I'm studying UML and I am confused.Could anyone explain me What is the difference between use-case diagram and sequence diagram in unified process model?
The use-case diagram shows the objectives that make external actors interact with the system. It‘s about relations with the outside world. Each use-case is independent and not sequenced with the others.
The sequence diagram shows a scenario of interaction between objects within the system. The interaction in the diagram correspond to message that are exchanged in a given sequence.
I want to draw an uml diagram for two systems that communicate through network.
It is similar to client-server scheme. Client send an event and server process it.
What kind of uml diagram should I use to do that? Components diagram?
You can create component elements to represent your systems and than you can use sequence diagram to define how your systems communicate. For communicating system involved in interaction defined in sequence diagram use lifeline. Life line refers component of your system in this case. You can use collaboration diagram as well but sequence diagram is more powerfull for this purpose.
As i read through UML specification superstructure that there is sequence diagram and there is a collaboration diagram
so,What is the differences between
sequence diagram and collaboration diagram?
Sequence and collaboration diagrams both aim at describing the dynamic interactions between objects.
The information you can describe are basically the same, but the two models have a different focus:
Sequence diagrams highlight more the temporal aspect, by showing invocation and responses along a (vertical) timeline and by explicitly showing the activation time of objects.
Sequence diagrams show how objects communicate with each other in terms of a temporal sequence of messages. The time flow is the most visible aspect in these diagrams, as messages are sequenced according to a vertical timeline and also the lifespan of objects associated to
those messages is reported. The figure below (taken from our book) shows an example of a sequence diagram describing 3 objects (instances of classes Shipment, Invoice and PartList) and the messages exchanged between each other. Interaction diagrams describe execution scenarios of the system.
Collaboration diagrams aim at showing the communications that happen between objects, by defining messages that flow between each other. They basically consist of superimposing the communication actions upon an object diagram. The temporal aspect can be shown here too, by numbering the interactions with sequential labels.
A collaboration diagram shows the interactions between objects or classes in terms of links (solid undirected lines connecting the elements that can interact) and messages that flow through the links. This describes at the same time some kind of static structure (links and nodes) and dynamic behavior (messages) of the system. An example is shown below.
UML1: These diagrams are the same, but present data from different points of view.
UML2: The Collaboration diagram is renamed to Communication diagram (there were misunderstanding since people thought that Collaboration diagram was used to show collaborations).
These diagrams are almost the same, but present the Sequence diagram has much more possibilities for visualization (for example, combined fragments, state invariants).
Sequence diagrams specify interaction in a time sequence manner which may be among objects and/or classes. These diagrams are created during early elaboration phase where each flow of the use case is defined in terms of sequences , i.e. after each step what is going to happen next. This kind of representation is very helpful to understand & discuss the use cases with the customer, where both can come out with all possible functional aspects.
On the other hand collaboration diagram provides a direct interaction among the object. These diagram seem to used more in the design phase of the development when you are designing the implementation of the relationship.
There is a difference between sequence diagrams and collaboration diagrams. Sequence diagrams shows object interaction in timely manner(so no need of numbering the messages). But collaboration diagram doesn't show object interaction in timely manner. (need to numbering the messages).
NOTE:
Now Collaboration diagrams are also called as communication diagrams.
A Sequence diagram is dynamic, and, more importantly, is time ordered. A Collaboration diagram is very similar to a Sequence diagram in the purpose it achieves; in other words, it shows the dynamic interaction of the objects in a system. A distinguishing feature of a Collaboration diagram is that it shows the objects and their association with other objects in the system apart from how they interact with each other. The association between objects is not represented in a Sequence diagram.
Link : http://www.developer.com/design/article.php/3102981/Collaboration-Diagram-in-UML.htm
Use sequence diagrams to show time and to emphasize the sequence or
the ordering of the interactions.
Use communication diagrams to emphasize the links among the
participants. Communication diagrams can be a helpful supplement
to the object diagrams.
May i know how to draw a Block Diagram for a system/ software development? I searched online and i couldn't find any guidelines or good example.
What should be on the top in Block Diagram?
Should i arrange the Block Diagram based on my Class Diagram (Inheritance, interface, abstract etc)?
Why use Block Diagram?
What does Block Diagram actually show? The process? The component? The overall architecture?
Can anyone please provide me any links regarding Block Diagram if there is any?
A block diagram is helpful mainly in the preliminary stages of software development.
A block diagram is similar to a UML package diagram in that it only shows very high level components of the design and how they interact.
What should be on the top? There isn't really a "top" in a block diagram. You may be confusing this with a layered architecture diagram. In a layered architecture diagram, top-level layers are generally the closest to the user.
Should I arrange the block diagram in terms of Inheritance? Not really, the block diagram is supposed to show only the high level interactions of the system. A UML class diagram is where you show the inheritance and interface behaviour.
Why use a block diagram? Primarily because it is easy to partition the system into components for component-based software engineering and because it makes it easy to discuss with clients/managers.
The block diagram generally shows the overall architecture.
This is an example of a layered architecture diagram:
(from http://www.acaltechnology.com/index.php?page=news&id=1577)
This is an example of a block diagram:
(from https://web.archive.org/web/20121106145142/http://www.simventions.com/whitepapers/uml/3000_borcon_uml.html)
The best way to draw a block diagram is using parts and connectors of the Composite Structure UML diagrams.
After having my use case diagrams, i can't found the logique to follow to implement the sequence diagram, how can i go from analysis the what to design the how from the actors and uses cases to a sequence diagram with many stereotype without thinking about the class diagram (to respect the order).
Or should i have to implement others diagrams to passe from the use case one to the sequence?
I've always created class diagrams and sequence diagrams together (and, at least, the UML modeller Sparx Enterprise Architect is compatible with that point of view), but I was never educated in the proper order if such a thing exist.