SRS content: analytical tools depicting existing systems

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Quick Questions

Shade in the A or B circle for each question.

1. Which diagrams can an SRS include to depict an existing system?

A Only a Gantt chart and a project log

B Context, data flow and use case diagrams

2. What role does a data flow diagram play in an SRS?

A It is evidence of how data moves through the existing system

B It is the final program code for the new system

3. A context diagram in an SRS shows the existing system as:

A One process with the external entities that exchange data with it

B A detailed set of every internal process and data store

4. Which diagram in an SRS shows who uses the existing system and what they can do?

A Context diagram

B Use case diagram

5. How should the diagrams in an SRS relate to the requirements?

A Each diagram should help explain or support specific requirements

B Diagrams are separate and should not match the requirements

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Context diagram (Level 0)		AShows the actors who use the existing system and the tasks they perform, which can be linked to the functional requirements
2Use case diagram		BShows the existing system as one process, with the external entities and the data flows between them, as evidence in the SRS
3An SRS includes a Level 1 DFD to show the processes and data stores of the existing system in detail		CFR4: The system must record returns (see DFD 1, process 3.0 Process Return)
4Linking a diagram to a requirement shows where the need came from, so the requirement is backed by evidence		DThe diagrams are not linked to the requirements. Each diagram should be referenced by the requirements it supports, otherwise it is not evidence.
5SRS diagrams section: includes only a use case diagram, so the existing data flows are shown		EA use case diagram does not show data flows or data stores. A context diagram or DFD is needed to depict how data moves in the existing system.
6SRS lists context, DFD and use case diagrams with no link to any requirement		FDFD Level 1: Process 2.0 Check Stock reads D1 Inventory

Definitions

SRS analytical tools

Fill in the Blanks

Complete each line of code by filling in the missing parts.

SRS diagram: _______ diagram = Level 0

SRS diagram: _________ diagram = Level 1

SRS diagram: ________ diagram = actors

Req __: Parents can book interviews Evidence: use case Book Interview -> R4

Purpose: show how the ________ system works

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A Diagram: Context (Level 0)

B Shows: many processes inside

C Evidence: how data flows now

D Links to: REQ-01, REQ-02

Question 2

A Diagram: Data flow (Level 0)

B Shows: processes and stores

C Evidence: current order steps

D Links to: REQ-03

Question 3

A Diagram: Use case

B Actors: Student, Teacher

C Shows: where data is stored

D Links to: REQ-05

Question 4

A SRS section: Existing system

B Tools: context, DFD, use case

C Purpose: show the new system

D Each diagram links to a REQ ID

Question 5

A REQ-06: Record each payment

B Evidence: none needed

C Shows how payments work now

Answer Key

SRS content: analytical tools depicting existing systems

Section A: Quick Questions

B — Context, data flow and use case diagrams

A — It is evidence of how data moves through the existing system

A — One process with the external entities that exchange data with it

B — Use case diagram

A — Each diagram should help explain or support specific requirements

Section B: Match the Pairs

Context diagram (Level 0) → Shows the existing system as one process, with the external entities and the data flows between them, as evidence in the SRS

Use case diagram → Shows the actors who use the existing system and the tasks they perform, which can be linked to the functional requirements

An SRS includes a Level 1 DFD to show the processes and data stores of the existing system in detail → DFD Level 1: Process 2.0 Check Stock reads D1 Inventory

Linking a diagram to a requirement shows where the need came from, so the requirement is backed by evidence → FR4: The system must record returns (see DFD 1, process 3.0 Process Return)

SRS diagrams section: includes only a use case diagram, so the existing data flows are shown → A use case diagram does not show data flows or data stores. A context diagram or DFD is needed to depict how data moves in the existing system.

SRS lists context, DFD and use case diagrams with no link to any requirement → The diagrams are not linked to the requirements. Each diagram should be referenced by the requirements it supports, otherwise it is not evidence.

Section C: Definitions

SRS analytical tools — An SRS includes context, data flow and use case diagrams to show how an existing system works, and these diagrams link to the requirements.

Section D: Fill in the Blanks

SRS diagram: context diagram = Level 0

SRS diagram: data flow diagram = Level 1

SRS diagram: use case diagram = actors

Req R4: Parents can book interviews
Evidence: use case Book Interview -> R4

Purpose: show how the existing system works

Section E: Spot the Error

B — A Level 0 context diagram shows the whole system as ONE process with its external entities. It does not show processes inside the system. That is the job of a Level 1 DFD. It should read 'Shows: one system, entities'.

A — The data flow diagram that shows processes and data stores is Level 1. Level 0 is the context diagram. The line should say 'Data flow (Level 1)'.

C — A use case diagram shows actors and what they can do with the system. Data stores belong on a data flow diagram. It should read 'Shows: what each actor can do'.

C — In this SRS section the diagrams depict the EXISTING system, so they show how it works now. They are not a design of the new system. It should read 'Purpose: show how it works now'.

B — Diagrams act as evidence for requirements. Each requirement should point to the diagram element that supports it, such as DFD process 2.0 Pay. Saying no evidence is needed is wrong.