weapon=gear
|
||||
hp=random.randrange(0,20)
|
||||
ac=random.randrange(0,20)
|
||||
return [enemy,weapon,hp,ac]
|
||||
|
||||
def fight(tgt):
|
||||
print("You take a swing at the " + tgt[0] + ".")
|
||||
hit=random.randrange(0,20)
|
||||
if hit > tgt[3]:
|
||||
print("You hit the " + tgt[0] + " for " + str(hit) + " damage!")
|
||||
tgt[2] = tgt[2] - hit
|
||||
else:
|
||||
print("You missed.")
|
||||
|
||||
|
||||
foe=enemy("troll","great axe")
|
||||
print("You meet a " + foe[0] + " wielding a " + foe[1])
|
||||
print("Type the a key and then RETURN to attack.")
|
||||
|
||||
while True:
|
||||
action=input()
|
||||
|
||||
if action.lower() == "a":
|
||||
fight(foe)
|
||||
|
||||
if foe[2] < 1:
|
||||
print("You killed your foe!")
|
||||
else:
|
||||
print("The " + foe[0] + " has " + str(foe[2]) + " HP remaining")
|
||||
```
|
||||
|
||||
`enemy` 函数创造了一个具有多个属性的敌人，例如谱系、武器、生命值和防御等级。它返回每个属性的列表，表示敌人全部特征。
|
||||
|
||||
从某种意义上说，这段代码创建了一个对象，即使它还没有使用类。程序员将这个 `enemy` 称为*对象*，因为该函数的结果（本例中是一个包含字符串和整数的列表）表示游戏中一个单独但复杂的*东西*。也就是说，列表中字符串和整数不是任意的：它们一起描述了一个虚拟对象。
|
||||
|
||||
在编写描述符集合时，你可以使用变量，以便随时使用它们来生成敌人。这有点像模板。
|
||||
|
||||
在示例代码中，当需要对象的属性时，会检索相应的列表项。例如，要获取敌人的谱系，代码会查询 `foe[0]`，对于生命值，会查询 `foe[2]`，以此类推。
|
||||
|
||||
这种方法没有什么不妥，代码按预期运行。你可以添加更多不同类型的敌人，创建一个敌人类型列表，并在敌人创建期间从列表中随机选择，等等，它工作得很好。实际上，[Lua][3] 非常有效地利用这个原理来近似了一个面对对象模型。
|
||||
|
||||
然而，有时候对象不仅仅是属性列表。
|
||||
|
||||
### 使用对象
|
||||
|
||||
在 Python 中，一切都是对象。你在 Python 中创建的任何东西都是某个预定义模板的*实例*。甚至基本的字符串和整数都是 Python `type` 类的衍生物。你可以在这个交互式 Python shell 中见证：
|
||||
|
||||
```
|
||||
>>> foo=3
|
||||
>>> type(foo)
|
||||
<class 'int'>
|
||||
>>> foo="bar"
|
||||
>>> type(foo)
|
||||
<class 'str'>
|
||||
```
|
||||
|
||||
当一个对象由一个类定义时，它不仅仅是一个属性的集合，Python 类具有各自的函数。从逻辑上讲，这很方便，因为只涉及某个对象类的操作包含在该对象的类中。
|
||||
|
||||
在示例代码中，`fight` 的代码是主应用程序的功能。这对于一个简单的游戏来说是可行的，但对于一个复杂的游戏来说，世界中不仅仅有玩家和敌人，还可能有城镇居民、牲畜、建筑物、森林等等，它们都不需要使用战斗功能。将战斗代码放在敌人的类中意味着你的代码更有条理，在一个复杂的应用程序中，这是一个重要的优势。
|
||||
|
||||
此外，每个类都有特权访问自己的本地变量。例如，敌人的生命值，除了某些功能之外，是不会改变的数据。游戏中的随机蝴蝶不应该意外地将敌人的生命值降低到 0。理想情况下，即使没有类，也不会发生这种情况。但是在具有大量活动部件的复杂应用程序中，确保不需要相互交互的部件永远不会发生这种情况，这是一个非常有用的技巧。
|
||||
|
||||
Python 类也受垃圾收集的影响。当不再使用类的实例时，它将被移出内存。你可能永远不知道这种情况会什么时候发生，但是你往往知道什么时候它不会发生，因为你的应用程序占用了更多的内存，而且运行速度比较慢。将数据集隔离到类中可以帮助 Python 跟踪哪些数据正在使用，哪些不在需要了。
|
||||
|
||||
### 优雅的 Python
|
||||
|
||||
下面是一个同样简单的战斗游戏，使用了 `Enemy` 类：
|
||||
|
||||
```
|
||||
#!/usr/bin/env python3
|
||||
|
||||
import random
|
||||
|
||||
class Enemy():
|
||||
def __init__(self,ancestry,gear):
|
||||
self.enemy=ancestry
|
||||
self.weapon=gear
|
||||
self.hp=random.randrange(10,20)
|
||||
self.ac=random.randrange(12,20)
|
||||
self.alive=True
|
||||
|
||||
def fight(self,tgt):
|
||||
print("You take a swing at the " + self.enemy + ".")
|
||||
hit=random.randrange(0,20)
|
||||
|
||||
if self.alive and hit > self.ac:
|
||||
print("You hit the " + self.enemy + " for " + str(hit) + " damage!")
|
||||
self.hp = self.hp - hit
|
||||
print("The " + self.enemy + " has " + str(self.hp) + " HP remaining")
|
||||
else:
|
||||
print("You missed.")
|
||||
|
||||
if self.hp < 1:
|
||||
self.alive=False
|
||||
|
||||
# 游戏开始
|
||||
foe=Enemy("troll","great axe")
|
||||
print("You meet a " + foe.enemy + " wielding a " + foe.weapon)
|
||||
|
||||
# 主函数循环
|
||||
while True:
|
||||
|
||||
print("Type the a key and then RETURN to attack.")
|
||||
|
||||
action=input()
|
||||
|
||||
if action.lower() == "a":
|
||||
foe.fight(foe)
|
||||
|
||||
if foe.alive == False:
|
||||
print("You have won...this time.")
|
||||
exit()
|
||||
```
|
||||
|
||||
这个版本的游戏将敌人作为一个包含相同属性（谱系、武器、生命值和防御）的对象来处理，并添加一个新的属性来衡量敌人时候已被击败，以及一个战斗功能。
|
||||
|
||||
类的第一个函数是一个特殊的函数，在 Python 中称为 `init` 或初始化的函数。这类似于其他语言中的[构造器][4]，它创建了类的一个实例，你可以通过它的属性和调用类时使用的任何变量来识别它（示例代码中的 `foe`）。
|
||||
|
||||
### Self 和类实例
|
||||
|
||||
类的函数接受一种你在类之外看不到的新形式的输入：`self`。如果不包含 `self`，那么当你调用类函数时，Python 无法知道要使用的类的*哪个*实例。这就像在一间充满兽人的房间里说：“我要和兽人战斗”，向一个兽人发起。没有人知道你指的是谁，所有兽人就都上来了。
|
||||
|
||||
![Image of an Orc, CC-BY-SA by Buch on opengameart.org][5]
|
||||
|
||||
*CC-BY-SA by Buch on opengameart.org*
|
||||
|
||||
类中创建的每个属性都以 `self` 符号作为前缀，该符号将变量标识为类的属性。一旦派生出类的实例，就用表示该实例的变量替换掉 `self` 前缀。使用这个技巧，你可以在一间满是兽人的房间里说：“我要和谱系是 orc 的兽人战斗”，这样来挑战一个兽人。当 orc 听到 “gorblar.orc” 时，它就知道你指的是谁（他自己），所以你得到是一场公平的战斗而不是斗殴。在 Python 中：
|
||||
|
||||
```
|
||||
gorblar=Enemy("orc","sword")
|
||||
print("The " + gorblar.enemy + " has " + str(gorblar.hp) + " remaining.")
|
||||
```
|
||||
|
||||
通过检索类属性（`gorblar.enemy` 或 `gorblar.hp` 或你需要的任何对象的任何值）而不是查询 `foe[0]`（在函数示例中）或 `gorblar[0]` 来寻找敌人。
|
||||
|
||||
### 本地变量
|
||||
|
||||
如果类中的变量没有以 `self` 关键字作为前缀，那么它就是一个局部变量，就像在函数中一样。例如，无论你做什么，你都无法访问 `Enemy.fight` 类之外的 `hit` 变量：
|
||||
|
||||
```
|
||||
>>> print(foe.hit)
|
||||
Traceback (most recent call last):
|
||||
File "./enclass.py", line 38, in <module>
|
||||
print(foe.hit)
|
||||
AttributeError: 'Enemy' object has no attribute 'hit'
|
||||
|
||||
>>> print(foe.fight.hit)
|
||||
Traceback (most recent call last):
|
||||
File "./enclass.py", line 38, in <module>
|
||||
print(foe.fight.hit)
|
||||
AttributeError: 'function' object has no attribute 'hit'
|
||||
```
|
||||
|
||||
`hit` 变量包含在 Enemy 类中，并且只能“存活”到在战斗中发挥作用。
|
||||
|
||||
### 更模块化
|
||||
|
||||
本例使用与主应用程序相同的文本文档中的类。在一个复杂的游戏中，我们更容易将每个类看作是自己独立的应用程序。当多个开发人员处理同一个应用程序时，你会看到这一点：一个开发人员负责一个类，另一个开发人员负责主程序，只要他们彼此沟通这个类必须具有什么属性，就可以并行地开发这两个代码块。
|
||||
|
||||
要使这个示例游戏模块化，可以把它拆分为两个文件：一个用于主应用程序，另一个用于类。如果它是一个更复杂的应用程序，你可能每个类都有一个文件，或每个逻辑类组有一个文件（例如，用于建筑物的文件，用于自然环境的文件，用于敌人或 NPC 的文件等）。
|
||||
|
||||
将只包含 `Enemy` 类的一个文件保存为 `enemy.py`，将另一个包含其他内容的文件保存为 `main.py`。
|
||||
|
||||
以下是 `enemy.py`：
|
||||
|
||||
```
|
||||
import random
|
||||
|
||||
class Enemy():
|
||||
def __init__(self,ancestry,gear):
|
||||
self.enemy=ancestry
|
||||
self.weapon=gear
|
||||
self.hp=random.randrange(10,20)
|
||||
self.stg=random.randrange(0,20)
|
||||
self.ac=random.randrange(0,20)
|
||||
self.alive=True
|
||||
|
||||
def fight(self,tgt):
|
||||
print("You take a swing at the " + self.enemy + ".")
|
||||
hit=random.randrange(0,20)
|
||||
|
||||
if self.alive and hit > self.ac:
|
||||
print("You hit the " + self.enemy + " for " + str(hit) + " damage!")
|
||||
self.hp = self.hp - hit
|
||||
print("The " + self.enemy + " has " + str(self.hp) + " HP remaining")
|
||||
else:
|
||||
print("You missed.")
|
||||
|
||||
if self.hp < 1:
|
||||
self.alive=False
|
||||
```
|
||||
|
||||
以下是 `main.py`：
|
||||
|
||||
```
|
||||
#!/usr/bin/env python3
|
||||
|
||||
import enemy as en
|
||||
|
||||
# game start
|
||||
foe=en.Enemy("troll","great axe")
|
||||
print("You meet a " + foe.enemy + " wielding a " + foe.weapon)
|
||||
|
||||
# main loop
|
||||
while True:
|
||||
|
||||
print("Type the a key and then RETURN to attack.")
|
||||
|
||||
action=input()
|
||||
|
||||
if action.lower() == "a":
|
||||
foe.fight(foe)
|
||||
|
||||
if foe.alive == False:
|
||||
print("You have won...this time.")
