I just published a new technical article for developers titled Asynchronous Ribbon Enable Rules and Executing Workflows from the Ribbon with Microsoft Dynamics CRM 2011 and Microsoft Dynamics CRM Online.
However when looking at the scenarios where you might want to do this, we found that the more challenging task is controlling when the button to execute the workflow should be enabled. Especially for an action like a workflow that is executed asynchronously. You don’t want to have a UI where someone can repeatedly click a control and generate multiple workflow instances to execute. To get information about whether to enable the button or not you generally have to query data to determine if the conditions are right.
Furthermore, EnableRules for the ribbon cannot depend on (relatively) long running processes such as those to retrieve data. A long running process for an enable rule will affect the person’s experience using the ribbon controls so it is important to minimize the impact of these types of rules. The strategy described in this article is to use asynchronous requests for data and then refreshing the ribbon when the data is returned. The SDK topic Define Ribbon Enable Rules mentions this strategy in regard to custom rules, but this article provides a specific example.
I hope that this article will help you if your requirements are to execute a workflow from a ribbon control.
Read the complete post at http://blogs.msdn.com/b/crm/archive/2012/09/22/how-to-execute-a-workflow-from-a-ribbon-button-and-control-when-the-button-is-enabled.aspx
Microsoft Dynamics CRM Team Blog