Web services are building blocks of interoperable systems. Composing Web services makes the processes capable of doing complex tasks. Composite services may fail during their execution which can be diagnosed by a mediator. The mediator adapts the structure so that the failure is recovered. Moreover, future executions should avoid the situation or organize a strategy to repair the structure with a minimum delay. In this paper the failure reasons of a composite service are reviewed. Furthermore, the requirements of a solution for recovery of a system from a failure are investigated.