|
||||
exit()
|
||||
```
|
||||
|
||||
导入模块 `enemy.py` 使用了一条特别的语句，引用类文件名称而不用带有 `.py` 扩展名，后跟你选择的命名空间指示符（例如，`import enemy as en`）。这个指示符是在你调用类时在代码中使用的。你需要在导入时添加指示符，例如 `en.Enemy`，而不是只使用 `Enemy()`。
|
||||
|
||||
所有这些文件名都是任意的，尽管在原则上不要使用罕见的名称。将应用程序的中心命名为 `main.py` 是一个常见约定，和一个充满类的文件通常以小写形式命名，其中的类都以大写字母开头。是否遵循这些约定不会影响应用程序的运行方式，但它确实使经验丰富的 Python 程序员更容易快速理解应用程序的工作方式。
|
||||
|
||||
在如何构建代码方面有一些灵活性。例如，使用该示例代码，两个文件必须位于同一目录中。如果你只想将类打包为模块，那么必须创建一个名为 `mybad` 的目录，并将你的类移入其中。在 `main.py` 中，你的 `import` 语句稍有变化：
|
||||
|
||||
```
|
||||
from mybad import enemy as en
|
||||
```
|
||||
|
||||
两种方法都会产生相同的结果，但如果你创建的类足够通用，你认为其他开发人员可以在他们的项目中使用它们，那么后者更好。
|
||||
|
||||
无论你选择哪种方式，都可以启动游戏的模块化版本：
|
||||
|
||||
```
|
||||
$ python3 ./main.py
|
||||
You meet a troll wielding a great axe
|
||||
Type the a key and then RETURN to attack.
|
||||
a
|
||||
You take a swing at the troll.
|
||||
You missed.
|
||||
Type the a key and then RETURN to attack.
|
||||
a
|
||||
You take a swing at the troll.
|
||||
You hit the troll for 8 damage!
|
||||
The troll has 4 HP remaining
|
||||
Type the a key and then RETURN to attack.
|
||||
a
|
||||
You take a swing at the troll.
|
||||
You hit the troll for 11 damage!
|
||||
The troll has -7 HP remaining
|
||||
You have won...this time.
|
||||
```
|
||||
|
||||
游戏启动了，它现在更加模块化了。现在你知道了面对对象的应用程序意味着什么，但最重要的是，当你向兽人发起决斗的时候，你知道是哪一个。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/7/get-modular-python-classes
|
||||
|
||||
作者：[Seth Kenlon][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[MjSeven](https://github.com/MjSeven)
|
||||
校对：[wxy](https://github.com/wxy)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/seth
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/code_development_programming.png?itok=M_QDcgz5 (Developing code.)
|
||||
[2]: https://linux.cn/article-11295-1.html
|
||||
[3]: https://opensource.com/article/17/4/how-program-games-raspberry-pi
|
||||
[4]: https://opensource.com/article/19/6/what-java-constructor
|
||||
[5]: https://opensource.com/sites/default/files/images/orc-buch-opengameart_cc-by-sa.jpg (CC-BY-SA by Buch on opengameart.org)
|
||||
@ -0,0 +1,59 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Two AMD Epyc processors crush four Intel Xeons in tests)
|
||||
[#]: via: (https://www.networkworld.com/article/3435727/two-amd-epyc-processors-crush-four-intel-xeons-in-tests.html)
|
||||
[#]: author: (Andy Patrizio https://www.networkworld.com/author/Andy-Patrizio/)
|
||||
|
||||
Two AMD Epyc processors crush four Intel Xeons in tests
|
||||
======
|
||||
Tests show the AMD Epyc processors performed almost 25% better, and they cost about one quarter less.
|
||||
AMD
|
||||
|
||||
Tests by the evaluation and testing site ServeTheHome found a server with two AMD Epyc processors can outperform a four-socket Intel system that costs considerably more.
|
||||
|
||||
If you don’t read [ServeTheHome][1], you should. It’s cut from the same cloth as Tom’s Hardware Guide and AnandTech but with a focus on server hardware, mostly the low end but they throw in some enterprise stuff, as well.
|
||||
|
||||
[ServeTheHome ran tests][2] comparing the AMD Epyc 7742, which has 64 cores and 128 threads, and the Intel Xeon Platinum 8180M with its 28 cores and 56 threads. The dollars, though, show a real difference. Each Epyc 7742 costs $6,950, while each Xeon Platinum 8180M goes for $13,011. So, two Epyc 7742 processors cost you $13,900, and four Xeon Platinum 8180M processors cost $52,044, four times as much as the AMD chips.
|
||||
|
||||
**Also read: [How AI can boost data-center availability and efficiency][3]**
|
||||
|
||||
And that’s just the chips. The actual servers will also set you back a pretty penny, especially since four-socket servers cost much more than two-socket servers regardless of the processor you use.
|
||||
|
||||
ServeTheHome used GeekBench, a Linux-based benchmark tool that measures both single- and multi-core performance. It’s purely a performance measure and looks only to see how fast a processor can go. It does not use real-world apps the way PCMark uses spreadsheets and graphics apps to test application performance.
|
||||
|
||||
Nonetheless, the dual Epyc system racked up single- and multi-core scores of 4,876 and 193,554 points, respectively, while the quad Xeon Platinum 8180M system scored 4,700 and 155,050 points in the single-core and multi-core tests, respectively.
|
||||
|
||||
So, the two-socket AMD system outperforms the four-socket Intel system by up to 3.74% in single-core workloads and 24.83% in multi-core workloads. And it costs one quarter the price. In terms of price/performance, it’s not even close.
|
||||
|
||||
**[ [Get certified as an Apple Technical Coordinator with this seven-part online course from PluralSight.][4] ]**
|
||||
|
||||
And ServeTheHome used an AMD reference server for the Epyc tests, while it used a Dell PowerEdge R840 for the Xeons. What that means is when HPE, Dell, Lenovo, Supermicro, etc. start shipping their servers, they will tune and optimize the daylights out of them vs. the AMD reference box and get even better performance.
|
||||
|
||||
There are other advantages to the AMD processor, as well: support for up to 4TB per socket vs. Xeon’s 1.5TB per socket, and PCI Express 4 for AMD vs. PCI Express 3 for Intel, which is half the speed of PCIe 4.
|
||||
|
||||
AMD has clearly built a better mousetrap. Now to bring in the customers.
|
||||
|
||||
Join the Network World communities on [Facebook][5] and [LinkedIn][6] to comment on topics that are top of mind.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.networkworld.com/article/3435727/two-amd-epyc-processors-crush-four-intel-xeons-in-tests.html
|
||||
|
||||
作者：[Andy Patrizio][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://www.networkworld.com/author/Andy-Patrizio/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://www.servethehome.com/
|
||||
[2]: https://www.servethehome.com/geekbench-4-2p-amd-epyc-7742-sets-world-record/
|
||||
[3]: https://www.networkworld.com/article/3274654/ai-boosts-data-center-availability-efficiency.html
|
||||
[4]: https://pluralsight.pxf.io/c/321564/424552/7490?u=https%3A%2F%2Fwww.pluralsight.com%2Fpaths%2Fapple-certified-technical-trainer-10-11
|
||||
[5]: https://www.facebook.com/NetworkWorld/
|
||||
[6]: https://www.linkedin.com/company/network-world
|
||||
@ -1,240 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Manage your daily schedule with Git)
|
||||
[#]: via: (https://opensource.com/article/19/4/calendar-git)
|
||||
[#]: author: (Seth Kenlon https://opensource.com/users/seth)
|
||||
|
||||
Manage your daily schedule with Git
|
||||
======
|
||||
Treat time like source code and maintain your calendar with the help of
|
||||
Git.
|
||||
![website design image][1]
|
||||
|
||||
[Git][2] is one of those rare applications that has managed to encapsulate so much of modern computing into one program that it ends up serving as the computational engine for many other applications. While it's best-known for tracking source code changes in software development, it has many other uses that can make your life easier and more organized. In this series leading up to Git's 14th anniversary on April 7, we'll share seven little-known ways to use Git. Today, we'll look at using Git to keep track of your calendar.
|
||||
|
||||
### Keep track of your schedule with Git
|
||||
|
||||
What if time itself was but source code that could be managed and version controlled? While proving or disproving such a theory is probably beyond the scope of this article, it happens that you can treat time like source code and manage your daily schedule with the help of Git.
|
||||
|
||||
The reigning champion for calendaring is the [CalDAV][3] protocol, which drives popular open source calendaring applications like [NextCloud][4] as well as popular closed source ones. There's nothing wrong with CalDAV (commenters, take heed). But it's not for everyone, and besides there's nothing less inspiring than a mono-culture.
|
||||
|
||||
Because I have no interest in becoming invested in largely GUI-dependent CalDAV clients (although if you're looking for a good terminal CalDAV viewer, see [khal][5]), I started investigating text-based alternatives. Text-based calendaring has all the usual benefits of working in [plaintext][6]. It's lightweight, it's highly portable, and as long as it's structured, it's easy to parse and beautify (whatever _beauty_ means to you).
|
||||
|
||||
And best of all, it's exactly what Git was designed to manage.
|
||||
|
||||
### Org mode not in a scary way
|
||||
|
||||
If you don't impose structure on your plaintext, it quickly falls into a pandemonium of off-the-cuff thoughts and devil-may-care notation. Luckily, a markup syntax exists for calendaring, and it's contained in the venerable productivity Emacs mode, [Org mode][7] (which, admit it, you've been meaning to start using anyway).
|
||||
|
||||
The amazing thing about Org mode that many people don't realize is [you don't need to know or even use Emacs][8] to take advantage of conventions established by Org mode. You get a lot of great features if you _do_ use Emacs, but if Emacs intimidates you, then you can implement a Git-based Org-mode calendaring system without so much as installing Emacs.
|
||||
|
||||
The only part of Org mode that you need to know is its syntax. Org-mode syntax is low-maintenance and fairly intuitive. The biggest difference in calendaring with Org mode instead of a GUI calendaring app is the workflow: instead of going to a calendar and finding the day you want to schedule a task, you create a list of tasks and then assign each one a day and time.
|
||||
|
||||
Lists in Org mode use asterisks (*) as bullets. Here's my gaming task list: ****
|
||||
|
||||
```
|
||||
* Gaming
|
||||
** Build Stardrifter character
|
||||
** Read Stardrifter rules
|
||||
** Stardrifter playtest
|
||||
|
||||
** Blue Planet @ Mike's
|
||||
|
||||
** Run Rappan Athuk
|
||||
*** Purchase hard copy
|
||||
*** Skim Rappan Athuk
|
||||
*** Build Rappan Athuk maps in maptool
|
||||
*** Sort Rappan Athuk tokens
|
||||
```
|
||||
|
||||
If you're familiar with [CommonMark][9] or Markdown, you'll notice that instead of using whitespace to create a subtask, Org mode favors the more explicit use of additional bullets. Whatever your background with lists, this is an intuitive and easy way to build a list, and it obviously is not inherently tied to Emacs (although using Emacs provides you with shortcuts so you can rearrange your list quickly).
|
||||
|
||||
To turn your list into scheduled tasks or events in a calendar, go back through and add the keywords **SCHEDULED** and, optionally, **:CATEGORY:**.
|
||||
|
||||
```
|
||||
* Gaming
|
||||
:CATEGORY: Game
|
||||
** Build Stardrifter character
|
||||
SCHEDULED: <2019-03-22 18:00-19:00>
|
||||
** Read Stardrifter rules
|
||||
SCHEDULED: <2019-03-22 19:00-21:00>
|
||||
** Stardrifter playtest
|
||||
SCHEDULED: <2019-03-25 0900-1300>
|
||||
** Blue Planet @ Mike's
|
||||
SCHEDULED: <2019-03-18 18:00-23:00 +1w>
|
||||
|
||||
and so on...
