Written entirely in .Net and using SQL Server as the database of choice, the Corporate Modelling Workflow Engine is a companion product to the modelling tool Enterprise Improvement. The modelling tools are used to:   • Define the current process   • Analyse the current process for Six Sigma quality   • Define the new improved process   • Analyse the current and new processes for costing   • Simulate the processes both costing and resources   • Control the new processes when deployed in a suitable environment The process modelling structure used in these tools is industry standard Business Process Modelling Notation (BPMN). This notation was chosen for its easy conversion into BPEL, the business process execution language so that alternate workflow engines can be used to deploy the process defined as required. The Workflow Engine is our companion product that allows the deployment of these advanced business process models into a workflow solution with many advanced features, at low cost. Workflow and process flows (processes with no user intervention) are critical to the operation of the business and as such Corporate Modelling believes the engine they are built upon has to be fault tolerant. Our solution uses a State Entity machine rather than a messaging approach to ensure that the queues are always transaction safe, and since these are stored in SQL server tables this provides us with:   • The ability to mirror the queues across multiple disks   • The ability to partition the queues across multiple machines   • The ability to cluster the servers for resilience   • The ability to scale the solution dealing with tens of thousands of users and hundreds of millions of cases being     processes simultaneously