WebSphere eXtreme Scale REST data service technical preview

The WebSphere® eXtreme Scale REST data service is a Java™ HTTP service that implements Microsoft’s ADO.NET Data Services. The REST data service allows any HTTP client to access a WebSphere eXtreme Scale 7.0 grid.

Updated 18 September 2009: Relationship, batch retrieval, and OrderBy support added.

Updated 30 October 2009: JavaScript Object Notation (JSON), full batch and partitioned entity relationship support added.

Microsoft® has defined the ADO.NET data services protocol for their .NET clients to talk to data sources via a REST interface, as shown in Figure 1 below. Clients can get metadata from the REST data service that defines data structure and relationships that they may subsequently use to get data.

The WebSphere eXtreme Scale REST data service is a Java HTTP service that implements Microsoft's ADO.NET Data Services protocol, as shown in Figure 2. The REST data service allows any HTTP client to access a WebSphere eXtreme Scale 7.0 grid and is compatible with the ADO.NET Data Services support that is supplied with the Microsoft .NET Framework 3.5 SP1. Microsoft Visual Studio 2008 SP1 can be used to build rich ADO.NET Data Service clients.

The WebSphere eXtreme Scale REST data service is a gateway between HTTP clients and the eXtreme Scale grid, communicating with the grid through an eXtreme Scale client connection, as shown in Figure 2. The WebSphere eXtreme Scale REST data service is a Java servlet (packaged in a WAR file) that may be deployed on an application server such as WebSphere Application Server or Tomcat. A cluster of gateways may be run for high availability. Multiple gateways may be run fronted by an IP sprayer for scalability.

The WebSphere eXtreme Scale REST data service allows HTTP clients, including .NET and AJAX clients, to use and exploit WebSphere eXtreme Scale. Figure 1 above shows ADO.NET clients using the ADO.NET Data Service protocol accessing their database data (SQL Server and DB2). In Figure 2, these same clients may now use WebSphere eXtreme Scale as a write-through/read-through cache provider to the database, thus gaining the scaling, performance, and availability advantages of WebSphere eXtreme Scale. Existing Visual Studio 2008 SP1 tooling can be used to build ADO.NET Data Services clients that use the WebSphere eXtreme Scale REST data service. All that changes is the HTTP URL for the data service. Non-Java clients using Ruby, Python, JavaScript and Perl may access WebSphere eXtreme Scale grids with this service.

The WebSphere eXtreme Scale REST data service utilizes the WebSphere eXtreme Scale EntityManager API schema to automatically create the appropriate Entity Data Model for REST clients. Clients that are compatible with ADO.NET Data Services can read the metadata and automatically discover and use the REST data service without any complicated configuration.

The WebSphere eXtreme Scale benefits of availability, performance, and scalability are now available to .NET and non-Java clients, just with the configuration change of a data service URL.

The WebSphere eXtreme Scale REST data service is being delivered as a technology preview and is included with the freely available trial version of WebSphere eXtreme Scale. See the following Installation section for details on how to download and install the trial. Additional enhancements will be added to the technology preview until it is delivered as part of the eXtreme Scale product.

The first WebSphere eXtreme Scale REST data service technical preview included these features:

• Create, Read, Update, Delete (CRUD) Operation support
• AtomPUB XML support
• Automatic data type conversion
• EntitySet modeling using the EntityManager configuration or annotations
• WebSphere Application Server and Tomcat support

The second WebSphere eXtreme Scale REST data service technical preview included these features:

• Relationship support

  Relationships between two or more entities can now be modeled. The REST data service allows navigation and modification of entity instance relationships at runtime.

• Batch retrieval support

  Multiple queries can now run within a single HTTP request and transaction, improving performance.

• OrderBy support

  Query results can now be returned in ascending or descending order by one or more properties.

New with the October 30 update: The WebSphere eXtreme Scale REST data service technical preview 3 includes the following additional features:

• JavaScript Object Notation (JSON) support Allows clients to interact with the REST data service using both JSON and ATOMPub.
• Full batch support Clients can update and retrieve data from the REST data service using a single remote procedure call to the REST data service.
• Partitioned support for entity relationships The REST data service can realize the full scalability of the eXtreme Scale grid by partitioning the data and using key relationships between entities to identify partition-able schema root entities.

For support and questions, see the WebSphere eXtreme Scale wiki and WebSphere eXtreme Scale forum, listed in the Community resources section.

A sample application is provided to demonstrate the operation of the REST data service. Instructions are provided for running it in WebSphere Application Server and Tomcat. Source is included, as well as an Eclipse project and instructions. See the User Guide in the docs directory, and READMEs in the gettingstarted directory.

Additional information about ADO.NET Data Services may be found in the MSDN library.

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To install this technical preview:

• Download the WebSphere eXtreme Scale version 7.0 trial. The REST data service is packaged within this trial. You may use the REST data service with the trial version, or a product version of WebSphere eXtreme Scale version 7.0 that you have.
• Extract the trial zip file to your hard drive, for example: c:\extremescale.
• Read the REST data service documentation, which includes detailed installation instructions in the extracted restservice\docs subdirectory.

For the latest information about sample applications, instructional videos, and other resources, see the REST Data Service Technical Preview wiki.

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