Exposing data from WCF services as oData

Question

Is it possible to use oData with a WCF service application but not use WCF Data Services?

It will be great if someone could shed more light on oData. I have done some Googling on this topic, but whenever I search for "wcf odata", I get information about WCF Data Services.

Any help/links will be appreciated.

Answer 1

WCF Data Services is the Microsoft implementation of the general OData protocol. As such, only WCF Data Services are / support / implement OData - a "normal" WCF service does not (and can not).

You might need to elaborate exactly why you feel the need or urge to use OData but not use WCF Data Services. What's the issue / problem you have with that setup? WHY do you want to use only a "normal" WCF service??

Update: ok, so you want to have services that expose data in different fashions and with different methods. What you could do is create a regular WCF service that's exposing both SOAP endpoints as well as a webHttpBinding REST endpoint. This will work - but then it's a "regular" WCF service, with methods that take parameters and return some data structure. This is not WCF Data Service (OData).

OData is more of a "here's my data collection, you can browse around in it" kind of approach - it's more about exposing an entire data model to the outside world using REST. This doesn't mix and match with SOAP - which is a lot more procedure-oriented, e.g. LoadCustomer, SaveInvoice and so forth.

So while it's absolutely possible to have procedure-oriented WCF services exposing both SOAP and REST endpoints at the same time, I don't really see how you can mix and match the "expose-this-resource" kind of approach for WCF Data Services / OData with a SOAP binding - this just doesn't work, I believe.

So if you must expose your data model of WCF Data Services (OData), you will need to author a second, pretty different looking regular WCF services for the SOAP clients, that might be based on the same data in the end (access the same database, for instance), but it's "face" will look quite different.

Answer 2

There is a new(ish) project from Microsoft called WCF WebApi (NuGet Package), which is simplifying doing RESTful WCF. It really takes to heart the "Representation" part of REST, so that you can expose your data in many representations (JSON, XML, oData, PNG, etc) based on content negotiation (or optionally whatever convention you want) all from the same service contract operation. Currently baked into the framework is the ability to support oData GET queries, by simply returning a collection .AsQueryable().

While this isn't a pure WCF/oData solution, as your question is speaking to, I thought I would mention the project in case it fit your specific requirements. The current Go-Live licensing might prove prohibitive, as might the "preview" status of this code; but if not, this may be a solution for you.

* UPDATE * This project was rolled into ASP.NET (usually in conjunction with ASP.NET MVC) and is no longer under the WCF team. The new product is called ASP.NET WebAPI.