I have an assignment that states the following criteria:
For this view you may use a truncated version of
your Design Class Diagram (DCD) including
only the architecturally significant classes.
For context, this is for the Logical View of a 4 + 1 Architectural View. How does a design class diagram (DCD) differ from a regular class diagram? Is it the UML diagram without the functions or variables included (i.e. just the names of the classes and their interactions with each other)?
Most of the time, people model their code. That's good! In that case, class diagram modeling is used to graphically represent the structure of (object-oriented) classes: class, method, attribute, annotations with stereotypes. Imagine all the JPA, Spring, whatever annotations in the class diagram of a JPA-J2EE based architecture...
As it's said above, the "design class diagram" should only design your domain model, from an architecture level. What are the basic entities your structural system rely on?
No details about the programming language, no "dto", "dao" or technical stuff like that.
Here's a good example I use: online shopping cart domain model. It only contains the architecturally significant classes.
HTH, Tom
Still its amibigous to understand. The main difference between analysis class diagrams and design class diagram is the analysis phase focus on designing a class diagram without concerning about the implementation detail. where as, desgin modelling concern with the implementaion and architechture since, it the high-level static view of the system.
Related
So I'm currently studying UML and I have a question regarding the difference between a Domain Model how this is compared with an Activity Diagram. I a bit confused with the following terms:
Activity Diagram (AD)
Domain Model (DM)
OO Domain Model (OO DM)
Class Diagram (as a term)
Domain Class Diagram (CD)
Design Class Diagram (DCD)
In Visual Paradigm, you have two the option between Activity & Class Diagrams to draw out your designs. So far I have been using Class Diagrams for my Domain Model but a friend of mine told me you should not be using Class Diagrams for your Domain Model. So my question what's the difference and how does a program like Visual Paradigm differentials with the standards of the subject I'm trying to learn.
Domain model and domain diagram do not exist in UML, so all depends on the definition you use.
If I look at the literature it seems the 'standard' diagram to show a domain model is a class diagram, may be associated with object diagram to show example of instances.
An activity is a behavior, to use common word an 'algorithm'. An activity can be used to model the body of an operation. The goal of an activity and a class are totally different, one cannot replace the other.
Even the definition in Wikipedia is a domain model is a conceptual model of the domain that incorporates both behaviour and data the associated diagram in the article is a class diagram. In the article the word behaviour visibly refer to the rules the business uses in relation to that data.
Anyway, whatever, all depends on what you have to model, there is no definitive rules saying in case 1 use only class diagram, in case 2 use only activity diagram, and so on. You use all the diagrams you want while they are adapted for to say something useful
Activity diagrams are used for represent the behavior which shows flow of control or object flow with emphasis on the sequence and conditions of the flow.
Example:
The class diagram is used to specify the relations that exist between the classes from your model, also you can represent their attributes and methods.
Example:
Going back to your question, if you want to represent the behavior of your model, I should recommend using an activity diagram, but if you only want to specify classes that you want to use and their relation then you can use a class diagram.
I had been doing some UML class diagram examples from the recent exams for my software design course, and I found one where it says:"Design a class model for a specific problem, by using MVC and STATE pattern, but no need to include getters and setters." Is this the same thing as the regular class diagram? I've been googling and I found nothing UML based by searching for class MODEL.
The model is abstract. A diagram is a view on the model. UML offers a number of different diagrams. There are mainly two categories: static and behavioral. Class diagrams fall under the static category and they show how the classes in the model are related to each other. You can create multiple class diagrams like one with all classes (assuming that you have a rather limited number of classes) and/or one per class with that in focus. Or you have sub-domains with related classes placed in one diagram. The behavioral diagrams shed light on how class instances communicate with each other at run time.
As a side note you can think of it in terms of Platon's Cave Allegory. The diagrams are the shadows of the real world projected by a fire to the wall you can see from you chained position.
"Design a class model" means: "Create one or more class diagrams that together form a consistent model".
A model in computer science is a graphical representation of (a piece of) software or of (a part of) the business domain in order to help people know or understand the subject the model represents (see wikipedia). This graphical representation may consist of one or more diagrams.
Can someone explain me the difference between class diagram during analysis and design?
So far, I understand that the class diagram of design would be the real class diagram, with all methods and attributes (ready to become code), but what about analysis? Do I have to do a class diagram for every sequence diagram? Do I have to add methods and attributes at the design stage already ? Or only connection?
The UML class model is produced and refined iteratively as the understanding of the system increases. There's only one model for your system, although different diagrams may outline different aspects and level of details of this model.
Typically you would start with the domain model based on the requirements (e.g. use cases, user stories, statement of work, user interviews, etc.):
Top priority is to get an overview. So the first sketch would identify the domain classes and how they relate to each other.
You would then enrich this initial understanding by outlining in the diagram the key properties and methods that are essential to the understanding of the domain.
