// Copyright (c) 2017, 2024 IBM Corporation and others. // Licensed under Creative Commons Attribution-NoDerivatives // 4.0 International (CC BY-ND 4.0) // https://creativecommons.org/licenses/by-nd/4.0/ // // Contributors: // IBM Corporation // :projectid: maven-intro :page-layout: guide-multipane :page-duration: 15 minutes :page-releasedate: 2017-09-19 :page-guide-category: basic :page-essential: true :page-essential-order: 3 :page-description: Learn how to build and test a simple web application using Maven and Open Liberty :page-related-guides: ['maven-multimodules', 'gradle-intro'] :page-tags: ['maven'] :page-permalink: /guides/{projectid} :common-includes: https://raw.githubusercontent.com/OpenLiberty/guides-common/prod :page-seo-title: Building and testing a Java web application with Maven and Open Liberty :page-seo-description: A getting started tutorial with examples of how to build and test a simple Java EE or Jakarta EE web application using a Maven Project Object Model (POM) file. :guide-author: Open Liberty = Building a web application with Maven
[.hidden] NOTE: This repository contains the guide documentation source. To view the guide in published form, view it on the https://openliberty.io/guides/{projectid}.html[Open Liberty website].
Learn how to build and test a simple web application using Maven and Open Liberty.
// ================================================================================================= // What you'll learn // =================================================================================================
== What you'll learn
You will learn how to configure a simple web servlet application using https://maven.apache.org/what-is-maven.html[Maven^] and the https://github.com/OpenLiberty/ci.maven/blob/main/README.md[Liberty Maven plugin^]. When you compile and build the application code, Maven downloads and installs Open Liberty. If you run the application, Maven creates an Open Liberty instance and runs the application on it. The application displays a simple web page with a link that, when clicked, calls the servlet to return a simple response of Hello! How are you today?.
One benefit of using a build tool like Maven is that you can define the details of the project and any dependencies it has, and Maven automatically downloads and installs the dependencies. Another benefit of using Maven is that it can run repeatable, automated tests on the application. You can, of course, test your application manually by starting a Liberty instance and pointing a web browser at the application URL. However, automated tests are a much better approach because you can easily rerun the same tests each time the application is built. If the tests don't pass after you change the application, the build fails, and you know that you introduced a regression that requires a fix to your code.
Choosing a build tool often comes down to personal or organizational preference, but you might choose to use Maven for several reasons. Maven defines its builds by using XML, which is probably familiar to you already. As a mature, commonly used build tool, Maven probably integrates with whichever IDE you prefer to use. Maven also has an extensive plug-in library that offers various ways to quickly customize your build. Maven can be a good choice if your team is already familiar with it.
You will create a Maven build definition file that's called a pom.xml file, which stands for Project Object Model, and use it to build your web application. You will then create a simple, automated test and configure Maven to automatically run the test.
// ================================================================================================= // Installing Maven // =================================================================================================
== Installing Maven
ifndef::cloud-hosted[]
If Maven isn't already installed, https://maven.apache.org/download.cgi[download the binary zip or tar.gz file^]. Then, follow the https://maven.apache.org/install.html[installation instructions for your operating system^] to extract the .zip file and add the bin directory, which contains the mvn command to the PATH on your computer.
endif::[]
Run the following command to test that Maven is installed:
If Maven is installed properly, you see information about the Maven installation similar to the following example:
// ================================================================================================= // Getting Started // ================================================================================================= [role='command'] include::{common-includes}/gitclone.adoc[]
// ================================================================================================= // Try what you'll build // =================================================================================================
=== Try what you'll build
The finish directory in the root of this guide contains the finished application. Give it a try before you proceed.
// tag::runCommand[]
To try out the application, first go to the finish directory and run Maven with the liberty:run goal to build the application and deploy it to Open Liberty:
[role='command']
cd finish
mvn liberty:runAfter you see the following message, your Liberty instance is ready.
// end::runCommand[]
ifndef::cloud-hosted[]
Navigate your browser to the http://localhost:9080/ServletSample/servlet[^] URL to access the application. The servlet returns a simple response of Hello! How are you today?.
endif::[]
ifdef::cloud-hosted[] Select Terminal > New Terminal from the menu of the IDE to open another command-line session. Run the following curl command to view the output of the application:
curl -s http://localhost:9080/ServletSample/servletThe servlet returns a simple response of Hello! How are you today?. endif::[]
[role='command'] include::{common-includes}/twyb-end.adoc[]
// ================================================================================================= // Creating a simple application // =================================================================================================
== Creating a simple application
The simple web application that you will build using Maven and Open Liberty is provided for you in the start directory so that you can focus on learning about Maven. This application uses a standard Maven directory structure, eliminating the need to customize the pom.xml file so that Maven understands your project layout.
