For process modeling, AristaFlow provides an easy-to-use graphical editor – the AristaFlow Process Template Editor. It applies a correctness-by-construction principle by offering at any time only those operations to the process implementer, which allow to transform a structurally correct process model into another one (e.g., ensuring the absence of deadlocks). In addition, a number of error checks is performed concurrently to process modeling; e.g., in order to display inconsistencies in the modeled flow of data to the process implementer.

In the example depicted in Fig. 1, for instance, activity OrderProc reads data element OrderDoc though no value will have been assigned to OrderDoc when invoking this activity. If, for example, a “write edge” connecting activity OrderEntry (or the start node) with data element OrderDoc is added, the displayed error message will disappear.

 

Fig. 1: AristaFlow Process Template Editor Displaying an Inconsistent Flow of Data

Generally, only those process templates can be deployed to the AristaFlow Server (i.e., the AristaFlow Process Engine and its Process Repository), which are error-free and complete. The latter requires, for example, that each activity node (except “silent nodes”) is associated with an executable component. Furthermore, interactive activities need to be associated with actor assignment expressions refering to entities from the organizational model (e.g., roles or organizational units).

To speed up application development the AristaFlow Process Template Editor supports service composition in a  “plug & play" style complemented by the aforementioned correctness checks (cf. Fig. 2). All activity templates registered in the AristaFlow Activity Repository can be chosen in the Process Template Editor. The process implementer just drags and drops an activity template from the Activity Repository Browser window of the Process Template Editor onto the desired location in the process graph. Depending on the chosen location then either a new process node is created or the activity template is assigned to an existing process node.

 

Fig. 2: Composing New Processes in a Plug & Play Style

The left sub window of Fig. 3 (Activity Repository Browser) displays some examples of application-specific activities which refer to a database relation “Customer”. Below, this sub window also shows some generic (i.e., application-independent) activity templates (as listed under "Generics"). Generally, not only activity templates from the Activity Repository may be plugged into a process step, but also whole process models, which then results in a hierarchical process structure. Like activity templates, sub-processes can be added to a process graph in a “drag & drop”-like style. In this context, AristaFlow distinguishes between different modes for executing these sub-processes within the parental process (e.g., treating them as dependent sub processes or as autonomous process instance).

 

Fig.3: Plug & Play Support in the AristaFlow Process Template Editor