document/TranslateProject
2
0
Fork 0
mirror of https://github.com/LCTT/TranslateProject.git synced 2025-01-25 23:11:02 +08:00
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #5273 from xiaow6/master

Browse Source 
translated by xiaow6
This commit is contained in:
VicYu 2017-03-13 18:07:40 +08:00 committed by GitHub
commit 0b45620861
2 changed files with 70 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

71
sources/tech/20170215 Using Scripting Languages in IoT Challenges and Approaches.md
View File

@ -1,71 +0,0 @@
translating by xiaow6
Using Scripting Languages in IoT: Challenges and Approaches
============================================================
![Scripting IoT](https://www.linux.com/sites/lcom/files/styles/rendered_file/public/scripting-languages-iot.jpg?itok=d6uog0Ss "Scripting IoT")
At the upcoming Embedded Linux Conference + OpenIoT Summit, Paul Sokolovsky will discuss some of the challenges of using scripting languages in embedded development.[Creative Commons Zero][2]Pixabay
Scripting languages (aka Very High-Level Languages or VHLLs), such as Python, PHP, and JavaScript are commonly used in desktop, server, and web development. And, their powerful built-in functionality lets you develop small useful applications with little time and effort, says Paul Sokolovsky, IoT engineer at Linaro. However, using VHLLs for deeply embedded development is a relatively recent twist in IoT.
![Paul Sokolovsky](https://www.linux.com/sites/lcom/files/styles/floated_images/public/paul-sokolovsky-2014-09-21.jpg?itok=nUlGjxf3 "Paul Sokolovsky")
Paul Sokolovsky, IoT engineer at Linaro[Used with permission][1]
At the upcoming [Embedded Linux Conference][6] + [OpenIoT Summit][7], Sokolovsky will discuss the challenges of using VHLLs in embedded development and compare different approaches, based on the  examples of MicroPython and JerryScript + Zephyr.js projects. We talked with Sokolovsky to get more information.
**Linux.com: Can you please give our readers some background on VHLLs?**
Paul Sokolovsky: Very High Level Languages have been a part of the computer science and information technologies landscape for several decades now. Perhaps the first popular scripting language was a Unix shell (sh), although it's rarely considered a VHLL, but rather a domain-specific language, due to its modest feature set. However, the first truly record-breaker VHLLs were Perl (1987) and Tcl (1988), soon followed by Python (1991), Ruby (1995), PHP (1995), JavaScript (1995), and many others.
The distinctive features of VHLLs are their interpreted nature (from the user's point of view, there may be sophisticated compilers inside), built-in availability of powerful data types like arbitrary-sized lists and mappings, sizable standard library, and external modules system allowing users to access even larger third-party libraries. All that is coupled with a general easy feel (less typing, no build times, etc.) and an easy learning curve.
**Linux.com: What are the benefits of these languages for development?**
Sokolovsky: The benefits stem from the features described above. One can start with a scripting language quite easily and learn it quickly. Many VHLLs offer a powerful interactive mode, so you don't need to read thick manuals to get started but can explore and experiment right away. Powerful built-in functionality allows you to develop small useful applications -- scripts -- with little time and effort (that's where the "scripting languages" name came from). Moving to larger applications, vast third-party libraries and an easy-to-use module system make developing them also streamlined and productive.
**Linux.com: How does scripting for embedded platforms differ from development for other platforms?**
Sokolovsky: With all the exciting capabilities of VHLLs discussed above, there's an idea -- why we can't enjoy all (or at least some) benefits of them when developing for embedded devices? And by "embedded devices" I mean here not just small Linux systems with 8-32MB of RAM, but deeply embedded systems running on microcontrollers (MCUs) with mere kilobytes of memory. Small, and sometimes really scarce, resources definitely add complexity to this idea. Another issue is device access and interaction. Embedded devices usually don't have displays and keyboards, but fortunately the answer is known for decades thanks to Unix -- just use a terminal connection over a serial (UART). Of course, on a host side, it can be hidden behind a graphical IDE, which some users prefer.
So, with all the differences the embedded devices have, the idea is to provide as familiar a working environment as possible. That's on one side of the spectrum and, on the other, the idea is to make it as scaled down as possible to accommodate even the smallest of devices. These conflicting aims require embedded VHLLs implementations to be highly configurable, to adjust for the needs of different projects and hardware.
**Linux.com: What are the specific challenges of using these languages for IoT? How do you address memory constraints, for example?**
Sokolovsky: It's definitely true that the interpreter consumes scarce hardware resources. But nowadays the most precious resource is the human time. Whether you are an R&D engineer, a maker with only a few hours on weekend, a support engineer overwhelmed with bugs and security issues, or a project manager planning a product -- you likely don't have extra time on your hands. The idea is to deliver the productivity of VHLLs into the hands of embedded engineers.
