SOA Integration - Modernizing an Integration Solution

This section uses an example to illustrate how an existing integration solution that has grown over time can be modernized using SOA methods, and the scenarios from the previous sections.

The example is a simplified version of a specific customer project in which an existing solution was modernized with the help of SOA.

The task of the integration solution is to forward orders entered in the central ERP system to the external target applications.

Initial situation

The current solution is primarily based on a file transfer mechanism that sends the new and modified orders at intervals to the relevant applications, in the form of files in two possible formats (XML und CSV). The applications are responsible for processing the files independently.

At a later date, another application (IT app in the following diagram) was added to the system using a queuing mechanism, because this mechanism allowed for the guaranteed exchange of messages with the application by reading new orders, and sending appropriate messages through the queue in the form of a transaction. The following diagram shows the initial situation before the modernization process took place:

The extraction and file creation logic is written in PL/SQL. A Unix shell script is used to send the files through the File Transfer Protocol (FTP), as no direct FTP call was possible in PL/SQL. Both a shell script and the PL/SQL logic are responsible for
orchestrating the integration process.

Oracle Advanced Queuing (AQ) is used as the queuing infrastructure. As PL/SQL supports sending of AQ messages through an API (package), it was possible to implement this special variant of the business case entirely in PL/SQL, without a call to a
shell script being needed. In this case, the integration is bi-directional. This means that when the order has been processed by the external system, the application must send a feedback message to the ERP system. A second queue, which is implemented in the
integration layer using PL/SQL, is used for this purpose.