Which UML diagram is the best for showing dependency between our IT system and other external IT systems?
For example I would like to show on diagram:
system A gets data from system B
system B can call some functionality from system A
I'm wondering between component diagram and sequence diagram.
What do you think?
your question is not very specific as all UML diagrams display some kind of dependency or pathway how to get data or make a call, so I'm not sure if I got substance of your question right
1. there is no such thing as one best UML diagram to show it all
There is usually one system that you are modeling (+ some black boxes in its surrounding environment) and one UML model. At best the tool you use should support Model Driven Architecture (MDA) and perhaps even Executable UML so that the result of your modeling can be more then set of "pictures". It can become skeleton of source code forming the backbone of the application or it can be even model-click-and-run product.
In order to provide full or sufficient description of the system you'll usually need more UML diagrams each representing different point of view with focus on different aspects with different level of detail (yet all of them being parts of one model).
(This ↑ was the hard part for me to understand)
2. before deciding which diagrams to use make some paper & pencil prototypes
It is quite importtant to make sure which diagram fits your needs before you start drawing it in a good looking sharable form using a tool. Even drawing in Enterprise Architect takes some time to get used to and to get it right.
Very good guide how to do a paper & pencil diagrams and which of them is used for what and how to spend only as much time as is needed:
Agile Modeling - Start Here
...
Agile Modeling - UML 2 Component Diagrams: An Agile Introduction
Agile Modeling - UML 2 Sequence Diagramming Guidelines
...
3. sequence diagrams are expressive simple and useful for programmers
There are even tools that can turn sequence diagrams into code or tools that can turn source code into a sequence diagram.
overview UML sequence diagrams overview of graphical notation
overview IBM Rational Edge - UML basics: The sequence diagram
tutorial Enterprise Architect - 14 minute video - Create Sequence Diagram
4. activity diagrams are expressive and useful for programmers
overview Debenedetti Emanuele, Activity diagrams in UML 2.0
background by Conrad Bock (one of UML authors), UML 2 Activity and Action Models, The Journal of Object Technology
UML 2 Activity and Action Models
UML 2 Activity and Action Models, Part 2: Actions
UML 2 Activity and Action Models, Part 3: Control Nodes
UML 2 Activity and Action Models, Part 4: Object Nodes
UML 2 Activity and Action Models, Part 5: Partitions
UML 2 Activity and Action Models, Part 6: Structured Activities
tool manuals
PaceStar UML Diagrammer, UML Diagramming Guide - http://www.pacestar.com/uml/udg60.pdf
Sparx Enterprise Architect, Using UML Part Two – Behavioral Modeling Diagram - http://www.sparxsystems.com.au/downloads/whitepapers/UML_Tutorial_Part_2_Introduction.pdf
Microsoft Visual Studio, UML Activity Diagrams - http://msdn.microsoft.com/en-us/library/vstudio/dd409360.aspx
5. high level overview diagrams useful for programmers and others (not UML)
poster Business Process Model and Notation
Wikipedia - Business Process Model and Notation
clear expressive language easy to comprehend ARIS Event-Driven Process Chain (EPC) (my favorite since the first time I met it back in 1999)
6. = 1 + 2 + you
make some paper & pencil sketches and decide yourself which diagrams best suit your needs
Further to your thoughts and what Aleks has said, people usually use a combination of both to articulate the inter-system relationships
EA allows you to reuse components in component diagram & Sequence diagram, which allows you to update model from one diagram and have the changes reflected in the other.
Below snapshots show how two components in the model are used in a component diagram (for structural relationships) and sequence diagram(for behavioral flow)
Components definitelly, and dependencies. Dependency does not go in direction of the data-flow, but from the component that "knows" other component (invokes something from it, creates an object, etc).
The following diagram shows the idea.
It is common (and highly recommendable) practice, to use interfaces between the components and channel dependencies through interface. This permits clearer specification and better design (if possible of course).
Sequence diagram can further be used to specify concrete usage scenario and is also recommendable. So, components for structural, static dependencies and sequence for dynamic behavior.
Related
I am working on a data science project for my 3-2 mini project. My project analyzes the performance of a country in the Olympics based on some attributes. But I am confused about the UML diagrams I should be using in my project.
