Using REST APIs of TFS and Visual Studio Online

Microsoft has been providing APIs for Team Foundation Services (TFS) from the earliest version of TFS (since Visual Studio 2005). Using these APIs, we can create TFS clients and also write event handlers for the events raised by TFS. In the early days of TFS, we were expected to write only Microsoft .NET clients. We could give reference to the components that contained these APIs, and use the referred classes in the code to access various TFS services. Over the years, to facilitate collaboration between different platforms, we are now also expected to create clients in technologies other than Microsoft.NET; like Java, JavaScript and many others.