3.3.  Create and manage Business Level Applications (BLA's) (e.g., OSGi applications, Service Component Architecture (SCA) ).


A business-level application (BLA) is a concept that aims to expand the notion of an "application" beyond Java EE. Its administration model provides the entire definition of an application as it makes sense to the business. In contrast with an enterprise application (EAR file), a business-level application is only a logical WebSphere configuration artifact, similar to a server or cluster, that is stored in the configuration repository.

Figure below shows the concept of business-level applications:

Figure 3.2. Business-level application concept

Business-level application concept

Business-level applications can be used in several different ways. Often a business application, such as an Order System, does not consist of only one enterprise application (EAR), but rather multiple applications that must all be running for the whole business application to work.

One way of using business-level applications is to group the separate enterprise applications that make up the business application into one manageable unit that can be started, stopped, updated, and so on. However, a business-level application can reference Java EE components as well as assets that are not part of the Java EE concept, for example, CORBA (C++) executables that are hosted in a generic server or files on the file system that are not managed by WebSphere but that are required by the application.

A business-level application does not represent or contain application binary files. Instead, it is a configuration that lists one or more composition units that represent the application binary files. A business-level application uses the binary files to run the application business logic. Administration of binary files is done using the normal methods for managing modules (for example, web or EJB modules) and is separate from administration of the application definition.

A business-level application does not introduce any new programming, runtime, or packaging models:

The terminology for business-level applications introduces two new terms:

Figure below shows the relationship between assets, composition units, and business-level applications:

Figure 3.3.  Relationship between business-level application artifacts

Relationship between business-level application artifacts

If an asset depends on another asset, you can create a relationship between them to allow, for example, a web module asset to reference classes in a shared library.

So, to summarize, a business-level application consists of composition units. When you add an asset to a business-level application, a composition unit is created for the asset. The composition unit is the configured (installed) asset.

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