There are some 15 UML diagram types out there. A sensible sequence of diagrams to be created depends on your approach.
If you'd like to create an analysis model that is a conceptual model of your problem domain then a sensible sequence of diagrams might be:
Usecase diagrams
Activity diagrams
Class diagrams
and if your project gets bigger you might need package diagrams.
If you'd like to create a design model that is a conceptual model of your solution domain then a sensible sequence of diagrams might be:
1. Component diagrams
2. Class diagrams
3. Sequence diagrams
4. Statecharts
In both cases a starting point is having a diagram for your system context. Some people like to mix component and usecase diagram features to denote a system context.
The aspects you might want to take into concideration of your diagram choices are:
syntax - how strictly would you like to follow the UML standard and what use does adhering to the standard have for you
semantics - what is your need - what do you want to document - and who needs to understand it
pragmatics - what is the best way to achieve your projects goal e.g. being efficient and effective
tool - what tools do you have at hand and are used and known to your peers - what can you afford to invest in keeping the tool infrastructure up
While your question is very broad, I could imagine that in view of:
My project analyzes the performance of a country in the Olympics based on some attributes.
you'll certainly need a class-diagram. Because the class diagram will clarify what kind of objects your software will manipulate (e.g. Olympic game, Participating countries, Teams, Athletes, Discipline, Competition), how they are related, and what attributes are associated with which each.
This will enable you to determine for the different analysis you want the access path to the relevant attributes. It will also allow you to find missing attributes, and to desing a convenient interface for the different classes.
You may also use other diagrams. But with the few requirements you've shared, it's difficult to guess which one and I do not want to do a lot of guesses. I could nevertheless imagine that a use-case diagram could help to give the big picture of who is going to do what with your software.
I'm creating a use case diagram for a checkers game that I programmed. How in-depth are you really supposed to go when making these? I read that they are supposed to be simple, but that is kind of vague. Do I need to create more arrows, for example between "move regular" (which means move a regular piece, as oppose to a king) and "jump"? Or is it fine not having a connection there? I just don't want to make too many arrows because it will begin to look pretty messy. Any input will be appreciated.
1) ..UML..diagram..how in-depth are you..supposed to..do I need..more arrows..don't want..it..look..messy..?
How in-depth and how simple depends on many factors, basically on an answer to "why you need it" and "who will read it".
Actually the set of questions and guides and other practices that can help you decide can be quite long. Especially useful one is listed in the chapter Agine Modeling: Agile/Lean Documentation: Strategies for Agile Software Development in Scott W. Ambler's online book.
One thing that you should get absolutely clear is what kinds of UML diagrams you need/want
2) UML..use case diagram..more arrows..or..no..connection..too many arrows..?
The arrows in use case diagrams are not an arbitrary connection lines but instead they have precise meaning, especially the <<include>> and <<extend>> relationship, see http://www.uml-diagrams.org/use-case-reference.html for their definition and examples
Besides being graphical bubbles the use case represent how an actor interacts with the System Under Design. Content of the bubbles is then described in more/less formalized text form, see Wikipedia: Use case and especially Alistair Cockburn's use case pages as he basically defined meaning of the term (later adopted by UML) his opinion matters.
3) I'm creating a..UML..diagram for a checkers game that I programmed..
In your case the King Piece bubble does not seem to be included-in or extending the Start Game bubble initiated by the Player and I don't see what sequence of steps might be hidden inside its textual representation (or in your code).
The things you began to draw look much more like UML Activity Diagram, an example
and some explaining links:
overview Debenedetti Emanuele, Activity diagrams in UML 2.0
background by Conrad Bock (one of UML authors), UML 2 Activity and Action Models, The Journal of Object Technology
UML 2 Activity and Action Models
UML 2 Activity and Action Models, Part 2: Actions
UML 2 Activity and Action Models, Part 3: Control Nodes
UML 2 Activity and Action Models, Part 4: Object Nodes
UML 2 Activity and Action Models, Part 5: Partitions
UML 2 Activity and Action Models, Part 6: Structured Activities
tool manuals
PaceStar UML Diagrammer, UML Diagramming Guide - http://www.pacestar.com/uml/udg60.pdf
Sparx Enterprise Architect, Using UML Part Two – Behavioral Modeling Diagram - http://www.sparxsystems.com.au/downloads/whitepapers/UML_Tutorial_Part_2_Introduction.pdf
Microsoft Visual Studio, UML Activity Diagrams - http://msdn.microsoft.com/en-us/library/vstudio/dd409360.aspx
There are much less use cases here. Pls refer to the following diagram drawn by myself:
The other requirements can be written in use case specification, specially the business rules.
