Architecting large Node.js applications

largeArchitecting

node.jsapplications

Monday, October 22, 12

@sergimansilla


P r o g r a m

☐ C l o u d 9 I D E ?

☐ G r o w i n g p a i n s

☐ I n t r o d u c i n g A r c h i te c t

☐ Le s s o n s l e a r n e d


Normal developers


JavaScript Developer


Cloud9 IDE - http://c9.io


http://c9.io

http://c9.io

debuggingReal


(Smart!)Code completion


analysisStatic


FreeLinux VM


Bring your own machineMonday, October 22, 12

Real terminal


Collaboration


See each other typeDebug togetherProductivity++


Create

Share Test

Deploy Run/Debug


P r o g r a m

☑ C l o u d 9 I D E ?

☐ G r o w i n g p a i n s




10,000s

of JavaScriptLOC


dynamic,typedweakly

languageMonday, October 22, 12

onethreadsingle


Remote VM

Cloud9 datacenter

IDE server Remote VM

Remote VM

Openshift


Pure madness


ModularizationMonday, October 22, 12

Blackboxcoding



Java/.NET

Node.js

import(s)

require


abstractingawayGreat for

require


applicationmodularity

Not Great forrequ

ire


duplicated modulesmaps to folder names

Relies on FSrequ

ire

Hard to configure module


Dependency error handling

coding time compile time run time

KA-BO

OM!

- Server crash- Unhappy customers- Developer gets fired


How to fix it?

Static dependency list

Named services

Easy configuration

Resolve at startup

No FS required

Pass an object


P r o g r a m

☑ C l o u d 9 I D E ?

☑ G r o w i n g p a i n s




Architect

github.com/c9/architect


https://github.com/ajaxorg/treehugger

https://github.com/ajaxorg/treehugger

Architect

Everything is a plugin

Plugins can consume plugins

An application is just a set of plugins


Dependency model

require

Architect

runtime

compile time


Dependency error handlingArchitect

coding time compile time run time

- Happy customers- Developer keeps job- Fails before release



Declare entity ‘presenter’ with behaviorUse ‘presenter’ to do a presentation


Presenter Presentation

Dependency model


Express our model

package.json

Builds dependency tree

executing codewithout



What’s next?

Extract the codeWrap in Architect plugin code

Make two plugins


Function signature

Call when done


Architect plugin code

Module.exportsOptions - we’ll get to thatImports - everything you ‘consume’Register - invoke when done




Easy to testMock dependencies


Assert ‘dance’ is called 11 times


No black magic

Specify dependency modelFeed architect a config file

Call ‘createApp’




Configuration

Per-plugin optionsNo global options objectSpecify in config file




Options

Automatically passed in at startupOptions are also dependencies

Fail if options aren’t present




Architect makes you think of your app as chunks of functionality

rather than sets of classes


Think ‘chunks of functionality’

Implicit type constraintsKeep implementation private

Swap features instead of interfaces


How does Cloud9 use it?

Open source version

Local version (OS + sync)

Hosted version

Normal

FTP

SSH



Swap feature per implementation

On Open source: talk local filesystem

On FTP: talk FTP library

On SSH: talk via a SSH bridge


Here is something your DI framework can’t do


IDE instance(FTP)

IDE instance(SSH)

IDE instance(Normal)

IDE instance(Normal)

Single node.js process

Other code (dashboard etc.)



Architect can do

Multiple instances of same pluginRun independently

But in the same process




HERE’S SOMETHING COOL


Centralized eventbus

Loose coupling between plugins

No hard dependencies!

Can also do inter-context communication


Eventbus

Plugin

Other plugin

Emit event

React on event




And now scale up

Need something inter-server

Swap it with i.e. Redis PubSub

Plugins will never notice

Modular awesomeness!


P r o g r a m

☑ C l o u d 9 I D E ?

☑ G r o w i n g p a i n s

☑ I n t r o d u c i n g A r c h i te c t



Modularize in feature blocks

Don’t over engineerDon’t create too small blocksThey aren’t interfaces!


Use dependency injection

Architect (JavaScript)StructureMap (.NET)Spring (Java)


Avoid context switching

Less code!Less errors!Less boilerplate!


Loose coupling

Use an event bus

Smaller dependency graph


github.com/c9/architect


http://c9.io

http://c9.io

Happy coding!


Sergi Mansilla@sergimansilla

github.com/sergi

http://c9.io


http://c9.io

http://c9.io

Architecting large Node.js applications

Technology

n g pai n s i n t ro

c i n g arc hitec t

p ro g ra

architect plugin codeextract

architect plugin codemodule

interserver swap i

dependency tree

plugin plugins