In engineering, system integration is defined as the process of bringing together the component subsystems into one system and ensuring that the subsystems function together as a system. In today's busienss enviroment, systems integration is the process of linking together different business systems and software applications physically or functionally, to act as a coordinated whole.
The system integrator brings together discrete systems utilizing a variety of techniques such as computer networking, enterprise application integration, business process management or manual programming. A system is an aggregation of subsystems cooperating so that the system is able to deliver the overarching functionality. System integration involves integrating existing often disparate systems.
System integration (SI) is also about adding value to the system, capabilities that are possible because of interactions between subsystems.
In today’s connected world, the role of system integration engineers is becoming more and more important: more and more systems are designed to connect, both within the system under construction and to systems that are already deployed.
A system integration engineer needs a broad range of skills and is likely to be defined by a breadth of knowledge rather than a depth of knowledge. These skills are likely to include software, systems and enterprise architecture, software and hardware engineering, interface protocols, and general problem solving skills. It is likely that the problems to be solved have not been solved before except in the broadest sense. They are likely to include new and challenging problems with an input from a broad range of engineers where the system integration engineer "pulls it all together."