Nowadays, the state of art is very enabling of this. It's fair to say that, even of microcontroller units (MCUs), an average now is 16-32KB RAM and 128-256K ROM. That's just enough to host a core interpreter, a no-nonsense subset of standard library types, some hardware drivers, and a small -- but still useful -- user application. If you go slightly above the middle line, capabilities raise rapidly -- it's actually a well-known trick from 1970s that using custom bytecode/pcode lets you achieve greater code/feature density than the raw machine code.
There are a lot of challenges on that road, scarcity of RAM being the main one. I write these words on a laptop with 16GB of RAM (and there're still slowdowns due to swapping), and the 16KB mentioned above is a million times less! And yet, by using carefully chosen algorithms and coding techniques, it's possible to implement a scripting language that can execute simple applications in that amount of RAM, and fairly complex ones in 128-256K.
There are many technical challenges to address (and which are being successfully addressed), and there wouldn't be a space to cover them here. Instead, my presentation at OpenIoT Summit will cover experiences and achievements of two embedded scripting languages: MicroPython (Python3 language subset) and Zephyr.js (JavaScript/Node.js subset), both running on top of The Linux Foundation's Zephyr RTOS, which is expected to do for the IoT industry what Linux did for the mobile and server industries. (The slides will be available afterwards for people who can't attend OpenIoT Summit.)
**Linux.com: Can you give us some examples of applications for which VHLLs are most appropriate? And for which they are inappropriate?**
Sokolovsky: Above are many bright prospects for VHLLs, fairly speaking; in embedded, there's a lot of wishful thinking in that (or hopefully, self-fulfilling prophecy). Where VHLLs in embedded can deliver right now are: rapid prototyping, and educational/maker markets where easy learnability and usage is a must. There are pioneers that use VHLLs in other areas, but generally, it requires more investment into infrastructure and tools. It's important that such investment be guided by open source principles and be shared, or otherwise it undermines the idea that VHLLs can save their users time and effort.
With that in mind, embedded VHLLs are full-fledged ("Turing complete") languages suitable for any type of application, subject to hardware constraints. For example, if an MCU is below the thresholds stated above, of a legacy 8-bit micro, good old C is the only choice you can enjoy. Another limit is when you really want to get the most out of the hardware -- C or Assembler is the right choice. But, here's a surprise -- the developers of embedded VHLLs thought about that, too, and, for example, MicroPython allows you to combine Python and Assembler in one application.
