How to correctly model Node with multiple devices

Started by vladap, July 26, 2019, 15:46:22 PM

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vladap

Hi All,

My goal is to model Node which our application component is using. This Node is powered by multiple Devices. I put an example below, but I am not sure if my diagram is designed correctly, I was trying to find another examples with multiple devices, but I haven´t been successful so far :/ .

Q1: How to handle multiple devices which together build this node and what is the correctly placing of the App / OS / Node / Devices

Q2: What relations to use in this diagram

thanks for any PRO tips :)

Hervé

Hi,

I personally use two representations depending whether the number and the name of the devices are important.

As for the relations, I use an Assignment Relationship between the node and the device.

Hope this helps

Best regards
Hervé

Alberto

Question about the directionality...  I tend to model from bottom up, physical/technology at the bottom, business/strategy at the top. In this case, I would have recreated the Assignment Relationhip the other way.  Is there a rule around what direction relationships should go?

Hervé

I personally put the users at the top in order to put the emphasis on them because, we tend to look at the top of a picture before its bottom. Therefore the low level layer (like technical) is at the bottom. (I do not create multi layered views at the moment, so I do not mix business and technical layers).

But there is no rule. Some people do the opposite. I'm not sure this is really important.

As per the relationship direction, I believe you're talking about the relationships between the node and the devices. It really depends on what they stand for.

In my representation, the node would be a virtual machine and the devices the physical hosts where the VM can run. In that case, the assignment relationship stands for "the VM is assigned / can be assigned to the physical host" so is in the right direction.

vladap

Thanks for the comment and diagram , I will use your variant 1 . I was double checking the direction with "Mastering Archimate" book , and I agree with the direction.

Hervé

In fact, in this particular case, I would even add an intermediary "technology collaboration" that would represent the cluster and a "composition relationship" between the devices and the technology collaboration (the collaboration technology is composed of devices).

Jean-Baptiste Sarrodie

Hi,

Quote from: vladap on July 29, 2019, 13:26:48 PM
Thanks for the comment and diagram , I will use your variant 1 . I was double checking the direction with "Mastering Archimate" book , and I agree with the direction.

But in fact that's wrong in this case and the assignment relationship should be in the opposite direction: from Devices to Node. In this context the semantic of the assignment is "hosts", and your devices "host" the virtual machine.

To be even more exact, there is not even a really meaningful assignment relationship from Devices to Node. In fact, there is a derived assignment from your devices (physical hosts) to your "Linux" system software. This assignment is derived from another (unshown) system software for the virtualization engine itself which is assigned from the device and is assigned to "Linux" system software.

The node simply aggregates of composes your system software so you can't derive any relationship from the devices, but I personally think that Device assigned to Node would make sens and is acceptable in this context. Another option would be to model the dependency with a serving: Devices Serve Node.

Quote from: Hervé on July 29, 2019, 13:39:40 PM
In fact, in this particular case, I would even add an intermediary "technology collaboration" that would represent the cluster and a "composition relationship" between the devices and the technology collaboration (the collaboration technology is composed of devices).

Yes, Technology Collaboration could be used to model your cluster, but the relationship to use is an aggregation (only real relationship allowed for a collaboration) and not a composition, and should be from the Collaboration to the Devices.

Regards,

JB
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Hervé

Still a lot of things to learn ...

Again, Archimate is very intuitive ... or not  ???