When a conversation starts, the Process Engine selects the appropriate process model to use for the conversation. The Process Engine can run multiple instances of the same process model at one time. Each instance is a different conversation. To keep the instances of the conversation distinct, each instance must have its own unique ConversationID. The webMethods Chem eStandards Module assigns each Chem eStandards‐transaction conversation a unique ConversationID.

For the Process Engine to associate documents in a single conversation with the correct running instance of a process model, all documents entering the conversation must specify the same ConversationID. In a process model, the Send to Back‐End step transitions the business document to the back‐end. When this occurs, the back‐end system is passed information, including the ConversationID. For the conversation to continue properly, when the back‐end system returns the response, the business documents from the back‐end system must include the correct ConversationID. This means that, at design time, when you set up your back‐end systems to participate in a conversation, you must ensure that the back‐end system maintains the ConversationID when it receives a business document.

You must maintain the ConversationID on your back‐end system when you receive a business document. You then must include the ConversationID in any Response document you send back so that the webMethods Chem eStandards Module can identify the proper conversation to which the Response document belongs and make sure the Response document rejoins the correct existing conversation.