Where embedded VHLLs excel is configurability and (re)programmability, coupled with flexible connectivity support. That's exactly what IoT and smart devices are all about, and many IoT applications don't have to be complex to be useful. Consider, for example, a smart button you can stick anywhere to do any task. But, what if you need to adjust the double-click time? With a scripting language, you can. Maybe you didn't think about triple-clicks at all, but now find that even four clicks would be useful in some cases. With a scripting language you can change that -- easily.
_Embedded Linux Conference + OpenIoT Summit North America will be held on February 21 - 23, 2017 in Portland, Oregon. [Check out over 130 sessions][5] on the Linux kernel, embedded development & systems, and the latest on the open Internet of Things._
--------------------------------------------------------------------------------
via: https://www.linux.com/news/event/elcna/2017/2/using-scripting-languages-iot-challenges-and-approaches
作者：[AMBER ANKERHOLZ][a]
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.linux.com/users/aankerholz
[1]:https://www.linux.com/licenses/category/used-permission
[2]:https://www.linux.com/licenses/category/creative-commons-zero
[3]:https://www.linux.com/files/images/paul-sokolovsky-2014-09-21jpg
[4]:https://www.linux.com/files/images/scripting-languages-iotjpg
[5]:http://events.linuxfoundation.org/events/embedded-linux-conference/program/schedule?utm_source=linux&utm_campaign=elc17&utm_medium=blog&utm_content=video-blog
[6]:http://events.linuxfoundation.org/events/embedded-linux-conference
[7]:https://events.linuxfoundation.org/events/openiot-summit/program/schedule

70
translated/tech/20170215 Using Scripting Languages in IoT Challenges and Approaches.md Normal file
View File

@ -0,0 +1,70 @@
在物联网中使用脚本语言的挑战与途径
============================================================
![Scripting IoT](https://www.linux.com/sites/lcom/files/styles/rendered_file/public/scripting-languages-iot.jpg?itok=d6uog0Ss "Scripting IoT")
在即将到来的嵌入式 Linux 会议 + OpenIoT 峰会中，Paul Sokolovsky 将会讨论在嵌入式开发中使用脚本语言的一些挑战。来自Pixabay，基于CC0协议。
脚本语言（又称作超高级语言或 VHLLs ），例如 Python, PHP, 以及 JavaScript 都常常在桌面、服务器和网页开发中被使用。而且，它们强大的内置功能能够让你花费少量的时间和精力来开发小型却有用的应用，Paul Sokolovsky，Linaro 公司物联网工程师如是说。然而，目前在物联网中使用超高级语言深度开发嵌入式应用相对来说有些别扭。
![Paul Sokolovsky](https://www.linux.com/sites/lcom/files/styles/floated_images/public/paul-sokolovsky-2014-09-21.jpg?itok=nUlGjxf3 "Paul Sokolovsky")
Paul Sokolovsky，Linaro 公司物联网工程师。[图片已获授权][1]
在即将到来的[嵌入式 Linux 会议][6] + [OpenIoT 峰会][7]中，Sokolovsky 会讨论在嵌入式开发中使用 VHLLs 的挑战并且比较不同的实现途径，基于 MicroPython 的例子与 JerryScript + Zephyr.js 项目。 我们与Sokolovsky进行了一番交谈来获得更多信息。
**Linux.com：您可以给我们的读者一些 VHLLs 的背景知识吗？**
Paul Sokolovsky: 超高级语言成为计算机科学和信息技术风景中的一部分已经几十年了。也许第一个流行的脚本语言是 Unix shell（sh），尽管由于较小的特征集，它很少被认为是一种超高级语言，而是一种特定领域语言。所以第一个真正破纪录的 VHLLs 是 Perl（1987）和 Tcl（1988），很快紧跟着出现了 Python（1991），Ruby（1995），PHP（1995），JavaScript（1995）以及许多其它语言。
不同 VHLLs 之间的区别特性包括：它们的解析本能（从使用者的角度来看，也许是因为其中复杂的编译器作祟），内置可用的强大的数据类型如任意大小的列表和映射，大小合适的标准库，以及允许用户访问甚至更大的第三方库的外部的模块系统。所有的这些特性都与相对容易使用的感觉（更少的打字，没有构建时间等）和简单的学习曲线相耦合。
**Linux.com: 使用这些语言做开发有哪些优势？**
Sokolovsky: 优势的根源来自于以上描述的这些特性。一个新手可以非常轻松的开始使用脚本语言并且快速的学习它。很多 VHLLs 提供了一个强大的交互模式，所以你不需要去读那些厚厚的使用手册来开始使用脚本语言，而是直接去探索和体验它们。强大的内置功能允许你去开发小而有用的应用——脚本——仅仅使用很少的时间和精力（这就是“脚本语言”名字的来源）。如果要转向开发大型应用，广泛的第三方库和轻而易举被使用的模块系统使得开发变得流畅和高产。
