Process Instance
When you run any process, it creates an execution scope for the activities that are a part of the process and this scope is called a process instance. Each process instance has a unique ID, which is referred to as "ProcessInstanceId".
The execution of a process is triggered by various events. For example, events can be generated by a Timer that is scheduled to trigger at specific time intervals, or by changes that occur in the file system, or by messages that are sent by a client over a specific protocol (for example, HTTP, JMS), or simply by messages sent by other processes.
The TIBCO BusinessWorks Container Edition engine is a multi-threaded engine capable of triggering the execution of the same process multiple times, concurrently, once for each event. When the events that trigger the execution of a process occur concurrently, the engine runs the same process multiple times, concurrently, once for each event. And for each execution, the engine creates a process instance that provides an execution scope for the activities that are a part of the process.