Scenarios for Constructing Proxy Objects

Article
05/18/2015

Applies To: Microsoft Dynamics AX 2012 R3, Microsoft Dynamics AX 2012 R2, Microsoft Dynamics AX 2012 Feature Pack, Microsoft Dynamics AX 2012

There are different scenarios for constructing a proxy object from a proxy class that is written in C# or in another .NET Framework language:

Scenario 1: Implicit construction by parameter passing.
Scenario 2: Use a proxy object as input to construct a copy in a different namespace.
Scenario 3: Construct a Session object in C#.

Scenario 1: Implicit Construction by Parameter Passing

This scenario starts when an X++ job passes an X++ DictClass object to a C# method. The C# method takes a parameter type of a proxy for the X++ class DictClass. The system performs the marshaling by automatically constructing a proxy object from the DictClass object.

1a: The X++ Job

    static void StartInteropFromXppJob2a(Args _args)  // X++
    {
        DictClass dictClass2;
        int classId;
        str className;
    
        classId = classnum(DateTimeUtil);
        dictClass2 = new DictClass(classId);
    
        // Initiate interop from X++.
        className = CSharpDll.CSharpClass::CalledFromXppDc(dictClass2);
    
        info(strFmt("%1 , %2", classId, className));
    }
    /*** Output copied from the Infolog:
    64900 , DateTimeUtil
    ***/

1b: The C# Method

The system automatically constructs a proxy object from the X++ DictClass object, and the C# method receives the proxy as a parameter.

using System;  // C#
namespace CSharpDll
{
    public class CSharpClass
    {
        static public string CalledFromXppDc
                (MyProxyNamespace.DictClass pxyDictClass)
        {
            return pxyDictClass.name();
        }
    }
}

Scenario 2: Use a Proxy Object as Input to Construct a Copy in a Different Namespace

A C# application can have two proxy classes to the same X++ class, because the two proxies could have different namespaces. This section describes a scenario where you construct an instance of one proxy from an instance of the other, despite the namespace difference.

In the following example, at run time your C# code has an instance of the proxy class Finance.TownBank. But your code must pass an Economics.TownBank object to a method. The namespaces do not match.

The solution is to construct an instance of the Economics.TownBank proxy class from the Finance.TownBank object. Your C# code can use the following proxy constructor for this:

public Bank(Microsoft.Dynamics.AX.ManagedInterop.Object axObject)

After the constructor is called, both proxies reference the same TownBank object in Microsoft Dynamics AX. If one proxy changes the state of the underlying TownBank X++ object, the other proxy sees the changes.

// C# method to create a proxy object from an equivalent proxy object.
using System;
public TestTheProxy3
{
    public CloneAProxy(Finance.TownBank finBank)
    {
        Economics.TownBank ecoBank;
        Economics.AuditManager auditMgr;

        // Constructor call.
        ecoBank = new Economics.TownBank(finBank);

        auditMgr = new Economics.AuditManager();
        // Use the copy of the proxy, ecoBank.
        auditMgr.AuditABank(ecoBank);
    }
}

Scenario 3: Construct a Session object in C#

A C# .exe program that is started from the console can construct an instance of the Microsoft.Dynamics.AX.ManagedInterop.Session class. Then the C# code can call the constructor on a proxy class. For a code example, see Walkthrough: Adding an X++ Object to a Visual Studio Project.

Call Dispose on Proxy Objects

After your C# executable program is finished using an instance of a proxy, we recommend that you call the Dispose method on the instance. A proxy might reference a large amount of unmanaged memory, and calling Dispose prompts the release of the memory. An example follows.

proxyCustTable.Dispose();

Next is another example that relies on the using block construct to call the Dispose method.

using (CustTable proxyCustTable = new CustTable())
{
// Use proxyCustTable here.
} // Here the system calls the Dispose method on proxyCustTable.