Conflicts of requirements and modeling with time

[Luis Oliveira]

Hello, everyone.

Two questions have come up and I would like to ask for your opinion:

1 - Does SysML have any mechanism to model conflicts of requirements?

2 - The work I'm developing involves modeling real-time systems, where I have several blocks with independent clocks, which correspond to several equipments. These equipments are connected based on pre-established schedules, and may exist time discrepancies, for example, two equipments may mark six in the morning at different moments.

The question is, without counting with the use of notes, does SysML have any way to specify schedules and time based behaviors?

Thanks for the answers!

Regards,

Luis Oliveira.

[Eran Peleg]

Hi Luis

Yes.  There are at least 3 diagrams for dealing with schedule and timing:

1. Timing diagram with timing and state change according to schedule
2. Sequence diagram with objects as lifelines with specific time oriented syntax.
3. Activity Diagram – it the least schedule oriented diagram, but you may use it with additional information, using Tags, on flows and constraints.

Best regards

Eran

 

===================

Eran Peleg, CEO

Metaphor Vision Ltd.

www.metaphor.co.il

+972545346060

epe...@metaphor.co.il

===================

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[ransom...@gmail.com]

Luis,

1.) It depends! If you want to say 'This textual specification of what a subject needs to achieve (aka a <<Requirement>> element) and that <<requirement>> element are in conflict with each other" I've seen it done before with using a comment with the 'problem' stereotype. The example I'm thinking of is Fig 12 of this document on pg. 12 - https://www.omg.org/ocsmp/HSUV.pdf

However, a block can be considered a modeled specification for what the element being modeled needs to be and do. If you know that the system needs to be less than 100 pounds, and is made up of 3 physical components that each have non-negligible mass, then you can specify that the system needs to have a value property for a Kilogram value type, named 'System Mass', and the same for each component as 'Component N Mass : Kilogram'. Then you may be able to build a parametric diagram that says 'System Mass = Component 1 Mass + Component 2 Mass + Component 3 Mass' If component 1, 2 and 3 all have constraints on them that their mass can't be less than 34 pounds for some reason, you may then have an parametric definition that will have an error result from it. I would guess that the tool would passively validate that 'yes this all works out, unless it doesn't, at which point I'll throw a flag to the modeled to say there's an error." However, I can't confirm that for most tools, and am not sure this would be the most useful example against which this is applied (i.e. it's very easy to figure out that 34+34+34 > 100; there's a lot more interesting SE problems that are of much more value to try and solve.) But as a starting point, consider looking into parametric diagrams applied to value types of specifications to see if conflicts can be detected through some calculations and other error checking in your tool.

Interested to see what others have to say on the topic.

2.) Real Time System => Agile Systems Engineering by Dr. Bruce Powel Douglass. All his stuff is built in Rational Rhapsody which I've seen evangelized for being real time systems oriented (although fully applicable for non-RTSs!). His whole approach defined in more or less for an RTS and may be an interesting look for you. Always recommend a physical purchase if you can cop it; desk references, even when they're not perfect, are always awesome to have on hand. 

Ok into the meat of it. So let me make sure I'm reading you correctly; 1 block represents 1 piece of equipment, and each piece of equipment has it's own internal clock running, and those clocks have NO synchronization mechanism between them, so we can't reliably say that the system composed of integrating those blocks is always running with the same time values on their clocks. And then, based on some schedule that you have specified outside of any one of those (i.e. you have a clip board that says it), a connection is formed (are destructions of the connections also time based?) between two components (which may or may not have been connected before, but I will assume that they likely were not already connected.) so that they can interact in some meaningful way.

I'd probably think that you would find the most utility in a sequence diagram, which at their most simple don't show time so much as a time-ordered sequence of events. (i.e. if I have an sequence diagram that has 3 messages on it, one that's me cutting a bunch of vegetable, cooking an all day stew, and eating, they're in that order, even though cutting vegetables only took 20 minutes, cooking took 5 hours, and eating took 45 minutes; there's not relative based on visuals) However, using time observations and constraints and duration observations and constraints, you can explicitly define time on your diagrams. More details on in Ch 10.6 of A Practical Guide to SysML, and this link: https://www.sciencedirect.com/topics/computer-science/duration-constraint

Without knowing more about your problem, I can't say much else to go look into. Without knowing anything about real time systems, I don't know that I'd be able to say anything helpful even with more context. Hope this helps!

[James Towers]

Technically Timing Diagrams are UML diagrams excluded (for some odd reason) from SysML, but obviously if your tool supports them you can use them.

To view this discussion on the web visit https://groups.google.com/d/msgid/sysmlforum/059001d68a85%249de803c0%24d9b80b40%24%40metaphor.co.il.

[Hari Mahalingam]

hi ransom,

How do I model real timing for an activity in the SYSML.I tried all the option in the tool and cannot find. i am using 19 version.

For example. I from stating the project to a task i need to give 30 hours and I should be able to monitor real-time as well in the diagram

YThanks

harry

[Hari Mahalingam]

Hi Eran,

How to add real timing in an activity I tried all the options and cannot find any option. For example from to start of the project, I need to give 30 hours to a task and I should be able to monitor?

I have another question hoe to specify tasks and activity and now I am adding them as a to-do list but this not visible in the acitivity.

