How to: Implement a Business Logic Handler for a Merge Article (RMO Programming)
The Microsoft.SqlServer.Replication.BusinessLogicSupport namespace implements an interface that enables you to write custom business logic to handle events that occur during the merge replication synchronization process. Methods in the business logic handler can be invoked by the replication process for each changed row that is replicated during synchronization.
The general process for implementing a business logic handler is:
- Create the business logic hander assembly.
- Register the assembly at the Distributor.
- Deploy the assembly at the server on which the Merge Agent runs. For a pull subscription the agent runs on the Subscriber, and for a push subscription the agent runs on the Distributor. When you are using Web synchronization, the agent runs on the Web server.
- Create an article that uses the business logic handler, or modify an existing article to use the business logic handler.
The business logic handler you specify is executed for every row that is synchronized. Complex logic and calls to other applications or network services can impact performance. For more information about business logic handlers, see Executing Business Logic During Merge Synchronization.
To create a business logic handler
In Microsoft Visual Studio, create a new project for the .NET assembly that contains the code that implements the business logic handler.
Add references to the project for the following namespaces.
Assembly Reference Location C:\Program Files\Microsoft SQL Server\90\COM (default installation)
GAC (component of the .NET Framework)
GAC (component of the .NET Framework)
Add a class that overrides the BusinessLogicModule class.
Implement the HandledChangeStates property to indicate the types of changes that are handled.
Override one or more of the following methods of the BusinessLogicModule class:
- CommitHandler - invoked when a data change is committed during synchronization.
- DeleteErrorHandler - invoked if an error occurs while a DELETE statement is being uploaded or downloaded.
- DeleteHandler - invoked when DELETE statements are being uploaded or downloaded.
- InsertErrorHandler - invoked if an error occurs when an INSERT statement is being uploaded or downloaded.
- InsertHandler - invoked when INSERT statements are being uploaded or downloaded.
- UpdateConflictsHandler - invoked when conflicting UPDATE statements occur at the Publisher and Subscriber.
- UpdateDeleteConflictHandler - invoked when UPDATE statements conflict with DELETE statements at the Publisher and Subscriber.
- UpdateErrorHandler - invoked if an error occurs when an UPDATE statement is being uploaded or downloaded.
- UpdateHandler - invoked when UPDATE statements are being uploaded or downloaded.
Note
Any article conflicts not explicitly handled by your custom business logic are handled by the default resolver for the article.
Build the project to create the business logic handler assembly.
To register a business logic handler
Create a connection to the Distributor by using the ServerConnection class.
Create an instance of the ReplicationServer class. Pass the ServerConnection from step 1.
Call EnumBusinessLogicHandlers and check the returned ArrayList object to ensure that the assembly has not already been registered as a business logic handler.
Create an instance of the BusinessLogicHandler class. Specify the following properties:
- DotNetAssemblyName - the name of the .NET assembly. If the assembly is not deployed in the same directory as the Merge Agent executable, in the same directory as the application that synchronously starts the Merge Agent, or in the GAC, you must include the full path with the assembly name. You must include the full path with the assembly name when using a business logic handler with Web synchronization.
- DotNetClassName - the fully-qualified name of the class that overrides BusinessLogicModule and implements the business logic handler.
- FriendlyName - a friendly name you use when you access the business logic handler.
- IsDotNetAssembly - a value of true.
To deploy a business logic handler
- Deploy the assembly on the server where the Merge Agent runs in the file location specified when the business logic handler was registered at the Distributor. For a pull subscription the agent runs on the Subscriber, and for a push subscription the agent runs on the Distributor. When you are using Web synchronization, the agent runs on the Web server. If the full path was not included with the assembly name when the business logic handler was registered, deploy the assembly in the same directory as the Merge Agent executable, in the same directory as the application that synchronously starts the Merge Agent. You may install the assembly in the GAC if there are multiple applications that use the same assembly.
To use a business logic handler with a new table article
Create a connection to the Publisher by using the ServerConnection class.
Create an instance of the MergeArticle class. Set the following properties:
- The name of the article for Name.
- The name of the publication for PublicationName.
- The name of the publication database for DatabaseName.
