Intersystem Testing Technique:

Background	§ Application systems are frequently interconnected to other application system. § The interconnection may be data coming from another application system, leaving for another application system or both. § Frequently multiple systems (applications) sometimes called cycles or functions are involved.
Usage	§ To ensure interconnection between application functions correctly.
Objectives	§ Determining – - Proper parameters and data are correctly passed between the applications - Documentation for involved system is correct and accurate. § Ensure Proper timing and coordination of functions exists between the application system.
How to Use	§ Operations of multiple systems are tested. § Multiple systems are run from one another to check that they are acceptable and processed properly.
When to use	§ When there is change in parameters in application system § The parameters, which are erroneous then risk associated to such parameters, would decide the extent of testing and type of testing. § Intersystem parameters would be checked / verified after the change or new application is placed in the production.
Examples	§ Develop test transaction set in one application and passing to another system to verify the processing. § Entering test transactions in live production environment and then using integrated test facility to check the processing from one system to another. § Verifying new changes of the parameters in the system, which are being tested, are corrected in the document.
Disadvantage	§ Time consuming § Cost may be expensive if system is run several times iteratively.