Which WCF Binding to use

Ever wondered which binding to use and why?  Ever wondered what is the difference between wsHttpBinding and ws2007HttpBinding?

For binding selection generally follow this:

Common Binding Capability Matrix

Name	Transport	Encoding	Interop. With non-.Net	Reliability	Ordered Delivery	Security
BasicHttpBinding	Http/Https	Soap1.1*/Mtom	Yes	No	No	None*, Transport, Message, Mixed
NetTcpBinding	Tcp	Binary	No	Yes (off*)	Yes (on*)	None, Transport*, Message, Mixed
NetNamedPipeBinding	IPC	Binary	No	No (**)	Yes (on*)	None, Transport*
WsHttpBinding	Http/Https	Soap1.2*/Mtom	Yes	Yes (off*)	Yes (on*)	None, Transport, Message*, Mixed
NetMsMqBinding	MsMq	Binary	No	No	No	None, Transport*, Message, Both
webHttpBinding	Http/Https	Xml*/Json	Yes	No	No	None*, Transport, Mixed

* = The Default.
** = NetNamedPipeBinding doesn't support reliability but is classified as inherently reliable because its communicating within the same machine.

Client Credentials Supported with Transport Security

Name	None	Windows	UserName	Certificate
BasicHttpBinding	Yes*	Yes	Yes	Yes
NetTcpBinding	Yes	Yes*	No	Yes
NetNamedPipeBinding	No	Yes*	No	No
WsHttpBinding	Yes	Yes*	Yes	Yes
NetMsMqBinding	Yes	Yes*	No	Yes
WebHttpBinding	Yes*	Yes	Yes	Yes

* = The Default.

Client Credentials Supported with Message Security

Name	None	Windows	UserName	Certificate	Issued Token
BasicHttpBinding	No	No	No	Yes*	No
NetTcpBinding	Yes	Yes*	Yes	Yes	Yes
NetNamedPipeBinding	N/A	N/A	N/A	N/A	N/A
WsHttpBinding	Yes	Yes*	Yes	Yes	Yes
NetMsMqBinding	Yes	Yes*	Yes	Yes	Yes
WebHttpBinding	N/A	N/A	N/A	N/A	N/A

Standard Behavior Defaults
[ServiceBehavior(
    AutomaticSessionShutdown=true,
    ConcurrencyMode=ConcurrencyMode.Single,
    InstanceContextMode=InstanceContextMode.PerSession,
    IncludeExceptionDetailInFaults=false,
    UseSynchronizationContext=true,
    ValidateMustUnderstand=true)]

[OperationBehavior(
        TransactionAutoComplete=true,
        TransactionScopeRequired=false,
        Impersonation=ImpersonationOption.NotAllowed)]

http://msdn.microsoft.com/en-us/library/ms751438.aspx
Of all the settings shown above InstanceContextMode is the most tricky.  Just because it defaults to PerSession, does not mean a session is always present.  If the binding does not support it or the service contract has been configured to not allow it (ServiceContract.SessionMode).

Here's a table showing the resulting instance context mode as a result of binding, service cotract's session mode and service behavior's instance mode.

Binding	Service Behavior Session Mode	Service Contract Context Mode	Resulting Actual Instance Mode
BasicHttp	Allowed or Not Allowed	Per Call or Per Session	PerCall
netTCP and netNamedPipes	Allowed or Required	Per Call	PerCall
netTCP and netNamedPipes	Allowed or Required	Per Session	PerSession
WsHttp (no message security and no reliability)	Allowed or Not Allowed	Per Call or Per Session	PerCall
WsHttp (with message secuity or reliability)	Allowed or Required	Per Session	PerSession
WsHttp (with message security or reliability)	Not Allowed	Per Call or Per Session	PerCall
WebHttpBinding	Allowed or Not Allowed	Per Call or Per Session	PerCall

Invalid configurations are not shown (invalid configurations will throw runtime exceptions such as InvalidOperationException: Contract requires Session, but Binding 'WebHttpBinding' doesn't support it).

Using JSON
I have little experience using JSON with the standard bindings, but my understanding is that you will be forced to use BasicHttpBinding or WebHttpBinding (not WsHttpBinding).  When doing so you will loose most of the support for other WCF features like security, reliability, ordered messages, and transactions.  With regard to security, SSL is supported by both Web and Basic, any other form of security (message and credentials) you'll be forced to hand craft service side extensions to support these.

WTF is Ws2007HttpBinding?
I came across this MSDN article that explains in detail the differences in a capability matrix between the Http bindings and W3C recommendations when to use which one.

http://msdn.microsoft.com/en-us/library/ms730294.aspx

Simply put, the difference with the newer 2007 Http binding is that is supports extensions to the Organization for the Advancement of Structured Information Standards (OASIS).  This means it supports minor changes to the WS Security standards. There is no real compelling reason for a developer to choose these bindings, there's no amazing new features to take advantage of, merely protocol level changes.  You might choose the 2007 binding if a client insists on a specific standard being used, or you're integrating into existing clients or services that use it.

Further Reading