- The friendly name of the business logic handler (FriendlyName) for ArticleResolver.
Call the Create method. For more information, see How to: Define an Article (RMO Programming).
To use a business logic handler with an existing table article
Create a connection to the Publisher by using the ServerConnection class.
Create an instance of the MergeArticle class.
Set the Name, PublicationName, and DatabaseName properties.
Set the connection from step 1 for the ConnectionContext property.
Call the LoadProperties method to get the properties of the object. If this method returns false, either the article properties in step 3 were defined incorrectly or the article does not exist. For more information, see How to: View and Modify Article Properties (RMO Programming).
Set the friendly name of the business logic handler for ArticleResolver. This is the value of the FriendlyName property specified when registering the business logic handler.
Example
This example is a business logic handler that logs information about inserts, updates, and deletes at the Subscriber.
using System;
using System.Text;
using System.Data;
using System.Data.Common;
using Microsoft.SqlServer.Replication.BusinessLogicSupport;
using Microsoft.Samples.SqlServer.BusinessLogicHandler;
namespace Microsoft.Samples.SqlServer.BusinessLogicHandler
{
public class OrderEntryBusinessLogicHandler :
Microsoft.SqlServer.Replication.BusinessLogicSupport.BusinessLogicModule
{
// Variables to hold server names.
private string publisherName;
private string subscriberName;
public OrderEntryBusinessLogicHandler()
{
}
// Implement the Initialize method to get publication
// and subscription information.
public override void Initialize(
string publisher,
string subscriber,
string distributor,
string publisherDB,
string subscriberDB,
string articleName)
{
// Set the Publisher and Subscriber names.
publisherName = publisher;
subscriberName = subscriber;
}
// Declare what types of row changes, conflicts, or errors to handle.
override public ChangeStates HandledChangeStates
{
get
{
// Handle Subscriber inserts, updates and deletes.
return ChangeStates.SubscriberInserts |
ChangeStates.SubscriberUpdates | ChangeStates.SubscriberDeletes;
}
}
public override ActionOnDataChange InsertHandler(SourceIdentifier insertSource,
DataSet insertedDataSet, ref DataSet customDataSet, ref int historyLogLevel,
ref string historyLogMessage)
{
if (insertSource == SourceIdentifier.SourceIsSubscriber)
{
// Build a line item in the audit message to log the Subscriber insert.
StringBuilder AuditMessage = new StringBuilder();
AuditMessage.Append(String.Format("A new order was entered at {0}. " +
"The SalesOrderID for the order is :", subscriberName));
AuditMessage.Append(insertedDataSet.Tables[0].Rows[0]["SalesOrderID"].ToString());
AuditMessage.Append("The order must be shipped by :");
AuditMessage.Append(insertedDataSet.Tables[0].Rows[0]["DueDate"].ToString());
// Set the reference parameter to write the line to the log file.
historyLogMessage = AuditMessage.ToString();
// Set the history log level to the default verbose level.
historyLogLevel = 1;
// Accept the inserted data in the Subscriber's data set and
// apply it to the Publisher.
return ActionOnDataChange.AcceptData;
}
else
{
return base.InsertHandler(insertSource, insertedDataSet, ref customDataSet,
ref historyLogLevel, ref historyLogMessage);
}
}
public override ActionOnDataChange UpdateHandler(SourceIdentifier updateSource,
DataSet updatedDataSet, ref DataSet customDataSet, ref int historyLogLevel,
ref string historyLogMessage)
{
if (updateSource == SourceIdentifier.SourceIsPublisher)
{
// Build a line item in the audit message to log the Subscriber update.
