Node.js is one of the newest and most exciting open web technologies to surface in the last few years. This presentation explores considerations for business stakeholders and technology decision-makers looking to switch their existing stacks to Node.js. Mike examines questions like: What is Node.js? What are the benefits from using Node.js? What are the drawbacks? Who is using this technology today? In a world of people demanding responsive, real-time applications, Node.js makes a compelling argument for change. Mike includes case studies from companies like LinkedIn and Yammer to illustrate the business cases that make sense. About Node.js: Node.js (Node) , the brain child of Ryan Dahl, was released in 2009 when he worked for Joyent, Inc. Node is one of the most hyped technologies to arrive on the web development scene, though it is also one of the most misunderstood. So what is Node? Is it a programming language like Python, Java, or C++? Is it an application framework like Django, Rails, or Symphony? Is it maybe some type of middleware that can be plugged into existing web stacks like Memcached or RabbitMQ? Actually, it is none of the above. Node is simply a set of JavaScript language bindings to Google's powerful V8 engine. This begs the question: "what is a language binding and what is V8?"

1. 6000 Greenwood Plaza Blvd
Suite 110
Greenwood Village, CO 80111
303.798.5458
www.aspenware.com
Business
Considerations
for Node.js Applications
Michael Filbin
m.filbin@aspenware.com

2. Agenda…
• Definitions
• Introduction to Node.js
• Problems it attempts to solve
• Drawbacks and challenges to adoption
• Use cases and case studies
• Hello World example (if time)
• Summary and conclusion
Business Considerations
for Node.js Applications

3. Who Am I?
• Consultant at Aspenware Internet Solutions Inc.
• Background in Open Source technologies
• Currently JavaScript engineer at Pearson
• Member of Linux and Free Software foundations
• Co-founder of Gogy Inc.
Business Considerations
for Node.js Applications

4. Who Are You?
Business Considerations
for Node.js Applications

5. Acknowledgements
Business Considerations
for Node.js Applications

6. Key Terms…
• API: A collection of publically exposed methods to
facilitate use of a library
• Asynchronous: The execution of a function and its
result are not mutually exclusive.
• JavaScript Runtime: Optimizes and executes
JavaScript code
• Language Binding: Uses of one programming language
to ‘wrap’ a library in another
• Callback: A reference to executable code that is passed
as an argument to a function.
• I/O Operations: Operations that involve reading/writing
data through some time of interface.
• Procedural Programming: Programs are expressed in
terms of steps (procedures) to be carried out
• Event-driven Programming: Execution of a program is
carried out in response to events.
• Blocking Process: A process that prevents the
continuation of execution until it returns.
Business Considerations Brief Introduction to Node
for Node.js Applications

7. What Is Node?
Business Considerations
for Node.js Applications

8. What does Node do?
• API for interacting with low-level system libraries
asynchronously
• Leverages features inherent in the JavaScript language
• Intends to manage concurrency, latency, parallelism
Business Considerations
for Node.js Applications

9. Visualizing Latency
300000000
250000000
240000000
Processor
Cycles
200000000
150000000
100000000
41000000
50000000
3
14
250
0
1
L1
Cache
3
L2
Cache
14
RAM
250
Hard
Disk
41000000
Network
240000000
Business Considerations
for Node.js Applications

10. Web Application Life Cycle?
Route Request to Controller Action
Respond to Request
Make Database Query
Write to log file
Operate on results
Business Considerations
for Node.js Applications

11. Traditional Scaling Model…
Route Request to Controller Action Route Request to Controller Action Route Request to Controller Action Route Request to Controller Action Route Request to Controller Action
Respond to Request Respond to Request Respond to Request Respond to Request Respond to Request
Make Database Query Make Database Query Make Database Query Make Database Query Make Database Query
Operate on results Operate on results Operate on results Operate on results Operate on results
Operate on results Operate on results Operate on results Operate on results Operate on results
Route Request to Controller Action Route Request to Controller Action Route Request to Controller Action Route Request to Controller Action Route Request to Controller Action
Respond to Request Respond to Request Respond to Request Respond to Request Respond to Request
Make Database Query Make Database Query Make Database Query Make Database Query Make Database Query
Operate on results Operate on results Operate on results Operate on results Operate on results
Operate on results Operate on results Operate on results Operate on results Operate on results
Route Request to Controller Action Route Request to Controller Action Route Request to Controller Action Route Request to Controller Action Route Request to Controller Action
Respond to Request Respond to Request Respond to Request Respond to Request Respond to Request
Make Database Query Make Database Query Make Database Query Make Database Query Make Database Query
Operate on results Operate on results Operate on results Operate on results Operate on results
Operate on results Operate on results Operate on results Operate on results Operate on results
Business Considerations
for Node.js Applications

12. Resource Limited Scaling
Load
Balancer
Web
App
App
Server
Server
Server
Search
Database
Engine
Business Considerations
for Node.js Applications

