[IV] STRUCTURED WALKTHROUGH
The development process must include checks throughout the process to ensure that the final product meet the original user requirements.
Quality assurance thus becomes an important component of the development process : The Quality Assurance program includes
- Validation of the system against requirements.
- Checking of errors in design documents and in system itself.
- Checking for qualitative features such as portability and flexibility.
- Checking for usability.
Since the goal of quality assurance is to look at earlier work, designers are required to prepare for a review, inspection or walkthrough and be ready for carrying out any checks or follow-up work needed.
Walkthrough : The walkthrough is a procedure that is used to check the correctness of models produced by structured analysis, although its techniques are applicable to other design methodologies. Such checking has always been necessary in system analysis and design.
Specific tasks are allocated to various members of the walkthrough team and require documentation to be produced during and after the walkthrough.
The team must check that the model :
- meets system objectives.
- is a correct representation of the system.
- has no omissions or ambiguities;
- null do the job it is supposed to do.
- is easy to understand.
Walkthroughs are one important method used in quality assurance. Another important feature of walkthrough is that no actual design or system alteration takes place during the walkthrough.
When are walkthroughs Carried Out ?
Walkthrough can take place throughout system development. In structural systems analysis, they begin when the physical and logical models of the existing system have been completed. The first walkthrough checks the existing system models to detect emissions and inaccuracies in them.
Walkthrough should also be carried out on the new logical design to detect flows, weaknesses, errors and omissions in the proposed design.
How are Walkthroughs Carried Out ?
The procedure followed in a walkthrough is shown in figure ahead :
Before the walkthrough begins, the producer should ensure that obvious problems have been eliminated from the models. A walkthrough team is brought together to apply the benefits of its combined knowledge to the whole system and to detect the less obvious system problems. One should use the checklist on a structured model before the
documents of a walkthrough are submitted. The checklist includes the common kinds of errors that often occur in modeling and serves as a guide for detecting such errors.
Once the producers are satisfied with the model, it is time for the walkthrough. Two outcomes are possible from the walkthrough. One is that no errors are found in the model and it is accepted. In that case, review documents are prepared for a subsequent project review.
The other outcome is where errors are detected in the model. In that case, an action list is produced. The model is then amended and later submitted to another walkthrough.
The outcome of the walkthrough is always documented. Usually only two documents are produced. One is a summary that describes the walk through outcome and the other is an action list. The action list shows all the issues raised during the walkthrough and, more importantly, who is to be responsible for resolving these issues.
All information system create, read, update and delete data. This data is stored in files and databases. A file is a collection of similar records. e.g., customer file. A database is a collection of interrelated files. The records in each file must allow for relationships to the records in other files. e.g., A sales database night contain order records that are linked to their corresponding CUSTOMER and PRODUCT records.
Conventional File Based System
In most organizations, many existing information systems and applications are built around conventional files.
Conventional files are relatively easy to design and implement because they are normally designed for use with a single application or information system such as accounts receivable or payroll.
If one understand the user’s output requirements for a system, the data that have to be captured and stored to produced these outputs can be determined and the best file organization for those requirements can be defined.
Another advantage of conventional file has been processing speed. They can be optimized for the access of the application.
Databases possesses the ability to share the same data across multiple applications and systems. Database technology offers the, advantage of storing data in flexible formats. It also provide superior scalibility, meaning that the database and the systems use it can be grown or expanded to meet the changing needs of the organization. It provides better technology for client/server and network computing architecture.
If the database is well designed, different combinations of the same data can be easily accused to fulfill future report and query needs.