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I'm currently learning the second part of object-oriented programming and we have moved on to UML. We are learning about use cases and actors currently and we need to create: List of actors and use cases initiated by each actor for a given problem.

I understand what each of the individual components are but we haven't been given any examples. I've looked up examples but it only seems to give the final result of the use case diagram. What I am struggling with is using a problem statement ( the requirements of the system) to then create and find the actors and use cases:

https://www.scribd.com/document/401208954/Pms

This is my example of what I think to do but not sure if im on the right track...

2.2 MONITOR Each bed has a separate monitor that collects patient data, sends information to the display, and responds to user commands and queries.

The requirement is going to be: collects patient data, the goal: sends info to the display and the owner: the patient????

Christophe
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JavaScr
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  • My advise is to ignore the software for a moment, and study the words in the document you attached. A Use Case will include a noun and a verb. Remember that it must be business-useful, i.e. deliver discrete value to the user. An example might be "Add Monitor for Waveform X" which I pulled from 3.4.2. Your example -- "collects patient data" is not a Use Case, it's a function of the system that is probably used in implementing many of the Use Cases in your domain. – muszeo Mar 11 '19 at 18:42
  • What is your question? Deduce a requirement from what? Write a requirements spec? – qwerty_so Mar 11 '19 at 19:00
  • So im guessing something along the lines of i need to go through each of the requirements? But then for 2.1 Im already stuck. Im struggling to understand how to structure this. First i need to identify a list of actors and use cases initiated by each actor – JavaScr Mar 11 '19 at 19:02
  • @ThomasKilian the requirements / problem statement is the link attached. I need to create a list of actors and use cases initiated by each actor – JavaScr Mar 11 '19 at 19:03
  • Well, to make it short: this question is way too broad and nobody here will do your homework. Please read the help about what kind of questions can be asked. You're welcome back with a manageable question. – qwerty_so Mar 11 '19 at 19:17
  • im not asking for the complete answer or work to be done, im just confused on how to go about it or how to even get started. An example of what to do would set me up. From my understanding i simply need to go through the requirements and list the actors, and then find the use cases associated with each actor – JavaScr Mar 11 '19 at 19:19

1 Answers1

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First, you need to find in your document the actors who use the system and initiate interaction with it. These are the primary actors. For example:

1.PURPOSE

Blablabla... The users of the system are nurses and doctors

Then you need to find in your document any secundary actors. It's the actors that might be involved in an interaction in the system, but as a participant, not as initiator. For example:

3.1.4 ECG AND HEART RATE (HRT)

The ECG signal is carried by cables connected to electrodes attached to the patient's skin.

Here, clearly, the patient is involved, at least passively.

Attention, primary and secondary actors could also be systems, that would be independent of the system under consideration (e.g. a central admission system that would feed the system with patient data). I'm not sure that we have this case here.

Then you need to go again through your text, keeping the primary actors in mind, and looking for what they could want to use the system for. That's the use case, and it should in principle correspond to an actor's goal. For example:

3.1.8 PATIENT ADMISSION AND DISCHARGE

In order to blablabla..., the patient must be admitted. Patient admission consists of blablabla....

3.3 EVENT RECORDING

The user must be able to input textual remarks on the patient condition. Blablabla...

In these examples, the users will definitively want to admit a patient, monitor the vital signs of the patient, and record events. The difficulty is to filter out what the users want to do (the goal), and the details of how they do it or how the system looks like. For example, entering the name and age, plugging the ECG cable, or the NBP are operational details of the admission.

Some of those details are purely descriptive (where the info will be shown on the screen), but some details could be a secondary goal (a subgoad for the user, in order to achieve a higher level goal). For example silencing the monitoring. You may list those as a use case, but you should then note that it's not a top level. These details are only needed when refining the main use cases.

Then you may associate secondary actors to identified use cases where appropriate.

Christophe
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