MSCRM 4.0: A Convenience Workflow Base Class

When writing CRM workflow code, you often need to look up some information from its execution context, or instantiate CRM Web Service from the context. If your workflow is complex, you might have more than one method in your workflow activity class, in which case, you are most likely going to pass around the execution context object or the instance of CRM Web Service from one method to another, which is really tedious.

I have come up a convenience workflow base class which might help you become more proficient when developing your custom workflow activity code.

using System;
using System.Workflow.Activities;
using Microsoft.Crm.Workflow;
using System.Workflow.ComponentModel;
using Microsoft.Crm.Sdk;
using System.Web.Services.Protocols;

namespace CrmSpikes.Workflow
{
    /// <summary>
    /// Base class for all Sequence Workflow Activities which consist of only a single workflow activity.
    /// @author Daniel Cai, http://danielcai.blogspot.com/
    /// </summary>
    public abstract class SingleActivityBase : SequenceActivity
    {
        private ICrmService _crmServiceHandle;
        private IMetadataService _metadataServiceHandle;

        #region Base class members

        public IWorkflowContext Context { get; set; }

        /// <summary>
        /// CRM Web Services, instantiated on-demand.
        /// </summary>
        public ICrmService CrmServiceHandle
        {
            get
            {
                _crmServiceHandle = _crmServiceHandle ?? Context.CreateCrmService();
                return _crmServiceHandle;
            }
        }

        /// <summary>
        /// CRM Metadata Service, instantiated on-demand.
        /// </summary>
        public IMetadataService MetadataServiceHandle
        {
            get
            {
                _metadataServiceHandle = _metadataServiceHandle ?? Context.CreateMetadataService();
                return _metadataServiceHandle;
            }
        }
        #endregion

        #region SequenceActivity

        /// <summary>
        /// Workflow step.
        /// </summary>
        protected override ActivityExecutionStatus Execute(ActivityExecutionContext executionContext)
        {
            try
            {
                IContextService _contextService = (IContextService) executionContext.GetService(typeof (IContextService));
                Context = _contextService.Context;

                ExecuteBody();
            }
            catch (SoapException ex)
            {
                string errMsg = string.Format("{0}: {1}", ex, ex.Detail.InnerText);
                throw new InvalidPluginExecutionException(errMsg);
            }
            catch (Exception ex)
            {
                string errMsg = string.Format("{0}: {1}", ex, ex.Message);
                throw new InvalidPluginExecutionException(errMsg);
            }
            finally
            {
                if (_crmServiceHandle != null)
                    _crmServiceHandle.Dispose();

                if (_metadataServiceHandle != null)
                    _metadataServiceHandle.Dispose();

                Context = null;
            }

            return ActivityExecutionStatus.Closed;
        }

        /// <summary>
        /// Overridden in derived classes: contains the actual workflow step.
        /// </summary>
        protected abstract void ExecuteBody();

        #endregion
    }
}

To take advantage of the base class, your workflow class should inherit from the above SingleActivityBase class, such as this one.

using Microsoft.Crm.Workflow;

namespace CrmSpikes.Workflow
{
    [CrmWorkflowActivity("My Custom Workflow", "Custom Workflow")]
    public class MyCustomWorkflow : SingleActivityBase
    {
        #region Workflow Parameters
        #endregion

        #region SequenceActivity

        protected override void ExecuteBody()
        {
            // Do my stuff
        }

        #endregion
    }
}

The benefits of using the convenient base class are:

1. You can use the base class’s Context property to access the your workflow execution context anywhere in your activity class that you inherit from the base class.
2. You can use the base class’s CrmServiceHandle property to make CRM service calls right away. The base class takes care of instantiating (and also disposing) CRM Web Service in an on-demand fashion.
3. Similar to the above, you can use the base class’s MetadataServiceHandle property to make CRM metadata service calls right away. The base class takes care of instantiating (and also disposing) CRM Metadata Service in an on-demand fashion as well.
4. The base class tries to handle exceptions in a consistent way.

The idea was originally inspired by one of open source projects on CodePlex.com site, but I don't remember which project it is. However, the code here is pretty much a complete rewrite from the scratch. If you happen to know the project, please let me know, I will include a link here to the original project. :-)

It’s not rocket science, but it should make your CRM workflow development a little more convenient. Of course, if you have even better idea about the base class, I would appreciate to have your comments here.

Cheers!