You would then enrich the model with more detailed design diagrams as you design your solution. So you would add any classes required for the implementation (e.g.user interface classes, application controllers, persistence layers, etc.).
Design diagrams are used to get a shared understanding about the software structure within the development team. So they should be easy to understand (i.e.focus on important aspects and not necessarily be cluttered with too many details that would anyhow have to be implemented in code and quickly be outdated if you don't have an army of analysts to update the model).
If you'd use an UML tool able to generate code or if you are contractually obliged to provide all the details in UML form, you would further refine the model with a fully detailed implementation diagram. Attention: for scholar work it is frequent that the teacher asks for a design diagram but expects in reality an implementation diagram.
We have 3 major types of class diagram in Object Oriented Methodologies.
Class Diagrams in Requirement (Domain Modeling)
Analysis Class Diagrams
Design Class Diagrams
Main difference of these class diagrams is their Abstraction.
In Domain Modeling, we use Class Diagrams. BUT, we do not use any Inheritance or any Interfaces, or any preforming analysis on the classes. We just write so little attributes of classes (about 3 attributes). we don't write any methods of classes. WHY? because of Abstraction. Main goal of Domain Modeling is modeling the domain. And detect Which classes should be in problem domain of system.
In Analysis modeling, we use class diagram. Classes in analysis is more detailed than classes in Domain. But it is not the final specification.
In Analysis, we determine Analysis Classes. We can use Inheritance between them. We can write their attributes and methods in detail. BUT, this phase is done by System Analysts. (Not System Designers or Programmer). Their profession is both knowing the Business Logics and Software Techniques. So they can write analysis classes in more detailed than Domain. However, they can not write very detailed as System Designers can.
In the other hand, we can use some analysis patterns to determine our Analysis Classes. For example RUP introduce Boundary/Control/Entity pattern. If we decided to use an existing analysis pattern, we can use the guidelines exist in the pattern documentations.
The guideline of Boundary/Control/Entity about the abstraction of classes are in this reference. In this pattern we should write only attributes for Entity classes and write only methods for Control classes and write attributes and methods for Boundary classes.
However, In my idea, we can follow the guideline or not. We can write more attributes and methods for analysis classes. What is happening? If our System Analyst try to write more detailed attributes or methods, what's happening:
I think that 1) our system analyst is not system analyst. maybe system designer. 2) we don't need their details. It is just time consuming for analysis phase. 3) ONLY if our analysis and design team are the same, or we combine analysis and design (like Agile Methodologies) the details in Analysis can be logical and useable.
In Design modeling, we use class diagram, this type of class diagram should be the final specification and should contain all attributes and methods. This classes are not conceptual. we can use all OOD technologies, Design Pattern and etc.
Can someone briefly explain the difference between a Conceptual Class Diagram and a Detailed Class Diagram?
While a "Conceptual Class Diagram" expresses a conceptual (domain) model, it's not clear what you (or your professor) mean(s) with "Detailed Class Diagram": it could refer to a (language-/platform-independent) design model or to an implementation model like a C++ class model or a Java class model.
See also my answer to this related SO question.
The one-to-many relationships between conceptual models and design models, and between design models and implementation models are illustrated in the following Figure:
As an example that illustrates how the derivation chain from concept via design to implementation works, consider the following model of a people/Person concept/class:
Domain models are solution-independent descriptions of a problem domain produced in the analysis phase of a software engineering project. The term "conceptual model" is often used as a synonym of "domain model". A domain model may include both descriptions of the domain’s state structure (in conceptual information models) and descriptions of its processes (in conceptual process models). They are solution-independent, or ‘computation-independent’, in the sense that they are not concerned with making any system design choices or with other computational issues. Rather, they focus on the perspective and language of the subject matter experts for the domain under consideration.
In the design phase, first a platform-independent design model, as a general computational solution to the given software engineering problem, is developed on the basis of the domain model. The same domain model can potentially be used to produce a number of (even radically) different design models representing different design choices. Then, by taking into consideration a number of implementation issues ranging from architectural styles, nonfunctional quality criteria to be maximized (e.g., performance, adaptability) and target technology platforms, one or more platform-specific implementation models are derived from the design model.
A conceptual class diagram is used to understand and analyze a problem domain. A detailed class diagram is a design artifact, where many things may have been optimized away. For example, every dog might bark, but a dog-salon application doesn't care, so it can optimize away that fact.
I don't know of any standard or methodology that defines both these concepts. For example, the UML specification does not mention them. I think every answer will be subjective. I will give my own answer, based on more than 25 years of experience with IT-related modeling.