StringBuilder AuditMessage = new StringBuilder();
AuditMessage.Append(String.Format("An existing order was updated at {0}. " +
"The SalesOrderID for the order is ", subscriberName));
AuditMessage.Append(updatedDataSet.Tables[0].Rows[0]["SalesOrderID"].ToString());
AuditMessage.Append("The order must now be shipped by :");
AuditMessage.Append(updatedDataSet.Tables[0].Rows[0]["DueDate"].ToString());
// Set the reference parameter to write the line to the log file.
historyLogMessage = AuditMessage.ToString();
// Set the history log level to the default verbose level.
historyLogLevel = 1;
// Accept the updated data in the Subscriber's data set and apply it to the Publisher.
return ActionOnDataChange.AcceptData;
}
else
{
return base.UpdateHandler(updateSource, updatedDataSet,
ref customDataSet, ref historyLogLevel, ref historyLogMessage);
}
}
public override ActionOnDataDelete DeleteHandler(SourceIdentifier deleteSource,
DataSet deletedDataSet, ref int historyLogLevel, ref string historyLogMessage)
{
if (deleteSource == SourceIdentifier.SourceIsSubscriber)
{
// Build a line item in the audit message to log the Subscriber deletes.
// Note that the rowguid is the only information that is
// available in the dataset.
StringBuilder AuditMessage = new StringBuilder();
AuditMessage.Append(String.Format("An existing order was deleted at {0}. " +
"The rowguid for the order is ", subscriberName));
AuditMessage.Append(deletedDataSet.Tables[0].Rows[0]["rowguid"].ToString());
// Set the reference parameter to write the line to the log file.
historyLogMessage = AuditMessage.ToString();
// Set the history log level to the default verbose level.
historyLogLevel = 1;
// Accept the delete and apply it to the Publisher.
return ActionOnDataDelete.AcceptDelete;
}
else
{
return base.DeleteHandler(deleteSource, deletedDataSet,
ref historyLogLevel, ref historyLogMessage);
}
}
}
}
Imports System
Imports System.Text
Imports System.Data
Imports System.Data.Common
Imports Microsoft.SqlServer.Replication.BusinessLogicSupport
Namespace Microsoft.Samples.SqlServer.BusinessLogicHandler
Public Class OrderEntryBusinessLogicHandler
Inherits BusinessLogicModule
' Variables to hold server names.
Private publisherName As String
Private subscriberName As String
' Implement the Initialize method to get publication
' and subscription information.
Public Overrides Sub Initialize( _
ByVal publisher As String, _
ByVal subscriber As String, _
ByVal distributor As String, _
ByVal publisherDB As String, _
ByVal subscriberDB As String, _
ByVal articleName As String _
)
' Set the Publisher and Subscriber names.
publisherName = publisher
subscriberName = subscriber
End Sub
' Declare what types of row changes, conflicts, or errors to handle.
Public Overrides ReadOnly Property HandledChangeStates() As ChangeStates
Get
' Handle Subscriber inserts, updates and deletes.
Return (ChangeStates.SubscriberInserts Or _
ChangeStates.SubscriberUpdates Or ChangeStates.SubscriberDeletes)
End Get
End Property
Public Overrides Function InsertHandler(ByVal insertSource As SourceIdentifier, _
ByVal insertedDataSet As DataSet, ByRef customDataSet As DataSet, _
ByRef historyLogLevel As Integer, ByRef historyLogMessage As String) _
As ActionOnDataChange
If insertSource = SourceIdentifier.SourceIsSubscriber Then
' Build a line item in the audit message to log the Subscriber insert.
Dim AuditMessage As StringBuilder = New StringBuilder()
AuditMessage.Append(String.Format("A new order was entered at {0}. " + _
"The SalesOrderID for the order is :", subscriberName))
AuditMessage.Append(insertedDataSet.Tables(0).Rows(0)("SalesOrderID").ToString())
AuditMessage.Append("The order must be shipped by :")
AuditMessage.Append(insertedDataSet.Tables(0).Rows(0)("DueDate").ToString())
' Set the reference parameter to write the line to the log file.
historyLogMessage = AuditMessage.ToString()
' Set the history log level to the default verbose level.
historyLogLevel = 1
' Accept the inserted data in the Subscriber's data set and
' apply it to the Publisher.
Return ActionOnDataChange.AcceptData
Else
Return MyBase.InsertHandler(insertSource, insertedDataSet, customDataSet, _
historyLogLevel, historyLogMessage)
End If
End Function
Public Overrides Function UpdateHandler(ByVal updateSource As SourceIdentifier, _
ByVal updatedDataSet As DataSet, ByRef customDataSet As DataSet, _
ByRef historyLogLevel As Integer, ByRef historyLogMessage As String) _
As ActionOnDataChange
If updateSource = SourceIdentifier.SourceIsPublisher Then
' Build a line item in the audit message to log the Subscriber update.
