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This two-part article discusses application deployment, particularly automated updates, to IBM WebSphere Application Server in a large-scale enterprise environment. It applies to Application Server versions 5.0, 5.1, and 6.0, and also includes an introduction to a few version 6.0 enhancements. This article is not intended to be used as a reference for all the details of Application Server administration, but it does describe the key concepts used and contains a list of references. Although the beginning of the article reviews some fairly basic base server and managed server concepts and operations, much of the remainder of the article will discuss certain complex concepts or operational considerations that will be new even to very experienced enterprise application server administrators.
Part one of this article discussed wsadmin deployment to base and managed servers. It examined why phased deployments are needed to maintain applications in an Application Server Network-Deployment managed cell, and how to maintain high availability in such an environment.
This article discusses pre- and post-deployment validation as well as gradual deployment of incompatible versions. It also discusses the design and implementation of a downloadable Automated Deployment example program that illustrates how to automate the deployment of randomly built collections of enterprise applications or updates, and how to automatically target those applications or updates to the correct servers, including stagespecific application setup.
Pre- and Post-Validation to Maximize Availability
As in all of the deployment scenarios mentioned in Part 1 of this article, it makes no sense to start deploying an application update if it contains problems that are likely to cause the deployment to fail.
Typical pre-validations can include validating that (see Figure 1):
* The application (EAR) appears to be complete and well formed.
* The deployment targets and the required application settings are known.
* The deployment target nodes and servers, or clusters, are valid.
* The deployment target nodes and servers, or clusters, are running and are accessible.
* The application settings are valid.
* The application is already installed, in the case of an application update.
* The application is not already installed, in the case of an …