Friday, May 13, 2005

What are Application Domains?

Many of us have come across the word "Application Domains" during our projects. But mostly I have seen many people having a wrong notion on what Application Domains really are.
Now lets examine what these App Domains are.

Application domains are basically logical boundaries which provide a secure, versatile unit of processing that the Common Language Runtime (CLR) uses to provide isolation between applications.

Thus, you can run several application domains in a single process with the same level of isolation that would exist in separate processes, but without incurring the additional overhead of making cross-process calls or switching between processes.
The ability to run multiple applications within a single process dramatically increases server scalability.

Thus, the Application domains provide an isolation that has the following advantages:
  1. Application Security
  2. Faults in one application cannot affect other applications.
  3. Individual applications can be stopped without stopping the entire process.
  4. Code running in one application cannot directly access code or resources from another application. The CLR enforces this isolation by preventing direct calls between objects in different application domains.
  5. The Scope of the code is controlled by the Application domain. The Application domain provides configuration settings such as application version policies, the location of any remote assemblies it accesses, and information about where to locate assemblies that are loaded into the domain.
  6. The Permissions granted to code can be controlled by the application domain in which the code is running.

Friday, May 06, 2005

HOW TO: Programmatically create SSIS packages using Whidbey


If you had read my last two articles, you would now be familiar with SSIS and how to create simple packages Business Intelligence Development Studio.

In this article, let us now check how to programmatically create a package/edit an existing package using the APIs provided with SQL Server 2005.

Let us start with creating a simple Console Application in Whidbey.

First of all, we need to add the following references to your Whidbey project:

1. Microsoft.SqlServer.DTSPipelineWrap.dll
2. Microsoft.SQLServer.DTSRuntimeWrap.dll
3. Microsoft.SQLServer.ManagedDTS.dll

The reference dlls can be found in the following location:
C:\Program Files\Microsoft SQL Server\90\SDK\Assemblies

You must then add the namespace references in the Program.cs file as follows:

#region Using directives
using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.SqlServer.Dts.Runtime;
using Microsoft.SqlServer.Dts.Pipeline.Wrapper;

An SSIS package can be created using the Package class present in the Microsoft.SqlServer.Dts.Runtime namespace as follows:

Package pkg = new Package();
pkg.Name = "MyCreatedPackage";
pkg.ID = "MyPackageID";

Now lets see how to take an existing package, modify its properties and save the package to your file system or to Yukon server.

We begin with defining a Package object and an Application object.

Package pkg = new Package();
Application a = new Application();

The Application class is used to discover and access Package objects.
Next we declare the MainPipe interface which is used to programmatically configure the data flow task. The IDTSComponentMetaData90 Interface contains the definition of a data flow component; including the custom properties, inputs, outputs, and input and output columns defined on a data flow component.

IDTSComponentMetaData90 oledbSource;
IDTSComponentMetaData90 oledbDestination;
MainPipe dataFlow;

In case you are trying to modify the properties of an existing package, you must first load the external package that you already have as a template.

pkg = a.LoadPackage(@"C:\TestPackages\MyPackage.dtsx", null);

You must now add the connection using the ConnectionManager class and set connection properties. The ConnectionManager class contains all the information necessary to connect to a single type of data source.
//Add connections
ConnectionManager conMgr = pkg.Connections.Add("OLEDB");

/// Set stock properties
conMgr.Name = "OLEDBConnection";
conMgr.ConnectionString = "Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=Test;Data Source=mdpkb2e139;Auto Translate=False;";

The next step is to add/edit the data flow task. The following is the code to add a Data Flow Task and set its properties:

TaskHost th = pkg.Executables.Add("DTS.Pipeline") as TaskHost;
th.Name = "DataFlow";
dataFlow = th.InnerObject as MainPipe;

//set source component
oledbSource = dataFlow.ComponentMetaDataCollection.New();
oledbSource.ComponentClassID = "DTSAdapter.OLEDBSource";
oledbSource.Name = "OLEDBSource";
CManagedComponentWrapper instanceSource = oledbSource.Instantiate();

oledbSource.RuntimeConnectionCollection[0].ConnectionManagerID = pkg.Connections["OLEDBConnection"].ID;

oledbSource.RuntimeConnectionCollection[0].ConnectionManager = DtsConvert.ToConnectionManager90(pkg.Connections["OLEDBConnection"]);

instanceSource.SetComponentProperty("OpenRowset", "Emp");
instanceSource.SetComponentProperty("AccessMode", 0);

// Acquire Connections and reinitialize the component


In case you already have a template with the data flow task, we can get the handle of it using the Executable collection. The following is the code for modifying a DataFlow task:

Executable exe = x.Executables["Data Flow Task"];
TaskHost th2 = exe as TaskHost; d
ataFlow = th2.InnerObject as MainPipe;
IDTSComponentMetaDataCollection90 metadataCollection = dataFlow.ComponentMetaDataCollection;
//set source component

oledbSource = dataFlow.ComponentMetaDataCollection[0];
if (oledbSource.RuntimeConnectionCollection.Count > 0)
oledbSource.RuntimeConnectionCollection[0].ConnectionManager = DtsConvert.ToConnectionManager90(x.Connections["OLEDBConnection"]);
oledbSource.RuntimeConnectionCollection[0].ConnectionManagerID = x.Connections["OLEDBConnection"].ID;
CManagedComponentWrapper instanceSource = oledbSource.Instantiate();

instanceSource.SetComponentProperty("OpenRowset", "Temp_1");
instanceSource.SetComponentProperty("AccessMode", 0);

// Acquire Connections and reinitialize the component

The same steps are followed for setting the properties of the destination component. The following is the code for modifying the connection properties of OLEDB Destination component:

//set destination component
oledbDestination = dataFlow.ComponentMetaDataCollection[1];
if (oledbDestination.RuntimeConnectionCollection.Count > 0)
oledbDestination.RuntimeConnectionCollection[0].ConnectionManager = DtsConvert.ToConnectionManager90(x.Connections["OLEDBConnection"]);
oledbDestination.RuntimeConnectionCollection[0].ConnectionManagerID = x.Connections["OLEDBConnection"].ID;
CManagedComponentWrapper instanceDest = oledbDestination.Instantiate();
instanceDest.SetComponentProperty("OpenRowset", "Temp_2");

instanceDest.SetComponentProperty("AccessMode", 0);
// Acquire Connections and reinitialize the component


The next step is to "Map" the columns of the source and destination components. The following is the code to map the input column collection (source collection) to the External Metadata column collection (Destination collection):

IDTSInput90 input = oledbDestination.InputCollection[0];
IDTSVirtualInput90 vInput = input.GetVirtualInput();
foreach (IDTSVirtualInputColumn90 vColumn in vInput.VirtualInputColumnCollection)
IDTSInputColumn90 vCol = instanceDest.SetUsageType(input.ID, vInput, vColumn.LineageID, DTSUsageType.UT_READWRITE);
instanceDest.MapInputColumn(input.ID, vCol.ID, input.ExternalMetadataColumnCollection[vColumn.Name].ID);

Finally we save the package to the file system.

string currentDirectory = System.IO.Directory.GetCurrentDirectory();
a.SaveToXml(currentDirectory + "\\DTSDataflow.dtsx", pkg, null);
Console.WriteLine("Successfully created an SSIS package");


In case you want to save the package directly to Yukon server, you can use the following code:

a.SaveToSqlServer(pkg, null, "mdpkb2e139", "", "");

Here it goes! You have now programmatically created a simple SSIS package.