Thursday, December 14, 2017

Build Tools in Java World

Build tools in Java (or JVM ecosystem) have evolved over period of time. Each successive build tool has tried to solve some of the pains of the previous one. But before going further down on tools, let’s start with basic features of standard build tools. 

Dependency Management
Each project requires some external libraries for build to be successful.  So these incoming files/jars/libraries are called as dependencies of the project.  Managing dependencies in a centralized manner is de-facto feature of modern build tools.  Output artifact of the project also gets published and then managed by dependency management. Apache IVY and Maven are two most popular tools which support dependency management.

Build By Convention
Build script needs to be as simple and compact as possible. Imagine specifying each and every action which needs to be performed during build (compile all files from src directory, copy them to dir file, create jar file and so on); this will definitely make the script huge and hence managing and evolving it becomes a daunting task. So, modern build tools uses convention like by default (or can be configured as well) it knows that source files are in src directory. This minimizes number of lines in the build file and hence it becomes easier to write and manage build scripts.  
So any standard build tool should have above two as de-facto. Below are list of tools which have these features.

ANT + IVY (Apache IVY for dependency management)
·         MAVEN
·         GRADLE

I have listed only most popular build tools above. ANT by default doesn’t have dependency management but other two have native support for dependency management. Java world is basically divided between MAVEN and GRADLE.  So, I have focused below on these two tools.

Maven vs Gradle

  • MAVEN uses XML to write build script where as GRADLE uses a DSL language based on Groovy (one of the JVM language). GRADLE build script tends to be shorter and cleaner compared to maven build script.
  • GRADLE build script is written in Groovy (and can also be extended using Java). This definitely gives more flexibility to customize the build process. Groovy is a real programming language (unlike XML). Also, GRADLE doesn’t force to always use convention, it can be overridden. 
  • GRADLE has first class support for multi-project build whereas multi-project build of MAVEN is broken. GRADLE support dependency management natively using Apache open source project IVY (is an excellent dependency management tool).  Dependency management of GRADLE is better than MAVEN.
  • MAVEN is quite popular tool so it has wide community and Java community have been using it for a while; GRADLE on the other hand is quite new so there will be learning curve for developers.
  • Both are plugin based (and GRADLE being a newer); finding plugin might be difficult for GRADLE. But adoption of GRADLE is growing at good pace, Google supports GRADE for Android. Integration of GRADLE with servers, IDEs and CI tools is not as much as that of MAVEN (as of now).


    Most of the cons for GRADLE are mainly because it’s a new kid in the block. Other than this, rest all looks quite impressive about GRADLE. It scores better on both core features i.e. Dependency Management and Build by Convention. IMO, configuring build through a programming language is going to be more seamless once we overcome the initial learning curve.
    Also, considering we are going down the microservices path, so we will have option and flexibility to experiment with build tool as well (along with language/framework).


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