Understanding System Integration
System integration implies the bringing together of a component subsystems into one system. System integration subsequently ensures that all subsystems function together as one system. When implemented in information technology, this is seen as that process which links together different computing systems and software applications either functionally or physically. System integration utilizes a variety of techniques to bring different systems together. Some of these techniques include business process management, computer networking, manual programming, and enterprise application integration.
Methods of System Integration
- Horizontal Integration or Enterprise Service Bus (ESB)
This is a method where a specialized subsystem is used for communication between other subsystems. A horizontal integration system cuts the number of connections/interfaces to only one per subsystem; this means the interface will connect directly to the enterprise service bus. The enterprise service bus has the capability to translate the interface into another interface. This allows for the integration costs to be cut, and also provides extreme flexibility. It is thus completely possible to replace one subsystem with another subsystem through the use of a horizontal integration system. Similar functionality is thus provided although different interfaces are exported. The rest of the subsystems can now follow by implementing the new interface between the enterprise service bus and the new subsystem.
- Star Integration (Spaghetti Integration)
This is a system integration method where each system is interconnected to each of the remaining subsystems. When this method is seen from the perspective of the subsystem being integrated the connections look like a star; however, when the overall diagram of the system is presented, the different connections look like spaghetti. The cost of the star integration system varies according to the interfaces which subsystems are exporting. The integration cost can rise substantially in cases where the subsystems are exporting heterogeneous or proprietary interfaces. When adding additional subsystems, time and cost needed to integrate these systems show an exponential increase. This system integration method often seems more preferable due to the extreme flexibility of the reuse of functionality.
This is a method which integrates subsystems according to their functionality by creating functional entities referred to as silos. The benefit to this system integration method is that the integration is performed quickly and involves only the necessary vendors; vertical integration is thus cheaper in the short term. However, the cost-of-ownership involved is substantially higher than those in other system integration methods. This is due to the fact that, in case of new or enhanced functionality, the only way to implement or scale the system would be by means of implementing another silo. Reusing subsystems to create functionality is thus not possible.