|
||||
```
|
||||
|
||||
The **SCHEDULED** keyword marks the entry as an event that you expect to be notified about and the optional **:CATEGORY:** keyword is an arbitrary tagging system for your own use (and in Emacs, you can color-code entries according to category).
|
||||
|
||||
For a repeating event, you can use notation such as **+1w** to create a weekly event or **+2w** for a fortnightly event, and so on.
|
||||
|
||||
All the fancy markup available for Org mode is [documented][10], so don't hesitate to find more tricks to help it fit your needs.
|
||||
|
||||
### Put it into Git
|
||||
|
||||
Without Git, your Org-mode appointments are just a file on your local machine. It's the 21st century, though, so you at least need your calendar on your mobile phone, if not on all of your personal computers. You can use Git to publish your calendar for yourself and others.
|
||||
|
||||
First, create a directory for your **.org** files. I store mine in **~/cal**.
|
||||
|
||||
```
|
||||
$ mkdir ~/cal
|
||||
```
|
||||
|
||||
Change into your directory and make it a Git repository:
|
||||
|
||||
```
|
||||
$ cd cal
|
||||
$ git init
|
||||
```
|
||||
|
||||
Move your **.org** file to your local Git repo. In practice, I maintain one **.org** file per category.
|
||||
|
||||
```
|
||||
$ mv ~/*.org ~/cal
|
||||
$ ls
|
||||
Game.org Meal.org Seth.org Work.org
|
||||
```
|
||||
|
||||
Stage and commit your files:
|
||||
|
||||
```
|
||||
$ git add *.org
|
||||
$ git commit -m 'cal init'
|
||||
```
|
||||
|
||||
### Create a Git remote
|
||||
|
||||
To make your calendar available from anywhere, you must have a Git repository on the internet. Your calendar is plaintext, so any Git repository will do. You can put your calendar on [GitLab][11] or any other public Git hosting service (even proprietary ones), and as long as your host allows it, you can even mark the repository as private. If you don't want to post your calendar to a server you don't control, it's easy to host a Git repository yourself, either using a bare repository for a single user or using a frontend service like [Gitolite][12] or [Gitea][13].
|
||||
|
||||
In the interest of simplicity, I'll assume a self-hosted bare Git repository. You can create a bare remote repository on any server you have SSH access to with one Git command:
|
||||
```
|
||||
$ ssh -p 22122 [seth@example.com][14]
|
||||
[remote]$ mkdir cal.git
|
||||
[remote]$ cd cal.git
|
||||
[remote]$ git init --bare
|
||||
[remote]$ exit
|
||||
```
|
||||
|
||||
This bare repository can serve as your calendar's home on the internet.
|
||||
|
||||
Set it as the remote source for your local (on your computer, not your server) Git repository:
|
||||
|
||||
```
|
||||
$ git remote add origin seth@example.com:/home/seth/cal.git
|
||||
```
|
||||
|
||||
And then push your calendar data to the server:
|
||||
|
||||
```
|
||||
$ git push -u origin HEAD
|
||||
```
|
||||
|
||||
With your calendar in a Git repository, it's available to you on any device running Git. That means you can make updates and changes to your schedule and push your changes upstream so it updates everywhere.
|
||||
|
||||
I use this method to keep my calendar in sync between my work laptop and my home workstation. Since I use Emacs every day for most of the day, being able to view and edit my calendar in Emacs is a major convenience. The same is true for most people with a mobile device, so the next step is to set up an Org-mode calendaring system on a mobile.
|
||||
|
||||
### Mobile Git
|
||||
|
||||
Since your calendar data is in plaintext, strictly speaking, you can "use" it on any device that can read a text file. That's part of the beauty of this system; you're never without, at the very least, your raw data. But to integrate your calendar on a mobile device the way you'd expect a modern calendar to work, you need two components: a mobile Git client and a mobile Org-mode viewer.
|
||||
|
||||
#### Git client for mobile
|
||||
|
||||
[MGit][15] is a good Git client for Android. There are Git clients for iOS, as well.
|
||||
|
||||
Once you've installed MGit (or a similar Git client), you must clone your calendar repository so your phone has a copy. To access your server from your mobile device, you must set up an SSH key for authentication. MGit can generate and store a key for you, which you must add to your server's **~/.ssh/authorized_keys** file or to your SSH keys in the settings of your hosted Git account.
|
||||
|
||||
You must do this manually. MGit does not have an interface to log into your server or hosted Git account. If you do not do this, your mobile device cannot access your server to access your calendar data.
|
||||
|
||||
I did it by copying the key file I generated in MGit to my laptop over [KDE Connect][16] (but you can do the same over Bluetooth, or with an SD card reader, or a USB cable, depending on your preferred method of accessing data on your phone). I copied the key (a file called **calkey** to my server with this command:
|
||||
|
||||
```
|
||||
$ cat calkey | ssh seth@example.com "cat >> /home/seth/.ssh/authorized_keys"
|
||||
```
|
||||
|
||||
You may have a different way of doing it, but if you ever set your server up for passwordless login, this is exactly the same process. If you're using a hosted Git service like GitLab, you must copy and paste the contents of your key file into your user account's SSH Key panel.
|
||||
|
||||
![Adding key file data to GitLab][17]
|
||||
|
||||
Once that's done, your mobile device can authorize to your server, but it still needs to know where to go to find your calendar data. Different apps may use different notation, but MGit uses plain old Git-over-SSH. That means if you're using a non-standard SSH port, you must specify the SSH port to use:
|
||||
|
||||
```
|
||||
$ git clone ssh://seth@example.com:22122//home/seth/git/cal.git
|
||||
```
|
||||
|
||||
![Specifying SSH port in MGit][18]
|
||||
|
||||
If you use a different app, it may use a different syntax that allows you to provide a port in a special field or drop the **ssh://** prefix. Refer to the app documentation if you experience issues.
|
||||
|
||||
Clone the repository to your phone.
|
||||
|
||||
![Cloned repositories][19]
|
||||
|
||||
Few Git apps are set to automatically update the repository. There are a few apps you can use to automate pulls, or you can set up Git hooks to push updates from your server—but I won't get into that here. For now, after you make an update to your calendar, be sure to pull new changes manually in MGit (or if you change events on your phone, push the changes to your server).
|
||||
|
||||
![MGit push/pull settings][20]
|
||||
|
||||
#### Mobile calendar
|
||||
|
||||
There are a few different apps that provide frontends for Org mode on a mobile device. [Orgzly][21] is a great open source Android app that provides an interface for Org mode's greatest features, from the Agenda mode to the TODO lists. Install and launch it.
|
||||
|
||||
From the Main menu, choose Setting Sync Repositories and select the directory containing your calendar files (i.e., the Git repository you cloned from your server).
|
||||
|
||||
Give Orgzly a moment to import the data, then use Orgzly's [hamburger][22] menu to select the Agenda view.
|
||||
|
||||
![Orgzly's agenda view][23]
|
||||
|
||||
In Orgzly's Settings Reminders menu, you can choose which event types trigger a notification on your phone. You can get notifications for **SCHEDULED** tasks, **DEADLINE** tasks, or anything with an event time assigned to it. If you use your phone as your taskmaster, you'll never miss an event with Org mode and Orgzly.
|
||||
|
||||
![Orgzly notification][24]
|
||||
|
||||
Orgzly isn't just a parser. You can edit and update events, and even mark events **DONE**.
|
||||
|
||||
![Orgzly to-do list][25]
|
||||
|
||||
### Designed for and by you
|
||||
|
||||
The important thing to understand about using Org mode and Git is that both applications are highly flexible, and it's expected that you'll customize how and what they do so they will adapt to your needs. If something in this article is an affront to how you organize your life or manage your weekly schedule, but you like other parts of what this proposal offers, then throw out the part you don't like. You can use Org mode in Emacs if you want, or you can just use it as calendar markup. You can set your phone to pull Git data right off your computer at the end of the day instead of a server on the internet, or you can configure your computer to sync calendars whenever your phone is plugged in, or you can manage it daily as you load up your phone with all the stuff you need for the workday. It's up to you, and that's the most significant thing about Git, about Org mode, and about open source.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/4/calendar-git
|
||||
|
||||
作者：[Seth Kenlon (Red Hat, Community Moderator)][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/seth
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/web-design-monitor-website.png?itok=yUK7_qR0 (website design image)
|
||||
[2]: https://git-scm.com/
|
||||
[3]: https://tools.ietf.org/html/rfc4791
|
||||
[4]: http://nextcloud.com
|
||||
[5]: https://github.com/pimutils/khal
|
||||
[6]: https://plaintextproject.online/
|
||||
[7]: https://orgmode.org
|
||||
[8]: https://opensource.com/article/19/1/productivity-tool-org-mode
|
||||
[9]: https://commonmark.org/
|
||||
[10]: https://orgmode.org/manual/
|
||||
[11]: http://gitlab.com
|
||||
[12]: http://gitolite.com/gitolite/index.html
|
||||
[13]: https://gitea.io/en-us/
|
||||
[14]: mailto:seth@example.com
|
||||
[15]: https://f-droid.org/en/packages/com.manichord.mgit
|
||||
[16]: https://community.kde.org/KDEConnect
|
||||
[17]: https://opensource.com/sites/default/files/uploads/gitlab-add-key.jpg (Adding key file data to GitLab)
|
||||
[18]: https://opensource.com/sites/default/files/uploads/mgit-0.jpg (Specifying SSH port in MGit)
|
||||
[19]: https://opensource.com/sites/default/files/uploads/mgit-1.jpg (Cloned repositories)
|
||||
[20]: https://opensource.com/sites/default/files/uploads/mgit-2.jpg (MGit push/pull settings)
|
||||
[21]: https://f-droid.org/en/packages/com.orgzly/
|
||||
[22]: https://en.wikipedia.org/wiki/Hamburger_button
|
||||
[23]: https://opensource.com/sites/default/files/uploads/orgzly-agenda.jpg (Orgzly's agenda view)
|
||||
[24]: https://opensource.com/sites/default/files/uploads/orgzly-cal-notify.jpg (Orgzly notification)
|
||||
[25]: https://opensource.com/sites/default/files/uploads/orgzly-cal-todo.jpg (Orgzly to-do list)
|
||||
@ -1,44 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How many browser tabs do you usually have open?)
|
||||
[#]: via: (https://opensource.com/article/19/6/how-many-browser-tabs)
|
||||
[#]: author: (Lauren Pritchett https://opensource.com/users/lauren-pritchett/users/sarahwall/users/ksonney/users/jwhitehurst)
|
||||
|
||||
How many browser tabs do you usually have open?
|
||||
======
|
||||
Plus, get a few tips for browser productivity.
|
||||
![Browser of things][1]
|
||||
|
||||
Here's a potentially loaded question: How many browser tabs do you usually have open at one time? Do you have multiple windows, each with multiple tabs? Or are you a minimalist, and only have a couple of tabs open at once. Another option is to move a 20-tabbed browser window to a different monitor so that it is out of the way while working on a particular task. Does your approach differ between work, personal, and mobile browsers? Is your browser strategy related to your [productivity habits][2]?
|
||||
|
||||
### 4 tips for browser productivity
|
||||
|
||||
1. Know your browser shortcuts to save clicks. Whether you use Firefox or Chrome, there are plenty of keyboard shortcuts to help make switching between tabs and performing certain functions a breeze. For example, Chrome makes it easy to open up a blank Google document. Use the shortcut **"Ctrl + t"** to open a new tab, then type **"doc.new"**. The same can be done for spreadsheets, slides, and forms.
|
||||
2. Organize your most frequent tasks with bookmark folders. When it's time to start a particular task, simply open all of the bookmarks in the folder **(Ctrl + click)** to check it off your list quickly.
|
||||
3. Get the right browser extensions for you. There are thousands of browser extensions out there all claiming to improve productivity. Before you install, make sure you're not just adding more distractions to your screen.
|
||||
4. Reduce screen time by using a timer. It doesn't matter if you use an old-fashioned egg timer or a fancy browser extension. To prevent eye strain, implement the 20/20/20 rule. Every 20 minutes, take a 20-second break from your screen and look at something 20 feet away.
|
||||
|
||||
|
||||
|
||||
Take our poll to share how many browser tabs you like to have open at once. Be sure to tell us about your favorite browser tricks in the comments.
|
||||
|
||||
There are two components of productivity—doing the right things and doing those things efficiently...
