Foreword
Prior to 1960, we believe that software technology omnipotent, but by 1960 the software industry software crisis broke out. The National General Accounting Office, in 1983, were studied for all software project delivery government. It found that only 3% of the project can be delivered on time, and the quality of clearance, 49% of the project is not available, 48% of the project must be re-modified to use after delivery.
In large companies, the average cost of 1.78 times the IT project overruns, schedule overruns 2.3 times. Only 42% of the original requirements can be implemented in the final version of the product after project delivery.
Therefore, software engineering came into being, I will summarize this in software engineering, object-oriented modeling language UML, and show how it is to solve the software crisis.
Software features of crisis
1. serious software development cycle exceeds a specified date
2. Software development costs far exceeded
3. Software quality is difficult to guarantee
The reason the software crisis
1. The size of the software produced increases gradually, more and more complex structure
2. Software development costs far exceeded
3. Software quality is difficult to guarantee
If the document software engineering, the successful solution of the problem of communication between the various audiences, and through the establishment of a document related to the development plan and operation and maintenance programs to address the software development cycle of overtime, operation and maintenance cost overrun problems. So UML modeling language is to help various audiences, from different angles can be an intuitive understanding of software systems, so as to solve the structure of magic weapon scale of the problem.
UML Modeling Language
1.UML is a visual object-oriented modeling language
2.UML describes the dynamic behavior and static behavior of the system, graphical way to show the entire structure of object-oriented systems
3.UML from different angles for the system model, and forming a different system views.
Structure of things
class
Object class is a description of the same attributes, methods, relationships, and semantics of a group of
interface
Interface describes a set of operations of a service class or member. Interface specification only defines a set of operations, it does not give a specific implementation of this set of operations.
cooperation
Collaboration defines an interactive, it is by working together to provide a set of groups, roles and other elements of a cooperative composed of these collaborative behavior greater than the respective behavior of all the elements combined. Therefore, there is collaboration structure, behavior, and latitude. A given class can participate in multiple collaboration.
example
Examples of these actions is performed with the description of a set of operation sequences, the system will generate a value of the particular participant and observable results.
Active class
Active class A class whose objects have at least one process or thread, so he can start control activities.
member
Member is a physical system, an alternative member, provided he follows and implement a set of interfaces.
node
Node is a physical elements present in the run-time, he represents a quantifiable resource, he usually has at least some of the processing power and memory, a set of components can reside within a node, you can migrate from one node to another node.
Behavior of things
Alternately
Such a behavior interaction, exchange of messages between him a set of objects together to complete certain specific tasks in a particular context components. Behavior or behavior of a target group of a single operation may be used to describe the interaction. Further interaction is also directed to a number of other elements, including the message sequence of actions (a series of actions caused by the messages), links (links between objects)
state machine
The state machine is a behavior, describe an object or an interactive response to events in the life of the experienced state sequence. A single class or set of classes collaboration between the state machine behavior can be described. A state machine involves a number of other elements, including state transition (from one state to another stream) event (spontaneous conversion of things) and activities (in response to a transition)
Packet things
Grouping things are part of the organization UML model, the most important thing is the group package
UML package is the only organization mechanism, the mechanism responsible for the elements organized into groups
Relationship in UML
Association (Association)
It describes the structural relationship between two or more classes
Dependence (Dependency)
Use one another from the relationship between two things
Generalization (Generalization)
Generalization is actually a more specific and general relationships, specifically the object element (child element) may be substituted for elements common objects (parent element). In this way, the child elements share the structure and behavior of the parent element. Generalization is therefore an element of the UML object-oriented technology inherited modeling.
Realization (Realization)
It describes a class of another class meta-membered guarantee contract implementation.
UML in Fig.
Use Case Diagram
Used to describe the needs of users, system functions from a user perspective description, and pointed out various executive functions, emphasizing who is using the system, which features complete system for the performer.
Class Diagram
System is used to define classes, including the relationship between the internal structure and class description classes. FIG mainly static class structure described system.
Object graph
FIG example of an object class is a diagram describing the relationship between objects in the system comprising the specific time point and each of the objects
State diagram
Transition conditions for the object classes describe all possible states and state occurs when the time
Activity Diagram
Satisfies the constraints used to describe the relationship between events and activities required to be performed by embodiments using the parallel activity diagram beneficial activity recognition system
Sequence Diagram
Describe the interaction between the target sequence, the transmission order reflects the emphasis messages between objects, but also shows the interaction between objects
Collaboration Diagrams
Cooperation between the objects described, there is more emphasis on passing messages between objects which illustrate
Sequence and collaboration diagrams can be transformed into each other.
FIG member
FIG member used to describe the structure of the physical dependencies between the code member and the respective members. A member may make a resource file, a binary file or an executable file.
Embodiment of FIG.
FIG deployment system defines the physical hardware architecture, used to describe the connections between them and the physical device.
to sum up
After completing the first few episodes video UML, UML understanding of the basic building blocks, knowing that their play in software engineering role. Next you need to know the actual use of rational rose tools and a variety of graphs.