Could someone please explain the purpose of the Call Activity object in ARIS? I understand that it 1) is found in BPMN and BPMN Subprocess models and 2) that it links to other models or objects. If you want to link it to another model, why not just use a Task object and link it to another model via an Assignment? What's the difference between Call Activities and Assignments other than Assignments can be found all all models, not just BPMN models? Thanks :)
8 Replies
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The ARIS process modelling tools include modeltypes covering a standard implementation of BPMN 2.0 (see OMG specifiation). Part of BPMN 2.0 is the call activity object. That means this is not ARIS specific but part of the BPMN standard. The call activity "calls" a global process or a global task. A global task is atomic with no further details. Technically this is realized as assignment in ARIS.
Regards
Klemens
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Ok, thanks. Just to break this down a little further...
Since there are various options when linking models, I'm going to try and clarify where and when to use them. I welcome your feedback.
Linking options & when to use them:
- Call Activities (object) -Use this object for 1) Enterprise BPMN Collaboration and 2) BPMN Subprocess models in ARIS when 1) there are enterprise-wide processes that may occur within several other processes, and contain no variation when performed and 2) BPMN 2.0 notation is being required
- Sub Processes (object) - Use this object for 1) Enterprise BPMN Collaboration and 2) BPMN Subprocess models in ARIS when 1) there are detailed steps behind a process that you don't want to show on the main diagram and 2) BPMN 2.0 notation is required
- Process Interface (object) Use this object for EPC (event driven process chain) diagrams when you are looking for something similar to the Off-page Connector in Visio that links a current process to a successive process. Unlike Off-page Connectors, when you click on the Process Interface, it doesn't automatically take you to the linked model.
- Assignments - Use this connection 1) to link any object to any model when you would like to drill down levels and create models from higher objects in ARIS (cited from training materials)
I'm wondering why someone would use Assignments when Sub-processes could be used. If anyone has experience using Assignments, could you please share an example of your work and a give a reason why one of the other three options wouldn't have worked to accomplish your goal. Thank you!
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I think you are mixing the theoretical concept of linking objects and the technical concept doing this by an assignment. In top 1,2,3 you are describing the theoretical concept of BPMN resp. EPC. And this is realized technically in ARIS by assignments. So there is NO contradiction between sub-processes and assignments.
Hope this brings some clarifications.
Regards
Klemens
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I agree with everything @Klemens Hauk writes. Just to elaborate on Sub-Process vs. Call Activity in BPMN a bit further:
Call Activity literally embeds a globally available process in the process where you are modelling the Call Activity. Triggering the Call Activity creates an instance of the global process and it only finishes after the global process has been terminated completely (i. e. the last end event was reached). Technically the called global process is assigned to the Call Activity object.
A sub-process is a representation of a local process, which is NOT reusable by any other process, not even in the same process. You can "expand" the sub-process symbol and it will show the process inside the symbol. Technically the sub-process is modelled in an assigned "BPMN 2.0 process diagram" or "Enterprise BPMN process diagram" with the additional restriction that you cannot use lanes in those, because they are not allowed inside sub-process symbols according to the BPMN specification.
To raise more confusion: "Task", "Sub-Process", "Call Activity", "Process Interface" are represented by the same "Function" object type in ARIS.
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Call Activities are clear and I've used sub-process for years, so there is no misunderstanding there. If anyone has experience using Assignments, could you please share an example of your work and a give a reason why one of the other three options wouldn't have worked to accomplish your goal. Thank you!
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Hello Dana,
assignment is a generic mechanism to link an object definition to a model. Any occurrence of the object in any model can be used to navigate the assignment link to that model. So the general idea is, that you use it to assign a model, that describes the object in more detail or more detail of the object's context. Possible use-cases are:
- Navigating a hierarchy of processes in Value-added chain diagrams (VACD), "zooming in" via the assignment link. Instead of modelling a giant hierarchy tree in a single model, you just model a single level of the hierarchy in a VACD. I. e. the VACD only shows the children of the object you assign the VACD to. Optionally you also show an occurrence of the object in the assigned model and use box-in-box modelling with implicit connections or explicit connections in a tree-like fashion between the superior and subordinate process objects.
- Show the context of a task in a Function allocation diagram (FAD). You can connect all RACI-Roles to the task, supporting applications, inputs and outputs, supporting business services, risks, ... you name it for the single task. All the resources you need to show for the process step and BPMN does not provide for, because it is only focused on process logic.
- Assign the BPMN Collaboration diagram itself to the white-box Pool of each BPMN Collaboration diagram. This way you can navigate to the model where-ever you make an occurrence of the Pool as Black-box Pool in other BPMN Collaboration diagrams
- Assign data models to input and output objects.
- Assign context for Applications in Access diagrams
- ...
You get the idea why also the link between Sub-Process and Process diagram and the link between Call Activity and BPMN Collaboration diagram is supported through this generic assignment mechanism. So it serves as a generic "zoom" and "navigation" function - not only in process models but also for other stakeholder disciplines.
The only reason why I would not assign more detailed process models to Task symbols is that such a mechanism is not specified in the BPMN 2.0 standard. However feel free to use it to add information in FADs that the BPMN standard does not support by design.
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Thank you for the very detailed explanation of the assignment mechanism in ARIS. One remark to your statements:
All the resources you need to show for the process step and BPMN does not provide for, because it is only focused on process logic.
The only reason why I would not assign more detailed process models to Task symbols is that such a mechanism is not specified in the BPMN 2.0 standard. However feel free to use it to add information in FADs that the BPMN standard does not support by design.
- Indeed a task is described as "atomic" in BPMN, so it cannot be divided in more detailed activities.
- BPMN includes the concept of "extensibility". So it is allowed to add new data ("attributes") and link them to the model itself and to objects on any level. In this way it is not only possible but desired to document all information in the BPMN model (additional resources, risk management, describing values like duration of the task and so on). You also need additional data to automate your process. A BPMN model is a diagram and the related data.
- It is not mandatory (but optional) to show all those attributes in the diagram. Not to overload the diagram you can display the attributes or part of them as FAD called by the object (e.g. task) done by an assignment. This is tool specific but does not stay in conflict with the BPMN standard.
Regards
Klemens
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Agreed. Not overloading the diagram is the key point here. In fact ARIS allows you to customize your method and add all the resource satellites in BPMN models (like you might do in an EPC). But who will want to read that? Legibility suffers.
You can use custom attributes, extending the BPMN method. But where you enter into other stakeholders' domains of governed objects it is advantageous to use those objects. And ARIS provides views/model types for other domains: data models, service models, architecture models, organizational charts...
So there are strong arguments to use BPMN for what it was designed for (compare chapter 7 of the specification, what is out of scope) and use the fantastic other notations for the other modelling domains.