Passing Data Between Plug-ins [Microsoft Dynamics CRM 4.0]

The message pipeline model provides for a PropertyBag of custom data values in the execution context that is passed through the pipeline and shared among registered plug-ins. This collection of data can be used by different plug-ins to communicate information between plug-ins and enable chain processing where data processed by one plug-in can be processed by the next plug-in in the sequence and so on. This feature is especially useful in pricing engine scenarios where multiple pricing plug-ins pass data between one another to calculate the total price for a sales order or invoice. Another potential use for this feature is to communicate information between a plug-in registered for a pre-event and a plug-in registered for a post-event.

The name of the parameter that is used for passing information between plug-ins is SharedVariables. This is a collection of System.Object. A common type of object that is used to fill the collection is DynamicEntity. At run time, plug-ins can add, read, or modify properties in the SharedVariables property bag. This provides a method of information communication among plug-ins.

Note Only types that are XML serializable should be placed in SharedVariables. All types derived from BusinessEntity are XML serializable.

The following code example shows how to use SharedVariables to pass data from a pre-event registered plug-in to a post-event registered plug-in.

 
using System;
using Microsoft.Crm.Sdk;
using Microsoft.Crm.SdkTypeProxy;

public class AccountSetStatePreHandler : IPlugin
{
    public void Execute(IPluginExecutionContext context)
    {
        // Create or retrieve some data that will be needed by the post event
        // handler. You could run a query, create an entity, or perform a calculation.
        //In this sample, the data to be passed to the post plug-in is
        // represented by a GUID.
        Guid contact = new Guid("{74882D5C-381A-4863-A5B9-B8604615C2D0}");

        // Pass the data to the post event handler in an execution context shared
        // variable named PrimaryContact.
        context.SharedVariables.Properties.Add(
            new PropertyBagEntry("PrimaryContact", (Object)contact.ToString()));
        // Alternate code: context.SharedVariables["PrimaryContact"] = contact.ToString();
    }
}

public class AccountSetStatePostHandler : IPlugin
{
    public void Execute(IPluginExecutionContext context)
    {
        // Obtain the contact from the execution context shared variables.
        if (context.SharedVariables.Contains("PrimaryContact"))
        {
            Guid contact = 
                new Guid((string)context.SharedVariables["PrimaryContact"]);
            // Do something with the contact.
        }
    }
}