Explain why adaptors are usually needed when systems are constructed by integrating application systems. Suggest three practical problems that might arise in writing adaptor software to link two application systems.

What will be an ideal response?

Adaptors are usually required because the application system products are
independently developed at different times and, therefore, they are not designed for
integration. There is no reason why the database organisation, user interfaces,
APIs, etc. should take into account the integration with other components.
Three practical problems that may arise when integrating application
systems are:
1. Missing information. Application A may require information from
application B to work properly. However, application B may not need this
information (or it may be optional) and so it cannot guarantee that it can be
made available to application A.
2. Control incompatibilities. Application A and application B may have
different control philosophies. For example, application A may be reactive,
depending on the user inputs whereas application B may be proactive and
use workflow-based, pre-defined interaction.
3. Semantic mismatches. This occurs when different applications use the same
name for some kind of information but that actually means different things.
For example, a system that manages project budgets may record ‘start date’
of the project as the date after which funding may be spent whereas the
project management system considers start date to the date that work
actually started.