websphere

WebSphere refers to a brand of IBM software products, although the term also popularly refers to one specific product: WebSphere Application Server. WebSphere helped define the middleware software category and is designed to set up, operate and integrate e-business applications across multiple computing platforms using web technologies. IBM constructs WebSphere using open standards such as the Java 2 Platform, Enterprise Edition (J2EE), XML and Web Services standards. Multiple IBM labs around the world participate in designing and developing WebSphere products. IBM has shipped several versions and editions of the application server:

WebSphere Application Server V3.0

This version of WebSphere was a JDK 1.2, J2EE 1.0 version. IBM provided many enhancements to the basic J2EE 1.0 spec. example of what Lisa can do....

WebSphere Application Server V3.5

WebSphere Application Server V4.0

This was a J2EE 1.1 certified application server. It inherited the database based configuration model from V3.x.

WebSphere Application Server V4.0 Enterprise Edition

WebSphere Application Server V5.0

This was a J2EE 1.3 certified application server. It was a major rewrite of the V3.x,V4.0 code base. The database based configuration repository was replaced with a replication file based configuration repository. A server called the deployment manager had the master copy of the cell configuration and nodes had the file they needed for the node copied from this master server when ever they changed. It also included a cut down version of MQ 5.3 called the embedded JMS server.

WebSphere Application Server V5.0 Enterprise Edition

This version added a workflow engine for the first time. This wasn't using the BPEL standard yet. It also added the first fully supported application threading model. This was called WebSphere Async Beans.

WebSphere Application Server V5.1

WebSphere Application Server V5.1.1

The main change from 5.1 was a JDK upgrade to 1.4.2.

WebSphere Business Integration Server Foundation v5.1

This is the follow on product to WebSphere Application Server Enterprise Edition v5.0. The workflow engine was updated to support BPEL rather than the proprietary FDML format used in V5.0. The product was also repriced.

WebSphere Application Server V5.1 Extended Deployment Edition

What is WebSphere XD?

WebSphere Extended Deployment or XD is an addon for WebSphere 5.1.1 or WebSphere WBISF 5.1 (our integration offering). It's a new product that first shipped in October 2004. It provides advanced features for both administrators who manage multiple J2EE applications and developers building advanced applications that require asymettric clustering techniques.

What does WebSphere XD offer to administrators?

A lot of customers tell us that they want to consolidate multiple server farms in to a single smaller server farm. They want to do this because most server farms are underutilizied or over provisioned. The boxes are only typically running at 10% load. This is quite costly and is not flexible. For example, one server farm goes hot and maxes out while the farm in the next room is still basically idle at 10%. XD allows administrator to define a single cluster (a node group) and then deploy multiple applications to that node group. The administrator then tells XD that application A should have a response time of one second, application B 500ms and application C two seconds. The administrator can also tell us that A is more important than B and C and C is more important than B. XD will then monitor the workload and dynamically decide which boxes in the node group should host which application in order to meet these goals. If application A currently has a response time of 1.5 seconds then XD will add run A on more nodes and reduce the number of nodes running B and C to bring more resources to application A so it can meet its goal. XD can also predict that A will likely exceed its response time in 10 minutes based on a trend and react in anticipation of the event. This greatly simplifies the life of an administrator and allows the machines to be more efficiently used than a conventional multiple, independent farm of farms approach. XD also offers options to generate various email alerts then conditions are exceeded, it can restart servers when they appear to have a memory leak or after X requests.

What does WebSphere XD offer to developers?

Traditional J2EE applications work well for a large class of applications. The class can broadly be categorized as applications that run in a stateless cluster in front of a database. I call this a symmetric cluster:

     * all the cluster members can perform any task at any time     * the application is stateless     * the application is modal which means it only performs work synchronously in response to a client request which can be received using HTTP/IIOP or JMS.

There are other applications that do not work well in such an environment, for example, an electronic trading system in a bank. Such applications typically use tricks that can greatly improve performance such as partitioning, multi-threading and write through caching. These are applications that can exploit asymmetric clustering. An asymmetric cluster is practically the opposite of a symmetric cluster:

     * applications can declare named partitions at any point while it's running     * partitions are highly available, are mobile within the cluster and usually only run on a single cluster member at a time     * incoming work for a partition is routed to the cluster member hosting the partition     * the application is amodal. Partitions have a lifecycle of their own and can start background threads/alarms as well as respond to incoming events whether they are IIOP/HTTP or JMS/foreign messages.

WebSphere XD offers a new set of programming APIS called the "WebSphere Partition Facility" or WPF for short. These APIs allow applications that require an asymmetric cluster to be deployed on a J2EE server for the first time to my knowledge.

WebSphere Application Server V6.0

This version was released in December 2004. It is a J2EE 1.4 compliant application server. Many programming model extensions previously found in WebSphere Application Server V5.0 Enterprise Edition were moved out of enterprise and into base. These APIs included application profile, startup beans, the scheduler and async beans. The JMS engine was rewritten in 100% Java and its functionality greatly enhanced. The clustering was rewritten to use the high availability manager. This manages all singletons in the WebSphere environment and can provide hot recovery for those singletons.