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/6/how-many-browser-tabs
|
||||
|
||||
作者：[Lauren Pritchett][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/lauren-pritchett/users/sarahwall/users/ksonney/users/jwhitehurst
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/browser_desktop_website_checklist_metrics.png?itok=OKKbl1UR (Browser of things)
|
||||
[2]: https://enterprisersproject.com/article/2019/1/5-time-wasting-habits-break-new-year
|
||||
@ -1,59 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How to stream music with GNOME Internet Radio)
|
||||
[#]: via: (https://opensource.com/article/19/6/gnome-internet-radio)
|
||||
[#]: author: (Alan Formy-Duval https://opensource.com/users/alanfdoss/users/r3bl)
|
||||
|
||||
How to stream music with GNOME Internet Radio
|
||||
======
|
||||
If you're looking for a simple, straightforward interface that gets your
|
||||
streams playing, try GNOME's Internet Radio plugin.
|
||||
![video editing dashboard][1]
|
||||
|
||||
Internet radio is a great way to listen to stations from all over the world. Like many developers, I like to turn on a station as I code. You can listen to internet radio with a media player for the terminal like [MPlayer][2] or [mpv][3], which is what I use to listen via the Linux command line. However, if you prefer using a graphical user interface (GUI), you may want to try [GNOME Internet Radio][4], a nifty plugin for the GNOME desktop. You can find it in the package manager.
|
||||
|
||||
![GNOME Internet Radio plugin][5]
|
||||
|
||||
Listening to internet radio with a graphical desktop operating system generally requires you to launch an application such as [Audacious][6] or [Rhythmbox][7]. They have nice interfaces, plenty of options, and cool audio visualizers. But if you want a simple, straightforward interface that gets your streams playing, GNOME Internet Radio is for you.
|
||||
|
||||
After installing it, a small icon appears in your toolbar, which is where you do all your configuration and management.
|
||||
|
||||
![GNOME Internet Radio icons][8]
|
||||
|
||||
The first thing I did was go to the Settings menu. I enabled the following two options: show title notifications and show volume adjustment.
|
||||
|
||||
![GNOME Internet Radio Settings][9]
|
||||
|
||||
GNOME Internet Radio includes a few pre-configured stations, and it is really easy to add others. Just click the ( **+** ) sign. You'll need to enter a channel name, which can be anything you prefer (including the station name), and the station address. For example, I like to listen to Synthetic FM. I enter the name, e.g., "Synthetic FM," and the stream address, i.e., <https://mediaserv38.live-streams.nl:2199/tunein/syntheticfm.pls>.
|
||||
|
||||
Then click the star next to the stream to add it to your menu.
|
||||
|
||||
However you listen to music and whatever genre you choose, it is obvious—coders need their music! The GNOME Internet Radio plugin makes it simple to get your favorite internet radio station queued up.
|
||||
|
||||
In honor of the Gnome desktop's 18th birthday on August 15, we've rounded up 18 reasons to toast...
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/6/gnome-internet-radio
|
||||
|
||||
作者：[Alan Formy-Duval][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/alanfdoss/users/r3bl
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/video_editing_folder_music_wave_play.png?itok=-J9rs-My (video editing dashboard)
|
||||
[2]: https://opensource.com/article/18/12/linux-toy-mplayer
|
||||
[3]: https://mpv.io/
|
||||
[4]: https://extensions.gnome.org/extension/836/internet-radio/
|
||||
[5]: https://opensource.com/sites/default/files/uploads/packagemanager_s.png (GNOME Internet Radio plugin)
|
||||
[6]: https://audacious-media-player.org/
|
||||
[7]: https://help.gnome.org/users/rhythmbox/stable/
|
||||
[8]: https://opensource.com/sites/default/files/uploads/titlebaricons.png (GNOME Internet Radio icons)
|
||||
[9]: https://opensource.com/sites/default/files/uploads/gnomeinternetradio_settings.png (GNOME Internet Radio Settings)
|
||||
@ -1,117 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (An introduction to Hyperledger Fabric)
|
||||
[#]: via: (https://opensource.com/article/19/9/introduction-hyperledger-fabric)
|
||||
[#]: author: (Matt Zand https://opensource.com/users/mattzandhttps://opensource.com/users/ron-mcfarlandhttps://opensource.com/users/wonderchook)
|
||||
|
||||
An introduction to Hyperledger Fabric
|
||||
======
|
||||
Hyperledger is a set of open source tools aiming to build a robust,
|
||||
business-driven blockchain framework.
|
||||
![Chain image][1]
|
||||
|
||||
One of the biggest projects in the blockchain industry, [Hyperledger][2], is comprised of a set of open source tools and subprojects. It's a global collaboration hosted by The Linux Foundation and includes leaders in different sectors who are aiming to build a robust, business-driven blockchain framework.
|
||||
|
||||
There are three main types of blockchain networks: public blockchains, consortiums or federated blockchains, and private blockchains. Hyperledger is a blockchain framework that aims to help companies build private or consortium permissioned blockchain networks where multiple organizations can share the control and permission to operate a node within the network.
|
||||
|
||||
Since a blockchain is a transparent, immutable, and secure decentralized system, it is considered a game-changing solution for traditional supply chain industries. It can support an effective supply chain system by:
|
||||
|
||||
* Tracking the products in the entire chain
|
||||
* Verifying and authenticating the products in the chain
|
||||
* Sharing the entire chain's information between supply chain actors
|
||||
* Providing auditability
|
||||
|
||||
|
||||
|
||||
This article uses the example of a food supply chain to explain how a Hyperledger blockchain can transform a traditional supply chain.
|
||||
|
||||
### Food industry supply chains
|
||||
|
||||
The main reason for classic supply chain inefficiency is lack of transparency, leading to unreliable reporting and competitive disadvantage.
|
||||
|
||||
In traditional supply chain models, information about an entity is not fully transparent to others in the chain, which leads to inaccurate reports and a lack of interoperability. Emails and printed documents provide some information, but they can't contain fully detailed visibility data because the products are hard to trace across the entire supply chain. This also makes it nearly impossible for a consumer to know the true value and origin of a product.
|
||||
|
||||
The food industry's supply chain is a difficult landscape, where multiple actors need to coordinate to deliver goods to their final destination, the customers. The following diagram shows the key actors in a food supply chain (multi-echelon) network.
|
||||
|
||||
![Typical food supply chain][3]
|
||||
|
||||
Every stage of the chain introduces potential security vulnerabilities, integration problems, and other inefficiency issues. The main growing threat in current food supply chains remains counterfeit food and food fraud.
|
||||
|
||||
A food-tracking system based on the Hyperledger blockchain enables full visibility, tracking, and traceability. More importantly, it ensures the authenticity of food by recording a product's details in an immutable and viable way. By sharing a product's details over an immutable framework, the end user can self-verify a product's authenticity.
|
||||
|
||||
### Hyperledger Fabric
|
||||
|
||||
Hyperledger Fabric is the cornerstone of the Hyperledger project. It is a permission-based blockchain, or more accurately a distributed ledger technology (DLT), which was originally created by IBM and Digital Asset. It is designed as a modular framework with different components (outlined below). It is also a flexible solution offering a pluggable consensus model, although it currently only provides permissioned, voting-based consensus (with the assumption that today's Hyperledger networks operate in a partially trustworthy environment).
|
||||
|
||||
Given this, there is no need for anonymous miners to validate transactions nor for an associated currency to act as an incentive. All participants must be authenticated to participate and transact on the blockchain. Like with Ethereum, Hyperledger Fabric supports smart contracts, called Chaincodes in Hyperledger, and these contracts describe and execute the system's application logic.
|
||||
|
||||
Unlike Ethereum, however, Hyperledger Fabric doesn't require expensive mining computations to commit transactions, so it can help build blockchains that can scale up with less latency.
|
||||
|
||||
Hyperledger Fabric is different from blockchains such as Ethereum or Bitcoin, not only in its type or because it is currency-agnostic, but also in terms of its internal machinery. Following are the key elements of a typical Hyperledger network:
|
||||
|
||||
* **Ledgers** store a chain of blocks that keep all immutable historical records of all state transitions.
|
||||
* **Nodes** are the logical entities of the blockchain. There are three types:
|
||||
– **Clients** are applications that act on behalf of a user to submit transactions to the network.
|
||||
– **Peers** are entities that commit transactions and maintain the ledger state.
|
||||
– **Orderers** create a shared communication channel between clients and peers; they also package blockchain transactions into blocks and send them to committing peers
|
||||
|
||||
|
||||
|
||||
Along with these elements, Hyperledger Fabric is based on the following key design features:
|
||||
|
||||
* **Chaincode** is similar to a smart contract in other networks, such as Ethereum. It is a program written in a higher-level language that executes against the ledger's current-state database.
|
||||
* **Channels** are private communication subnets for sharing confidential information between multiple network members. Each transaction is executed on a channel that is visible only to the authenticated and authorized parties.
|
||||
* **Endorsers** validate transactions, invoke Chaincode, and send the endorsed transaction results back to the calling applications.
|
||||
* **Membership Services Providers** (MSPs) provide identity validation and authentication processes by issuing and validating certificates. An MSP identifies which certification authorities (CAs) are trusted to define the members of a trust domain and determines the specific roles an actor might play (member, admin, and so on).
|
||||
|
||||
|
||||
|
||||
### How transactions are validated
|
||||
|
||||
Exploring how a transaction gets validated is a good way to understand how Hyperledger Fabric works under the hood. This diagram shows the end-to-end system flow for processing a transaction in a typical Hyperledger network:
|
||||
|
||||
![Hyperledger transaction validation flow][4]
|
||||
|
||||
First, the client initiates a transaction by sending a request to a Hyperledger Fabric-based application client, which submits the transaction proposal to endorsing peers. These peers simulate the transaction by executing the Chaincode (using a local copy of the state) specified by the transaction and sending the results back to the application. At this point, the application combines the transaction with the endorsements and broadcasts it to the Ordering Service. The Ordering Service checks the endorsements and creates a block of transactions for each channel before broadcasting them to all peers in the channel. Peers then verify the transactions and commit them.
|
||||
|
||||
The Hyperledger Fabric blockchain can connect food supply chain participants through a transparent, permanent, and shared record of food-origin data, processing data, shipping details, and more. The Chaincode is invoked by authorized participants in the food supply chain. All executed transaction records are permanently saved in the ledger, and all entities can look up this information.
|
||||
|
||||
### Hyperledger Composer
|
||||
|
||||
Alongside blockchain frameworks such as Fabric or Iroha, the Hyperledger project provides tools such as Composer, Hyperledger Explorer, and Cello. Hyperledger Composer provides a toolset to help build blockchain applications more easily. It consists of:
|
||||
|
||||
* CTO, a modeling language
|
||||
* Playground, a browser-based development tool for rapid testing and deployment
|
||||
* A command-line interface (CLI) tool
|
||||
|
||||
|
||||
|
||||
Composer supports the Hyperledger Fabric runtime and infrastructure, and internally the composer's API utilizes the underlying Fabric API. Composer runs on Fabric, meaning the business networks generated by Composer can be deployed to Hyperledger Fabric for execution.