In a conceptual class diagram, every class is a concept, usually related to the business domain, the real world, e.g. Customer, Order etc. It may also show concepts that cannot be directly found in the business domain, but are needed to model the functionality of a particular application, e.g. BackupCopy. These are concepts the user of the application must understand. See also www.agilemodeling.com
There are other types of class diagram, e.g. class diagrams that model the source code, where every class corresponds to a Java class or a C# class, or class diagrams that model the physical database structure, where every class corresponds to a database table.
Each of these types of class diagrams may or may not be detailed. If a class diagram is not detailed, it typically does not show any attributes, or only the main attributes. If a class diagram is detailed, it shows all attributes relevant for the problem at hand and the data types of these attributes.
The concept of a conceptual class diagram is e.g. explained by Scott Ambler at http://www.agilemodeling.com/artifacts/classDiagram.htm#ConceptualClassDiagrams.
Basically "Conceptual" here means that the content of the diagram is taken from an analytic view point that takes the "concepts" of a domain and describes them.
For "concept" you could also say:
thing
item
aspect
object
topic
The conceptual diagram is basically what you get if you ask people for what problem they'd like to get solved by your software. So you analyze the situation/problem by asking questions that will help you create you diagram:
what are the things that are relevant? - these will be your candidates for classes
what are the features of those things? - these are the candidates for your attributes
how are the things releated to each other - e.g. is one part of another? Does it need the other? - these are the candidates for your relations
what should you be able to do with these things in your system ? - these are the candidates for your operations
In the past this step was called OOA - object oriented analysis. The steps following this are OOD - object oriented design and OOI - object oriented implementation. Many years ago some authors proposed to create three different models for OOA/OOD and OOI. Therefore you'd have different and usually more detailed diagrams for OOD and OOI. For the term "Detailed Class Diagram" i'd guess that one of the OOD and/or OOI views would be meant. Be careful though - some of the diagrams created this way will have patterns or pattern-like ideas as a basis. You'r diagrams would tend to be very repetitive and redundant if you keep capturing such patterns in concrete diagrams for every conceptual diagram. I'd rather recommend to give just one example of how to go from problem to solution and then comment "do it this way for all other concepts that are similar".
If I create a conceptual class diagram such that each class captures 'name' and 'attributes' but not 'operations', have I not basically created what would be otherwise considered an ERD? I'm trying to gain an understanding of what the differences are between creating a conceptual class diagram as I have described versus calling it a ERD? If these are still two different animals, can somebody please explain what the differences are?
The class diagram contains just the classes in your object model with eventual links/relationships connecting diagram elements. However those links don't necessarily correspond to physical relationships like in an ERD diagram, but instead they represent logical connections.
The class diagram is just the object model of your application and does not contain any persistence-specific information. When you think about the class diagram forget about the database or any other storage you may use.
The ERD diagram on the other side, is a persistence-specific diagram which display the entities (tables) existing in a (most often) relational database. It also displays the physical relations (and cardinalities) between those tables and all other database-specific information. The ERD diagram can sometimes look similar to the class diagram, but that doesn't mean is the same as a class diagram.
There´s little difference in the expressiveness of both (if we just focus on the attributes, classes and associations part) if you use Extended Entity Relationship diagrams (the most common case nowadays)
True, they look very different at the graphical level since they use different symbols for the elements but the "semantics" are quite similar. They both allow inheritance (again, I´m talking about EER), n-ary associations, association classes, ...
The ER diagrams I've seen (most frequently ERWin IE notation) have focused on the design for a database. They are concerned with primary keys, foreign keys, have unnamed relationships, and usually have no generalization / specialization.
A good UML conceptual class diagram, on the other hand, is not concerned with keys, reflects the problem domain, and has association-end properties that at least hint at the semantics of why things are related. This helps communicate the domain down to more junior developers so they don't have to guess.
It depends on the situation where you may not like to do the ER-D. But imagine if you have a seperate data layer where the data logic is handled. In this case many details of data shall not be shared with the application layer. And you class diagram shall not go beyond the application layer. I must stress that both the diagrams are not equal. And there are situations where you need to do both, mainly in multi-tier architecture, and there are situations where you may be able to just use class diagram; e.g. single-tier application.
I strongly advocate the view that class diagram doesn't abrogate the E-R diagram.
Design class diagrams are made from conceptual model and collaboration diagrams.
Design class diagrams include:
Classes, associations and attributes
Methods
Types of attributes
Navigability
Dependencies
IMO In Simple terms
Class diagram depicts the details of how will the system work.
ER diagram depicts how the system persists 'state' as a blue print.
Goal:
Detail out state and behavior of the components(classes) of the system.
Design 'efficient', flexile system(less coupling and more cohesion) using Solid principles.
Goal:
Design a blue print of how to 'efficiently' persist the state of the system.
Consider what kind of queries will be made (read vs write), are there any joins required
consequently figure out the columns for indexing
Use Normalization, ACID properties.
PS: notice the both the diagram tries to efficiently do thing in their on respect.