The document discusses architecting large Node.js applications. It introduces the Cloud9 IDE and how it was used to build a JavaScript application with 10,000s of lines of code. It describes how the application was difficult to maintain due to lack of modularity. The Architect module is introduced as a way to modularize Node.js applications by treating everything as plugins that can import other plugins. Architect allows defining dependency models, easy testing of modules, and configuration of modules through options. Cloud9 uses Architect to build features like local, FTP, and SSH versions of the IDE that can run independently in a single process. Architect also enables loose coupling between modules through an event bus and centralized configuration.

1. large
Architecting
node.js
applications
Monday, October 22, 12

2. @sergimansilla
Monday, October 22, 12

3. P ro g ra m
☐ C l o u d9 ID E?
☐ Grow in g pai n s
☐ I n t ro du c i n g Arc hitec t
☐ Le ss on s le arn e d
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4. Normal developers
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5. JavaScript Developer
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6. Cloud9 IDE - http://c9.io
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7. Real
debugging
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8. (Smart!)
Code completion
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9. Static
analysis
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10. Free
Linux
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VM

11. Bring your own machine
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12. Real terminal
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13. Collaboration
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14. See each other type
Debug together
Productivity++
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15. Create
Deploy Run/Debug
Share Test
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16. P ro g ra m
☑ C l o u d9 ID E?
☐ Grow in g pai n s
☐ I n t ro du c i n g Arc hitec t
☐ Le ss on s le arn e d
Monday, October 22, 12

17. 10,000s
LOC
of JavaScript
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18. dynamic,
weakly
typed
language
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19. one
single
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thread

20. Openshift
Cloud9 datacenter
Remote VM
IDE server Remote VM
Remote VM
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21. Pure madness
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22. Modularization
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23. Black
box
coding
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24. Monday, October 22, 12

25. Java/.NET import(s)
Node.js require
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26. Great for
re
requi
abstracting
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away

27. re
requi
Not Great for
application
modularity
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28. re
requi
Relies on FS
duplicated modules
maps to folder names
Hard to configure module
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29. Dependency error handling
coding time compile time run time
!
OM
- BO
KA
- Server crash
- Unhappy customers
- Developer gets fired
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30. How to fix it?
Static dependency list Resolve at startup
Named services No FS required
Easy configuration Pass an object
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31. P ro g ra m
☑ C l o u d9 ID E?
☑ G row i n g pai n s
☐ I n t ro du c i n g Arc hitec t
☐ Le ss on s le arn e d
Monday, October 22, 12

32. Architect
github.com/c9/architect
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33. Architect
Everything is a plugin
Plugins can consume plugins
An application is just a set of plugins
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34. Dependency model
require runtime
Architect compile time
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35. Dependency error handling
Architect
coding time compile time run time
- Happy customers
- Fails before release - Developer keeps job
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36. Monday, October 22, 12

37. Declare entity ‘presenter’ with behavior
Use ‘presenter’ to do a presentation
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38. Dependency model
Presenter Presentation
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39. Express our model
package.json
Builds dependency tree
without
executing code
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40. Monday, October 22, 12

41. What’s next?
Wrap in Architect plugin code
Extract the code
Make two plugins
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42. Function
signature
Call when done
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43. Architect plugin code
Module.exports
Options - we’ll get to that
Imports - everything you ‘consume’
Register - invoke when done
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44. Monday, October 22, 12

45. Monday, October 22, 12

46. Easy to test
Mock dependencies
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47. Assert ‘dance’ is called 11 times
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48. No black magic
Specify dependency model
Feed architect a config file
Call ‘createApp’
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49. Monday, October 22, 12

50. Monday, October 22, 12

51. Configuration
Per-plugin options
No global options object
Specify in config file
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52. Monday, October 22, 12

53. Monday, October 22, 12

54. Options
Automatically passed in at startup
Options are also dependencies
Fail if options aren’t present
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55. Monday, October 22, 12

56. Monday, October 22, 12

57. Architect makes you think of your app as
chunks of functionality
rather than sets of classes
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58. Think ‘chunks of functionality’
Implicit type constraints
Keep implementation private
Swap features instead of interfaces
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59. How does Cloud9 use it?
Open source version
Local version (OS + sync)
Hosted version
Normal
FTP
SSH
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60. Monday, October 22, 12

61. Swap feature per
implementation
On Open source: talk local filesystem
On FTP: talk FTP library
On SSH: talk via a SSH bridge
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62. Here is something your
DI framework can’t do
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63. Single node.js process
IDE instance IDE instance
(FTP) (SSH)
Other code
(dashboard etc.)
IDE instance IDE instance
(Normal) (Normal)
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64. Monday, October 22, 12

65. Architect can do
Multiple instances of same plugin
Run independently
But in the same process
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66. Monday, October 22, 12

67. Monday, October 22, 12

68. HERE’S SOMETHING COOL
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69. Centralized eventbus
Loose coupling between plugins
No hard dependencies!
Can also do inter-context communication
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70. React on event
Other plugin
Event
bus
Emit event
Plugin
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71. Monday, October 22, 12

72. Monday, October 22, 12

73. And now scale up
Need something inter-server
Swap it with i.e. Redis PubSub
Plugins will never notice
Modular awesomeness!
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74. P ro g ra m
☑ C l o u d9 ID E?
☑ G row i n g pai n s
☑ I n t ro du c i n g Arc hitec t
☐ Le sson s learn ed
Monday, October 22, 12

75. Modularize in feature blocks
Don’t over engineer
Don’t create too small blocks
They aren’t interfaces!
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76. Use dependency injection
Architect (JavaScript)
StructureMap (.NET)
Spring (Java)
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77. Avoid context switching
Less code!
Less errors!
Less boilerplate!
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78. Loose coupling
Use an event bus
Smaller dependency graph
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79. github.com/c9/architect
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80. Happy coding!
Monday, October 22, 12

81. http://c9.io
Sergi Mansilla
@sergimansilla
github.com/sergi
Monday, October 22, 12