Dim AuditMessage As StringBuilder = New StringBuilder()
AuditMessage.Append(String.Format("An existing order was updated at {0}. " + _
"The SalesOrderID for the order is ", subscriberName))
AuditMessage.Append(updatedDataSet.Tables(0).Rows(0)("SalesOrderID").ToString())
AuditMessage.Append("The order must now be shipped by :")
AuditMessage.Append(updatedDataSet.Tables(0).Rows(0)("DueDate").ToString())
' Set the reference parameter to write the line to the log file.
historyLogMessage = AuditMessage.ToString()
' Set the history log level to the default verbose level.
historyLogLevel = 1
' Accept the updated data in the Subscriber's data set and apply it to the Publisher.
Return ActionOnDataChange.AcceptData
Else
Return MyBase.UpdateHandler(updateSource, updatedDataSet, _
customDataSet, historyLogLevel, historyLogMessage)
End If
End Function
Public Overrides Function DeleteHandler(ByVal deleteSource As SourceIdentifier, _
ByVal deletedDataSet As DataSet, ByRef historyLogLevel As Integer, _
ByRef historyLogMessage As String) As ActionOnDataDelete
If deleteSource = SourceIdentifier.SourceIsSubscriber Then
' Build a line item in the audit message to log the Subscriber deletes.
' Note that the rowguid is the only information that is
' available in the dataset.
Dim AuditMessage As StringBuilder = New StringBuilder()
AuditMessage.Append(String.Format("An existing order was deleted at {0}. " + _
"The rowguid for the order is ", subscriberName))
AuditMessage.Append(deletedDataSet.Tables(0).Rows(0)("rowguid").ToString())
' Set the reference parameter to write the line to the log file.
historyLogMessage = AuditMessage.ToString()
' Set the history log level to the default verbose level.
historyLogLevel = 1
' Accept the delete and apply it to the Publisher.
Return ActionOnDataDelete.AcceptDelete
Else
Return MyBase.DeleteHandler(deleteSource, deletedDataSet, _
historyLogLevel, historyLogMessage)
End If
End Function
End Class
End Namespace
This example registers a business logic handler at the Distributor.
// Specify the Distributor name and business logic properties.
string distributorName = publisherInstance;
string assemblyName = @"C:\Program Files\Microsoft SQL Server\90\COM\CustomLogic.dll";
string className = "Microsoft.Samples.SqlServer.BusinessLogicHandler.OrderEntryBusinessLogicHandler";
string friendlyName = "OrderEntryLogic";
ReplicationServer distributor;
BusinessLogicHandler customLogic;
// Create a connection to the Distributor.
ServerConnection distributorConn = new ServerConnection(distributorName);
try
{
// Connect to the Distributor.
distributorConn.Connect();
// Set the Distributor properties.
distributor = new ReplicationServer(distributorConn);
// Set the business logic handler properties.
customLogic = new BusinessLogicHandler();
customLogic.DotNetAssemblyName = assemblyName;
customLogic.DotNetClassName = className;
customLogic.FriendlyName = friendlyName;
customLogic.IsDotNetAssembly = true;
Boolean isRegistered = false;
// Check if the business logic handler is already registered at the Distributor.
foreach (BusinessLogicHandler registeredLogic
in distributor.EnumBusinessLogicHandlers())
{
if (registeredLogic == customLogic)
{
isRegistered = true;
}
}
// Register the custom logic.
if (!isRegistered)
{
distributor.RegisterBusinessLogicHandler(customLogic);
}
}
catch (Exception ex)
{
// Do error handling here.
throw new ApplicationException(string.Format(
"The {0} assembly could not be registered.",
assemblyName), ex);
}
finally
{
distributorConn.Disconnect();
}
' Specify the Distributor name and business logic properties.
