Professional SQL Server™ 2005 Integration Services

10.2. Understanding the SSIS Data Flow and Control Flow

From an architectural perspective, the difference between Integration Services Data Flow and Control Flow is important. One aspect that will help illustrate the distinction is to look at them from the perspective of how the components are handled. In the Control Flow, the task is the smallest unit of work, and tasks require completion (success, failure, or just completion) before the subsequent tasks are handled. In the Data Flow, the transformation is the basic component; however, a transformation functions very differently from a task. Instead of one transformation necessarily waiting for associated transformations before work can be done, the transformations work together to process and manage data.

10.2.1. Comparing and Contrasting the Data Flow and Control Flow

Although the Control Flow looks very similar to the Data Flow with processing objects (tasks and transformations) and green and red connectors that bridge them, there is a world of difference between them. The Control Flow, for example, does not manage or pass data between components; rather it functions as a task coordinator with isolated units of work. Here are some of the Control Flow concepts:

• Workflow orchestration

• Process-oriented

• Serial or parallel tasks execution

• Synchronous processing

As highlighted, the Control Flow tasks can be designed to execute both serially and in parallel—in fact, more often than not there will be aspects of both. A Control Flow ...