|
||||
|
||||
To learn more about Hyperledger, visit the [project's website][2], where you can view the members, access training and tutorials, or find out how you can contribute.
|
||||
|
||||
* * *
|
||||
|
||||
_This article is adapted from [Coding Bootcamp's article Building A Blockchain Supply Chain Using Hyperledger Fabric and Composer][5] and is used with permission._
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/9/introduction-hyperledger-fabric
|
||||
|
||||
作者：[Matt Zand][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/mattzandhttps://opensource.com/users/ron-mcfarlandhttps://opensource.com/users/wonderchook
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/chain.png?itok=sgAjswFf (Chain image)
|
||||
[2]: https://www.hyperledger.org/
|
||||
[3]: https://opensource.com/sites/default/files/uploads/foodindustrysupplychain.png (Typical food supply chain)
|
||||
[4]: https://opensource.com/sites/default/files/uploads/hyperledger-fabric-transaction-flow.png (Hyperledger transaction validation flow)
|
||||
[5]: https://coding-bootcamps.com/ultimate-guide-for-building-a-blockchain-supply-chain-using-hyperledger-fabric-and-composer.html
|
||||
@ -0,0 +1,94 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: ( )
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How to Install Shutter Screenshot Tool in Ubuntu 19.04)
|
||||
[#]: via: (https://itsfoss.com/install-shutter-ubuntu/)
|
||||
[#]: author: (Abhishek Prakash https://itsfoss.com/author/abhishek/)
|
||||
|
||||
How to Install Shutter Screenshot Tool in Ubuntu 19.04
|
||||
======
|
||||
|
||||
Shutter is my favorite tool for [taking screenshots in Linux][1]. You can take screenshots with it and you can also edit screenshots or other images with it. It’s a nifty tool for adding arrows and text on the images. You can also use it to [resize images in Ubuntu][2] or whichever Linux distribution you are using. Most of the screenshot tutorials on It’s FOSS have been edited on Shutter.
|
||||
|
||||
![][3]
|
||||
|
||||
Though [Shutter][4] has been a great tool so far, its development is stalled. There has been no new release of Shutter in several years. Even simple bugs like [editing mode being disabled in Shutter][5] hasn’t been fixed. There is no news from the developer at all.
|
||||
|
||||
Perhaps this is the reason why newer release of Ubuntu have dropped it. Until Ubuntu 18.04 LTS, you could install it from the software or [using apt-get command][6] by [enabling the universe repository][7]. But from Ubuntu 18.10 and later releases, you cannot do it anymore.
|
||||
|
||||
All the shortcomings aside, Shutter is till a great tool and I want to continue using it. Perhaps you too are a Shutter fan like me and want to use it. The good things is that you can still install Shutter in Ubuntu 19.04 thanks to an unofficial PPA.
|
||||
|
||||
### Installing Shutter on Ubuntu 19.04
|
||||
|
||||
![Install Shutter Ubuntu][8]
|
||||
|
||||
I hope you are familiar with concept of PPA. If not, I highly recommend reading my detailed guide to know more about [what is PPA and how to use it][9].
|
||||
|
||||
Now, open a terminal and use the following command to add the new repository:
|
||||
|
||||
```
|
||||
sudo add-apt-repository -y ppa:linuxuprising/shutter
|
||||
```
|
||||
|
||||
No need to use apt update anymore because starting Ubuntu 18.04, the repositories are automatically updated after adding a new entry.
|
||||
|
||||
Now use the apt command to install Shutter:
|
||||
|
||||
```
|
||||
sudo apt install shutter
|
||||
```
|
||||
|
||||
That’s it. You should have Shutter screenshot tool installed. You can search for it in the menu and start from there.
|
||||
|
||||
[][10]
|
||||
|
||||
Suggested read Managing Linux Kernel Upgrades In Debian
|
||||
|
||||
### Removing Shutter installed via the unofficial PPA
|
||||
|
||||
I’ll complete this tutorial by adding the steps to uninstall Shutter and remove the repository you added.
|
||||
|
||||
First, remove Shutter from your system:
|
||||
|
||||
```
|
||||
sudo apt remove shutter
|
||||
```
|
||||
|
||||
Next, remove the PPA from your list of repositories:
|
||||
|
||||
```
|
||||
sudo add-apt-repository --remove ppa:linuxuprising/shutter
|
||||
```
|
||||
|
||||
You may also want to take a look at [Y PPA Manager][11], a tool for managing PPA graphically.
|
||||
|
||||
Shutter
|
||||
|
||||
Shutter is an excellent tool and I would prefer that it is actively developed. I hope that its developer is alright and he/she can find some time to work on it. Or perhaps it’s time for someone else to fork it and continue to make it more awesome.
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/install-shutter-ubuntu/
|
||||
|
||||
作者：[Abhishek Prakash][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://itsfoss.com/author/abhishek/
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://itsfoss.com/take-screenshot-linux/
|
||||
[2]: https://itsfoss.com/resize-images-with-right-click/
|
||||
[3]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2018/08/shutter-screenshot.jpg?ssl=1
|
||||
[4]: http://shutter-project.org/
|
||||
[5]: https://itsfoss.com/shutter-edit-button-disabled/
|
||||
[6]: https://itsfoss.com/apt-get-linux-guide/
|
||||
[7]: https://itsfoss.com/ubuntu-repositories/
|
||||
[8]: https://i0.wp.com/itsfoss.com/wp-content/uploads/2019/09/Install-Shutter-ubuntu.jpg?resize=800%2C450&ssl=1
|
||||
[9]: https://itsfoss.com/ppa-guide/
|
||||
[10]: https://itsfoss.com/kernel-upgrade-debian/
|
||||
[11]: https://itsfoss.com/y-ppa-manager/
|
||||
@ -1,143 +0,0 @@
|
||||
2018年前5名的 Linux 可用 CAD 软件
|
||||
======
|
||||
[计算机辅助设计 (CAD)][1] 是很多工程流的必不可少的部分。CAD 被专业地使用于建筑，汽车零部件设计，航天飞机研究，航空，桥梁施工，室内设计，甚至服装和珠宝设计。
|
||||
|
||||
在 Linux 上，一些专业级 CAD 软件，像 SolidWorks 和 Autodesk AutoCAD ，不是本地支持的。因此，今天，我们将看看排名靠前的 Linux 可用的 CAD 软件。我们马上进去看看。
|
||||
|
||||
### Linux 可用的最好的 CAD 软件
|
||||
|
||||
![CAD Software for Linux][2]
|
||||
|
||||
在我们看 Linux 的 CAD 软件列表前，你应该记住一件事，在这里不是所有的应用程序都是开源软件。我们包含一些非自由和开源软件的 CAD 软件来帮助平常的 Linux 用户。
|
||||
|
||||
基于 Ubuntu 的 Linux 发行版已经提供安装操作指南。你可以检查各自的网站来学习其它发行版的安装程序步骤。
|
||||
|
||||
列表没有任何特殊顺序。在第一顺位的 CAD 应用程序不能认为比在第三顺位的好，以此类推。
|
||||
|
||||
#### 1\. FreeCAD
|
||||
|
||||
对于 3D 建模，FreeCAD 是一个极好的选项，它是自由 (啤酒和演讲) 和开源软件。 FreeCAD 以构建坚持机械工程和产品设计为目标目的。FreeCAD 是多平台的，可用于 Windows，Mac OS X+ ，以及 Linux。
|
||||
|
||||
![freecad][3]
|
||||
|
||||
尽管 FreeCAD 已经是很多 Linux 用户的选择，应该注意到，FreeCAD 仍然是 0.17 版本，因此，不适用于重要的部署。但是最近开发加速了。
|
||||
|
||||
[FreeCAD][4]
|
||||
|
||||
FreeCAD 不专注于 2D 直接绘图和统一形状动画，但是它对机械工程相关的设计极好。FreeCAD 的 0.15 版本在 Ubuntu 存储库中可用。你可以通过运行下面的命令安装。
|
||||
```
|
||||
sudo apt install freecad
|
||||
|
||||
```
|
||||
|
||||
为获取新的每日构建(目前0.17)，打开一个终端(ctrl+alt+t)，并逐个运行下面的命令。
|
||||
```
|
||||
sudo add-apt-repository ppa:freecad-maintainers/freecad-daily
|
||||
|
||||
sudo apt update
|
||||
|
||||
sudo apt install freecad-daily
|
||||
|
||||
```
|
||||
|
||||
#### 2\. LibreCAD
|
||||
|
||||
LibreCAD 是一个自由，开源，2D CAD 解决方案。一般来说，CAD 倾向于一个资源密集型任务，如果你有一个相当普通的硬件，那么我建议你使用 LibreCAD ，因为它在资源使用方面真的轻量化。LibreCAD 是几何图形结构方面的一个极好的候选者。
|
||||
|
||||
![librecad][5]
|
||||
作为一个 2D 工具，LibreCAD 是好的，但是它不能在 3D 模型和渲染上工作。它有时可能不稳定，但是，它有一个可靠的自动保存，它不会让你的工作浪费。
|
||||
|
||||
[LibreCAD][6]
|
||||
|
||||
你可以通过运行下面的命令安装 LibreCAD
|
||||
```
|
||||
sudo apt install librecad
|
||||
|
||||
```
|
||||
|
||||
#### 3\. OpenSCAD
|
||||
|
||||
OpenSCAD 是一个自由的 3D CAD 软件。OpenSCAD 非常轻量和灵活。OpenSCAD 不是交互式的。你需要‘编程’模型，OpenSCAD 解释这些代码来渲染一个可视化模型。在某种意义上说，它是一个编译器。你不能直接绘制模型，而是你描述模型。
|
||||
|
||||
![openscad][7]
|
||||
|
||||
OpenSCAD 是这个列表上最复杂的工具，但是，一旦你了解它，它将提供一个令人愉快的工作经历。
|
||||
|
||||
[OpenSCAD][8]
|
||||
|
||||
你可以使用下面的命令来安装 OpenSCAD。
|
||||
```
|
||||
sudo apt-get install openscad
|
||||
|
||||
```
|
||||
|
||||
#### 4\. BRL-CAD
|
||||
|
||||
BRL-CAD 是最老的 CAD 工具之一。它也深受 Linux/UNIX 用户喜爱，因为它与模块化和自由的 *nix 哲学相一致。
|
||||
|
||||
![BRL-CAD rendering by Sean][9]
|
||||
|
||||
BRL-CAD 始于1979年，并且，它仍然在积极开发。现在，BRL-CAD 不是 AutoCAD ，但是对于像热穿透和弹道穿透等等的运输研究仍然是一个极好的选择。BRL-CAD 构成 CSG 的基础，而不是边界表示。在选择 BRL-CAD 是，你可能需要记住这一点。你可以从它的官方网站下载 BRL-CAD 。
|
||||
|
||||
[BRL-CAD][10]
|
||||
|
||||
#### 5\. DraftSight (非开源)
|
||||
|
||||
如果你习惯在 AutoCAD 上作业。那么， DraftSight 将是完美的替代。
|
||||
|
||||
DraftSight 是一个在 Linux 上可用的极好的 CAD 工具。 它有相当类似于 AutoCAD 的工作流，这使得迁移更容易。它甚至提供一种类似的外观和感觉。DrafSight 也兼容 AutoCAD 的 .dwg 文件格式。 但是，DrafSight 是一个 2D CAD 软件。截至当前，它不支持 3D CAD 。
|
||||
|
||||
![draftsight][11]
|
||||
|
||||
尽管 DrafSight 是一款起价149美元的商业软件。在 [DraftSight 网站][12]上可获得一个免费版本。你可以下载 .deb 软件包，并在基于 Ubuntu 的发行版上安装它。为了开始使用 DraftSight ，你需要使用你的电子邮件 ID 来注册你的免费版本 。
|
||||
|
||||
[DraftSight][12]
|
||||
|
||||
#### 荣誉提名
|
||||
|
||||
* 随着云计算技术的巨大发展，像 [OnShape][13] 的云 CAD 解决方案已经变得日渐流行。
|
||||
* [SolveSpace][14] 是另一个值得一提的开源软件项目。它支持 3D 模型。
|
||||
* 西门子 NX 是一个在 Windows，Mac OS 及 Linux 上可用的工业级 CAD 解决方案，但是它贵得离谱，所以，在这个列表中被忽略。
|
||||
* 接下来，你有 [LeoCAD][15]，它是一个 CAD 软件，在软件中你使用乐高积木来构建东西。你使用这些信息做些什么取决于你。
|
||||
|
||||
|
||||
|
||||
#### 在 Linux 上的 CAD ，以我的看法
|
||||
|
||||
尽管在 Linux 上游戏变得流行，我总是告诉我的铁杆游戏朋友坚持使用 Windows 。 类似地，如果你是一名在你是课程中使用 CAD 的工科学生，我建议你使用学校规定的软件 (AutoCAD，SolidEdge，Catia)，这些软件通常只在 Windows 上运行。
|
||||
|
||||
对于高级专业人士来说，当我们讨论行业标准时，这些工具根本达不到标准。
|
||||
|
||||
对于想在 WINE 中运行 AutoCAD 的那些人来说，尽管一些较旧版本的 AutoCAD 可以安装在 WINE 上，它们根本不执行工作，小故障和崩溃严重损害这些体验。
|
||||
|
||||
话虽如此，我高度尊重上述列表中软件的开发者的工作。他们丰富了 FOSS 世界。很高兴看到像 FreeCAD 一样的软件在近些年中加速开发速度。
|
||||
|
||||
好了，今天到此为止。使用下面的评论区与我们分享你的想法，不用忘记分享这篇文章。谢谢。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://itsfoss.com/cad-software-linux/
|
||||
|
||||
作者：[Aquil Roshan][a]
|
||||
选题：[lujun9972](https://github.com/lujun9972)
|
||||
译者：[robsean](https://github.com/robsean)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://itsfoss.com/author/aquil/
|
||||
[1]:https://en.wikipedia.org/wiki/Computer-aided_design
|
||||
[2]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/08/cad-software-linux.jpeg
|
||||
[3]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/07/freecad.jpg
|
||||
[4]:https://www.freecadweb.org/
|
||||
[5]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/07/librecad.jpg
|
||||
[6]:https://librecad.org/
|
||||
[7]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/07/openscad.jpg
|
||||
[8]:http://www.openscad.org/
|
||||
[9]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/07/brlcad.jpg
|
||||
[10]:https://brlcad.org/
|
||||
[11]:https://4bds6hergc-flywheel.netdna-ssl.com/wp-content/uploads/2018/07/draftsight.jpg
|
||||
[12]:https://www.draftsight2018.com/
|
||||
[13]:https://www.onshape.com/
|
||||
[14]:http://solvespace.com/index.pl
|
||||
[15]:https://www.leocad.org/
|
||||
@ -0,0 +1,44 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (lujun9972)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How many browser tabs do you usually have open?)
