Integrating Existing Applications

Abstract

Enterprise applications are usually designed, developed, and deployed for well predefined business domains. In other words, domain-based applications mainly meet the needs of their focused business domains. Frequently, they complement each other by playing support roles during normal business operations. It is well recognized that organizations can maximally capitalize on their investments by fully leveraging all the available IT supports enabled by individual applications through enterprise integration. However, integrating distributed applications across an organization is challenging as these distributed applications are quite often found disparate and heterogeneous in many aspects. Regardless of how distributed applications were built and how they are disparate and heterogeneous, there are essentially four main categories of integration approaches used to address the integration needs in an organization. These categories are classified based on the hierarchical levels at which the integration takes place. The four level-based categories are data-, method-, API-, and process-levels. Accordingly, four integration methodologies are defined. This chapter mainly focuses on the explorations of the technical fundamentals of data-, method-, API-, and process-level integrations. An interface is the interaction channel provided by an application, which delivers a designated computing service for invocation. The accessibility of the interface to a computing service at any integration level in the hierarchy of a given application depends on the privilege enabled for the end users who requires the services. Different examples are used to demonstrate how data-, method-, and API-level integrations can be effectively applied in integrating distributed applications across an organization. An introduction to the process-level integration is presented in this chapter.