I am creating a class diagram.
Process
1)Read Employee data from Active Directory
2) Add Employee detail to SQL Employee table
3) Read Details from XML file and update SQL table
4) update the employee detail in active directory
I have created a class for employee , XML file and a class for Linq to SQL crud functions and another class for the Linq to LDAP.
Question
I am not sure if i need to add all the crud operations and logging functions into the class diagram
It is impossible to answer your question unless you provide more information. Do you have any specific design rules which tell what needs to be specified in the class diagram and what doesn't need to be specified in it? If there are no such rules, I would first consider adding the database layer functions to the class diagram and if the class diagram becomes too complicated then perhaps consider removing these.
This might be a good moment to have a discussion with the other team members what rules are used to make the class diagrams. What do you want to be in the diagrams and what can be omitted? If different persons have different opinions, then this conflict needs to be resolved somehow quickly because it's not a productive use of people's time to keep endlessly arguing what should be specified in a UML class diagram.
Related
Hello I'm trying to prepare an ER diagram + a class diagram.
The system is very simple. It involves a simple flight reservation system with two roles (actors).
In the ERD, we can distinguish between the two roles using the "IsAdmin" attribute("true" for admin, and "false" for customer).
In the class diagram, I have a base class named "User" (containing all the attributes and methods of the customer role and all the attributes and some of the methods of the admin role).
Should I use the User class when dealing with the customer entity (since the attributes and methods are the same), or should I create an empty class derived from the User class for clarity?
It depends...
Basically when dealing with business objects I would not use a class named "User" which says all or nothing. You have a "Customer" and an "Admin" and likely many other "User"s. Don't make the "User" a "Customer".
Setting that aside, if you are using a serialization framework that often requires table and class to have the same name.
Also you shouldn't start a system with optimization. Give clarity an advantage in favor of that. It will pay out more sooner than later. And in any case: you can optimize at later stages as well.
ER Diagrams (ERDs) and UML Class Diagrams (CDs) are both information modeling languages that essentially cover the same concepts, but using a different visual syntax. Both allow modeling classes with properties/attributes (and operations/methods in the case of CDs) defining entity types, and associations (or relationship types).
Since CDs have been defined more recently, they are more expressive than, and subsume, ERDs. Consequently, there is no need to duplicate an information model both as an ERD and a CD. Rather, you should make a logical class design diagram from which you can obtain both OOP class models (defining, e.g., Java classes) and RDB table models.
If needed, you can derive an ERD from your CD.
I was wondering if it was possible to have differences between my conceptual model and the class diagram?
In the conceptual model, I explain that the user can create a message.
But in the class diagram the user must go through a class that contains all methods of creating a "ManageMessage" message.
here is an example
Can you help me ? Thank you
It's up to you how you show your classes in different diagrams. So in one you can show detailed attributes and operations and in another you show just the class name. However, in most cases it's better to create domain model which focuses on business aspects in the beginning. It does not have technically imposed structural elements and mainly you use attributes (YMMV). Later you derive a technical design from that model where you create a copy that links back with <<trace>> dependencies (UML tools offer transformation for that). Although you have to (mostly) manually synch the two models it's best to communicate with either business and developers.
N.B. about your design above: A message with zero related users does not seem to make much sense. Also you should not use the shared aggregation since it has no defined semantics.
I am at beginner stage of OOP. Got an academic project, need to make a UML Class Diagram of C# Code.
I am developing a project which will use database, I am confused about 1 thing. In UML we use inheritance like department and student, we create 2 classes and put department ID in student class.
Coming to my confusion, I will make some classes like department, student and teacher, and also a database with same tables. How can I use classes, because I know that on user request I can process data on database (on runtime), Like adding teacher or student to department, getting all students, etc. I am supposed to get all data from database when program loads? and save data in variables and put it in database when required? Simplifying my confusion, How to use classes when we use database to get data dynamically?
What you are talking about is a transition, which is not inheritance. At least not really. Once you have developed a class model you will think about persistence. The persistence can be designed in many ways (in most cases you will derive just one persistence scheme, though). Now what you do is to "copy" your classes from your design model to a new package for the persistence. Thereby <<trace>> from the persistence back to the design class. Now you almost independently optimize your persistence towards your desired schema. You will introduce primary and foreign keys, redundancy and things like that. Anyhow, your persistence model only remembers where it came from (via the <<trace>>) but it now has a living on his own.
Note that some UML tools offer automated transition from design models to various derivates.
i'm php developer using MVC architecture that i'm new to UML
i know use-case , class , object , activity, sequence diagrams but i don't know for modeling a application where i should start.
i know use-case and class diagrams are structural diagrams and activity and sequence are behavior diagrams
but my questions are:
1. for modeling a app when i should use use-case diagram and when i should use class diagram?