Dim distributorName As String = publisherInstance
Dim assemblyName As String = "C:\Program Files\Microsoft SQL Server\90\COM\CustomLogic.dll"
Dim className As String = "Microsoft.Samples.SqlServer.BusinessLogicHandler.OrderEntryBusinessLogicHandler"
Dim friendlyName As String = "OrderEntryLogic"
Dim distributor As ReplicationServer
Dim customLogic As BusinessLogicHandler
' Create a connection to the Distributor.
Dim distributorConn As ServerConnection = New ServerConnection(distributorName)
Try
' Connect to the Distributor.
distributorConn.Connect()
' Set the Distributor properties.
distributor = New ReplicationServer(distributorConn)
' Set the business logic handler properties.
customLogic = New BusinessLogicHandler()
customLogic.DotNetAssemblyName = assemblyName
customLogic.DotNetClassName = className
customLogic.FriendlyName = friendlyName
customLogic.IsDotNetAssembly = True
Dim isRegistered As Boolean = False
' Check if the business logic handler is already registered at the Distributor.
For Each registeredLogic As BusinessLogicHandler _
In distributor.RegisteredSubscribers
If registeredLogic Is customLogic Then
isRegistered = True
End If
Next
' Register the custom logic.
If Not isRegistered Then
distributor.RegisterBusinessLogicHandler(customLogic)
End If
Catch ex As Exception
' Do error handling here.
Throw New ApplicationException(String.Format( _
"The {0} assembly could not be registered.", _
assemblyName), ex)
Finally
distributorConn.Disconnect()
End Try
This example changes an existing article to use the business logic handler.
// Define the Publisher, publication, and article names.
string publisherName = publisherInstance;
string publicationName = "AdvWorksSalesOrdersMerge";
string publicationDbName = "AdventureWorks";
string articleName = "SalesOrderHeader";
// Set the friendly name of the business logic handler.
string customLogic = "OrderEntryLogic";
MergeArticle article = new MergeArticle();
// Create a connection to the Publisher.
ServerConnection conn = new ServerConnection(publisherName);
try
{
// Connect to the Publisher.
conn.Connect();
// Set the required properties for the article.
article.ConnectionContext = conn;
article.Name = articleName;
article.DatabaseName = publicationDbName;
article.PublicationName = publicationName;
// Load the article properties.
if (article.LoadProperties())
{
article.ArticleResolver = customLogic;
}
else
{
// Throw an exception of the article does not exist.
throw new ApplicationException(String.Format(
"{0} is not published in {1}", articleName, publicationName));
}
}
catch (Exception ex)
{
// Do error handling here and rollback the transaction.
throw new ApplicationException(String.Format(
"The business logic handler {0} could not be associated with " +
" the {1} article.",customLogic,articleName), ex);
}
finally
{
conn.Disconnect();
}
' Define the Publisher, publication, and article names.
Dim publisherName As String = publisherInstance
Dim publicationName As String = "AdvWorksSalesOrdersMerge"
Dim publicationDbName As String = "AdventureWorks"
Dim articleName As String = "SalesOrderHeader"
' Set the friendly name of the business logic handler.
Dim customLogic As String = "OrderEntryLogic"
Dim article As MergeArticle = New MergeArticle()
' Create a connection to the Publisher.
Dim conn As ServerConnection = New ServerConnection(publisherName)
Try
' Connect to the Publisher.
conn.Connect()
' Set the required properties for the article.
article.ConnectionContext = conn
article.Name = articleName
article.DatabaseName = publicationDbName
article.PublicationName = publicationName
' Load the article properties.
If article.LoadProperties() Then
article.ArticleResolver = customLogic
Else
' Throw an exception of the article does not exist.
Throw New ApplicationException(String.Format( _
"{0} is not published in {1}", articleName, publicationName))
End If
Catch ex As Exception
' Do error handling here and rollback the transaction.
Throw New ApplicationException(String.Format( _
"The business logic handler {0} could not be associated with " + _
" the {1} article.", customLogic, articleName), ex)
Finally
conn.Disconnect()
End Try
See Also
Tasks
How to: Debug a Business Logic Handler (Replication Programming)
How to: Implement a Business Logic Handler for a Merge Article (Replication Programming)
Concepts
Programming with Replication Management Objects