Maven why snapshot

Also, Snapshot should exist only during development phase and it will not be having a release version. This implies that the build of the project will be changed at any time and it is still under the development process. In case of Version , maven once downloaded the mentioned version say JavaSamples To download the updated code, CoreJavaTutorials version is to be upgraded to 1.

Learn Core Java. Java Examples Java 8 Java 11 Java HTML 5 Interactive. These are specific, point-in-time releases. Released artifacts are considered to be solid, stable, and perpetual in order to guarantee that builds which depend upon them are repeatable over time. Released JAR artifacts are associated with PGP signatures and checksums verify both the authenticity and integrity of the binary software artifact.

The Central Maven repository stores release artifacts. Snapshots capture a work in progress and are used during development. Various Maven plug-ins may interpret this differently, so it is safer to use one of the other, more specific options. When Maven encounters multiple matches for a version reference, it uses the highest matching version. Generally, version references should be only as specific as required so that Maven is free to choose a new version of dependencies where appropriate, but knows when a specific version must be used.

This enables Maven to choose the most appropriate version in cases where a dependency is specified at different points in the transitive dependency graph, with different versions. When a conflict like this occurs, Maven chooses the highest version from all references. Although you can achieve some of the same results by using a version range expression, a SNAPSHOT works better in a continuous build system for the following reasons:. Because a single artifact can be deployed multiple times in a day, the number of unique instances maintained by the repository can increase very rapidly.

If you are constantly releasing a new version and incrementing the build number or version, the storage requirements can quickly become unmanageable. The two important scenarios where Maven version numbers are used in Oracle provided artifacts are as follows:. In the Maven coordinates of the artifact, that is, in the project. This section provides details on how version numbers are defined for Oracle artifacts in both the scenarios.

The version number of the artifact defined in the POM file is the same as the version number of the released product, for example The version numbers of artifacts as specified in project. The release version number of Oracle-owned components do not change by a one-off patch. The release version number changes with a release and always matches the release, even if the component has not changed from the previous release. The PatchSet fourth position changes when you apply a PatchSet.

Now that we have covered a little bit of the history and purpose of Maven let's get into some real examples to get you up and running with Maven! The defaults for Maven are often sufficient, but if you need to change the cache location or are behind a HTTP proxy, you will need to create configuration. See the Guide to Configuring Maven for more information. We are going to jump headlong into creating your first Maven project! To create our first Maven project we are going to use Maven's archetype mechanism.

An archetype is defined as an original pattern or model from which all other things of the same kind are made. In Maven, an archetype is a template of a project which is combined with some user input to produce a working Maven project that has been tailored to the user's requirements. We are going to show you how the archetype mechanism works now, but if you would like to know more about archetypes please refer to our Introduction to Archetypes. On to creating your first project!

In order to create the simplest of Maven projects, execute the following from the command line:. Once you have executed this command, you will notice a few things have happened. First, you will notice that a directory named my-app has been created for the new project, and this directory contains a file named pom.

The POM is the basic unit of work in Maven. This is important to remember because Maven is inherently project-centric in that everything revolves around the notion of a project.

In short, the POM contains every important piece of information about your project and is essentially one-stop-shopping for finding anything related to your project. Now let's get back to the project at hand. After the archetype generation of your first project you will also notice that the following directory structure has been created:. As you can see, the project created from the archetype has a POM, a source tree for your application's sources and a source tree for your test sources.

If you were to create a Maven project by hand this is the directory structure that we recommend using. This is a Maven convention and to learn more about it you can read our Introduction to the Standard Directory Layout. Now that we have a POM, some application sources, and some test sources you are probably asking Change to the directory where pom. The first time you execute this or any other command, Maven will need to download all the plugins and related dependencies it needs to fulfill the command.

From a clean installation of Maven, this can take quite a while in the output above, it took almost 4 minutes.

If you execute the command again, Maven will now have what it needs, so it won't need to download anything new and will be able to execute the command much more quickly. So, if you're a keen observer, you'll notice that by using the standard conventions, the POM above is very small and you haven't had to tell Maven explicitly where any of your sources are or where the output should go.

By following the standard Maven conventions, you can get a lot done with very little effort! Just as a casual comparison, let's take a look at what you might have had to do in Ant to accomplish the same thing.

Now, this is simply to compile a single tree of application sources and the Ant script shown is pretty much the same size as the POM shown above. But we'll see how much more we can do with just that simple POM! If you simply want to compile your test sources but not execute the tests , you can execute the following:.

Now that you can compile your application sources, compile your tests, and execute the tests, you'll want to move on to the next logical step so you'll be asking Making a JAR file is straight forward enough and can be accomplished by executing the following command:.

For more information on repositories you can refer to our Introduction to Repositories but let's move on to installing our artifact! To do so execute the following command:. Note that the surefire plugin which executes the test looks for tests contained in files with a particular naming convention.

By default the tests included are:. You have walked through the process for setting up, building, testing, packaging, and installing a typical Maven project.

This is likely the vast majority of what projects will be doing with Maven and if you've noticed, everything you've been able to do up to this point has been driven by an line file, namely the project's model or POM. If you look at a typical Ant build file that provides the same functionality that we've achieved thus far you'll notice it's already twice the size of the POM and we're just getting started!

There is far more functionality available to you from Maven without requiring any additions to our POM as it currently stands. To get any more functionality out of our example Ant build file you must keep making error-prone additions.

So what else can you get for free?