Hot answers tagged

64

Yes, UML CASE tools were one of the hot items of the 90s... and then failed to deliver. The fundamental reason for this is that UML (or most any other kinds of) diagrams help to understand the problem and/or the program solving it only insofar the diagram is abstracting away the implementation details of the actual code. Thus (for any nontrivial piece of ...


39

Well, I'm the academic who posted the original tweet. Tweets are not meant to be scholarly articles. They are advertisements, and I think they can also be controversial. Here are my follow-up tweets: 1) UML was created to model OO designs. It effect you are modeling the code of a system, not the system's behavior. UML is at wrong level. 2) the idea that 7 (...


37

There are different ways to use UML. Martin Fowler calls these UML modes and identifies four: UML as Notes, UML as Sketch, UML as Blueprint, and UML as a Programming Language. UML as a Programming Language never really took off. There has been some work in this area under different names, like Model Driven Architecture or Model Based Software Engineering. ...


36

So when I was at uni (a while ago now), I was told that UML was the future, UML will replace programming and we'll just generate code from diagrams etc. They were wrong. That will happen about the time people abandon speech and go back to cave painting. Real-world problems, and the programs that solve them, have an essential complexity that cannot be ...


31

The three links Association, Aggregation and Composition form a kind of scale on how closely two classes are related to each other. On the one end of the scale, there is Association, where objects of the two classes can know about each other, but they do not affect each others lifetime. The objects can exist independently and which class A object knows ...


23

I can't speak for all functional programmers, but those I know all start out by writing the type signatures of the top-level functions, then as they need more detail, they write the type signatures of the helper functions, and so forth. This works because of the lack of side effects in functional programming, so functions are all specified in terms of only ...


23

Both are "standard". The first picture as per UML specs is Structured Activity Nodes A StructuredActivityNode is an Action that is also an ActivityGroup (see sub clause 15.6) and whose behavior is specified by the ActivityNodes and ActivityEdges it so contains. Unlike other kinds of ActivityGroup, a StructuredActivityNode owns the ActivityNodes and ...


22

The benefit of modeling software systems vs. all in code is: I can fit the model on a whiteboard. I'm a big believer in the magic of communicating on one sheet of paper. If I tried to put code on the whiteboard, when teaching our system to new coders, there simply isn't any code at the needed level of abstraction that fits on a whiteboard. I know the ...


19

The UML standard defines over a dozen different diagram types, as shown in this handy chart: Source: https://en.wikipedia.org/wiki/File:UML_diagrams_overview.svg See also Figure A.5 The taxonomy of structure and behavior diagrams in the UML 2.5 spec. Note that this is an example of a class diagram, with is-a subtyping relationships between ...


19

To properly explain this, we need a short history lesson. In the early days of software engineering, an often used analogy was building a house. An architect and structural engineer discuss plans with a customer and come up with a design. Builders then follow that design to build the actual house. Writing code was seen as the equivalent to building the ...


18

It sounds like you're asking two different things Can UML be utilized to depict javascript systems? Can class diagrams be utilized to depict javascript systems? Keep in mind that UML includes many types of diagrams, specifically a branch of behavior diagrams, including sequence and use case diagrams. Such diagrams specifically address your concern of ...


18

Although I generally agree with Bart van Ingen Schenau's answer, I think a few points need additional elaboration. Th advantage of the 4+1 View Model is that it maps stakeholders to the type of information that they need, without requiring specific modeling notations to be used. The emphasis is on ensuring that all groups have the information to understand ...


17

As in many types of UML diagrams, you can use guards to denote a condition. A guard is a boolean expression that you can write over a transition. Here's a picture with an example: Notice the "[pastDueBalance = 0]" condition. You can also use combined fragments for more complicated conditional logic. See this nice msdn article for further information.


15

From the many diagrams proposed by UML, class diagrams and sequence diagrams are still widely used, certainly followed by state diagrams: they can easily be used on white boards to elaborate and discuss design before jumping in the code they allow to convey very quickly an overview which the code alone doesn't give so easily, and there's no viable ...


14

I have a start up background. What you are experiencing is highly typical, and despite what many say - if you are making enough money to survive, you are doing it right....for now. Your question is very valid, very relevant, and (assuming the start-up is about 2-3 years old, based on how long you have been there) very timely. The most common failure time ...


13

In order to better discuss the image, I annotated your image with some numbers. Hopefully this will help me be more clear in my writing. There are really three types of lines used here - association (1), composition (4->2), and inheritance (3). A solid line connecting two classes, such as between Client and BookComponent is simply an association ...


13

The more appropriate UML diagram to depict a platform's architecture is a component diagram. If you want to go a level lower, then you'd also need to draw one or more package diagrams, and perhaps even a deployment diagram. The diagram you linked to is not a UML diagram, it's a "marchitecture / marketecture" diagram. It's not really supposed to be ...


12

In a class diagram, you don't show the act of instantiation. That is something that a sequence or communication diagram would show. Class diagrams show the static structure of a system. If a class A "depends on" a class B, then you could look at the association and dependency relationships. Dependency is the weaker of the two and is usually used if the ...


12

The most important insight about how thread executions happen can be depicted by what is known as sequence diagram. Here is an example from wikipedia This diagram essentially draws the list of events along with a direction over a vertical single line often called lifeline. In this case, each thread is an owner of it's own life line. The diagram allow ...


12

Exactly those classes which are necessary to understand the aspect of the system which that particular class diagram depicts. It could be the entire domain model, or all classes that make up the external API of a particular layer or subsystem, or whatever you think is important. But note that class diagrams are not the only type of diagram, nor the most ...


11

As a general guideline: One deployment diagram for an overview of the architecture (good for any system) One use case diagram for an overview of what users will do with the system (dito) One class diagram for the data model Activity diagrams for the flow of individual use cases if they are complex Perhaps a state machine diagram if you have a create/review/...


11

Multiple endpoints are acceptable within an activity diagram. Here's a number of sites backing up that assertion. This DeveloperWorks article every activity diagram should have at least one final state symbol with "at least one" implying that multiples are allowed. This snippet from the book Java Server Programming on page 1551 An activity diagram ...


11

So you want to know, how to become an efficient developer? 1) You have to develop communication skills Before you start any project, you have to talk to you customer (in your case your boss) about what he wants. The difficulty here is not only to understand, what your customer says, but what he really means - these are most of the time two different things....


10

To some degree, yes. Anyone can recite syntax or copy/paste their way through a solution. We want to hire people who can solve problems. They expect you to document the design sufficiently that they can understand it (and no more than that). I ask people how they would solve XYZ problem, yes. Usually they just describe it verbally. I want to see if they ask ...


10

Use-cases are the description of the problem to solve, therefore, they must come before any other step in the process. I'd argue that it's not possible to make anything meaningful without knowing the problem. Use-cases will then determine what you design, whether you make class diagrams before writing any code, however, is personal preference.


9

Scott Ambler provides a very good overview of UML sequence diagrams and UML state chart/machine diagrams. Your differences aren't actually that far from the truth, though. A sequence diagram typically shows the execution of a particular use case for the application and the objects (as in instances of a class) that are involved in carrying out that use case....


9

Practices and SDLC within the industry vary wildly from company to company (or even from team to team within the same company). From your description it sounds like the SDLC as taught in your university is a more formal, heavyweight, non-agile process. There are lots of projects following such processes (using differing terminology, tools and artifacts, e.g. ...


9

NO The legend was based on the failed assumption that writing: class ClassName extends SomeThing { } ...it's hard and needs automation. You still may find the occasional believer, or crowds of believers. But that's how it goes with religions and cults.


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