Introduction
Osyl OpenSyllabus Client needs to interact with the Sakai's Server. OpenSyllabus used all the Sakai's platform services we needed, in addition of our own services.GWT interacts with a server
RPC
RPC (Remote Procedure Call) is the communication's Ajax workhorse of GWT.
GWT offers an easy-to-use RPC mechanism for the exchange of Java objects with a server using HTTP. that makes it easy for the client-side code and the server-side code to communicate Java objects (serialized objects) back and forth using standard HTTP.
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Remote procedure call (RPC) is a communication technique used in distributed client-server architecture which allows a program to cause a subroutine to be executed remotely on another computer. That said, the remote subroutine is written like a local one, avoiding the details of the interaction with the network. Note : Remote Method Invocation (RMI) can be considered as refering to a particular implementation of RPC in Java. |
In server mode, GWT provides automatic serialization of the request and automatic deserialization of the response from the server.
So, to communicate from our GWT web client to the Sakai's web server, we have just need to define serializable POJOS
In fact, OpenSyllabus server used GWT special RPC GWT servlets to implement exchange of serialized Models Objects with the client application.
Furthermore, OpenSyllabus could load complex data from the server by leveraging the GWT XML and JSON libraries.
REST based SData
OpenSyllabus Client uses REST based calls to SData (Sakai's Data) services on the Sakai server.
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The SData service is called via a REST Servlet in Sakai. SData allows data exchanges in JSON format of information about site, resource, etc.) In order to parse JSON in GIT we have used the JSONParser from the GWT library.
Basic communication techniques
GWT also offers more basic communication techniques, including the standard Ajax asynchronous HTTP request to load simple text or HTML from the server.
Communication architecture
