Week 117 — What is a Maven repository and why is it useful?
Question of the Week #117
What is a Maven repository and why is it useful?
4 Replies
In order to reuse code, developers can create a library (e.g. as a JAR file) containing the compiled code and give it to other developers who can then include that library in their projects and use the code included there.
However, manually sharing and including JAR files is tedious and error-prone, especially with transitive dependencies (libraries requiring other libraries). Libraries often need to be compatible with each other, some libraries might require different version of a transitive dependency and they should be kept up-to-date. Apart from these issues, there are issues with including JAR files in source control systems like git.
To solve these issues, build tools like Maven have been created. With Maven, dependencies are not distributed as JARs people have to download from arbitrary places. Instead, it uses a Maven repository with a well-defined structure for dependencies. A dependency in a Maven dependency contains a POM with configuration including other necessary (transitive) dependencies and a JAR file containing the actual code as well as some other files. Different versions of the same dependency are stored in directories next to each other and a
maven-metadata.xml file lists all available versions for any given dependency.
Maven can then build projects that include a list of dependencies declared in a pom.xml file by automatically resolving all dependencies including transitive ones, resolving conflicts between dependencies and then compiling and running the project with all dependencies available.
It furthermore allows suggesting and applying updates for dependencies as well as placing version ranges of dependencies in the pom.xml.With this, it is no longer necessary to worry about getting JAR files. Instead, developers specify the dependencies in the build configuration (pom.xml) and Maven ensures all dependencies are available. The pom.xml file can then be shared between multiple developers working on the same project to get a common setup.
📖 Sample answer from dan1st
You can host pre-built binaries there so other developers can use them as dependencies.
Submission from mrsalty__
maven repository is similar thing then gradle is, just an alternative, so developers can publish their libraries and apis there and then you can easy import them over maven for your projects.
Submission from waifu.janna