System requirements specification, classification of requirements as strategic, tactical, operational and statutory.

By -

System requirements specification, classification of requirements as strategic, tactical, operational and statutory

SYSTEM REQUIREMENTS SPECIFICATION (SRS)

SRS is obtained after excessive discussions with the user.

System requirements specification specifies what Information requirements will be provided. It does not specify how the system will be designed. Developing SRS is most important and difficult task of a Systems analyst

How SRS is developed

Analyst examines the current system, finds out the shortcomings of the

system as seen by the user. He then develops an SRS which is understandable by the user and which can be used for detailed design of the system.

Ideal characteristics of SRS

•Complete and Unambiguous.

•Specifies operational, tactical, and strategic information requirements

•Eliminates possible later disputes between users and Analyst

•Uses Graphical aids understood by users who are not computer literate and will also be useful in design.

•Jargon Free.

DEVELOPING A DOCUMENT FLOW DIAGRAM

EXAMPLE WORD STATEMENT

“Our company receives many items from several vendors each accompanied by a delivery note. A receiving office receives the item and checks the delivery note with corresponding order. Any discrepancy is reported to purchase office. The items received along with items received note (with details of items) is sent to the inspection office.”

ENTITIES IDENTIFIED-Vendors, Receiving office, Inspection office DOCUMENTS IDENTIFIED-Delivery note, discrepancy note, Items Received note.

Using these a document flow diagram is drawn

image

The diagram is interpreted as follows:

Vendors deliver items to receiving office accompanied by a delivery note

2) Receiving Office sends items to inspection office along with an items received note

3) Receiving office sends discrepancy note to Purchase office

ENTITIES: Vendor, Receiving office, Inspection office and purchase office

DOCUMENTS: Delivery note, Items received note and discrepancy note

DATA FLOW DIAGRAM (DFD)

DFD has entities and data flows, DFD specifies processing performed by some of the entities. It specifies which entities generate documents and also indicate their flow. Data stores which are referred while processing data and in which processed data may be written or stored are also represented in the Diagram

image

•Entities are, originators of data and “consumers” of data

•Vendor, Inspection office and purchase office are entities in the above diagram

•Data flows are delivery note, items received note and discrepancy note

•A circle is used to depict a process

•A pair of parallel lines depict a store

Data elements in the data flow:

Delivery note:

Order no,Vendor code,Vendor name and address,Item name, Item code,Delivery date,Quantity supplied,units.

Items Received note:

Order no,Item name,Item code,Delivery date,quantity,supplied,units.

Discrepancy note:

Order no,Vendor code,Vendor name and address,Item name, Item code,Order date, Delivery date,quantity supplied,units, excess/deficiency,No of days late/early.

Receiving office order file

Order no,Order date,Item name,Item code,Vendor code,Vendor Name and address,Quantity ordered,delivery period.

PROCESSING RULE

The statements given below are shown to the user for his approval.

English statement

1. Compare order no in delivery note with that in order file. If no match return item to vendor.

2. If order no matches then compare item codes, if no match return item to the vendor.

3. If order number matches compare qty delivered with quantity ordered. If excess or deficient send discrepancy note to purchase office.

4. If order number matches compare date of delivery with expected date. If

late or early send discrepancy note to purchase office.

5. In case3 and case4 send items received note to inspection office

MODULARIZING REQUIREMENTS SPECIFICATIONS

SRS Document now consists of Document flow diagrams(as many as needed), Data Flow Diagrams, Data elements of each data flow and Data store, processing rules carried out in each circle of DFD, a descriptive statement of operational,tactical,strategic information will be provided, a data dictionary which consolidates all data elements in the document and data store.

REFERENCES

1. Most of the material including the case study has been adapted from Chapter 4, Analysis and Design of Information Systems by V.Rajaraman published by Prentice Hall of India 2002 with permission from publisher.

Systems Analysis and Design, by K.E.Kendell and J.E.Kendell published by Pearson Education Asia 2002 discuss in detail fact gathering in pp.117-196. They cover interviewing, questionnaire use and observing an organization very thoroughly.

Comments

Post a Comment

Popular posts from this blog

WORKED EXAMPLES ON PROCESS SPECIFICATION.

By -
Image
PROCESS SPECIFICATION WORKED EXAMPLES 6.1 A bank has the following policy on deposits: On deposits of Rs. 5000 and above and for three years or above the interest is 12%. On the same deposit for a period less than 3 years it is 10%. On deposits below Rs. 5000 the interest is 8% regardless of the period of deposit. Write the above process using (i) Structured English (ii) A decision table 6.2 An organization maintains an employee file in which each record has following data: { Employee No., employee name, employee gross pay}. It has been decided to increase the pay as per the following formula: For pay of Rs. 1000 or less increase 15%. For pay of more than Rs. 1000 but up to Rs. 2500 increase 10%. For pay over Rs. 2500 increase 5%. (i) Writ e a structured English processing rule corresponding to the above policies. (ii) Express the policies as a decision table. (i) While employee records left in file do Read Number, name , gross pay 6.3 An offshore gas company bills it
Read more

Why do we need information systems, management structure, requirements of information at different levels of management.

By -
Image
Why do we need information systems, management structure, requirements of information at different levels of management NEED FOR INFORMATION SYSTEMS Information systems are needed when timely processing for fast action is needed, same data has to be processed in different ways and when organizations require innovative processing. MANAGEMENT STRUCTURE Functional areas of management are as follows: •PRODUCTION • MARKETING • MATERIALS – purchase, stores • FINANCE –Accounts • HUMAN RESOURCE DEVELOPMENT(HRD) • RESEARCH AND DEVELOPMENT (R&D) INFORMATION FOR MANAGEMENT A Production Management The following type of information is needed in production management: Strategic Information: 1)Yearly and monthly production quotas and alternate schedules 2)Policies on machine replacement, augmentation and modernization. 3)Identifying best product mix. Tactical Information 1)Identifying and controlling areas of high cost. 2) Identifying critical bottlenecks in production. 3)
Read more

The User Interface:Establishing User Interfaces

By -
Image
The User Interface Establishing User Interfaces The success factors in analysis start with the established interfaces from day one. What does this mean? You must start the process by meeting with the right people in the organization. In the best projects, the process is as follows: 1. Executive interface: There needs to be an executive-level supporter of the project. Without such a supporter, you risk not being able to keep the project on schedule. Most important, you need a supporter for the political issues that you may need to handle during the project (discussed in detail later). The executive supporter, sometimes known as a sponsor (JAD reference), should provide a preliminary schedule advising the organization of what is expected and the objectives of the project. The executive supporter should attach a letter to the preliminary schedule and send it to the project team members. The letter must put the importance of the project into perspective. Therefore, it is strongly rec
Read more