2. does class diagram has abstract concept? because when i'm developing web app i have some controller and model or view also several classes that i use for different purpose (like insert data to database - validate form inputs and so on) but they don't look like to examples of class diagram that i'v seen until now so my question is class diagram is used for show concept of our system and it doesn't need to generate real class code form it ?
for example modeling a ticket reservation that may have some classes like this:
but we don't write class codes like this and it can be different in programming but for view the concept we are using class diagrams . is it true ?
Use-case diagram is usually used for representing the business of the project, indicate who(actor) are going to utilize the system and what services(cases) does program provide?
The class-diagram is used for specifying the whole system structure, but there no code and exact behavior will be provided by the class, generally developers don't specify the exact behavior with each module in-detail.
for example, consider a simple login module. in use-case diagram, we just mention that user logins into the system.
In class diagram we specify the possible base classes are needed, in other word we apply the architecture (we are planning) basis.
In sequence diagram we focus more on what is going on each method(while this is not necessary).
In fact UMl is used for representing the system as abstract, not the exact(in-detail) functionality.
for example I pass the above class-diagram to a developer, and tell him about the detail login process as a separated document.
I have homework and I'm supposed to draw a class diagram AND data model. I wrote the class diagram. I don't know what to do about the data model. What are the differences?
According to texts on the Internet they seems to me, ie: class diagrams and data models are the same thing.
What is the difference between class diagrams and data models.
Unified Modelling Language, as you may already know, is a means of describing systems with diagrams. They don't just relate to software, but can also relate to hardware, economics, everyday items, in fact anything, although they are more generally used with software systems.
A class diagram details how you have split your system into discrete objects, how those objects relate to each other and any know interfaces that they may have. Each class in a class diagram can hold both data and function.
For example a Car class has an Engine, a Steering Wheel class and multiple Wheel, Door, Seat and Pedal classes linked to it. In all of this a class diagram is static.
I'm not exactly sure what you mean by data model.
I've seen class diagrams used to model database tables, usually these are without any functional element and just show how the data tables relate to each other.
There are those that argue that there needs to be an addition to the UML standard for Data Diagrams, but as yet none have been ratified.
This is because persistence of data, key relationships and constraints between tables can be difficult to model with a standard class diagram and most UML tools implement tweaks to the standard in order to allow this.
Then there are dataflow diagrams which are really Activity diagrams, used to show the flow of data between processes within a system.
Now if we go back to class diagrams and assume that a data diagram is used to model a database then you'll notice that there a few differences that may be overlooked.
A class on a class diagram can have data properties (code variables etc) and functional properties (methods, procedures, functions etc.) but these elements of a class can also have access properties (private, public etc.). A class diagram can also show inheritence e.g. a Volkswagon is a Car, so is a Ford, both will inherit from Car and this can be shown.
A data diagram in the database sense will show data items (columns/fields in database tables) but the idea of access properties (public, private etc.) or the idea of inheritence has no meaning and thus can't be shown.
This is because it isn't modelling discrete objects that have both data and function but the data associated with those objects. For example a Car table may have a relational link to a Manufacturers table in which is stored the values Volkswagon and Ford. It may have a Wheels column, but this will only show the number of wheels. Stored procedures for the database exist at a level labstracted from the data - they utilise the data, but are not governed or owned by the data tables that they get the data from.
I've probably not explained myself very well, but I hope that I've helped.
Here's a useful site
And here's another and on that site data modelling specifically.
Generally data models define how the database is implemented. Those diagrams are entity diagrams. A class model is the functional relationships between objects in your system. A class has data but it isn't the data model. A design has both a class model and a data model. As a simple example, a data model exists for a customer. That data model was the design for our customer database. A class model design exists to implement how to process a customer order. The data model is what the database designer uses. The class model is what the software designer uses to implement a ordering business function. Both the data model and class model have diagrams. They use different symbols and rules. Class diagram vs Entity diagram. Two different kinds of diagrams.
Datamodeling is not UML which is focused on object approach.
Having said that you can model inside a class diagram at object level and create your database using Hibernate annotations in the Java code.
I mean that you create your code and add persistence annotation at the same time. This would create your database at deployment.
UML which is not supposed to be datamodeling can also create data at deployment level if you use the Omondo Persistence profile. It means that you can model at object level and also create your database. Very powerful approach because the data creation stage is now joined with the object
This is still an initiative but it could become a standard if bigger companies adopt this approach which is for me one of the best practices when codding in Java that I would recommend.