Three Main Approach of Service Oriented Architecture (SOA) in the Financial Industry
Service-oriented Architecture (SOA) basically is an innovative concept for designing software infrastructures, which comes from the approach of:
1. Monolithic and host-based approaches:
The history of ICT started with monolithic software systems on mainframes. Typical applications in that era have been developed for the accounting, payroll and inventory purposes. Software primarily concentrated on the functions it should provide. Systems were designed as building blocks and therefore the reuse of system elements or components was largely impossible. Functionality was implemented on hosts, terminals provided the user interface to the systems. The next step in software architecture development was the era of client-server systems beginning in the 1980ths.
2. Client Server (CS) approaches:
With the CS paradigm software started to increasingly address the needs of single user groups through applications for Enterprise Resource Planning (ERP), Human Resource Management (HR) or Collaboration issues. Terminals were replaced by personal computers and software systems were divided into two parts: Servers built the backbone and provided necessary business functionality while the clients were used mainly for presentation purposes. Hardware and/or operating system of client and server became independent from each other. Hence, server functionalities were used by multiple clients while the communication scheme was based on the technology known as Remote Procedure Call (RPC). Clients and servers were still coupled quite tightly.
3. Multiple Tier approaches:
In the 90ths the object-oriented software developing paradigm became common and it was possible to divide complex systems into smaller parts (components and objects), which were able to communicate with each other to build the overall functionality. One central goal of the object-oriented paradigm was to ease the reuse of system parts and objects. To support the reuse of server objects in a distributed environment the concept of a communication middleware was introduced. So it became possible to build complex systems, but like in client-server systems all parts of the distributed system still were tightly coupled through the middleware.
