1.
PHP as a Middleware
in Embedded Systems
@phpconftw2012

2.
Hi, I'm sosorry

3.
不可能的電視
系統廠工程師

4.
本次分享
僅代表個人意見
不代表公司立場

5.
故事開始

6.
2012 年 , 連網電視正夯

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老闆想在電視上新增一個網路 App

8.
該如何開始？

9.
先來測個 API 吧

10.
●
Request the developer account to 3rd party
● Get the technical document
● Build the test environment
● Download sample code
● Test all APIs with JAVA
● … OK

11.
杯具發生了 ...

12.
板子上沒有 JVM

13.
歡迎來到嵌入式系統的世界

14.
Embedded System
An embedded system is a computer system
designed for specific control functions within a
larger system, often with real-time computing
constraints.

15.
● No APT, no YUM
● Hardware limitation
● ! Scale
● Deploy/update not easy

16.
Back to the basics

17.
Q1:
app 在嵌入式系統是如何顯示的？

18.
Display System
Application
GUI-ToolKit
Framebuffer
Hardware

19.
In Embedded System
/dev/fb driver
SoC

20.
application 受限於 GUI-Toolkit

21.
Q2:
是否可以讓 UI 只做 UI ？

22.
Software Glue
source: http://www.furniturefromturkey.com/

23.
Middleware
Application
Turnkey/Driver
Hardware

24.
Middleware
Application
Turnkey/Driver
Hardware

25.
Middleware
Application
interface
interface
Turnkey/Driver
Hardware

26.
Middleware
Application
interface
Portable Layer
interface
Turnkey/Driver
Hardware

27.
Q3:
rd
要能實做 3 Party App 的基本需求？

28.
● RESTFul API
● JSON/XML data format
● Symmetric/asymmetric encryption
● SSL communication
● Data storage
● Multi-byte encoding

29.
PHP as Software Glue
in Embedded Systems

30.
Why PHP

31.
● Tiny, low resource usage
● Community contribution (PEAR/PECL)
● 3rd party API (Youtube/Twitter/Facebook...)
● Integration with lots of libraries

32.
● RESTFul API /cURL
● JSON/XML data format /LibeXpat, Libxml2
● Symmetric/asymmetric encryption /Libmcrypt
● SSL communication /OpenSSL
● Data storage /SQLite3
● Multi-byte encoding /Libiconv
● Inter-Process Communication /Socket, SHM
● Core /PHP-CLI

33.
PHP as a Middleware
Application
Turnkey/Driver
Hardware

34.
Tasks
● Architecture design
● Porting libraries
● Development & debug
● Performance tunning

35.
Architecture Design

36.
Web Server + PHP ？

37.
● Apache MPM prefork + mod_php
● Nginx + FastCGI
● Lighttpd + PHP-FPM
● Boa + PHP-CGI

38.
杯具又發生了 ...

39.
●
資源吃很兇
● 不容易移植
●
記憶體洩漏
●
常常連不上

40.
砍掉重練

41.
PHP Inter-Process Communication

42.
PHP
invoke data exchange
Native Code

43.
● Shared library
PHP
invoke data exchange
Native Code

44.
● Shared library
● Embedded build (--enable-embed)
PHP
invoke data exchange
Native Code

45.
● Shared library
● Embedded build (--enable-embed)
● Shell command
PHP
invoke data exchange
Native Code

46.
● Shared library
● Embedded build (--enable-embed)
● Shell command
● Socket
PHP
invoke data exchange
Native Code

47.
Socket Server

48.
Design
● Concurrent server (No multi-thread in PHP)
● IPC mechanism (broadcast/multicast/unicast)
● Client/Server command protocol
● No framework, all things handmade

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PHP Work Flow

50.
Turnkey/Driver
Hardware

51.
application interface
socket server storage
Turnkey/Driver
Hardware

52.
application interface
socket server storage
Turnkey/Driver
Hardware

53.
application interface
socket server storage
Turnkey/Driver
Hardware

54.
You Tube application interface
socket server storage
Turnkey/Driver
Hardware

55.
You Tube application interface
Pandora socket server storage
Turnkey/Driver
Hardware

56.
You Tube application interface
Pandora socket server storage
Twitter Turnkey/Driver
Hardware

57.
You Tube application interface
Pandora socket server storage
Twitter Turnkey/Driver
Hardware

58.
You Tube application interface
Pandora socket server storage
Twitter Turnkey/Driver
Hardware

59.
Porting Libraries

60.
● Prepare toolchain
● Configure with minimized features
● Resolve dependency & version conflict
● Resolve compilation error
● Test all functions in the target machine
● Reduce library size

61.
Development & Debug

62.
Development Environment
● Ubuntu /OS
● Vim & plugin /editor
● Shell script /automation tool
● Meld /visual diff and merge tool
● SVN /version control system
● Jira /bug tracking system

63.
Console Debug
● print_r(), var_dump()
● Xdebug & xdebug_debug_zval()
● log_errors & error_log in php.ini
● debugging level in config.ini

64.
IDE Debug
● Set breakpoint
● Step into/step over/step out
● Watch variables
● Display call stack

65.
Performance Tunning

66.
Profiling
● Xdebug
● Kcachegrind
● VLD (Vulcan Logic Disassembler)

67.
Xdebug
● Stack/function traces
● Code coverage analysis
● Time tracking
● Memory usage

68.
tracefile-analyser
● Aggregate information from xdebug
● Sort by time/memory/calls

69.
Kcachegrind
● Analyze xdebug profiling data
● Call graph viewer(callers/callees)

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VLD
● An opcode dumper

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A simple comparison

72.
array_push

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array assignment

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# of Opcodes = 16

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# of Opcodes = 10

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Tunning

77.
Alternative PHP Cache (APC)
source: http://www.slideshare.net/shire/php-tek-2008-apc-facebook

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DB is always the bottleneck

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常見招數
●
買好一點的硬體
● 優化 SQL 語法
● 關掉同步 commit
● 增加寫入 buffer 的大小
● 增加 wait write 的 delay time
●
… 等等

80.
SQLite3 Tunning
● Configuration
● SQLITE_MAX_LENGTH=2147483647
● SQLITE_MAX_SQL_LENGTH=1073741824
● lock/unlock
● $handle->busyTimeout($time)
● Single statement
● Concat SQL string
● Begin; SQL; Commit;

81.
Write an Extension
● --enable-debug --enable-maintainer-zts
● ext_skel
$ vi ext/$extname/config.m4
$ ./buildconf
$ ./configure –[with|enable]-$extname
$ make
$ ./php -f ext/$extname/$extname.php
$ vi ext/$extname/$extname.c
$ make

82.
Extension for Debugging
● Change debugging level during runtime
● Dump debug information to a specific usb drive
● inotify + blkid

83.
Integration

84.
這又是另外一個故事了

85.
Thanks

86.
Special Thanks
● Jeffrey Chen
● Simon Wang

87.
Q &A