UML : Interaction Diagrams

Interaction Diagrams

• An interaction diagram is a graphical representation of how objects interact with one another in a scenario. 
• They capture the behavior of a single use case,showing the pattern of interaction among objects. 
• Objects communicate in an interaction diagram by sending messages. 
• Sending a message typically corresponds to invoking a method or function, where the message name is the name of the method. 
• A message may carry data as parameters being passed.

UML provides two forms of interaction diagrams :
A. Sequence diagrams
B. Collaboration diagrams

Since we have only sequence diagram here are some tips and some information about sequence diagram

Sequence Diagram shows an interaction arranged in a time sequence. It has two dimensions :

1.Vertical Dimension representing time

2.Horizontal Dimension representing different objects.

 Sequence Diagram : Objects

• An object is shown as a box of at the top of the dashed vertical line also know as the lifeline of the object.

• It represents the object’s existence during the interaction. 

 

Sequence Diagram : Message 

• An interaction is a set of messages exchanged among a set of objects to accomplish a particular purpose within a given context (such as a collaboration).

• A message is a conveyance of information from one object to one or more other objects with the expectation that activitywill ensue, in the form of an action.

• A message can be either a signal or a call. 

• Within a process or a thread, messages are ordered in sequence by time.

 MESSAGE NOTATION :

Sequence Diagram : Recursion And Delegation

An Example:  Sequence Diagram of An Airline Reservation Syatem