SOA and open standards paves the way for Composite Applications
Composite Application presents a new paradigm of application development which promises minimal writing of custom code and enables a business functionality through assembly of ready made components and services “harvested” out of existing enterprise applications and resources. These reusable assets have extension and configuration features or context, which need to be initialized while deploying the asset. Once deployed these would interact with the pre-exiting enterprise application through standardized interfaces and enable a new business use case or scenario. Since the new composite application is built out of pre-existing components and services after customization, the time to market is drastically reduced having obvious implications for the business. Having said that, these new breed of applications have a varied scope and touch points with diverse applications having different security mechanisms and models, database models, transaction models and so on. Hence, the composite has to take care of this distributed aspect which is not quite a simple thing to do.
Composite application building is not a new phenomenon, and most IT organizations have been undertaking this in a limited way. The maturity and open standards based seamless interoperability of tools and platform suite from most vendors have brought the vision of composite application closer to reality, along with a wider acceptance. Perhaps the most significant factor which has lead most vendors and clients to embrace seriously this style of development is the emergence of SOA principles, patterns and methodologies and tools based on SOA principles. SOA encourages modularity, standardized interfaces, reusability, open standards, etc. SCA is an open standard which is destined to play a big role in composite application development space http://www.osoa.org/display/Main/Service+Component+Architecture+Home. Composite application development style thrives in the presence of standardized enterprise models and modularized components having well designed interoperable interfaces. In order to facilitate the composite application development, quite a few of the big names among the IT product vendors have started providing out-of-box components, services, adapters and connectors which are specific to industry vertical domain such as healthcare, telecom, manufacturing, banking, etc. These reusable assets are usually based on industry specific open standards (information models, message models, etc.) and hence promise maximal interoperability.