Thanks

harry

[Murray, Alexander T (US 313I)]

Hi Harry,

 You can create Constraints – duration constraints, and apply them to Actions in an Activity.  You can also create time-driven transitions in State machines.    The simulation of these behaviors should take these timing constraints into account, I guess that depends on the tool you’re using.

--Alex

 

 

From: sysml...@googlegroups.com <sysml...@googlegroups.com> On Behalf Of Hari Mahalingam
Sent: Tuesday, November 17, 2020 5:47 AM
To: SysML Forum <sysml...@googlegroups.com>

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[Hari Mahalingam]

Alex,

It seems like you know the tool well. Can I ask you for another help on the tool?

1.       How to extract a model or how to extract a package diagram or state diagram for the word of pdf document?

2.       Is there any way enclose a real-time clock or date attached to an activity diagram?

Thanks

harry

To view this discussion on the web visit https://groups.google.com/d/msgid/sysmlforum/0462d57dfd314b35b6836a2fa61a38f6%40jpl.nasa.gov.

[Murray, Alexander T (US 313I)]

HI Harry,

See below

Alex

 

 

From: sysml...@googlegroups.com <sysml...@googlegroups.com> On Behalf Of Hari Mahalingam
Sent: Sunday, November 22, 2020 5:12 AM
To: sysml...@googlegroups.com
Subject: Re: [EXTERNAL] [SysML Forum] Re: Conflicts of requirements and modeling with time

 

Alex,

It seems like you know the tool well. Can I ask you for another help on the tool?

1.        How to extract a model or how to extract a package diagram or state diagram for the word of pdf document?

AM: I’m not aware of a way to do this. Maybe someone else knows of a way to scan a diagram.

2.        Is there any way enclose a real-time clock or date attached to an activity diagram?

AM: I’m not sure I understand your question.

Thanks

harry

To view this discussion on the web visit https://groups.google.com/d/msgid/sysmlforum/CAGe8kEopV9VDd5docQN%2BrSiNczhw00YjNAMA%3DJnevOJ%2BEqLW0Q%40mail.gmail.com.

[Hari Mahalingam]

Alex,

thanks for helping me. I am presently working for ATT and I was assigned to work and build a system in cameo and no training was provided. 

I could keep my work if I could help me with these tools. Thanks for your help and please also ask me if I can help.

i figure out later to create an extracted report. ahead of time

I have another question for you. I need to build a requirements diagram to explain the relationship with requirements. when I select the requirement box the box is coming only for a requirement with ID and cannot transport excel sheet for all requirements and how to capture multiple requirements in a requirement box with excel sheet

thanks

harry

To view this discussion on the web visit https://groups.google.com/d/msgid/sysmlforum/097805eb0b4c4bed86f7d4cbe8fe02c2%40jpl.nasa.gov.

[Shames, Peter M (US 312B)]

Hi Hari,

 

I have used Magic Draw extensively to model systems, and systems of systems.  This often resulted in papers, PPT presentations, or reports that needed figures.  I found that I could do a jpg export, or a “print to PDF” of the figures and that worked to make these available for inclusion in these document forms.

 

Something like that should work for you.  The attached INCOSE paper and presentation are examples of this, and the paper may also help you with an approach for modeling systems and interfaces.

 

Regards, Peter

To view this discussion on the web visit https://groups.google.com/d/msgid/sysmlforum/CAGe8kEqhxzoKKdoV2H%3Dk7TxRwky3H6hhYdeuzXcRsEgdOgU64w%40mail.gmail.com.

[Hari Mahalingam]

Peter,

thanks for your information. I have some specific questions about the tool. for an example.  in hierarchal and structured built activity diagram how to transport requirements from excel sheet?

If it not possible, how to transport requirements from an excel sheet from the requirement diagram under the requirement block. the requirement block capture a requirement under this block. cannot enter multiple entries in a requirement block? at least I need to cut and paste multiple requirements under this block.

Thanks

harry

To view this discussion on the web visit https://groups.google.com/d/msgid/sysmlforum/BDE519D6-D1FA-4224-BC93-95044C9B5DD4%40jpl.nasa.gov.

[Hari Mahalingam]

alex

thanks for your information. I have some specific questions about the tool. for an example.  in hierarchal and structured built activity diagram how to transport requirements from excel sheet?

If it not possible, how to transport requirements from an excel sheet from the requirement diagram under the requirement block. the requirement block capture a requirement under this block. cannot enter multiple entries in a requirement block? at least I need to cut and paste multiple requirements under this block.

Thanks

harry

On Wed, Nov 18, 2020 at 2:19 AM 'Murray, Alexander T (US 313I)' via SysML Forum <sysml...@googlegroups.com> wrote:

To view this discussion on the web visit https://groups.google.com/d/msgid/sysmlforum/0462d57dfd314b35b6836a2fa61a38f6%40jpl.nasa.gov.

[Saulius Pavalkis]

Hello Harry,

Nice to meet you. You can import requirements from excel or CSV file using Excel import capability. 

Documentation: https://docs.nomagic.com/display/MD190SP4/Sync+with+Excel+or+CSV+files

Video: https://www.youtube.com/watch?v=zkXCqnO4UQI&t=3s

Let me know if something else is needed.

Kind regards,

Saulius