process without prior completion event The above workflow patterns have been used to evaluate the functionality of commercial products supporting the development of process-oriented applications. They have also been used to evaluate a number of proposed standards, including BPEL, BPMN, UML Activity diagram, XPDL, etc. It has been noted that not all these patterns are relevant in all application domains, so care must be taken when using the above workflow patterns to select a particular language or system for a given application. The workflow patterns have also been used as initial requirements in the design of a workflow language and open-source system called YAWL (Yet Another Workflow Language). Several extensions to the above set of workflow patterns have been proposed. In particular, the same research groups that developed these patterns, have also proposed a set of Workflow Data Patterns, Workflow Resource Patterns, Workflow Exception Handling Patterns, and Service Interaction Patterns. Another classification Another classification of workflow patterns is the following: Independent/Pooled where each component of scheduled work is completed independent of each other component and no component has a specific dependency on any other component. An example would be where staff are serving at a counter - Raoul can serve a customer in his queue without waiting for Jamie to serve a customer in his queue. Sequential where each component of scheduled work is dependent on the preceding component. In this case the preceding component controls the advancement of the workflow through subsequent components. An example would be on a production line - Betty cannot affix the radiator cap to the Model T Ford until Veronica has put the radiator in place. Interdependent/Networked where each component of scheduled work is dependent on one or a number of other components being completed. In this case the preceding components control the workflow through subsequent components. An example would be a project team - Sarah must wait for several tasks to be completed by Kevin and George before she can execute her task. Other perspectives The workflow patterns are not limited to control-flow. Other (workflow) pattern collections include: resource patterns, data patterns, exception patterns, service interaction patterns. parallelism and pipelining patterns. These patterns collections have been used to evaluate a variety of workflow processes, both commercial (Websphere, Oracle BPEL, Staffware, SAP workflow, Windows Workflow Foundation, etc.) and open source. Workflow systems implementing patterns Tavaxy is a cloud-based workflow system that implements a pattern-based