Use case name: Move piece
Actors: Player (Primary)
Pre-conditions: ******
Post-conditions: ******
Stakeholders and Interests: ******
Basic Path:
Player selects one piece and the destination square, and submit a move request.
System validates destination square.
System moves the piece and calculates the moving.
System displays the moving result.
Exception Path:
2a. destination square is not valid:
2a1. System ****
Business Rule:
valid destination square : ……
calculating rule, such as king piece, win game……
I am new to UML. I have studied more tutorials.I learned two broad categories like,
UML Diagrams:
1. Structural Diagrams
Class diagram
Object diagram
Component diagram
Deployment diagram
2. Behavioral Diagrams
Use case diagram
Sequence diagram
Collaboration diagram
Statechart diagram
Activity diagram
But I dont know which one is high level design and low design. Anyone list out the UML diagram types based on priorities. (high-level diagrams to low level)
There is not really a well-defined order of higher-level versus lower-level diagram languages in UML. The same diagram language (e.g. class diagrams) can be used at different levels of abstraction. For instance, a conceptual information model, but also a Java data model, can be expressed as a class diagram.
Generally, a use case diagram is higher-level, since it describes requirements, while a deployment diagram is lower-level, since it describes system deployment structures.
But all other diagrams languages can be used at different levels of abstraction.
UML diagrams - from the most common to most detailed level.
Please, notice, that nowadays (the start of 2014) there are no special instrument for UI modelling. So, I'll explain how to do this part of work, too, with the tools we have. But they will be used in a less or more nonstandard way.
Human level. Use case diagrams and state machines. How people will work with the system.
Use cases are about what the system does, who works with it and maybe, grouping of those subjects. Subsystems can be defined here. Try not to show much structure or behaviour. Not to use any IT slang!
State machines show what states the system, subsystems and actors can have and what actions/events can happen in these states and to which other states can it lead. Not to use any IT slang!
Do not forget, that administrators, programmers and testers are users of the system, too. So, plan not only how the system helps to the work of the common user and his senior, but also to the installation/administration/testing/support processes. Don't forget to continue this work on all deeper diagraming levels. These use cases/state machines needn't be so human-oriented.
You can draw activities, sequence, timing diagrams for some dialogues between Actors and subsystems, if they are the part of the requirements. Or make them the part of requirements if they are important. Not to use any IT slang!
Draw the sketches for the UI and talk over them with client. The work on UI art design should be connected to UI planning and realization
Start to work on User Guide - create plan and structure. (I use class diagrams for that).
Deployment and component diagrams. Here you are starting to imagine the inner construction of your system
Components - What compact parts it has. It needn't have much in common with the subsystems, as user see them. Only some components are visible to the user. You could decide on the use of some interfaces between them. Think on the license problems of the third-party components.
Deployment - how the components could be distributed among PCs. The same question about interfaces, but more from the physical side.
A special deployment diagram for license politics of your product could be drawn, too. You can use other diagrams for it, as well. It is at your choice.
You could already plan your user interface by these diagrams, too. In MVC (model-viewer-controller) construction only the components of the controller level are mutually connected and obviously need this level modelling. But the viewer layer (UI) components are connected in a conceptual way, they should be, for the sake of user. So, it should be planned too, by the same diagrams.
On this level you also plan the architecture of the development environment. It consists of components, too.
Draw Interaction Overview and Communication diagrams to see the cooperation of components as a whole or in complex groups.
Package, activities, sequence, timing diagrams
Package diagrams are for planning the hierarchy of your code and mutual visibility of its parts. Don't forget the place for testing packages, too. Notice, that the structures of packages and components hierarchies are different, but they have to work together. It is very important part, frequently overlooked.
Use behavioral diagrams for better understanding how different processes could run.
