Web API or WCF - An Architectural Comparison

WCF & ASP.NET Web API – An
Architect’s Primer
 Presented at Southern California .NET Architecture User
Group; Feb 21st 2013.

Adnan Masood MS (CS). MCSD. MCPD.
Software Architect & Doctoral Candidate
blog.AdnanMasood.com
adnan.masood@owasp.org

About Me
Adnan Masood works as a system architect / technical lead for Green dot
Corporation where he develops SOA based middle-tier
architectures, distributed systems, and web-applications using
Microsoft technologies. He is a Microsoft Certified Trainer holding several
technical certifications, including MCPD (Enterprise Developer), MCSD
.NET, and SCJP-II. Adnan is attributed and published in print media and
on the Web; he also teaches Windows Communication Foundation (WCF)
courses at the University of California at San Diego and regularly presents
at local code camps and user groups. He is actively involved in the .NET
community as cofounder and president of the of San Gabriel Valley .NET
Developers group.

Adnan holds a Master’s degree in Computer Science; he is currently a
doctoral student working towards PhD in Machine Learning; specifically
discovering interestingness measures in outliers using Bayesian Belief
Networks. He also holds systems architecture certification from MIT and
SOA Smarts certification from Carnegie Melon University.

Abstract
WCF vs. ASP.NET Web API – An Architect’s Primer

ASP.NET Web API is a framework that makes it easy to build HTTP services that reach a
broad range of clients, including browsers and mobile devices. The new ASP.NET Web
API is a continuation of the previous WCF Web API projection. WCF was originally
created to enable SOAP-based services and other related bindings. However, for simpler
RESTful or RPCish services (think clients like jQuery) ASP.NET Web API is a good
choice.

In this meeting we discuss what do you need to understand as an architect to implement
your service oriented architecture using WCF or ASP.NET web API. With code
samples, we will elaborate on WCF Web API’s transition to ASP.NET Web API and
respective constructs such as Service vs. Web API controller, Operation vs. Action, URI
templates vs ASP.NET Routing, Message handlers, Formatters and Operation handlers vs
Filters, model binders. WebApi offers support for modern HTTP programming model with
full support for ASP.NET Routing, content negotiation and custom formatters, model
binding and validation, filters, query composition, is easy to unit test and offers improved
Inversion of Control (IoC) via DependencyResolver.

Agenda
 Difference between Web API and WCF REST Services
 How to Migrate from WCF Web API to ASP.NET Web API
 Model for RESTFul Maturity
 WCF or Web API – confusing?
 WCF evolution and strengths
 What ASP.NET Web API brings to the table?
 Architectures and comparing non functional requirements

Architectural Questions
 What is the purpose of the WebAPIs?
 Why do we need REST HTTP services? What’s wrong with
SOAP-over-HTTP?
 Why did the WebAPIs move from WCF to ASP.NET MVC?
 Is there still a use for WCF? When should I choose Web APIs
over WCF?

History of Web Services
1989 - Tim Berners-Lee invents HTTP/HTML
1998 - XML 1.0, SOAP begins ratification
2001 - SOAP standard
2000 - Fielding dissertation on REST

History of SOAP
Before SOAP we did this…
 HTTP GET/POST with Plain Old XML (POX)
 Out-of-band exchange of DTD or schema
SOAP evolved to provide us
 Specifications
 Tooling
 Metadata
 Productivity
 location transparency

Tools Evolution
 ASP.NET Web Services (ASMX)
 Web Services Enhancements (WSE)
 •.NET 3.0 => WCF = SOAP+WS*
 •.NET 3.5 => WCF = SOAP+WS*/ HTTP
 WebHttpBinding, contract attributes, JSON
 •REST Starter Kit (Codeplex)
 •WCF 4 => Features from starter kit
 •WCF Web API => ASP.NET Web API

Web API or WCF - An Architectural Comparison

SignalR
 What is ASP.NET SignalR
 ASP.NET SignalR is a new library for ASP.NET developers that makes it
incredibly simple to add real-time web functionality to your applications.
What is "real-time web" functionality? It's the ability to have your server-
side code push content to the connected clients as it happens, in real-
time.
 You may have heard of WebSockets, a new HTML5 API that enables bi-
directional communication between the browser and server. SignalR will
use WebSockets under the covers when it's available, and gracefully
fallback to other techniques and technologies when it isn't, while your
application code stays the same.
 SignalR also provides a very simple, high-level API for doing server to
client RPC (call JavaScript functions in your clients' browsers from
server-side .NET code) in your ASP.NET application, as well as adding
useful hooks for connection management, e.g. connect/disconnect
events, grouping connections, authorization.