|
||||
[#]: via: (https://opensource.com/article/19/6/how-many-browser-tabs)
|
||||
[#]: author: (Lauren Pritchett https://opensource.com/users/lauren-pritchett/users/sarahwall/users/ksonney/users/jwhitehurst)
|
||||
|
||||
您通常打开多少个浏览器选项卡？
|
||||
======
|
||||
外加一些提高浏览器效率的技巧。
|
||||
![Browser of things][1]
|
||||
|
||||
这里有一个别有用心的问题：您通常一次打开多少个浏览器选项卡？您是否有多个窗口，每个窗口都有多个选项卡？或者你是一个极简主义者，一次只打开几个标签。另一种选择是将一个 20 个选项卡的浏览器窗口移动到另一个屏幕上去，这样在处理特定任务时它就不会碍事了。您的处理方法在工作、个人和移动浏览器之间有什么不同吗？您的浏览器策略是否与您的[工作习惯 ][2] 有关？
|
||||
|
||||
### 4 个提高浏览器效率的技巧
|
||||
|
||||
1。了解浏览器快捷键以节省单击。无论你使用 Firefox 还是 Chrome，都有很多快捷键可以让你方便地执行包括切换标签页在内的某些功能。例如，Chrome 可以很方便地打开一个空白的谷歌文档。使用快捷键 **“Ctrl + t”** 打开一个新选项卡，然后键入 **“doc.new”** 即可。电子表格、幻灯片和表单也可以这样做。
|
||||
2。用书签文件夹组织最频繁的任务。当开始一项特定的任务时，只需打开文件夹**中的所有书签 (Ctrl + click)**，就可以快速地从列表中勾选它。
|
||||
3。使用正确的浏览器扩展。成千上万的浏览器扩展都声称可以提高工作效率。在安装之前，确定你不是仅仅在屏幕上添加更多的干扰而已。
|
||||
4。使用计时器减少看屏幕的时间。无论您使用的是老式的 egg 定时器还是花哨的浏览器扩展，都没有关系。为了防止眼睛疲劳，执行 20/20/20 规则。每隔 20 分钟，离开屏幕 20 秒，看看 20 英尺以外的东西。
|
||||
|
||||
|
||||
|
||||
参加我们的投票来分享你一次打开多少个浏览器标签。请务必在评论中告诉我们您最喜欢的浏览器技巧。
|
||||
|
||||
生产力有两个组成部分——做正确的事情和高效地做那些事情……
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/6/how-many-browser-tabs
|
||||
|
||||
作者：[Lauren Pritchett][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[lujun9972](https://github.com/lujun9972)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/lauren-pritchett/users/sarahwall/users/ksonney/users/jwhitehurst
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/browser_desktop_website_checklist_metrics.png?itok=OKKbl1UR (Browser of things)
|
||||
[2]: https://enterprisersproject.com/article/2019/1/5-time-wasting-habits-break-new-year
|
||||
@ -0,0 +1,58 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (lujun9972)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (How to stream music with GNOME Internet Radio)
|
||||
[#]: via: (https://opensource.com/article/19/6/gnome-internet-radio)
|
||||
[#]: author: (Alan Formy-Duval https://opensource.com/users/alanfdoss/users/r3bl)
|
||||
|
||||
如何使用 GNOME Internet Radio 播放流音乐
|
||||
======
|
||||
如果你正在寻找一个简单，直接的接口，让你可以播放流媒体，可以尝试一下 GNOME 的 Internet Radio 插件。
|
||||
![视频编辑仪表板 ][1]
|
||||
|
||||
网络广播是收听世界各地电台节目的好方法。和许多开发人员一样，我喜欢在编写代码时打开电台。您可以使用 [MPlayer][2] 或 [mpv][3] 等终端媒体播放器收听网络广播，我就是这样通过 Linux 命令行收听广播的。但是，如果您喜欢使用图形用户界面 (GUI)，您可能想尝试一下 [GNOME Internet Radio][4]，这是一个用于 GNOME 桌面的漂亮插件。您可以在包管理器中找到它。
|
||||
|
||||
![GNOME Internet Radio plugin][5]
|
||||
|
||||
使用图形桌面操作系统收听网络广播通常需要启动一个应用程序，比如 [Audacious][6] 或 [Rhythmbox][7]。它们有很好的界面，很多选项，以及很酷的音频可视化工具。但如果您只想要一个简单、直观的接口，播放您的流媒体，GNOME Internet Radio 就是你的选择。
|
||||
|
||||
安装之后，工具栏中会出现一个小图标，您可以在其中进行所有配置和管理。
|
||||
|
||||
![GNOME Internet Radio icons][8]
|
||||
|
||||
我做的第一件事是进入设置菜单。我启用了以下两个选项：显示标题通知和显示音量调整。
|
||||
|
||||
![GNOME Internet Radio Settings][9]
|
||||
|
||||
GNOME Internet Radio 包含一些预置的电台，并且很容易添加其他电台。只需点击(**+**)符号即可。您需要输入一个频道名称，它可以是您喜欢的任何名称(包括电台名称)和电台地址。例如，我喜欢听 Synthetic FM。我输入名称 (Synthetic FM)，以及流地址 (https://mediaserv38.live-streams.nl:2199/tunein/syntheticfm.pls)。
|
||||
|
||||
然后单击流旁边的星号将其添加到菜单中。
|
||||
|
||||
不管你听什么音乐，不管你选择什么类型，很明显，程序员需要他们的音乐！GNOME Internet Radio 插件使您可以轻松地让您排好喜爱的网络电台。
|
||||
|
||||
为了庆祝 Gnome 桌面在 8 月 15 日的 18 岁生日，我们总结了 18 个值得庆祝的理由。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/6/gnome-internet-radio
|
||||
|
||||
作者：[Alan Formy-Duval][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[lujun9972](https://github.com/lujun9972)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/alanfdoss/users/r3bl
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/video_editing_folder_music_wave_play.png?itok=-J9rs-My (video editing dashboard)
|
||||
[2]: https://opensource.com/article/18/12/linux-toy-mplayer
|
||||
[3]: https://mpv.io/
|
||||
[4]: https://extensions.gnome.org/extension/836/internet-radio/
|
||||
[5]: https://opensource.com/sites/default/files/uploads/packagemanager_s.png (GNOME Internet Radio plugin)
|
||||
[6]: https://audacious-media-player.org/
|
||||
[7]: https://help.gnome.org/users/rhythmbox/stable/
|
||||
[8]: https://opensource.com/sites/default/files/uploads/titlebaricons.png (GNOME Internet Radio icons)
|
||||
[9]: https://opensource.com/sites/default/files/uploads/gnomeinternetradio_settings.png (GNOME Internet Radio Settings)
|
||||
@ -1,302 +0,0 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (MjSeven)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (Learn object-oriented programming with Python)
|
||||
[#]: via: (https://opensource.com/article/19/7/get-modular-python-classes)
|
||||
[#]: author: (Seth Kenlon https://opensource.com/users/seth)
|
||||
|
||||
使用 Python 学习面对对象的编程
|
||||
======
|
||||
使用 Python 类使你的代码变得更加模块化。
|
||||
![Developing code.][1]
|
||||
|
||||
在我上一篇文章中，我解释了如何通过使用函数、创建模块或者两者一起来[使 Python 代码更加模块化][2]。函数对于避免重复多次使用的代码非常有用，而模块可以确保你在不同的项目中复用代码。但是模块化还有另一种方法：类。
|
||||
|
||||
如果你已经听过 _面对对象编程_ 这个术语，那么你可能会对类的用途有一些概念。程序员倾向于将类视为一个虚拟对象，有时与物理世界中的某些东西直接相关，有时则作为某种编程概念的表现形式。无论哪种表示，当你想要在程序中为你或程序的其他部分创建“对象”时，你都可以创建一个类来交互。
|
||||
|
||||
### 没有类的模板
|
||||
|
||||
假设你正在编写一个以幻想世界为背景的游戏，并且你需要这个应用程序能够涌现出各种坏蛋来给玩家的生活带来一些刺激。了解了很多关于函数的知识后，你可能会认为这听起来像是函数的一个教科书案例：需要经常重复的代码，但是在调用时可以考虑变量而只编写一次。
|
||||
|
||||
下面一个纯粹基于函数的敌人生成器实现的例子：
|
||||
|
||||
```
|
||||
#!/usr/bin/env python3
|
||||
|
||||
import random
|
||||
|
||||
def enemy(ancestry,gear):
|
||||
enemy=ancestry
|
||||
weapon=gear
|
||||
hp=random.randrange(0,20)
|
||||
ac=random.randrange(0,20)
|
||||
return [enemy,weapon,hp,ac]
|
||||
|
||||
def fight(tgt):
|
||||
print("You take a swing at the " + tgt[0] + ".")
