A control flow consists of one or more tasks and containers that execute when
the package runs. To control order or define the conditions for running the next
task or container in the package control flow, we use precedence constraints to
connect the tasks and containers in a package. A subset of tasks and containers
can also be grouped and run repeatedly as a unit within the package control flow.
SQL Server 2005 Integration Services (SSIS) provides three different types of
control flow elements: Containers that provide structures in packages, Tasks that
provide functionality, and Precedence Constraints that connect the executables,
containers, and tasks into an ordered control flow.