The WCF Web API => ASP.NET
Web API
 WCF Web API -> ASP.NET Web API
 Service -> Web API controller
 Operation -> Action
 Service contract -> Not applicable
 Endpoint -> Not applicable
 URI templates -> ASP.NET Routing
 Message handlers -> Same
 Formatters -> Same
 Operation handlers -> Filters, model binders

Integrated stack
 Modern HTTP programming model
 Full support for ASP.NET Routing
 Content negotiation and custom formatters
 Model binding and validation
 Filters
 Query composition
 Easy to unit test
 Improved Inversion of Control (IoC) via DependencyResolver
 Code-based configuration
 Self-host

SOAP
Simple Object Access Protocol
Uses a standard XML Schema over HTTP
Extremely cross platform compatible
Extremely Slow

REST
Representable State Transfer
Uses standard HTTP
Can use any text format including XML

XML vs JSON
XML tag based document formatting
Javascript Notation by Douglas Crockford
JSON less verbose than XML, more lightweight
Mobile devices have limited bandwidth

Public APIs
Twitter
Facebook
Flickr
Amazon
iTunes

WebAPI
Available now as Nuget Package
Built-in as part of MVC 4
Take advantage of HTTP features directly

Default route will use http method for action
Controller/action/id
API/Controller/id GET/POST/PUT/DELETE

HTTP methods as Actions

HTTP Method meanings
Get - Return an existing document
Post - Create a new document
Put - Update a document
Delete - Self explanatory

Configure Transport
Set Xml or JSON based on Content-Type or Accept
header
Accept: application/xml
Can also use Odata

Return Codes
Now have the ability to specify return codes beside 200
HttpResponseMessage<YourEntity>
HttpStatusCode.Created 201
response.Headers.Location = new Uri()

Http Status codes
201 Created
200 Success/204 Success but No Content
403 Not authorized
404 Does not exist
500 Server Error
301 Uri Moved

Security
[Authorize()]
https over port 443
Security Tokens
OAuth

Testing WebAPI
Download Fiddler2
Firebug (Firefox)
Chrome
On Mac use CocoaRestClient

Consuming WebAPI
Web Apps
(ASP.NET, MVC, PHP, Java, ColdFusion, Ruby(Rails), Pyt
hon, Perl(if you are masochistic))
JavaScript/JQuery
Mobile (iOS, Android, WP7, Blackberry OS)

Develop WebAPI and iOS on
Same Computer
Parallels or VMWare
Set Network Adapter to Bridged
Run Visual Studio as Administrator
Host on IIS (do not use IIS Express or Casini)

Consuming WebAPI
in iOS
Use NSURLConnection delegate or GCD
Show progress while waiting on response
Use JSON over XML
NSJSONSerialization class (new in iOS 5)

XML Parsing in iOS
NSXMLParser (Slowest)
libxml2 (C api)
TBXML (DOM, Fastest, no write or xpath)
TouchXML (DOM supports xpath, no write)
KissXML (based on Touch, can write)
GDataXML (DOM, from Google)
RaptureXML (DOM, supports xpath)

Create DefaultHttpClient();
Create request with HttpGet(Url);
Create response handler BasicResponseHandler();
httpClient.execute(request, handler);

Call WebAPI from Android

JSON in Android
use the JSONObject to parse
JSONObject jo = new JSONObject(jString);
jo.getJSONObject(“car”);
jo.getJSONArray(“cars”);

XML Parsing in Android
DOM, SAX and Pull
W3C Dom parser
Standard Java Sax Parser
SJXP (Pull parser)

