WebSphere Extended Deployment
WebSphere Extended Deployment
(WXD), a WebSphere product, adds grid and autonomic capabilities to WAS ND.
Whereas WAS ND essentially runs all applications in all servers in a cluster equally, WXD dynamically adjusts the number of servers running each application to maximize meeting SLAs based on application priority. So when a high-priority app gets too slow (as defined by you through configuration), WXD starts more instances of the app, perhaps shutting down instances of other apps which have too much capacity or even sacrificing their performance because they're lower priority (as defined by you through configuration). I like to think of WAS ND as providing symmetric clustering and WXD as providing asymmetric clustering.
WXD is not "WAS XD"; it's broader than WAS. The application servers that WXD manages and load balances across can not only be WAS servers, but also PHP Server, Apache TomCat, Ruby on Rails, JBoss Application Server, and BEA WebLogic Server (and others). (As usual, what exactly is supported is quite detailed and depends on the version of WXD; for an overview, see "XD Support for Non-WebSphere Environments.") So WXD is an environment for mixed-node app servers, kind of an app server operating system that runs across multiple host machines.
One of the components of WXD, ObjectGrid, is also available separately. (I thought the [OnDemand Router] is as well, but it is not.)
There is a developerWorks WebSphere Extended Deployment section and a developerWorks Forum for discussing WXD.
Two blogs that discuss WXD:
To learn more:
WXD v6.1
WXD (wiki), as of v5.1 and v6.0, was a single product. As of v6.1 (InfoCenter), it has been split into a suite of three products:
- WebSphere Virtual Enterprise - Virtual Enterprise contains the majority of the WXD v6.0 functionality. At its heart is dynamic clustering to adjust the capacity of each application and the on-demand router (ODR) to prioritize and distribute work according to service level agreements (SLAs). It also helps manage the deployment of large numbers of applications and the health of individual application servers, and integrates with separately available virtualization technologies. (wiki)
- WebSphere eXtreme Scale - eXtreme Scale is primarily the ObjectGrid and Partitioning Facility features from WXD v6.0 available as a separate product. ObjectGrid is an in-memory distributed cache which provides transactional access to frequently accessed data. The caches are configured by policies that control population and eviction of their data, write-through or write-behind committal of changes, and partitioning so that different replicas can contain data needed by different applications. The caches are replicated for scalability and availability. (eXtreme Scale wiki, ObjectGrid wiki, ObjectGrid V6.1 User Guide)
- Compute Grid - Compute Grid enables Java transactional workloads and batch workloads to peacefully coexist. Transactional jobs are created by typical user interaction applications; they consist of short-running transactions that consume small amounts of computing resources. Batch jobs are long-running, consuming large amounts of processing power and memory. In Compute Grid, job schedulers pair waiting jobs with available capacity in the cell and distribute the jobs. The job management console can be used to submit, monitor, and manage jobs. (wiki)
Virtual Enterprise and Compute Grid share some capabilities, such as the dynamic operations function and the application placement controller. All three products require WebSphere Application Server Network Deployment v6.1 or WebSphere Application Server for z/OS v6.1 as their runtime environment.
