REST (Representational State Transfer) provides access to resources
through the two methods GET and POST. REST Web services are a reduced subset
of the usual Web service stack.
The Axis2 REST implementation assumes the following properties:
REST Web services are Synchronous and Request Response in nature.
When REST Web services are accessed via GET, the service and the
operations are identified based on the URL. The parameters are assumed as
parameters of the Web service. In this case the GET based REST Web
services supports only simple types as arguments.
POST based Web services do not need a SOAP Envelope or a SOAP Body.
REST Web Services do not have Headers and the payload is sent
directly.
Axis2 can be configured as a REST Container and can be used to send and
receive RESTful Web services requests and responses. REST Web services can be
accessed in two ways, i.e. using HTTP GET and POST.
Doing REST Web Services with HTTP POST
Axis will acts as both a REST endpoint and SOAP endpoint. When a Message
is received, if the content type is text/xml and if the SOAP Action Headers
are missing, then the Message is treated as a RESTful Message. Else it is
treated as a usual SOAP Message.
On sending a message out, the fact that the message is RESTful or not, can
be decided from the client API.
Set a property in the client api.
...
Options options = new Options();
options.setProperty(Constants.Configuration.ENABLE_REST, Constants.VALUE_TRUE);
...
Sample REST - HTTP POST Client
There is an example named, userguide.clients.RESTClient.java which
demonstrates the usage of the above, using the "echo"operation of the
userguide.example1.MyService
of the samples.The class source will be as follows:
Access a REST Web Service via HTTP GET
Axis2 allow users to access Web services that have simple type parameters
via HTTP GET. For example the following URL requests the Version Service via
HTTP GET. But the Web service arriving via GET assumes REST. Other parameters
are converted in to XML and put in to the SOAP Body.
Result can be shown in the browser as follows:
For example, the following request,
will be converted to the following SOAP Message for processing by
Axis2.