aims
Understand the concept of needs analysis and get 1 minute demand method
2 Understanding demand modeling
demand analysis
The concept and significance of a needs analysis of
needs: user requirements for functionality and performance of the software that users want the software to do something, to complete what kind of function, to achieve what the performance
requirements analysis: description of system to be developed to be accomplished by the function
that allows system engineers depicts software functionality and performance , the interface and other elements of the system and software specified in the software must meet the constraints established
Reasons for the difficulties needs analysis of the
software functional complexity; demand variability; software products invisibility (computer application system requirements analysis work is done in the process of system analysts and users continue to interact in)
3 acquisition method needs:
interviews - field survey - Survey - access to information
Process Analysis requirements
(1) identify the problem: all by obtaining an understanding of the operating environment and to solve the problem and identification of the problem
(2) need to establish model: Analysis of the current can be used for structural analysis model or a system requirement information Object model
(3) description Requested:; function; information; performance; environment; other requirements
(4) to confirm Requested: review and confirmation, auditing requirements, data requirements, performance, and other data management needs
Requirement Modeling
Structured Analysis and Modeling:
the DFD IDEF modeling Modeling
Object-Oriented Analysis and Modeling:
the UML Use Case Modeling
5 structured analysis tasks
(1) analysis model: SA model is a description of a set of software requirements include: functional model; the data model and behavior model
(2) the preparation of requirements specifications:
SRS analysis stage is written in text-based documentation; include: introduction, description, functional description, behavior description, quality assurance and interface descriptions and other requirements, etc.
(3) structural analysis of the guiding ideology: abstraction and decomposition
6 DFD demand modeling
data flow diagram (the DFD Data Flow Diagram)
the DFD is a core data stream
data stream is a data propagation path in the system, the data must flow
DFD modeling process. 7
(1) clear objectives, the system determines the range of
the full functional requirements of the user target system, accurate, consistent describe
(2) the establishment of top-level DFD map
described system of input and output boundary data flow system, the top layer only a DFD
(3) construction of an exploded view of a first layer DFD
intermediate layer DFD decomposition of a process is described, but it has to be further decomposed part
(4) intermediate layer configuration diagram DFD (principles: maintaining a uniform depth model, by degree of difficulty selected)
underlying DFD by a number of processes no longer decomposable composition
(5) check the DFD FIG.
1 parent FIG described data stream must appear in the respective sub-figure
2 a process having at least one input and output streams
3 a data must be stored inflow and outflow of data
4 has at least one segment is a data processing block
5 describes the expression of full information, a complete, correct and consistent
8 IDEFO demand modeling
IDEF0: Description System and Its Relationship
relationship between the data and system information: IDEF1
IDEF2: system modeling, dynamic modeling
IDEF3: Process Description and method for acquiring
IDEF4: Object Oriented Design
Example 9 UML modeling method using
oriented thinking modeled object, using the system described with embodiments of FIG functional requirements;
use by the embodiment of FIG system; role; use cases a relation between the three model elements and