System analysis - the class diagrams level.
Some important classes could appear on the previous level diagrams - as definitions of intercomponent interfaces or subjects of processes. But now you should do all of them. Minimally a diagram for a component. You should do these class diagrams, using ready package diagrams.
Plan the content of UI, defining elements and functonalities and connections between them WITHOUT choosing the concrete components. Use diagrams that you like. Class ones are usable, but in not standard reading.
Deeper insight
If you have instances with specific behavior, use Object diagrams for their planning.
If you have some very complex classes or their tight groups, use Composite Structure Diagrams.
UI: Plan the content of screen elements WITH choice of the UI components (frames, buttons and so on) and connecting functionalities to them. On this level you can again use class/object and sequence/timing diagrams.
Code. Really, the coding, at least on the prototype level starts already on the stage of component planning. You have to control if and how different technologies will cooperate. But the real coding should be done only after you are sure you understand what are you doing. And to create all or some correct diagrams is the best way to be sure in it.
Notice the rule of thumb - structure diagrams set the sequence of levels. Behavioral diagrams support them on all levels. You can use state machine on the lowest level and timing diagram for to discuss with a client. But try not to mix the levels with the structural diagrams!
Also, do not try to mix diagrams, especially behavioral with structural ones. You should clearly set the rules, by which you can say, what part of information can be on the diagram and what not. And break these rules really only in the most exceptional cases.
As gwag noted, there is no separation of UML diagrams into high and low levels. The different diagrams are used for describing different aspects, not different levels, of a (software) system.
But if you look at UML in a broader context, the Unified Modelling Language is just one of a whole family of modelling languages standardized by OMG. These different languages do have more specific scopes.
SysML (Systems Modelling Language) shares many features with UML and looks very similar, but is specifically intended for the higher levels of systems analysis / design. It also includes a visual representation of requirements, which are conspicuously absent from UML.
Another related language is BPMN (Business Process Model and Notation), which is used for business processes. So you could for instance use BPMN for business analysis, SysML for system design and UML for software design.
UML does not specify level of details you define in diagram. Every diagram can be used for description on business level, implementation or design level as well.
It is up to modeler, what type of diagram uses to descrbe modeled system. Information in diagrams must correspond with each other and all diagrams must give complet view on system.
For example, you can declare services of Bank company using UseCase on business level or use UseCase to declare services implemented by concret physical component of program writen in Java.
I am not a big fan of UML. I believe UML is great in some rare instances, however I do not want to use a UML diagram to show a high level flow of calls through my application. Problem is - most of the tools (visio, lucidchart, websequencediagrams) force the user to either draw a very detailed UML diagram, or a sequence diagram. There is nothing that would be like a high-level version of a UML diagram. Or is there?
There is no such thing as a "higher level" UML diagram. UML has 12 (or was it 12? I can't remember) and you must choose from one of them, the best that fits your needs.
For a high level flow of calls I like activity diagrams, even though the objects that own the functions are harder to see. Sequence diagrams are a waste of time and space IMHO .
Back in the Dark Ages (mid-1980s), I used Data Flow Diagrams from Structured Analysis a fair amount, and found them very useful.
My current employer loves UML. I normally use BOUML, which doesn't do non-UML drawings.
What is the UML drawing that corresponds to the Data Flow Diagram?
If there isn't one, what is the recommended UML diagram to present the corresponding data?
Probably the closest thing is the activity diagram. It's not quite the same; more influenced by flow chart than dfd. However: you can do some of the useful things in DFDs, e.g. ADs do support concurrency and differentiate control flow from dataflow.
More details on comparisons & differences in this question.
[fwiw, I still use DFDs: they're simpler and more elegant in many circumstances]
hth.
UML 2 has a very good analogue to a data flow diagram:
the "information flow diagram".
Information flow diagrams are explained here:
https://web.archive.org/web/20121118061853/http://www.uml-diagrams.org/information-flow-diagrams.html
Note that UML 2.5 has information flows and information items, but the term "information flow diagram" is not part of official UML 2.5 diagram taxonomy. So formally, you just create a class or component diagram with lots of information flows in it to obtain your "information flow diagram".
I do this all the time, using information items of UML to represent my data.
