# Transitive Dependency

## About

A **transitive dependency** in Maven is a dependency that our project does not explicitly declare but is **included automatically** because another dependency requires it.

For example, if our project depends on **Spring Boot Starter Web**, it will automatically include **Spring MVC, Tomcat, and Jackson** without us having to specify them individually.

## Why Do We Need Transitive Dependencies?

Maven's transitive dependency mechanism helps in:

* **Reducing Manual Effort** – No need to specify every required library.
* **Avoiding Compatibility Issues** – Ensures all dependencies work together.
* **Maintaining a Clean `pom.xml`** – Only direct dependencies need to be declared.

## How Transitive Dependencies Work?

Maven resolves dependencies using a **dependency tree**, where

1. **Direct Dependencies** – Explicitly declared in your `pom.xml`.
2. **Transitive Dependencies** – Automatically included based on direct dependencies.

#### **Example: Understanding Transitive Dependencies**

Let's say we add **Spring Boot Starter Web** to our project:

```xml
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
```

This dependency internally requires:

* Spring MVC
* Jackson (for JSON processing)
* Tomcat (embedded web server)

We don’t need to specify these separately; Maven will fetch them automatically.

## How to View Transitive Dependencies?

Maven provides a command to analyze dependency trees:

```sh
mvn dependency:tree
```

**Example Output**

```
[INFO] org.springframework.boot:spring-boot-starter-web:jar:2.7.0
[INFO] ├─ org.springframework.boot:spring-boot-starter:jar:2.7.0
[INFO] │  ├─ org.springframework.boot:spring-boot:jar:2.7.0
[INFO] │  ├─ org.springframework.boot:spring-boot-autoconfigure:jar:2.7.0
[INFO] │  ├─ org.springframework:spring-core:jar:5.3.20
[INFO] ├─ org.springframework.boot:spring-boot-starter-json:jar:2.7.0
[INFO] │  ├─ com.fasterxml.jackson.core:jackson-databind:jar:2.13.2
[INFO] ├─ org.apache.tomcat.embed:tomcat-embed-core:jar:9.0.62
```

This means

* We included **spring-boot-starter-web**
* It pulled **Spring Boot Starter JSON**, **Jackson**, and **Tomcat Embed Core**

## How to Manage Transitive Dependencies?

### **A. Excluding Unwanted Transitive Dependencies**

Sometimes, a transitive dependency might cause conflicts or be unnecessary. We can **exclude** it using

```xml
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-core</artifactId>
        </exclusion>
    </exclusions>
</dependency>
```

This removes **Tomcat**, useful if we are using another web server like Jetty.

### **B. Forcing a Specific Version of a Transitive Dependency**

If a transitive dependency has **an older version**, we can override it in `dependencyManagement`:

```xml
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.14.0</version>
        </dependency>
    </dependencies>
</dependencyManagement>
```

This ensures **Jackson** uses version **2.14.0**, even if a lower version is pulled.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://www.pranaypourkar.co.in/the-programmers-guide/maven/dependency-management/dependency/transitive-dependency.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.