Gestionnaires de ressources de compensation (CRM)
Un gestionnaire de ressources de compensation (CRM*, Compensating Resource Manager*) est un service fourni par COM+ et qui vous permet d'inclure des objets non transactionnels dans des transactions Microsoft DTC (Distributed Transaction Coordinator). Bien que les CRM n'offrent pas les mêmes fonctionnalités qu'un gestionnaire de ressources complet, ils assurent néanmoins l'atomicité transactionnelle (comportement de type tout ou rien) et la durabilité via le journal de récupération.
L'exemple suivant est constitué de deux parties, un client et un serveur. Il illustre la création d'un CRM personnalisé au moyen d'une classe Worker, d'une classe Compensator et d'un objet Clerk, ainsi que l'exécution d'une validation et d'un abandon.
Serveur
Imports System
Imports System.IO
Imports System.Reflection
Imports System.EnterpriseServices
Imports System.EnterpriseServices.CompensatingResourceManager
<assembly: ApplicationActivation(ActivationOption.Server)>
<assembly: ApplicationCrmEnabled>
<assembly: AssemblyKeyFile("crm.key")>
Namespace CrmServer
' Create a Worker class.
<Transaction> Public Class CRMWorker
Inherits Servicedcomponent
Public Sub CRMMethod(filename As String, bCommit As Boolean)
' Create the clerk object.
Dim myclerk As Clerk=New Clerk(GetType(CRMCompensator), "CRMCompensator", CompensatorOptions.AllPhases)
myclerk.WriteLogRecord(filename)
myclerk.ForceLog()
If bCommit=true Then
ContextUtil.SetComplete()
Else
ContextUtil.SetAbort()
End If
End Sub
End Class
' Create a class derived from the Compensator class.
Public Class CRMCompensator
Inherits Compensator
Dim bBeginPrepareCalled As Boolean = False
Dim bPrepareRecordCalled As Boolean = False
Dim bBeginCommitCalled As Boolean = False
Dim bCommitRecordCalled As Boolean = False
Dim bBeginAbortCalled As Boolean = False
Dim bAbortRecordCalled As Boolean = False
Dim _filename as String
Public Overrides Sub BeginPrepare()
bBeginPrepareCalled = True
End Sub
Public Overrides Function PrepareRecord(rec As LogRecord) As Boolean
dim o as Object = rec.Record
_fileName = o.ToString()
bPrepareRecordCalled = True
Return False
End Function
Public Overrides Function EndPrepare() As Boolean
if not bBeginPrepareCalled then Return False
if not bPrepareRecordCalled then Return False
if _fileName="" then Return False
' This is a Prepare Phase success.
Return True
End Function
Public Overrides Sub BeginCommit(fRecovery As Boolean)
bBeginCommitCalled = True
End Sub
Public Overrides Function CommitRecord(rec As LogRecord) As Boolean
bCommitRecordCalled = True
Return True
End Function
Public Overrides Sub EndCommit()
if not bBeginCommitCalled then Return
if not bCommitRecordCalled then Return
if _fileName="" then Return
' This is a Commit Phase success.
End Sub
Public Overrides Sub BeginAbort(fRecovery As Boolean)
bBeginAbortCalled = True
End Sub
Public Overrides Function AbortRecord(rec As LogRecord) As Boolean
bAbortRecordCalled = True
dim o as Object = rec.Record
_fileName = o.ToString()
Return True
End Function
Public Overrides Sub EndAbort()
if not bBeginAbortCalled then Return
if not bAbortRecordCalled then Return
if _fileName="" then Return
' This is an Abort Phase success.
End Sub
End Class
End Namespace
[C#]
using System;
using System.IO;
using System.Reflection;
using System.EnterpriseServices;
using System.EnterpriseServices.CompensatingResourceManager;
[assembly: ApplicationActivation(ActivationOption.Server)]
[assembly: ApplicationCrmEnabled]
[assembly: AssemblyKeyFile("crm.key")]
namespace CrmServer
{
[Transaction]
// Create a Worker class.
public class CRMWorker:ServicedComponent
{
public void CRMMethod(string fileName, bool bCommit)
{
// Create clerk object.