There is no equivalent model in OOD. The emphasis on DFD's is data separated from the function. This is most helpful when dealing in a procedural way. DFD's scale much better than OOD, if you try to scale out (to the world view) using OOD you end up using Use Case diagrams, which are useful for capturing essences. I loved DFD's they are so high level, and yet can be expanded by opening up a DFD box and calling it level 1 etc.
I am currently in the process of learning the Go programming language, this does not use Objects whatsoever and in some respects I feel that DFD modelling would suit it much better.
I too am looking for a diagram that could do this sort of work. In Go structs are used intensively which are basic data types. You can have a primitive extension method attached to it which resembles OO but in fact if you look at the Assembly code it appears to be syntax sugar for a function, who's first parameter is the struct you wish the function to operate on.
My advice, is that if you're doing OO code, then use OOD. They map better, and do help in the thinking about a system. It takes a while to get your head out of Procedural code, especially if you're coming from programming from the 80's/90's. Once you're in the zone with thinking about objects then the OOD methods work fine. Its not strictly a methodology as there is no straight answer to which parts you use, just thinking in objects I find to be the hardest part. A good book on this is "Object Thinking--David West"...it helps to think about objects first. Once you start its very difficult to stop, you may even like some end up getting trapped in the kingdom of the nouns which is a horrible place to be, because you write endless boiler plate code, just so that the system is described perfectly. This is a form of coding hell which I have stayed clear of for many years.
If you are coding in a language that allows procedural code, or even mixed OO/Procedural, you need to decide your paradigm before you start coding, for example in both Python and Object Pascal (Delphi) you can go either route of OO or procedural coding mixing the code up into a mess of paradigms. This will decide which diagramming tools that should be used, and how you are going to analyze the system.
Recently there have been shifts in Java and c# to provide functional programming techniques. These I have discovered don't fall into either category of programming (OO or procedural). Trying to map functional programming code into an object is a nightmare.
I am sorry I haven't provided an answer, but it depends on what code you are writing.
There is no direct analogue, since UML emphasises OO design wheras DFD comes from structured systems analysis and design (SSAD). In UML a number of diagrams, specifically those in the with interaction diagrams group have characteristics that might model elements of data flow and processing. A Communication Diagram can be used to reflect most aspects of a DFD in general, while a sequence diagram may model specific sequences of flow. If you wanted to suggest DFD semantics then you could use stereotyped objects for data process and data store, and use actors for external entities.
It may be worth noting that Sparx Systems Enterprise Architect, while primarily a UML tool includes DFD as an extension.
Similar diagrams would be:
information flow diagram
communication diagram
sequence diagram
Theoretically, new diagram kinds can be defined in UML, optionally extending of one or more conventional diagram kinds. The canonical diagram kinds defined in UML are essentially defined as a part of the UML metamodel itself.
Formally, a definition of the UML metamodel is provided in the UML specification published by the Object Management Group (OMG), as well as the corresponding meta-metamodel defined of MOF - to which there is also a corresponding specification - moreover as accompanied with the formal OCL specification, as with regards to definitions of constraints in UML models in applications of the OCL language in UML - and then there's the XMI specification, as with regards to specifications for how UML models may be stored in machine-readable format.
Ostensibly, all of these specifications may be combined for application as though "Under the hood" of any single framework for UML modeling - whether in applications of the Ecore subset of the UML metmodel, or in canonical UML.
Reviewing a short academic presentation about Data Flow Diagrams -although somewhat in departing from formal definitions of UML diagram kinds, but nonetheless in a broader context of applications of the MOF meta-metamodel - perhaps the canonical BPMN metamodel - in its conventional, graphical abstract syntax - perhaps BPMN may serve to provide something of an analogy to Data Flow Diagrams?
Of course, modeling practices may vary by vendor and by application environment.
I consider a Data Flow Diagram as a Sequence Diagram, with Data Producers and Data Consumers creating, using and destroying Data objects by means of synchronous and/or asynchronous messages.
I use Enterprise Architect 'Dynamic View' Analysis diagram.
Control = Process
Information = Data Store
In many ways their Analysis diagram is much better than a data flow diagram, as you can also show events in the form of sending and receiving and there is a process symbol too but I prefer Control. It includes object and decision.