Considerations for workflow topology

The workflow infrastructure consists of the workflow runtime for Internet Information Services (IIS) and the workflow runtime for the Application Object Server (AOS). Logically, the workflow infrastructure is an extension of Microsoft Dynamics AX and is transparent to Microsoft Dynamics AX end users. Physically, however, the workflow runtime is hosted by IIS and the AOS. For more information on workflow architecture, see Workflow system architecture.

Factors impacting workflow topology

  • Internet Information Services (IIS) and Application Object Server (AOS) form key components of the workflow infrastructure. For up-to-date hardware and software requirements for Microsoft Dynamics AX, see the system requirements Web page.

  • You can deploy the workflow runtime for IIS on the same IIS server or IIS farm along with Enterprise Portal, Application Integration Framework (AIF) Web services, and SQL Server Reporting Services. We recommend using a dedicated IIS server or IIS farm for deploying workflow.

  • You need to carefully consider the workload generated by the workflow system on your IIS servers, AOS servers, and database server. Consider the following factors when planning your Microsoft Dynamics AX server infrastructure:

    • The Microsoft Dynamics AX application provides workflow forms, alerts and controls that end users can use to participate in the business processes using the workflow system. In addition, batch jobs can also participate in the workflow process, as can any component that can invoke X++ code. The workflow infrastructure is completely transparent to the end user. However, user participation in business processes through the workflow system will generate workload for both the IIS server and the AOS server.

    • While planning your system topology, you need to estimate the added load that workflow activities will generate on the workflow server and the database. When X++ code calls the workflow services in the AOS runtime to submit a document, it eventually triggers the workflow Web service on the IIS server to start a workflow instance via Windows Communication Foundation (WCF). This workflow instance will keep running for as long as it needs to communicate with the AOS. If you have two users submitting expense reports for approval, two workflow instances are started. As the number of concurrent users submitting documents or tasks to workflow increases, the number of workflow instances will also increase. The workflow runtime for IIS persists (copies) all idle instances to the Microsoft Dynamics AX database and removes them from the memory. When the workflow runtime receives another message from the AOS for such a workflow instance, it rehydrates (restores) the instance from the Microsoft Dynamics AX database into memory.

    • You can deploy a single IIS server or an IIS farm with Workflow runtime for IIS and configure it to interact with a single AOS server or multiple AOS servers. For more information about installing the Workflow system, see the Installation Guide.

Sample deployment scenarios

Sample deployment scenarios range from a single-server deployment to a large-scale distributed deployment. The scenarios are provided to assist you in planning your infrastructure and server requirements. These scenarios do not provide any infrastructure sizing guidelines. For more information, see Sample deployment scenarios.