Introduction to Scripting in SSIS

The Script Task and Script Component allow you to extend the functionality of SQL Server Integration Services (SSIS) by writing custom code. This is particularly useful when built-in tasks or transformations don't meet your specific requirements, such as performing complex data manipulation, interacting with external systems, or implementing custom business logic.

SSIS scripting typically involves using Microsoft Visual Studio and either Microsoft Visual Basic .NET or Microsoft C# as your programming language. The development environment provides a rich set of APIs and objects to interact with the SSIS runtime.

The Script Task

The Script Task is a control flow task that allows you to write code executed by the SSIS runtime during package execution. It's ideal for tasks that:

  • Perform custom administrative operations.
  • Automate SSIS package management.
  • Interact with COM objects or other external libraries.
  • Perform operations that are not directly supported by other SSIS tasks.

Key Features:

  • ReadWriteVariables: Access and modify SSIS variables.
  • ReadOnlyVariables: Access SSIS variables without modification.
  • PreExecute/PostExecute Events: Hook into package execution lifecycle.

You can configure the Script Task to use specific assemblies and access SSIS variables through the integrated script development environment.

The Script Component

The Script Component is a data flow transformation that allows you to write custom code to process data row by row within a data flow. It can be configured as:

  • Source: To generate data from a custom source.
  • Transformation: To modify or transform data as it flows through the data pipeline.
  • Destination: To write data to a custom destination.

Key Features:

  • Input/Output Columns: Define how data enters and leaves the component.
  • ProcessInputRow: The method where your custom row processing logic resides.
  • CreateOutputObject: For defining custom output structures.

Script Components are powerful for complex data cleansing, enrichment, and custom transformation logic that standard transformations cannot handle.

Supported Languages

The Script Task and Script Component in SSIS support:

  • Microsoft Visual Basic .NET
  • Microsoft C#

You choose your preferred language when configuring the script.

The Scripting Object Model

When you create a script, SSIS provides access to a set of built-in objects that enable interaction with the SSIS runtime and the data flow. The most common ones include:

  • Dts.Variables: For accessing and modifying SSIS variables.
  • Dts.LogBuffer: For writing custom log messages.
  • Dts.Events: For raising events.
  • Row (in Script Component): Represents the current row being processed.
  • Row.InputName: Accesses input columns.
  • Row.OutputName: Accesses output columns.

Understanding these objects is crucial for effective SSIS scripting.

Best Practices for SSIS Scripting

  • Keep Scripts Small and Focused: Avoid creating monolithic scripts. Break down complex logic into smaller, manageable pieces.
  • Use Meaningful Variable Names: For both SSIS variables and script variables.
  • Error Handling: Implement robust error handling using try-catch blocks and log errors effectively.
  • Performance Optimization: Be mindful of performance. Avoid unnecessary operations within loops, especially in Script Components processing large datasets.
  • Comments: Document your code with clear comments, especially for complex logic.
  • Type Safety: Use explicit data types and avoid implicit conversions where possible.
  • Avoid Hardcoding: Use SSIS variables for values that might change.

Code Examples

Example 1: Script Task to Log a Message

This example shows how to write a log message from a Script Task. In the Script Task editor, set ReadOnlyVariables to "User::PackageName".


' VB.NET Example
Public Sub Main()
    Dim packageName As String = Dts.Variables("User::PackageName").Value.ToString()
    Dts.Log("Executing Script Task for package: " & packageName, 0, Nothing)
    Dts.TaskResult = ScriptResults.Success
End Sub
                    

// C# Example
using System;
using Microsoft.SqlServer.Dts.Runtime;

public class ScriptMain
{
    public void Main()
    {
        string packageName = Dts.Variables["User::PackageName"].Value.ToString();
        Dts.Log("Executing Script Task for package: " + packageName, 0, null);
        Dts.TaskResult = (int)ScriptResults.Success;
    }
}

Example 2: Script Component Transformation to Modify a Column

This example assumes an input column named "CustomerName" and creates an output column named "Greeting" with a prefixed greeting. In the Script Component editor, add "CustomerName" to Input Columns, and create an output column "Greeting" of type `DT_WSTR`.


' VB.NET Example
Public Overrides Sub Input0_ProcessInputRow(ByVal Row As Input0Buffer)
    Row.Greeting = "Hello, " & Row.CustomerName
End Sub
                    

// C# Example
public override void Input0_ProcessInputRow(Input0Buffer Row)
{
    Row.Greeting = "Hello, " + Row.CustomerName;
}