we are currently on windows server 2008 R2, IIS 7.5 and we are going to open some of our data via WCF services.
To do that, we are planing to host our services on IIS but I heard that it is not a good idea for WCF services.
The problem with the WAS is that it is general purpose hosting engine. it's actually unaware that it's actually hosting a WCF service or a website (as far as I know)
I heard that we can install an extension to the WAS called the Windows Server AppFabric.
Thanks in advance.
I don't think IIS us a bad idea - many developers use IIS to host their WCF services. IMHO you'd only use what you need, so if all you need is a hosting framework, then IIS is a very good option for WCF services. It is (almost) unaware that it's hosting a WCF service, but that in the majority of the cases isn't an issue.
Windows Server AppFabric as it's currently released provides three capabilities: a distributed caching system (so if you need to scale out your service you can use this cache to share state among the nodes); a packaging / deployment interface (in which you can package a project and deploy it a little easier in IIS); and a management / monitoring interface (where you can monitor the instances of WCF and Workflow services which are running in your machine).
Answers to your questions: