Multi-module project structure in Spring Boot - Step-by-Step Execution

Concept Flow - Multi-module project structure

Parent Project (pom.xml)

↓

Build Parent -> Build Modules

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Modules share dependencies & build

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Run individual modules or combined app

The parent project manages common settings and dependencies. Each module has its own code and can be built separately or together.

Execution Sample

Spring Boot

<modules>
  <module>module-a</module>
  <module>module-b</module>
</modules>

This snippet shows the parent pom.xml listing two modules, telling Maven to build them together.

Execution Table

Step	Action	File/Module	Result
1	Read parent pom.xml	parent-pom.xml	Identify modules: module-a, module-b
2	Build module-a	module-a/pom.xml	Compile module-a code, resolve dependencies
3	Build module-b	module-b/pom.xml	Compile module-b code, resolve dependencies
4	Link modules	parent-pom.xml	Modules share common dependencies and build settings
5	Run module-a	module-a	Start module-a application or tests
6	Run module-b	module-b	Start module-b application or tests
7	Build parent	parent-pom.xml	Build all modules together
8	Exit	-	Build and run complete

💡 All modules built and linked successfully, ready to run individually or combined

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
modules	empty	[module-a, module-b]	[module-a, module-b]	[module-a, module-b]	[module-a, module-b]
module-a build status	not built	not built	built	built	built
module-b build status	not built	not built	not built	built	built
parent build status	not built	not built	not built	not built	built

Key Moments - 3 Insights

Why do we need a parent pom.xml in a multi-module project?

The parent pom.xml centralizes common dependencies and build settings so modules don't repeat them. See Step 1 and Step 4 in the execution_table.

Can modules be built and run independently?

Yes, each module has its own pom.xml and can be built or run separately, as shown in Steps 2, 3, 5, and 6.

How does building the parent project affect modules?

Building the parent triggers building all modules together, ensuring consistent versions and dependencies, as in Step 7.

Visual Quiz - 3 Questions

Look at the execution table, what modules does the parent pom.xml list?

A module-a and module-b

B Only module-a

C Only module-b

D No modules listed

💡 Hint

Check Step 1 in the execution_table where parent pom.xml identifies modules

At which step is module-b built?

A Step 2

B Step 3

C Step 5

D Step 7

💡 Hint

Look at the Action and File/Module columns in the execution_table

If the parent pom.xml did not list module-b, what would change in the execution table?

A Step 7 would build only module-b

B Step 2 would be missing

C Step 3 would be missing

D No change

💡 Hint

Modules are identified in Step 1 and built in Steps 2 and 3

Concept Snapshot

Multi-module project uses a parent pom.xml to manage common settings.
Modules have their own pom.xml files and code.
Parent pom lists modules to build together.
Modules can be built/run independently or combined.
This structure keeps code organized and dependencies consistent.

Full Transcript

A multi-module project in Spring Boot uses a parent pom.xml file that lists all modules. Each module has its own pom.xml and code. When building, Maven reads the parent pom.xml to find modules, then builds each module in order. Modules share dependencies and build settings from the parent. You can run modules separately or build the whole project together. This helps keep code organized and avoids repeating dependency info.