Compensator Classe

Definição

public ref class Compensator : System::EnterpriseServices::ServicedComponent

public class Compensator : System.EnterpriseServices.ServicedComponent

type Compensator = class
    inherit ServicedComponent

Public Class Compensator
Inherits ServicedComponent

Herança

Object

MarshalByRefObject

ContextBoundObject

ServicedComponent

Compensator

Exemplos

O seguinte exemplo de código demonstra a utilização desta classe.

// A CRM Compensator
public ref class AccountCompensator : public Compensator
{
private:
    bool receivedPrepareRecord;

public:
    AccountCompensator()
    {
        receivedPrepareRecord = false;
    } 

public:
    virtual void BeginPrepare() override 
    {
        // nothing to do
    }

public:
    virtual bool PrepareRecord(LogRecord^ log) override 
    {

        // Check the validity of the record.
        if (log == nullptr)
        {
            return false;
        }
        array<Object^>^ record = dynamic_cast<array<Object^>^>(log->Record);
        if (record == nullptr)
        {
            return false;
        }
        if (record->Length != 2)
        {
            return false;
        }

        // The record is valid.
        receivedPrepareRecord = true;
        return true;              
    }

public:
    virtual bool EndPrepare() override
    {
        // Allow the transaction to proceed onlyif we have received a prepare
        // record.
        if (receivedPrepareRecord)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

public:
    virtual void BeginCommit(bool commit) override
    {
        // nothing to do
    }

public:
    virtual bool CommitRecord(LogRecord^ log) override
    {
        // nothing to do
        return(false);
    }

public:
    virtual void EndCommit() override
    {
        // nothing to do
    }

public:
    virtual void BeginAbort(bool abort) override
    {
        // nothing to do
    }

public:
    virtual bool AbortRecord(LogRecord^ log) override
    {

        // Check the validity of the record.
        if (log == nullptr)
        {
            return true;
        }
        array<Object^>^ record = dynamic_cast<array<Object^>^>(log->Record);
        if (record == nullptr)
        {
            return true;
        }
        if (record->Length != 2)
        {
            return true;
        }

        // Extract old account data from the record.
        String^ filename = (String^) record[0];
        int balance = (int) record[1];

        // Restore the old state of the account.
        WriteAccountBalance(filename, balance);

        return false;
    }

public:
    virtual void EndAbort() override
    {
        // nothing to do
    }    

};

// A CRM Compensator
public class AccountCompensator : Compensator
{

    private bool receivedPrepareRecord = false;

    public override void BeginPrepare ()
    {
        // nothing to do
    }

    public override bool PrepareRecord (LogRecord log)
    {

        // Check the validity of the record.
        if (log == null) return(true);
        Object[] record = log.Record as Object[];
        if (record == null) return(true);
        if (record.Length != 2) return(true);

        // The record is valid.
        receivedPrepareRecord = true;
        return(false);
    }

    public override bool EndPrepare ()
    {
        // Allow the transaction to proceed onlyif we have received a prepare record.
        if (receivedPrepareRecord)
        {
            return(true);
        }
        else
        {
            return(false);
        }
    }

    public override void BeginCommit (bool commit)
    {
        // nothing to do
    }

    public override bool CommitRecord (LogRecord log)
    {
        // nothing to do
        return(false);
    }

    public override void EndCommit ()
    {
        // nothing to do
    }

    public override void BeginAbort (bool abort)
    {
        // nothing to do
    }

    public override bool AbortRecord (LogRecord log)
    {

        // Check the validity of the record.
        if (log == null) return(true);
        Object[] record = log.Record as Object[];
        if (record == null) return(true);
        if (record.Length != 2) return(true);

        // Extract old account data from the record.
        string filename = (string) record[0];
        int balance = (int) record[1];

        // Restore the old state of the account.
        AccountManager.WriteAccountBalance(filename, balance);

        return(false);
    }

    public override void EndAbort ()
    {
        // nothing to do
    }
}

' A CRM Compensator

Public Class AccountCompensator
    Inherits Compensator
    
    Private receivedPrepareRecord As Boolean = False
    
    
    Public Overrides Sub BeginPrepare() 
    