Clerk clerk = new Clerk(typeof(CRMCompensator), "CRMCompensator", CompensatorOptions.AllPhases);
clerk.WriteLogRecord(fileName);
clerk.ForceLog();
if (bCommit)
ContextUtil.SetComplete();
else
ContextUtil.SetAbort();
}
}
// Create class derived from Compensator class.
public class CRMCompensator:Compensator
{
bool bBeginPrepareCalled = false;
bool bPrepareRecordCalled = false;
bool bBeginCommitCalled = false;
bool bCommitRecordCalled = false;
bool bBeginAbortCalled = false;
bool bAbortRecordCalled = false;
String _fileName;
public override void BeginPrepare()
{
bBeginPrepareCalled = true;
}
public override bool PrepareRecord(LogRecord rec)
{
Object o = rec.Record;
_fileName = o.ToString();
bPrepareRecordCalled = true;
return false;
}
public override bool EndPrepare()
{
if (!bBeginPrepareCalled)
{return false;}
if (!bPrepareRecordCalled)
{return false;}
if (_fileName==null)
{return false;}
// This is a Prepare Phase success.
return true;
}
public override void BeginCommit(bool fRecovery)
{
bBeginCommitCalled = true;
}
public override bool CommitRecord(LogRecord rec)
{
bCommitRecordCalled = true;
return true;
}
public override void EndCommit()
{
if (!bBeginCommitCalled)
{return;}
if (!bCommitRecordCalled)
{return;}
if (_fileName==null)
{return;}
// This is a Commit Phase success.
}
public override void BeginAbort(bool fRecovery)
{
bBeginAbortCalled = true;
}
public override bool AbortRecord(LogRecord rec)
{
bAbortRecordCalled = true;
Object o = rec.Record;
_fileName = o.ToString();
return true;
}
public override void EndAbort()
{
if (!bBeginAbortCalled)
{return;}
if (!bAbortRecordCalled)
{return;}
if (_fileName==null)
{return;}
// This is an Abort Phase success.
}
}
}
Client
Imports System
Imports System.IO
Imports System.EnterpriseServices
Imports CrmServer
Imports System.Runtime.InteropServices
Public Class CRM
Public Shared Sub Main()
dim logfilename As String = "crm.log"
Console.WriteLine("Creating a managed CRM worker object...")
dim crmworker As CRMWorker = new CRMWorker()
Console.WriteLine("Demonstrating a worker commit...")
crmworker.CRMMethod(logfilename, True)
Console.WriteLine("Demonstrating a worker abort...")
crmworker.CRMMethod(logfilename, False)
Console.WriteLine("DONE!")
Return
End Sub
End Class
[C#]
using System;
using System.IO;
using System.EnterpriseServices;
using CrmServer;
using System.Runtime.InteropServices;
class CRM
{
public static int Main()
{
string logfilename = "crm.log";
Console.WriteLine("Creating a managed CRM worker object...");
CRMWorker crmworker = new CRMWorker();
Console.WriteLine("Demonstrating a worker commit...");
crmworker.CRMMethod(logfilename, true);
Console.WriteLine("Demonstrating a worker abort...");
crmworker.CRMMethod(logfilename, false);
Console.WriteLine("DONE!");
return 0;
}
}
Makefile.bat
Vous pouvez compiler le programme serveur et client comme suit :
sn –k crm.key
vbc /t:library /r:System.EnterpriseServices.dll crm.vb
vbc /r:crm.dll /r:System.EnterpriseServices.dll crmclient.vb
[C#]
sn –k crm.key
csc /t:library /r:System.EnterpriseServices.dll crm.cs
csc /r:crm.dll crmclient.cs
Voir aussi
Résumé des services COM+ disponibles | System.EnterpriseServices, espace de noms