|
||||
hit=random.randrange(0,20)
|
||||
if hit > tgt[3]:
|
||||
print("You hit the " + tgt[0] + " for " + str(hit) + " damage!")
|
||||
tgt[2] = tgt[2] - hit
|
||||
else:
|
||||
print("You missed.")
|
||||
|
||||
foe=enemy("troll","great axe")
|
||||
print("You meet a " + foe[0] + " wielding a " + foe[1])
|
||||
print("Type the a key and then RETURN to attack.")
|
||||
|
||||
while True:
|
||||
action=input()
|
||||
|
||||
if action.lower() == "a":
|
||||
fight(foe)
|
||||
|
||||
if foe[2] < 1:
|
||||
print("You killed your foe!")
|
||||
else:
|
||||
print("The " + foe[0] + " has " + str(foe[2]) + " HP remaining")
|
||||
```
|
||||
|
||||
**enemy** 函数创造了一个具有多个属性的敌人，例如祖先、武器、生命值和防御等级。它返回每个属性的列表，表示敌人全部特征。
|
||||
|
||||
从某种意义上说，这段代码创建了一个对象，即使它还没有使用类。程序员将这个 "enemy" 称为 _对象_，因为该函数的结果（本例中是一个包含字符串和整数的列表）表示游戏中一个单独但复杂的 _东西_。也就是说，列表中字符串和整数不是任意的：它们一起描述了一个虚拟对象。
|
||||
|
||||
在编写描述符集合时，你可以使用变量，以便随时使用它们来生成敌人。这有点像模板。
|
||||
|
||||
在示例代码中，当需要对象的属性时，会检索相应的列表项。例如，要获取敌人的祖先，代码会查询 **foe[0]**，对于生命值，会查询 **foe[2]**，以此类推。
|
||||
|
||||
这种方法没有什么不妥，代码按预期运行。你可以添加更多不同类型的敌人，创建一个敌人类型列表，并在敌人创建期间从列表中随机选择，等等，它工作得很好。实际上，[Lua][3] 非常有效地利用这个原理来近似面对对象模型。
|
||||
|
||||
然而，有时候对象不仅仅是属性列表。
|
||||
|
||||
### 使用对象
|
||||
|
||||
在 Python 中，一切都是对象。你在 Python 中创建的任何东西都是某个预定义模板的 _实例_。甚至基本的字符串和整数都是 Python **type** 类的衍生物。你可以在这个交互式 Python shell 中见证：
|
||||
|
||||
```
|
||||
>>> foo=3
|
||||
>>> type(foo)
|
||||
<class 'int'>
|
||||
>>> foo="bar"
|
||||
>>> type(foo)
|
||||
<class 'str'>
|
||||
```
|
||||
|
||||
当一个对象由一个类定义时，它不仅仅是一个属性的集合，Python 类具有各自的函数。从逻辑上讲，这很方便，因为只涉及某个对象类的操作包含在该对象的类中。
|
||||
|
||||
在示例代码中，fight 代码是主应用程序的功能。这对于一个简单的游戏来说是可行的，但对于一个复杂的游戏来说，世界中不仅仅有玩家和敌人，还可能有城镇居民、牲畜、建筑物、森林等等，他们都不需要使用战斗功能。将战斗代码放在敌人的类中意味着你的代码更有条理，在一个复杂的应用程序中，这是一个重要的优势。
|
||||
|
||||
此外，每个类都有特权访问自己的本地变量。例如，敌人的生命值，除了某些功能之外，是不会改变的数据。游戏中的随机蝴蝶不应该意外地将敌人的生命值降低到 0。理想情况下，即使没有类，也不会发生这种情况。但是在具有大量活动部件的复杂应用程序中，确保不需要相互交互的部件永远不会发生这种情况，这是一个非常有用的技巧。
|
||||
|
||||
Python 类也受垃圾收集的影响。当不再使用类的实例时，它将被移出内存。你可能永远不知道这种情况会什么时候发生，但是你往往知道什么时候它不会发生，因为你的应用程序占用了更多的内存，而且运行速度比较慢。将数据集隔离到类中可以帮助 Python 跟踪哪些数据正在使用，哪些不在需要了。
|
||||
|
||||
### 优雅的 Python
|
||||
|
||||
下面是一个同样简单的战斗游戏，使用了 Enemy 类：
|
||||
|
||||
```
|
||||
#!/usr/bin/env python3
|
||||
|
||||
import random
|
||||
|
||||
class Enemy():
|
||||
def __init__(self,ancestry,gear):
|
||||
self.enemy=ancestry
|
||||
self.weapon=gear
|
||||
self.hp=random.randrange(10,20)
|
||||
self.ac=random.randrange(12,20)
|
||||
self.alive=True
|
||||
|
||||
def fight(self,tgt):
|
||||
print("You take a swing at the " + self.enemy + ".")
|
||||
hit=random.randrange(0,20)
|
||||
|
||||
if self.alive and hit > self.ac:
|
||||
print("You hit the " + self.enemy + " for " + str(hit) + " damage!")
|
||||
self.hp = self.hp - hit
|
||||
print("The " + self.enemy + " has " + str(self.hp) + " HP remaining")
|
||||
else:
|
||||
print("You missed.")
|
||||
|
||||
if self.hp < 1:
|
||||
self.alive=False
|
||||
|
||||
# 游戏开始
|
||||
foe=Enemy("troll","great axe")
|
||||
print("You meet a " + foe.enemy + " wielding a " + foe.weapon)
|
||||
|
||||
# 主函数循环
|
||||
while True:
|
||||
|
||||
print("Type the a key and then RETURN to attack.")
|
||||
|
||||
action=input()
|
||||
|
||||
if action.lower() == "a":
|
||||
foe.fight(foe)
|
||||
|
||||
if foe.alive == False:
|
||||
print("You have won...this time.")
|
||||
exit()
|
||||
```
|
||||
|
||||
这个版本的游戏将敌人作为一个包含相同属性（祖先，武器，生命值和防御）的对象来处理，并添加一个新的属性来衡量敌人时候已被击败，以及一个战斗功能。
|
||||
|
||||
类的第一个函数是一个特殊的函数，在 Python 中称为 \_init\_ 或初始化函数。这类似于其他语言中的[构造器][4]，它创建了类的一个实例，你可以通过它的属性和调用类时使用的任何变量来识别它（示例代码中的 **foe**）。
|
||||
|
||||
### Self 和类实例
|
||||
|
||||
类的函数接受一种你在类之外看不到的新形式的输入：**self**。如果不包含 **self**，那么当你调用类函数时，Python 无法知道要使用的类的 _哪个_ 实例。这就像在一间充满兽人的房间里说：“我要和兽人战斗”，向一个兽人发起。没有人知道你指的是谁，所以坏事就发生了。
|
||||
|
||||
![Image of an Orc, CC-BY-SA by Buch on opengameart.org][5]
|
||||
|
||||
CC-BY-SA by Buch on opengameart.org
|
||||
|
||||
类中创建的每个属性都以 **self** 符号作为前缀，该符号将变量标识为类的属性。一旦派生出类的实例，就用表示该实例的变量替换掉 **self** 前缀。使用这个技巧，你可以在一间满是兽人的房间里说：“我要和祖先是 orc 的兽人战斗”，这样来挑战一个兽人。当 orc 听到 "gorblar.orc" 时，它就知道你指的是谁（他自己），所以你得到是一场公平的战斗而不是争吵。在 Python 中：
|
||||
|
||||
```
|
||||
gorblar=Enemy("orc","sword")
|
||||
print("The " + gorblar.enemy + " has " + str(gorblar.hp) + " remaining.")
|
||||
```
|
||||
|
||||
通过检索类属性而不是查询 **foe[0]**（在函数示例中）或 **gorblar[0]** 来寻找敌人（**gorblar.enemy** 或 **gorblar.hp** 或你需要的任何对象的任何值）。
|
||||
|
||||
### 本地变量
|
||||
|
||||
如果类中的变量没有以 **self** 关键字作为前缀，那么它就是一个局部变量，就像在函数中一样。例如，无论你做什么，你都无法访问 **Enemy.fight** 类之外的 **hit** 变量：
|
||||
|
||||
```
|
||||
>>> print(foe.hit)
|
||||
Traceback (most recent call last):
|
||||
File "./enclass.py", line 38, in <module>
|
||||
print(foe.hit)
|
||||
AttributeError: 'Enemy' object has no attribute 'hit'
|
||||
|
||||
>>> print(foe.fight.hit)
|
||||
Traceback (most recent call last):
|
||||
File "./enclass.py", line 38, in <module>
|
||||
print(foe.fight.hit)
|
||||
AttributeError: 'function' object has no attribute 'hit'
|
||||
```
|
||||
|
||||
**hi** 变量包含在 Enemy 类中，并且只能“存活”到在战斗种发挥作用。
|
||||
|
||||
### 更模块化
|
||||
|
||||
本例使用与主应用程序相同的文本文档中的类。在一个复杂的游戏中，我们更容易将每个类看作是自己独立的应用程序。当多个开发人员处理同一个应用程序时，你会看到这一点：一个开发人员处理一个类，另一个开发主程序，只要他们彼此沟通这个类必须具有什么属性，就可以并行地开发这两个代码块。
|
||||
|
||||
要使这个示例游戏模块化，可以把它拆分为两个文件：一个用于主应用程序，另一个用于类。如果它是一个更复杂的应用程序，你可能每个类都有一个文件，或每个逻辑类组有一个文件（例如，用于建筑物的文件，用于自然环境的文件，用于敌人或 NPC 的文件等）。
|
||||
|
||||
将只包含 Enemy 类的一个文件保存为 **enemy.py**，将另一个包含其他内容的文件保存为 **main.py**。
|
||||
|
||||
以下是 **enemy.py**：
|
||||
|
||||
```
|
||||
import random
|
||||
|
||||
class Enemy():
|
||||
def __init__(self,ancestry,gear):
|
||||
self.enemy=ancestry
|
||||
self.weapon=gear
|
||||
self.hp=random.randrange(10,20)
|
||||
self.stg=random.randrange(0,20)
|
||||
self.ac=random.randrange(0,20)
|
||||
self.alive=True
|
||||
|
||||
def fight(self,tgt):
|
||||
print("You take a swing at the " + self.enemy + ".")
|
||||
hit=random.randrange(0,20)
|
||||
|
||||
if self.alive and hit > self.ac:
|
||||
print("You hit the " + self.enemy + " for " + str(hit) + " damage!")
|
||||
self.hp = self.hp - hit
|
||||
print("The " + self.enemy + " has " + str(self.hp) + " HP remaining")
|
||||
else:
|
||||
print("You missed.")
|
||||
|
||||
if self.hp < 1:
|
||||
self.alive=False
|
||||
```
|
||||
|
||||
以下是 **main.py**：
|
||||
|
||||
```
|
||||
#!/usr/bin/env python3
|
||||
|
||||
import enemy as en
|
||||
|
||||
# game start
|
||||
foe=en.Enemy("troll","great axe")
|
||||
print("You meet a " + foe.enemy + " wielding a " + foe.weapon)
|
||||
|
||||
# main loop
|
||||
while True:
|
||||
|
||||
print("Type the a key and then RETURN to attack.")
|
||||
|
||||
action=input()
|
||||
|
||||
if action.lower() == "a":
|
||||
foe.fight(foe)
|
||||
|
||||
if foe.alive == False:
|
||||
print("You have won...this time.")
