What is RESTGroups?

RESTGroups is an extension of the Spread Toolkit with support for constructing robust RESTful Web Services and any distributed applications that use HTTP as a transport protocol. Spread toolkit provides a messaging service for point-to-point and multicast communication that is resilient to faults across local and wide area networks. Spread services range from reliable messaging to fully ordered messages with delivery guarantees. Spread supports several programming languages, for example C/C++, Java and Python. RESTGroups functions as a front-end for Spread that is architecture- and language-independent, i.e. communicating services can be implemented using different languages and run on different platforms.

RESTGroups consists of an API to the Spread library that conforms to REST, a daemon server for communication with a Spread daemon (they run on each computer that is part of the processor group), and various demonstration programs. REpresentational State Transfer (REST) is a key design idiom in the web services world that embraces a stateless client-server architecture in which the web services are viewed as resources and can be identified by their URLs. Web service clients that want to use these resources access a particular representation by transferring application content using a small globally defined set of remote methods that describe the action to be performed on the resource.

RESTGroups provides representation of Spread services as resources identified by URLs with a simple but powerful API that only uses the following methods of the HTTP protocol for invoking the services:

• GET is used to retrieve data (for example, a message) or perform a query on a resource. The data returned from the RESTGroups service is a representation of the requested resource.
• POST is used to create a new resource (for example, to extend a process group with a new process or to send a new message). The RESTGroups service may respond with data or status indicating success or failure.
• PUT is used to update existing resources or data (for example, ??).
• DELETE is used to remove a resource or data (for example, to remove a process from a process group). (In some cases, the update and delete actions may be performed with POST operations as well.)

See a short demo movie explaining the main concepts of group communication and RESTGroups's API to Spread using a small example program.

Distribution

A tarball file with source files is available here:

To deploy demonstration programs you will need the Spread 4.1, available from http://www.spread.org/.

Team

• Tadeusz Kobus
• Paweł Wojciechowski

Documentation

• API documentation in HTML format
• Koncepcja usługi komunikacji grupowej oraz mechanizmu operacji atomowych dla systemów opartych na paradygmacie SOA (In Polish). Tadeusz Kobus, Mateusz Mor, Paweł T. Wojciechowski. Technical Report TR-ITSOA-OB2-1-PR-09-3, Institute of Computing Science, Poznań University of Technology, May 2009.