SSIS Objects and Process Control Components
Before you begin learning how to create SSIS applications, it is important to familiarize yourself first with the SSIS process control components and the objects used to create SSIS applications. The first object to note within SSIS is the package.
An SSIS package is the highest-level object within an SSIS application. A package is a discrete unit of work that you define for ETL operations or SQL Server Services administration operations or both. It is a collection of SSIS process control components and their objects that define the operations, process dependencies, and sequence flow of activities and operations required for a data integration application. Package objects include containers, tasks, precedence constraints, variables, data sources, data destinations, SQL Server administration functions, and custom tasks that you can create to address unique requirements for your applications. Package objects are applied to package process control components that include the control flow, data flow, and event handler.
To control the sequence of activities and operations within a package, you apply the precedence constraint object. Precedence constraints are defined between your package objects and are used to specify the order sequence of operations processing and to control processing branching among optional process flows, dependent data values, and conditions or error conditions.
Another useful object of a package is the container. A container is the package object used to group other objects and other containers. Common uses of containers are for performing iterative processing such as looping through a dataset or processing a set of data files within a directory. Although the container object is within a package, you can consider the SSIS package itself as a special high-level container.
SSIS objects also include a comprehensive set of transformation tasks that are important for data integration and BI solutions. These tasks are designed for merging or aggregating data and for converting and transforming data formats and types. Some new tasks have been provided for handling specialized BI operations such as managing slowly changing dimension data. You can also extend SSIS with your own custom tasks and transformations to handle unique requirements within your business application systems environment.
Perhaps best of all, you will find that with all the SSIS objects available to you for package creation, you can create robust, high-performance ETL and data integration applications with no programming code required. By simply dragging and dropping containers, sources, destinations, transformations, and other objects, the SSIS designer automatically creates all the package executable code for you. Throughout the next several chapters, you will learn more about package objects and control components and practice with many of the objects available to design and develop SSIS packages.
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