Author Topic: Question about Time Constraint Scenarios in SD  (Read 1824 times)

johnm9

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Question about Time Constraint Scenarios in SD
« on: May 13, 2008, 07:12:42 pm »
How should I model the following scenarios with sequence diagram?

Object A sends an asychronous message to Object B.
If B reply A in 10ms, A send a success message to Object C.
If B reply A > 10ms, A will retry for 5 times.
If B fails to meet the constraint for all 5 retry, A send a fail message to Object C.

How can this be modeled in sequence diagram??

Jan ´Bary´ Glas

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Re: Question about Time Constraint Scenarios in SD
« Reply #1 on: May 14, 2008, 06:46:00 pm »
Wouldn't it be better to use plain text? Your words are very clear, I am affraid a diagram may be misinterpreted.
Jan 'Bary' Glas

thomas.kilian

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Re: Question about Time Constraint Scenarios in SD
« Reply #2 on: May 14, 2008, 08:02:25 pm »
I guess he's taking the proverb "A picture can say more than a 1000 words" too verbally ;D

Frank Horn

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Re: Question about Time Constraint Scenarios in SD
« Reply #3 on: May 14, 2008, 08:37:22 pm »
Sometimes we have do produce diagrams for trivial things cause those who pay our salaries insist.

It can be done in a sequence diagram using fragments for loops and decisions, but I hardly ever use them. They look clumsy, and EA doesn't handle them well (ever tried to move a fragment with all its contents?).

If I had to draw a diagram for this, I'd prefer an activity diagram.

Jan ´Bary´ Glas

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Re: Question about Time Constraint Scenarios in SD
« Reply #4 on: May 14, 2008, 09:01:46 pm »
I wouldn't prefer a Timing diagram, because noone knows it well ;-) but for this it may be most suitable.
Jan 'Bary' Glas

johnm9

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Re: Question about Time Constraint Scenarios in SD
« Reply #5 on: May 15, 2008, 02:31:00 pm »
Thanks for all your feed back.
When more I try to use UML, the more I found it's deficiency.

UML provides "enough" primitives for us to describe the system structure and behavior from different technical perspectives (data flow, activity flow, static structure, message passing). However, things have to be separated from diagram to diagram.

However, in practise, I found that when problem comes up and I need to revise the design, I need a picture that gives me all aspects in the same diagram. E.g. I want to know all possible concurrent state between systems (state diagram?), I want to see the underlining dependency between system states (state dependency?), I want to see how systems are communicating when an unfavourable states of system exist (thousands of sequence diagram?). It seems that no good solution to give all.

«Midnight»

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Re: Question about Time Constraint Scenarios in SD
« Reply #6 on: May 15, 2008, 08:31:56 pm »
No problem John,

We see the same thing when creating blueprints for a house. All the primitives are there for each view - electrical, plumbing, framework, landscape, etc. - but there is nothing to show the entire thing together.

There is an easy and obvious solution in the case of house construction. Just build the house and take a photograph. There, problem solved!

I suggest you solve your problem the same way. Write the system and give a copy of the source code, data files, screen prints, and installed application to your developers. They should be able to deliver what you want much faster.

Now, back to the problem of describing things that we don't already have...
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johnm9

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Re: Question about Time Constraint Scenarios in SD
« Reply #7 on: May 17, 2008, 02:27:50 pm »
The situation in Software seems not as simple as it happens in modeling a building construction.

Water, Air, Eletricity, Concrete structure... they are rather orthogonal aspects that seldomly need to view a whole picture of their relationships. Cross aspect interaction are rather minimal I would say.

But in terms of an Enterprise Architecture, it goes a lot more complex. Systems have data, have operations, have linkages with one another, have their own states. Their interactions and inter-dependency are a lot more sophisticated that its not easy to isolate one from another when a problem exist.

«Midnight»

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Re: Question about Time Constraint Scenarios in SD
« Reply #8 on: May 17, 2008, 10:22:37 pm »
Quote
The situation in Software seems not as simple as it happens in modeling a building construction...

...Systems have data, have operations, have linkages with one another, have their own states. Their interactions and inter-dependency are a lot more sophisticated that its not easy to isolate one from another when a problem exist.
Quite so!

Thus the role of the (Enterprise) Business Architect. This is not simple, nor is it meant to be; the systems involved are inherently complex. That does not mean that they cannot be modeled, nor does it mean that they cannot be abstracted.

(Get to) Know your audience, or communities thereof. Discover what they need to understand. Extract those things from the enterprise - as-is or to-be as appropriate - and present them clearly. Use the models to elaborate as required. [There are some key words there. Did you find them?]

Now back to work.
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johnm9

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Re: Question about Time Constraint Scenarios in SD
« Reply #9 on: May 18, 2008, 01:15:57 pm »
Yes. I agree with you this time and its really no easy job.
Architect needs to report to the whole spectrum of stakeholders.

I have a lot of experience in developing software and handling technical people. But quite young in Architect. How should we handle our business people's request for both clear architectural model and stardard architectural model?

You know, different business people have different concern. Their interest is itself not standard. Following the standard architectural model doesn't seem to satisfy their needs. But on the other hand, they want my solution to follow the industrial standard...... What a dilema

«Midnight»

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Re: Question about Time Constraint Scenarios in SD
« Reply #10 on: May 18, 2008, 11:13:53 pm »
How do you handle the family that requires a vehicle for taking everyone on a vacation, and separate vehicles for each member to commute to school and work? Of course this should all fit within the family's budget.

There are many answers, because each family has specific needs that cannot be seen from just a short textual description like above.

The appropriate answer will likely involve several vehicles. They might not all be engine powered. Perhaps some will be short-term rentals. Perhaps some might be public transport. Perhaps some family members will walk to places where they drove before. Perhaps when the transportation needs of the family are considered as a whole, options for combination or reuse will emerge. Maybe some trips just won't be practical after the resource implications are known.

The answers might not be popular, particularly at the beginning of the process, but if you come up with a good solution the pain will be much less than the alternatives. If you don't do the hard part up front then the end result will be an early failure, which will result in far more grief for (and from) the same family members.

The above analogy translates pretty well into your situation. It's you family, so it is you that needs to get them together to make the decisions.

Finally, note that I am not talking about system design or anything like that here. I'm talking about architecture deliverables. Just that, nothing else.

These are not problems that others can solve for you, but they are likely to yield to the wisdom you have developed in your career so far. Just make sure you are thinking about the right things, before you get into building the system when you are still talking about architectural style.

HTH, David
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johnm9

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Re: Question about Time Constraint Scenarios in SD
« Reply #11 on: June 04, 2008, 12:43:32 pm »
Thankyou Midnight, you've inspired me a lot.

We've identified some major target at the moment.
At the moment, we plan to put the first step in architectural modeling.

As our organization has over 100 large and small information systems interconnected and it seems not appropriate to work back for a complete architectural doc like those suggested by "Zachmman" or "ToGAF" etc... in terms of resources and time.

So, the first step would be focus on documenting (by UML) the inter-dependency (in terms of data-flow and control flow) between all these systems.

Do you have any suggestion on tools, methodology and books that is good for documenting systems inter-dependency?