Spiral model in Software Engineering - Step-by-Step Execution

Concept Flow - Spiral model

Start: Define Objectives

↓

Identify Risks

↓

Develop & Test

↓

Plan Next Phase

↓

Decision: More Phases?

No→End: Deliver Product

↩Back to Define Objectives

The Spiral model repeats four main steps in cycles: setting goals, checking risks, building/testing, and planning the next cycle until the product is complete.

Execution Sample

Software Engineering

Phase 1: Define objectives
Phase 2: Identify risks
Phase 3: Develop and test
Phase 4: Plan next phase
Repeat until done

This shows the four steps repeated in each cycle of the Spiral model.

Analysis Table

Cycle	Step	Action	Outcome	Next Step
1	Define Objectives	Set goals for requirements	Clear goals set	Identify Risks
1	Identify Risks	Analyze potential problems	Risks found and planned	Develop & Test
1	Develop & Test	Build prototype or part	Prototype created	Plan Next Phase
1	Plan Next Phase	Decide on next cycle	Plan ready	More Phases?
1	More Phases?	Is product complete?	No	Cycle 2: Define Objectives
2	Define Objectives	Refine goals based on feedback	Updated goals	Identify Risks
2	Identify Risks	Check new risks	Risks managed	Develop & Test
2	Develop & Test	Improve prototype	Better prototype	Plan Next Phase
2	Plan Next Phase	Plan next steps	Plan ready	More Phases?
2	More Phases?	Is product complete?	No	Cycle 3: Define Objectives
3	Define Objectives	Finalize goals	Final goals set	Identify Risks
3	Identify Risks	Final risk check	Risks minimized	Develop & Test
3	Develop & Test	Complete product build	Product ready	Plan Next Phase
3	Plan Next Phase	Prepare for delivery	Delivery plan ready	More Phases?
3	More Phases?	Is product complete?	Yes	End: Deliver Product

💡 Cycle 3 ends with product complete, so the process stops.

State Tracker

Variable	Start	After Cycle 1	After Cycle 2	After Cycle 3 (Final)
Objectives	Initial goals	Clear goals set	Updated goals	Final goals set
Risks	Unknown	Identified and planned	Managed	Minimized
Product	None	Prototype created	Better prototype	Complete product
Plan	None	Plan ready	Plan ready	Delivery plan ready

Key Insights - 3 Insights

Why does the Spiral model repeat the same steps multiple times?

Because each cycle refines the product and manages risks better, as shown in the execution_table where steps repeat with improved outcomes.

What happens if risks are found during the Identify Risks step?

They are analyzed and planned for before development, preventing problems later. This is clear in the execution_table rows where risks are identified and managed before building.

When does the Spiral model stop cycling?

It stops when the product is complete, as shown in the last row of the execution_table where 'More Phases?' is answered 'Yes' or 'No'.

Visual Quiz - 3 Questions

Look at the execution_table, what is the outcome after the 'Develop & Test' step in Cycle 2?

A Better prototype

B Complete product

C Prototype created

D Plan ready

💡 Hint

Check the row for Cycle 2 and step 'Develop & Test' in the execution_table.

At which cycle does the Spiral model deliver the final product?

A Cycle 2

B Cycle 3

C Cycle 1

D Cycle 4

💡 Hint

Look at the last rows in the execution_table where 'More Phases?' is 'Yes' or 'No'.

If risks were not identified in Cycle 1, how would the execution_table change?

A The 'Develop & Test' step would be skipped.

B The 'Plan Next Phase' step would be missing.

C The 'Identify Risks' step would show 'No risks found'.

D The process would end immediately.

💡 Hint

Refer to the 'Identify Risks' step outcome in the execution_table for Cycle 1.

Concept Snapshot

Spiral model repeats four steps in cycles:
1. Define objectives
2. Identify risks
3. Develop and test
4. Plan next phase
Each cycle improves the product and manages risks until completion.

Full Transcript

The Spiral model is a software development process that repeats four main steps in cycles. Each cycle starts by defining objectives or goals for that phase. Then it identifies risks to find potential problems early. Next, it develops and tests a prototype or part of the product. Finally, it plans the next phase based on feedback and results. This cycle repeats, refining the product and reducing risks until the product is complete. The process stops when the product meets all goals and is ready for delivery.