In these diagrams, I’ve named the participants using the style anOrder. In UML 1, participants were objects and so their names were underlined,īut in UML 2, they should be shown without the underline, as I’ve done here. So I use the term participants, a word that isn’t used formally in the UML spec. In UML 2, their roles are much more complicated, and to explain it all fully is beyond this book. Most of the time, you can think of the participants in an interaction diagram as objects, as indeed they were in UML 1. You can’t tell that from this diagram, although I’ll introduce some more notation to handle that later. The sequence of messages getQuantity, getProduct, getPricingDetails, and calculateBasePrice needs to be done for each order line on the order, while calculateDiscounts is invoked just once. The diagram, however, doesn’t show everything very well. GetDiscountInfo to an instance of customer. You can also see how we show the order invoking a method on itself and how that method sends Of order sends getQuantity and getProduct messages to the order line. One of the nice things about a sequence diagram is that I almost don’t have to explain the notation. A sequence diagram for centralized control Participant with a lifeline that runs vertically down the page and the ordering of messages by reading down the page.įigure 4.1. Sequence diagrams show the interaction by showing each Having done that for all the line items, the order then needs to computeĪn overall discount, which is based on rules tied to the customer.įigure 4.1 is a sequence diagram that shows one implementation of that scenario. On the pricing rules of the order line’s products. To do that, the order needs to look at all the line items on the order and determine their prices, which are based We have an order and are going to invoke a command on it to calculate To begin the discussion, I’ll consider a simple scenario. The messages that are passed between these objects within the use case. The diagram shows a number of example objects and Typically, a sequence diagram captures the behavior of a single scenario. The UML defines several forms of interaction diagram, of which Interaction diagrams describe how groups of objects collaborate in some behavior.
I drew them using Visual Paradigm and I dont know how to keep a control of the sequence numbers.UML Distilled: A Brief Guide to the Standard Object Modeling Language, 3rd Edition This time I drew sequence diagrams for borrowing a book and extending the date of return. I already drew the Use Case diagram and had it checked by a community member. Some books are for short term loans only. The library may have several copies of a given book. There is a limit on the number of books that can be borrowed by each member of the library. In order to borrow a book the borrower must be a member of the library. The task is to develop a computer system for borrowing books.
This is the problem I got from some PDF available on Google that simply had the following problem statement:Ī library contains books and journals. NOTE: I am self studying UML so I have nobody to verify my diagrams and hence I am posting here, so please bear with me.