This document discusses using PHP as middleware in embedded systems. It begins by describing challenges in embedded systems like hardware limitations and difficulties with deployment and updates. It then proposes using PHP and various PHP extensions to address these challenges by acting as software glue between applications and hardware. The document outlines various tasks like porting libraries to the embedded platform, developing and debugging PHP applications for embedded systems, and performance tuning. It provides examples of using PHP for tasks like interfacing with REST APIs, handling different data formats, encryption, and data storage. Overall it argues that PHP can serve as an effective middleware solution in embedded systems development.

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

7. 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

49. 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

66. Performance Tunning

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

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

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

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

74. VLD
● An opcode dumper

75. A simple comparison

76. array_push

77. array assignment

78. # of Opcodes = 16

79. # of Opcodes = 10

80. Tunning

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

82. DB is always the bottleneck

83. 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

84. 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;

85. 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

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

87. Integration

88. 這又是另外一個故事了

89. Thanks

90. Special Thanks
● Jeffrey Chen
● Simon Wang

91. Q &A