|
||||
exit()
|
||||
```
|
||||
|
||||
导入模块 **enemy.py** 使用了一条特别的语句，将类文件名称作为引用而不是 **.py** 扩展名，后跟你选择的命名空间指示符（例如，**import enemy as en**）。这个指示符是在你调用类时在代码中使用的。你需要在导入时添加指定符，例如 **en.Enemy**，而不是只使用 **Enemy()**。
|
||||
|
||||
所有这些文件名都是任意的，尽管在原则上并不罕见。将应用程序的中心命名为 **main.py** 是一个常见约定，和一个充满类的文件通常以小写形式命名，其中的类都以大写字母开头。是否遵循这些约定不会影响应用程序的运行方式，但它确实使经验丰富的 Python 程序员更容易快速理解应用程序的工作方式。
|
||||
|
||||
在如何构建代码方面有一些灵活性。例如，使用代码示例，两个文件必须位于同一目录中。如果你只想将类打包为模块，那么必须创建一个名为 **mybad** 的目录，并将你的类移入其中。在 **main.py** 中，你的 import 语句稍有变化：
|
||||
|
||||
```
|
||||
from mybad import enemy as en
|
||||
```
|
||||
|
||||
两种方法都会产生相同的结果，但如果你创建的类足够通用，你认为其他开发人员可以在他们的项目中使用它们，那么后者是更好的。
|
||||
|
||||
无论你选择哪种方式，都可以启动游戏的模块化版本：
|
||||
|
||||
```
|
||||
$ python3 ./main.py
|
||||
You meet a troll wielding a great axe
|
||||
Type the a key and then RETURN to attack.
|
||||
a
|
||||
You take a swing at the troll.
|
||||
You missed.
|
||||
Type the a key and then RETURN to attack.
|
||||
a
|
||||
You take a swing at the troll.
|
||||
You hit the troll for 8 damage!
|
||||
The troll has 4 HP remaining
|
||||
Type the a key and then RETURN to attack.
|
||||
a
|
||||
You take a swing at the troll.
|
||||
You hit the troll for 11 damage!
|
||||
The troll has -7 HP remaining
|
||||
You have won...this time.
|
||||
```
|
||||
|
||||
游戏启动了，它现在更加模块化了。现在你知道了面对对象的应用程序意味着什么，但最重要的是，当你向兽人发起决斗的时候，你要想清楚。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/7/get-modular-python-classes
|
||||
|
||||
作者：[Seth Kenlon][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[MjSeven](https://github.com/MjSeven)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/seth
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/code_development_programming.png?itok=M_QDcgz5 (Developing code.)
|
||||
[2]: https://opensource.com/article/19/6/get-modular-python-functions
|
||||
[3]: https://opensource.com/article/17/4/how-program-games-raspberry-pi
|
||||
[4]: https://opensource.com/article/19/6/what-java-constructor
|
||||
[5]: https://opensource.com/sites/default/files/images/orc-buch-opengameart_cc-by-sa.jpg (CC-BY-SA by Buch on opengameart.org)
|
||||
@ -0,0 +1,103 @@
|
||||
[#]: collector: (lujun9972)
|
||||
[#]: translator: (Morisun029)
|
||||
[#]: reviewer: ( )
|
||||
[#]: publisher: ( )
|
||||
[#]: url: ( )
|
||||
[#]: subject: (An introduction to Hyperledger Fabric)
|
||||
[#]: via: (https://opensource.com/article/19/9/introduction-hyperledger-fabric)
|
||||
[#]: author: (Matt Zand https://opensource.com/users/mattzandhttps://opensource.com/users/ron-mcfarlandhttps://opensource.com/users/wonderchook)
|
||||
|
||||
Hyperledger Fabric 介绍
|
||||
======
|
||||
Hyperledger （超级账本）是一组开源工具，旨在构建一个强大的，业务驱动的区块链框架。
|
||||
![Chain image][1]
|
||||
|
||||
[Hyperledger][2] 是区块链行业中最大的项目之一，它由一组开源工具和多个子项目组成。该项目是由 Linux 基金会主办的一个全球协作项目，其中包括一些不同领域的领导者们，这些领导者们的目标是建立一个强大的，业务驱动的区块链框架。
|
||||
|
||||
区块链网络主要有三种类型：公共区块链，联盟或联合区块链，以及私有区块链。 Hyperledger 是一个区块链框架，旨在帮助公司建立私人或财团许可的区块链网络，在该网络中，多个组织可以共享控制和操作网络内节点的权限。
|
||||
|
||||
因为区块链是一个透明的，基于不可变模式的安全分散系统，所以它被认为是传统供应链行业改变游戏规则的一种解决方案。 它可以通过以下方式支持有效的供应链系统：
|
||||
|
||||
* 跟踪整个区块链中的产品
|
||||
* 校验和验证区块链中的产品
|
||||
* 在供应链参与者之间共享整个区块链的信息
|
||||
* 提供可审核性
|
||||
|
||||
本文通过食品供应链的例子来解释 Hyperledger 区块链是如何改变传统供应链系统的。
|
||||
|
||||
### 食品行业供应链
|
||||
|
||||
传统供应链效率低下的主要原因是由于缺乏透明度而导致报告不可靠和竞争上的劣势。
|
||||
|
||||
在传统的供应链模式中，有关实体的信息对该区块链中的其他人来说并不完全透明，这就导致了报道不准确和缺乏互操作性问题。 电子邮件和印刷文档提供了一些信息，但它们不可能包含完整详细的可见性数据，因为很难在整个供应链中去追踪产品。 这也使消费者几乎不可能知道产品的真正价值和来源。
|
||||
|
||||
食品行业的供应链环境复杂，多个参与者需要协作将货物运送到最终目的地 - 客户手中。 下图显示了食品供应链（多级）网络中的主要参与者。
|
||||
![典型的食品供应链][3]
|
||||
|
||||
该区块链的每个阶段都会引入潜在的安全问题，整合问题和其他低效问题。 目前食品供应链中的主要威胁仍然是假冒食品和食品欺诈。
|
||||
|
||||
基于 Hyperledger 区块链的食品跟踪系统可实现对食品信息全面的可视性和和可追溯性。 更重要的是，它以一种不变但可行的方式来记录产品细节，确保食品信息的真实性。最终用户通过在不可变框架上共享产品的详细信息，可以自我验证产品的真实性。
|
||||
|
||||
### Hyperledger Fabric
|
||||
|
||||
Hyperledger Fabric 是 Hyperledger 项目的基石。它是基于权限的区块链，或者更准确地说是一种分布式分类帐技术（DLT），该技术最初由 IBM 公司和 Digital Asset 创建。分布式分类帐技术被设计为具有不同组件的模块化框架（概述如下）。 它也是提供可插入的共识模型的一种灵活的解决方案，尽管它目前仅提供基于投票的许可共识（假设今天的 Hyperledger 网络在部分可信赖的环境中运行）。
|
||||
|
||||
鉴于此，匿名矿工无需验证交易，相关货币也无需用作激励措施。 所有的参与者必须经过身份验证才能参与到区块链，在区块链中进行交易。 与以太坊一样，Hyperledger Fabric 支持智能合约，在 Hyperledger 中称为 Chaincodes（链码），这些合同描述并执行系统的应用程序逻辑。
|
||||
|
||||
然而，与以太坊不同，Hyperledger Fabric 不需要昂贵的挖掘计算来提交交易，因此它有助构建区块链，使其在更短的延迟内向上扩展。
|
||||
|
||||
Hyperledger Fabric 不同于以太坊或比特币这样的区块链，不仅在于它们类型不同，或者说是它与货币无关，而且它们在内部机制方面也不同。以下是典型的Hyperledger网络的关键要素：
|
||||
|
||||
* **Ledgers** 存储了一系列块，这些块保留了所有状态交易的所有不可变历史记录。
|
||||
* **Nodes** 区块链的逻辑实体。它有三种类型：
|
||||
– **Clients** 是代表用户向网络提交事务的应用程序。
|
||||
– **Peers** 是提交交易并维护分类帐状态的实体。
|
||||
– **Orderers** 在 Clients 和 peers 之间创建共享通信渠道，还将区块链交易打包成块发送给 peers 节点。
|
||||
|
||||
除了这些要素，Hyperledger Fabric 还有一下关键设计功能：
|
||||
|
||||
* **Chaincode** （链码）类似于其他网络中的智能合约，如以太坊。它是用一种更高级的语言编写的程序，在分类帐当前状态的数据库执行完毕后执行。
|
||||
* **Channels**（通道）是用于在多个网络成员之间共享机密信息的专用通信子网。每笔交易都在一个只有经过身份验证和授权的各方可见的通道上执行。
|
||||
* **Endorsers** （背书人）验证建交易，调用 Chaincode，并将背书交易结果返回给调用应用程序。
|
||||
* **Membership Services Providers** (MSPs)（会员服务提供商）通过颁发和验证证书来提供身份验证和身份验证过程。 MSP 确定信任哪些证书颁发机构（CA）去定义信任域的成员，并确定成员可能扮演的特定角色（成员，管理员等）。
|
||||
|
||||
|
||||
|
||||
### 如何验证交易
|
||||
|
||||
探究一笔交易是如何通过验证的是理解 Hyperledger Fabric 如何在底层工作的好方法。此图显示了在典型的 Hyperledger 网络中处理交易的端到端系统流程：
|
||||
![Hyperledger 交易验证流程][4]
|
||||
|
||||
首先，客户端通过向基于 Hyperledger Fabric 的应用程序客户端发送请求来启动交易，该客户端将交易提议提交给 Peers 节点。 这些节点通过执行交易指定的 Chaincode（使用状态的本地副本）并将结果发送回应用程序来模拟交易。 此时，应用程序将交易与背书相结合，并将其广播给 Ordering Service 节点。 Ordering Service 检查背书并为每个通道创建一个交易块，然后将其广播给通道中的其它节点，peers 验证交易并进行提交。
|
||||
|
||||
Hyperledger Fabric 区块链可以通过透明的、不变的、共享的食品来源数据记录，数据处理，及运输细节等信息将食品供应链中的参与者们连接起来。 Chaincode 由食品供应链中的授权参与者来调用。 所有执行的交易记录都永久保存在分类帐中，所有参与者都可以查看此信息。
|
||||
|
||||
### Hyperledger Composer
|
||||
|
||||
除了Fabric或Iroha等区块链框架外，Hyperledger项目还提供了Composer，Hyperledger Explorer和Cello等工具。 Hyperledger Composer提供了一个工具集，可帮助您更轻松地构建区块链应用程序。 它包括：
|
||||
|
||||
* CTO, 一种建模语言
|
||||
* Playground, 一种基于浏览器的开发工具，用于快速测试和部署
|
||||
* 命令行界面（CLI）工具
|
||||
|
||||
|
||||
Composer 支持 Hyperledger Fabric 的运行时和基础架构，在内部，Composer 的 API 使用底层 Fabric 的 API。 Composer 在 Fabric 上运行，这意味着 Composer 生成的业务网络可以部署到 Hyperledger Fabric 执行。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://opensource.com/article/19/9/introduction-hyperledger-fabric
|
||||
|
||||
作者：[Matt Zand][a]
|
||||
选题：[lujun9972][b]
|
||||
译者：[Morisun029](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]: https://opensource.com/users/mattzandhttps://opensource.com/users/ron-mcfarlandhttps://opensource.com/users/wonderchook
|
||||
[b]: https://github.com/lujun9972
|
||||
[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/chain.png?itok=sgAjswFf (Chain image)
|
||||
[2]: https://www.hyperledger.org/
|
||||
[3]: https://opensource.com/sites/default/files/uploads/foodindustrysupplychain.png (Typical food supply chain)
|
||||
[4]: https://opensource.com/sites/default/files/uploads/hyperledger-fabric-transaction-flow.png (Hyperledger transaction validation flow)
|
||||
[5]: https://coding-bootcamps.com/ultimate-guide-for-building-a-blockchain-supply-chain-using-hyperledger-fabric-and-composer.html
|
||||
Loading…
Reference in New Issue
Block a user