General software followed model of SDLC (Systems Development Life Cycle (SDLC)) which we have introduced. We need find a formalized approach to implementing the SDLC.
The approach or ‘find a way’ called methodology A methodology is a formalized approach to implementing the SDLC (i.e., it is a list of steps and deliverables).
Some methodologies are formal standards used by government agencies, whereas others have been developed by consulting fi rms to sell to clients. Many organizations have internal methodologies that have been honed over the years, and they explain exactly how each phase of the SDLC is to be performed in that company.
There are many ways to categorize methodologies, We will introduce two way
A process-centered methodology emphasizes process models as the core of the system concept. this methodology focus first on defining the processes (e.g., assemble sandwich ingredients).
Data-centered methodologies emphasize data models as the core of the system concept.
In Figure 1-1, data-centered methodologies would focus first on defining the contents of the storage areas (e.g., refrigerator) and how the contents were organized.
While object-oriented methodologies will balance the focus between process and data by incorporating both into one model.
this meth will focus first on defining major element in system, and look at the processes and data involved with each element.
we mainly talk(object-oriented Analysis and design) OOAD in this course
Another is the sequencing and effort of each phases. which will talk in 159.341
Object-oriented systems Analysis & design(OOSAD)
Object-oriented systems focus on capturing the structure and behavior of information systems in little modules that encompass both data and process.
OK, that hard to understand.
The primary difference between a traditional approach like structured design and an object-oriented approach is how a problem is decomposed. and processes and data are so closely related that it is difficult to pick one or the other as the primary focus.
let break a problem into small pieces
one single part or device will handle one problem, and the device or we called Modules contain both data and process. You can call it Objects if you want
with Object connected, a problem can be solved. any modern object-oriented approach to developing information systems must be use-case driven, architecture-centric, and iterative and incremental.
OOSAD IS USE-CASE DRIVEN
Requirement gathering is focus on users which means that use cases are the primary modeling tools defining the behavior of the system. Through use-cases, programmers can idntify problems and communicate require in system
A use case describes how the user interacts with the system to perform some activity, such as placing an order, making a reservation, or searching for information.
a non-use-case driven such as traditional structured methodology require the systems analyst and user to develop models of the entire system. They finished entire system through decomposed into small subsystem
This goes on until no further process decomposition makes sense, and it oft n requires dozens of pages of interlocking diagrams.
In contrast a use case focuses on only one business process at a time, so developing models is much simpler.
OOSAD has 3 view
the systems analysts develop their understanding of a user’s problem by building up the three architectural views little by little
analyst work with users to create functional requirement.
Next, the analyst attempts to build a structural representation of the evolving system. Using the structural representation of the system,
Lab2
Tutorial 2: Gathering Requirements for your chosen Case Study (no formal submission needed)
This week you can do the requirements gathering for one of the design briefs (mentioned in Assignment 1 – where you have to choose the design brief based on your family name). List these requirements appropriately (e.g. create requirements definition report).
first try:
Some Questions
- how to deal with third-part service or external service?
- list all possible task/information? or simplify that ?
- users or charities ? using use-case driven which entity are we talking about