**Linux.com: 在嵌入式平台上使用脚本开发和在其他平台开发有什么区别？**
Sokolovsky: 鉴于之前我们讨论过的 VHLLs 振奋人心的能力，有一个创意——为什么我们不能享受使用 VHLLs 为嵌入式设备做开发具有的所有（或者至少一部分）优势呢？这里我提到的“嵌入式设备”不仅仅是拥有 8-32 MB RAM 的小型 Linux 系统，还有运行在微控制器（MCUs）上有几千字节内存的深度嵌入式系统。少量（有些时候几乎没有）的相关资源肯定使这个创意的实现变得更加复杂。 另一个问题是设备访问和交互。嵌入式设备通常没有显示屏和键盘，但是幸运的是解决这个问题的答案已经存在几十年了，这里要感谢Unix，提供了使用串口（UART）来搭建一个终端连接的方法。当然，在主机端，有些用户喜欢使用图形集成开发环境（IDE）来隐藏串口通信细节。
所以，由于嵌入式设备所有的这些不同特性，这个创意就是提供一个尽可能熟悉的工作环境。但熟悉只是其中一方面，另一方面，为了适应甚至最小的设备，工作环境需要尽可能的缩小。要想解决这些冲突需要嵌入式 VHLLs 的操作能够被高度配置，来适应不同的项目和硬件的需求。
**Linux.com：只有在物联网中使用这些语言才会遇到的挑战有哪些？比如说你如何处理内存限制？**
Sokolovsky: 当然，解释程序本身几乎不怎么消耗硬件资源。但是在当今世界，最珍贵的资源是人类的时间。不管你是一个研发工程师，一个仅仅有几个小时周末的制造者，一个让 bug 和安全问题淹没的支持工程师，或者一个计划开发新产品的产品经理——你手头上大概都没有什么多余时间。因此需要将 VHLLs 的生产力提供到嵌入式工程师手上。
当前的工艺水平使得这些需求变得可行。公正的来讲，甚至于微处理器单元（MCUs）平均 RAM 都有 16-32 KB，ROM 128-256 KB。这仅仅足够搭载一个核心解释程序，一个标准库类型的规范子集，一些硬件驱动，以及一个很小——但是依旧有用——的应用程序。假如你的硬件配置稍微越过了中间线，其容量得以快速的增长——这实际上是由于一个从 1970 年代就闻名的技巧：使用自定义的字节码和精码相比原始机器代码能够让你获得更大的代码/特性密度。
在这条道路上有很多挑战，RAM 不够用是主要的一个。我是在一个 16 GB RAM 的笔记本上写下的这些话（但不断切换的话依然会很卡），而刚才提到的 16KB 比它小一百万倍！不过，通过小心的选择算法和编程技巧，在这样小的 RAM 下仍有可能通过脚本语言来执行简单程序，而相当复杂的程序可能需要128-256K。
有很多的技术挑战需要讲解（它们已经被成功的讲解了），这里没有足够的篇幅来涵盖它们。不过，我在 OpenIoT 峰会上的演讲会涵盖使用两种嵌入式脚本语言的经验和成就：MicroPython（Python3 的子集）和 Zephyr.js（JavaScript/Node.js 的子集），都运行在 Linux 基金会的 Zephyr 实时操作系统上，它被寄希望于为 IoT 工业界做出 Linux 为手机和服务器工业做出的贡献。（相关 PPT 会为无法参加 OpenIoT 会议的朋友在会议后放出。）
**Linux.com: 你能给我们一些 VHLLs 最适用的应用的例子吗？以及一些它们不适用的例子？**
Sokolovsky：以上是很多关于 VHLLs 的光明前景，公正的来说：在嵌入式开发中，这里有很多一厢情愿的幻想（或者说希望其是能够自我实现的预言）。在嵌入式开发中 VHLLs 现在可以提供的是：快速成型，以及教育/制造市场所必须的易学性和易用性。有一些先行者在其它领域使用 VHLLs，但是就目前来看，它需要在基础构造和工具开发上投入更多。这样的投入在开源和公开分享原则下被指引是非常重要的，否则会逐渐损害到 VHLLs 能够节省使用者时间和精力的优势。
谨记这些，嵌入式 VHLLs 是发育完全（“逐渐变的完整”）的语言，能够适应各种类型的应用，但是要屈服于硬件限制。例如，假如一个微处理器的规格低于之前提到的阈值，如一个老旧的 8-bit 微处理器，那么只有同样古老而优秀的 C 语言能够为你所用。另外一个限制是当你真的想要充分利用硬件时—— C 语言或者汇编程序才是正确的选择。但是，这里有一个惊喜——嵌入式 VHLLs 的开发者也想到了这一点，例如 MicroPython 允许你将 Python 和汇编程序在同一个应用中结合起来。
嵌入式 VHLLs 突出的的是其可配置性和可（重复）编程性，外加灵活的连接性支持。这恰恰是 IoT 和智能设备最需要的，很多 IoT 应用使用起来也不需要太复杂。考虑一下，例如，一个可以贴在任何地方用来完成任何任务的智能按钮。但是，如果你需要调整双击的时间时怎么办？使用脚本语言，你可以做到。也许你完全不会考虑三连击，但是现在在某些情况下四连击都可能是有用的。使用脚本语言，你可以轻易修改它。
_嵌入式 Linux 会议 + OpenIoT 北美峰会于 2017 年 2 月 21 - 23 号在美国俄勒冈州波特兰市举办。请[查阅][5]关于 Linux 内核、嵌入式开发和嵌入式系统，以及开放物联网最新事物相关的130个相关会议。_
--------------------------------------------------------------------------------
via: https://www.linux.com/news/event/elcna/2017/2/using-scripting-languages-iot-challenges-and-approaches
作者：[AMBER ANKERHOLZ][a]
译者：[xiaow6](https://github.com/xiaow6)
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.linux.com/users/aankerholz
[1]:https://www.linux.com/licenses/category/used-permission
[2]:https://www.linux.com/licenses/category/creative-commons-zero
[3]:https://www.linux.com/files/images/paul-sokolovsky-2014-09-21jpg
[4]:https://www.linux.com/files/images/scripting-languages-iotjpg
[5]:http://events.linuxfoundation.org/events/embedded-linux-conference/program/schedule?utm_source=linux&utm_campaign=elc17&utm_medium=blog&utm_content=video-blog
[6]:http://events.linuxfoundation.org/events/embedded-linux-conference
[7]:https://events.linuxfoundation.org/events/openiot-summit/program/schedule