13. Resource Limited Scaling
Business Considerations
for Node.js Applications

14. Node’s Execution Model
• Using an event loop
• Event occurs (emitted)
• Non-I/O operations return immediately
• I/O operations defer to libeio or libuv
• I/O interrupt received and callback is executed
• Data returned to client
Event
1
libeio
FS
…
Network
Crypto
Event
N
libuv
All
on
a
single
thread
on
a
single
processor
RESTful Web Services
with Node.js

15. Event Loop Analogy
RESTful Web Services
with Node.js

16. Node Architecture…
Async
DNS
V8
RunLme
OpenSSL
libuv
libeio
Business Considerations
for Node.js Applications

17. Scaling Node Applications:
Load
Balancer
/
Reverse
Proxy
App
Content
Server
Delivery
Network
(CDN)
Search
Database
Engine
Business Considerations
for Node.js Applications

18. Managing Node Dependencies
• ‘Requiring’ external libraries is handled though the
CommonJS module pattern.
• 3rd party libraries distributed though NPM package
management tool
• Packages can be installed globally or locally
• Application dependencies can be expressed in a manifest
file (package.json)
Business Considerations
for Node.js Applications

19. Including Dependencies
<script type="text/javascript" src="scripts/myscript.js"></script>
Business Considerations
for Node.js Applications

20. Including Dependencies
// System-wide (global) libraries/modules
// Stored in /usr/local/lib/node_modules
var path = require('path');
var fileSystem = require('fileSystem')
// Local (project) libraries
// ./node_modules
var restify = require('restify');
var nconf = require('nconf');
// Including scripts from somewhere in
// the file system
var MyModel = require("./lib/models/
MyModel");
Business Considerations
for Node.js Applications

21. Use Cases for Node.js
• Creating REST APIs (JSON APIs)
• Creating chat servers or messaging clients
• Single-page RIA
• Data Streaming
Business Considerations
for Node.js Applications

22. Challenges to
Adoption
Business Considerations
for Node.js Applications

23. Evolving API
• (2012.01.06 – 24.10.2012): 46 Releases!
• Minor, even release number is stable
• Minor, odd release number is development
Business Considerations
for Node.js Applications

24. Windows Support
• Was written originally for *NIX systems
• Node core largely supports WIN, 3rd party libs… not so
much
• Build tools recently switched to better support WIN
Business Considerations
for Node.js Applications

25. Error Handling & Debugging
• Asynchronous code breaks call stacks
• For synchronous code, you must handle exceptions
carefully (try/catch)
• For asynchronous code, you must pass errors around to
callbacks
Business Considerations
for Node.js Applications

26. Example:
outerFunction(arg1, arg2, function (callback){
if(!arg1 || !arg2){
return callback(new Error("Are you forgetting something?"));
} else {
return innerFunction(ar1, arg2, function (error, data){
if(error){
callback(error);
} else {
try{
var json = JSON.parse(data)
callback(null, json);
} catch(error){
callback(error);
}
}
})
}
});
Business Considerations
for Node.js Applications

27. Asynchronous Code is Complex
• Deeply nested callbacks can become difficult to read &
maintain
Business Considerations
for Node.js Applications

28. Single Threaded
Business Considerations
for Node.js Applications

29. Entire Stack Must Be Non-Blocking
Business Considerations
for Node.js Applications

30. Case Studies
Business Considerations
for Node.js Applications

31. Linkedin
• Originally build on Rails Application Framework
• Need to composite service calls for the client
• Persistent socket connections
• Much smaller code base (~50Kb when minified)
• Reduce the amount of memory leak (from mongrel)
• Benchmarked at 20X faster
• Using 10% original resource (from 30 servers to just 3! &
300MB or RAM to just over 30MB)
• More Stable
Business Considerations
for Node.js Applications

32. Linkedin Mobile Architecture
iOS
Android
Mobile
Client
Web
Libraries
Node.js
Mobile
Server
MongoDB
Database
ApplicaLon
Bg.
Data
Data
Other
Tracking
Queue
Service
Service
Process
Business Considerations Credit: Kirin Prasad, Linkedin Mobile Engineer
for Node.js Applications

33. Yammer
• Similar use case as LinkedIn (cross-domain proxy)
• JSON Out/JSON In
Business Considerations
for Node.js Applications

34. Resources:
• Concurrent Programming for Scalable Web Architectures, Benjamine Erb.
http://berb.github.com/diploma-thesis/community/042_serverarch.html
• Benchmark Comparisons:
http://shootout.alioth.debian.org/u64/benchmark.php?
test=all&lang=nodejs&lang2=fsharp
Business Considerations
for Node.js Applications

35. Conclusion
Business Considerations
for Node.js Applications

36. Summation
• Node.js leverages an evented programming model
to handle concurrency and availability
• Because Node does not rely on threads/processes to
scale, it can use considerably fewer resources
• Fewer resources means lower cost
• More concurrent users means greater revenue
potential
• Because node support the real-time web, you can
improve your user’s experience
Business Considerations
for Node.js Applications

37. 6000 Greenwood Plaza Blvd
Suite 110
Greenwood Village, CO 80111
303.798.5458
www.aspenware.com
Michael
Filbin
Michael Filbin, Software Developer m.filbin@aspenware.com