    End Sub
    
    ' nothing to do
    Public Overrides Function PrepareRecord(ByVal log As LogRecord) As Boolean 
        
        ' Check the validity of the record.
        If log Is Nothing Then
            Return True
        End If
        Dim record As [Object]() = log.Record
        
        If record Is Nothing Then
            Return True
        End If
        If record.Length <> 2 Then
            Return True
        End If 
        ' The record is valid.
        receivedPrepareRecord = True
        Return False
    
    End Function 'PrepareRecord
    
    Public Overrides Function EndPrepare() As Boolean 
        ' Allow the transaction to proceed onlyif we have received a prepare record.
        If receivedPrepareRecord Then
            Return True
        Else
            Return False
        End If
    
    End Function 'EndPrepare
    
    Public Overrides Sub BeginCommit(ByVal commit As Boolean) 
    
    End Sub
    
    ' nothing to do
    Public Overrides Function CommitRecord(ByVal log As LogRecord) As Boolean 
        ' nothing to do
        Return False
    
    End Function 'CommitRecord
    
    Public Overrides Sub EndCommit() 
    
    End Sub
    
    ' nothing to do
    Public Overrides Sub BeginAbort(ByVal abort As Boolean) 
    
    End Sub
    
    ' nothing to do
    Public Overrides Function AbortRecord(ByVal log As LogRecord) As Boolean 
        
        ' Check the validity of the record.
        If log Is Nothing Then
            Return True
        End If
        Dim record As [Object]() = log.Record
        
        If record Is Nothing Then
            Return True
        End If
        If record.Length <> 2 Then
            Return True
        End If 
        ' Extract old account data from the record.
        Dim filename As String = CStr(record(0))
        Dim balance As Integer = Fix(record(1))
        
        ' Restore the old state of the account.
        AccountManager.WriteAccountBalance(filename, balance)
        
        Return False
    
    End Function 'AbortRecord
    
    Public Overrides Sub EndAbort() 
    
    End Sub
End Class

Este compensador é utilizado pela seguinte classe de trabalhadores.

// A CRM Worker
[Transaction]
public ref class Account : public ServicedComponent
{

    // A data member for the account file name.
private:
    String^ filenameValue;

public:
    property String^ Filename
    {
        String^ get()
        {
            return filenameValue;
        }
        void set( String^ value )
        {
            filenameValue = value;
        }
    }

    // A boolean data member that determines whether to commit or abort the 
    // transaction.
private:
    bool allowCommitValue;

public:
    property bool AllowCommit
    {
        bool get()
        {
            return allowCommitValue;
        }
        void set( bool value )
        {
            allowCommitValue = value;
        }
    }

    // Debit the account, 
public:
    void DebitAccount(int amount)
    {

        // Create a new clerk using the AccountCompensator class.
        Clerk^ clerk = gcnew Clerk(AccountCompensator::typeid,
            "An account transaction compensator", CompensatorOptions::AllPhases);

        // Create a record of previous account status, and deliver it to the
        // clerk.
        int balance = ReadAccountBalance(Filename);

        array<Object^>^ record = gcnew array<Object^>(2);
        record[0] = Filename;
        record[1] = balance;

        clerk->WriteLogRecord(record);
        clerk->ForceLog();

        // Perform the transaction
        balance -= amount;

        Console::WriteLine("{0}: {1}", Filename, balance);

        WriteAccountBalance(Filename, balance);

        // Commit or abort the transaction 
        if (AllowCommit)
        {
            ContextUtil::SetComplete();
        }
        else
        {
            ContextUtil::SetAbort();
        }

    }

};

// A CRM Worker
[Transaction]
public class Account : ServicedComponent
{

    // A data member for the account file name.
    private string filename;

    public string Filename
    {
        get
        {
            return(filename);
        }
        set
        {
            filename = value;
        }
    }

    // A boolean data member that determines whether to commit or abort the transaction.
    private bool commit;

    public bool AllowCommit
    {
        get
        {
            return(commit);
        }
        set
        {
            commit = value;
        }
    }

