CSA (component service architecture), is an attempt by J2EE world to develop an xml based standard for defining components metadata. CSA was earlier known as SCA and is now an OASIS standard. Component metadata includes services exposed by components, services reference (used) by components and properties of components. CSA standard facilitates assembling of composite components by configuration, without requiring hard coded api calls. In CSA standards, there is clear separation between developments of components business logic and non functional requirements required for deploying the components into a run time environment. CSA is also called "programming by intend". Developer can write business logic in medium of their choice – java, C++, Cobal, Python, BPEL, Spring and even C#. etc. and express their intend for non functional requirements (NFR) a.k.a. as policy sets. Policy sets can be applied/modified during deployment time. SCA support two of annotations. One type of annotations can be used to define components services, references and properties. Other type of attributes are used for define policy sets. Subsequently, a tool can read these attributes to generate an XML file which defines a components metadata. During the deployment type, another tool introspects policy set related annotation and then applies policy sets for meeting NFR.
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