WebAPI as persistence
Don’t use WebAPI as default persistence on Mobile
Both Android and iOS have device persistence
local storage, CoreData and SQLite
iCloud to sync between iOS devices

Demo

Slides courtesy Michelle L. Bustamante

Comparison

 Transport Coupling
 HTTP is an application protocol, not just a transport protocol
 TCP, named pipes, MSMQ, UDP are transport only
 WCF is decoupled, message can traverse any
 Performance
 Sometimes a faster protocol/serialization mechanism is needed


Security
 Web API
 HTTP Services
 HTTPS / SSL
 Authorization header or custom headers
 OAuth 2.0
 WCF Services
 HTTPS / SSL
 SOAP Message Security
 WS-Trust
 OAuth 2.0


Error Handling
 Mostly automatic
 Helpful to control how things are returned to Ajax clients
 Setting status code and message


Hosting
 IIS or Self hosting


Feature Comparison
 Productivity
 Design effort
 Complexity
 Client code and proxy generation
 Communication stack
 State
 Both should be stateless
 Caching
 Built in to HTTP, but beware

The WS* Overload


SOAP vs REST – Focus on the
necessities

Slide courtesy Michelle L. Bustamante

Web API Selling Points
 If we need a Web Service and don’t need SOAP, then ASP.Net
Web API is very useful.
 Web API - Used to build simple, non-SOAP-based HTTP Services
on top of existing WCF message pipeline.
 Web API - No need for configurable like WCF REST services
 Web API - No need for Data contracts
 Web API - Could create fully blown REST Services
 Simple service creation with Web API. With WCF REST
Services, service creation is difficult.
 WCF is any wire protocol. Web API is focused at one thing, being
easy to define and expose and consume, while also facilitating
doing things in a RESTful way.
 Web API is light weight architecture.

The unified model? Kinda, sorta
Obsolete

Revision - WCF to ASP.NET Web
API
 ApiController (!=Controller, no common BaseClass)
 ASP.NET Routing (MapHttpRoute)
 Convention over Configuration
 Web API to go / NuGet Packages
 Web API hosted in ASP.NET: AspNetWebApi
 Self-hosted Web API: AspNetWebApi.Selfhost
 HttpClient including XML and JSON formatters:
 System.Net.Http.Formatting
 JsonValue for navigating and manipulating JSON:
 System.Json
 Go Live License

How to Migrate from WCF Web
API to ASP.NET Web API
 http://wcf.codeplex.com/wikipage?title=How%20to%20Migrate
%20from%20WCF%20Web%20API%20to%20ASP.NET%20
Web%20API

Resources & Credits
 http://www.asp.net/web-api
 http://blogs.msdn.com/b/henrikn/
 http://weblogs.asp.net/scottgu/archive/tags/Web+API/defa
 ult.aspx
 http://stackoverflow.com/questions/tagged/asp.net-web-api
 https://github.com/ChristianWeyer/Thinktecture.Web.Http
 http://blog.alexonasp.net
 http://aspnet.uservoice.com/forums/147201-webapi/suggestions/2618312-allow-for-
non-asynchronouscalls-to-the-web-api
 Thanks to Michele Leroux Bustamante’s slide-deck from Windows Azure
connections, March 26-29, 2012 Las Vegas, NV which I thoroughly enjoyed.
 Ida Flatow’s article on web API http://www.codeproject.com/Articles/341414/WCF-or-
ASP-NET-Web-APIs-My-two-cents-on-the-subjec
 Alexander Zeitler’s Web API Round up
 David Fekke Web API - www.fekke.com/Media/Default/powerpoint/webapi.ppt

Summary
 Choose wisely and quantitatively; avoiding the shiny object
syndrome.
 Enterprise WCF implementations will continue to be
important…
 The trend to HTTP services is here to stay, embrace it
 If you are starting from scratch for a mobile / web heavy
service, look at HTTP services first

Thank You!
Adnan Masood
adnan.masood@owasp.org
@adnanmasood
 Blog: www.AdnanMasood.com
 Pasadena .NET User Group: www.sgvdotnet.org

Web API or WCF - An Architectural Comparison

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Web API or WCF - An Architectural Comparison