    // Debit the account,
    public void DebitAccount (int ammount)
    {

        // Create a new clerk using the AccountCompensator class.
        Clerk clerk = new Clerk(typeof(AccountCompensator),
          "An account transaction compensator", CompensatorOptions.AllPhases);

        // Create a record of previous account status, and deliver it to the clerk.
        int balance = AccountManager.ReadAccountBalance(filename);

    Object[] record = new Object[2];
    record[0] = filename;
        record[1] = balance;

        clerk.WriteLogRecord(record);
        clerk.ForceLog();

        // Perform the transaction
        balance -= ammount;
        AccountManager.WriteAccountBalance(filename, balance);

        // Commit or abort the transaction
        if (commit)
        {
            ContextUtil.SetComplete();
        }
        else
        {
            ContextUtil.SetAbort();
        }
    }
}

' A CRM Worker
<Transaction()>  _
Public Class Account
    Inherits ServicedComponent
    
    ' A data member for the account file name.
    Private filename As String
    
    
    Public Property Filenam() As String
        Get
            Return Filename
        End Get
        Set(ByVal value As String)
            filename = Value
        End Set
    End Property
    
    
    ' A boolean data member that determines whether to commit or abort the transaction.
    Private commit As Boolean
    
    
    Public Property AllowCommit() As Boolean 
        Get
            Return commit
        End Get
        Set
            commit = value
        End Set
    End Property
    
    
    
    
    ' Debit the account, 
    Public Sub DebitAccount(ByVal ammount As Integer) 
        
        ' Create a new clerk using the AccountCompensator class.
        Dim clerk As New Clerk(GetType(AccountCompensator), "An account transaction compensator", CompensatorOptions.AllPhases)
        ' Create a record of previous account status, and deliver it to the clerk.
        Dim balance As Integer = AccountManager.ReadAccountBalance(Filenam)
        
        Dim record(1) As [Object]
        record(0) = filename
        record(1) = balance
        
        clerk.WriteLogRecord(record)
        clerk.ForceLog()
        ' Perform the transaction
        balance -= ammount
        AccountManager.WriteAccountBalance(filename, balance)
        
        ' Commit or abort the transaction 
        If commit Then
            ContextUtil.SetComplete()
        Else
            ContextUtil.SetAbort()
        End If
    End Sub
    
End Class

O exemplo de código seguinte demonstra um cliente que exerce este compensador e trabalhador.

#using "System.EnterpriseServices.dll"

using namespace System;

[assembly: System::Reflection::AssemblyKeyFile("CrmServer.key")];

int main ()
{

    // Create a new account object. The object is created in a COM+ server application.
    Account^ account = gcnew Account();

    // Transactionally debit the account.
    try
    {
        account->Filename = System::IO::Path::GetFullPath("JohnDoe");
        account->AllowCommit = true;
        account->DebitAccount(3);
    }
    finally
    {
        delete account;
    }

}

using System;

public class CrmClient
{

    public static void Main ()
    {

        // Create a new account object. The object is created in a COM+ server application.
        Account account = new Account();

        // Transactionally debit the account.
        try
        {
            account.Filename = System.IO.Path.GetFullPath("JohnDoe");
            account.AllowCommit = true;
            account.DebitAccount(3);
        }
        finally
        {
            account.Dispose();
        }
    }
}

Public Class CrmClient
    
    
    Public Shared Sub Main() 
        
        ' Create a new account object. The object is created in a COM+ server application.
        Dim account As New Account()
        
        ' Transactionally debit the account.
        Try
            account.Filenam = System.IO.Path.GetFullPath("JohnDoe")
            account.AllowCommit = True
            account.DebitAccount(3)
        Finally
            account.Dispose()
        End Try
    
    End Sub
End Class

Observações

O utilizador deve expandir-se a partir deste objeto para escrever um Compensador de transações personalizado.

Um Compensador deve ter sempre um construtor público; caso contrário, o motor de recuperação não consegue criá-lo.

Para mais informações, consulte Como: Criar um Resource Manager Compensador (CRM).