All the application source code, including the Open Liberty server.xml configuration file, is in the src/main/liberty/config directory:
└── src
└── main
└── java
└── resources
└── webapp
└── liberty
└── config// ================================================================================================= // Creating the project POM file // =================================================================================================
== Creating the project POM file
Navigate to the start directory to begin.
// cloud hosted instructions
ifdef::cloud-hosted[]
cd /home/project/guide-maven-intro/startendif::[]
Before you can build the project, define the Maven Project Object Model (POM) file, the pom.xml.
start directory.pom.xmlThe [hotspot file=0]pom.xml file starts with a root [hotspot=project file=0]project element and a [hotspot=modelVersion file=0]modelversion element, which is always set to 4.0.0.
A typical POM for a Liberty application contains the following sections:
properties): Any properties for the project go here, including compilation details and any values that are referenced during compilation of the Java source code and generating the application.dependencies): Any Java dependencies that are required for compiling, testing, and running the application are listed here.build): Maven is modular and each of its capabilities is provided by a separate plugin. This is where you specify which Maven plugins should be used to build this project and any configuration information needed by those plugins.The project coordinates describe the name and version of the application. The [hotspot=artifactID file=0]artifactId gives a name to the web application project, which is used to name the output files that are generated by the build (e.g. the WAR file) and the Open Liberty instance that is created. You'll notice that other fields in the [hotspot file=0]pom.xml file use variables that are resolved by the [hotspot=artifactID file=0]artifactId field. This is so that you can update the name of the sample application, including files generated by Maven, in a single place in the [hotspot file=0]pom.xml file. The value of the [hotspot=packaging file=0]packaging field is war so that the project output artifact is a WAR file.
The first four properties in the properties section of the project, just define the encoding ([hotspot=encoding file=0]UTF-8) and version of Java ([hotspot=java-version file=0]Java 11) that Maven uses to compile the application source code.
Open Liberty configuration properties provide you with a single place to specify values that are used in multiple places throughout the application. For example, the [hotspot=http.port file=0]http.port value is used in both the Liberty [hotspot=httpEndpoint file=2]server.xml configuration file and will be used in the test class that you will add (EndpointIT.java) to the application. Because the [hotspot=http.port file=0]http.port value is specified in the [hotspot file=0]pom.xml file, you can easily change the port number that the Liberty instance runs on without updating the application code in multiple places.
The [hotspot file=1]HelloServlet.java class depends on [hotspot=jakarta.jakartaee-api file=0]jakarta.jakartaee-api to compile. Maven will download this dependency from the Maven Central repository using the [hotspot=groupID-api file=0]groupId, [hotspot=artifactID-api file=0]artifactId, and [hotspot=version-api file=0]version details that you provide here. The dependency is set to [hotspot=scope-api file=0]provided, which means that the API is in the Liberty runtime and doesn't need to be packaged by the application.
The [hotspot=build file=0]build section gives details of the two plugins that Maven uses to build this project.
In the [hotspot=liberty-maven-plugin file=0]liberty-maven-plugin plug-in section, you can add a [hotspot=configuration file=0]configuration element to specify Open Liberty configuration details. For example, the [hotspot=serverName file=0]serverName field defines the name of the Open Liberty instance that Maven creates. You specified guideServer as the value for [hotspot=serverName file=0]serverName. If the [hotspot=serverName file=0]serverName field is not included, the default value is defaultServer.
// ================================================================================================= // Running the application // =================================================================================================
== Running the application
[role='command'] include::{common-includes}/devmode-lmp33-start.adoc[]
ifndef::cloud-hosted[]
Navigate your browser to the http://localhost:9080/ServletSample/servlet[^] URL to access the application. The servlet returns a simple response of Hello! How are you today?.
endif::[]
ifdef::cloud-hosted[] Select Terminal > New Terminal from the menu of the IDE to open another command-line session. Run the following curl command to view the output of the application:
curl -s http://localhost:9080/ServletSample/servletThe servlet returns a simple response of Hello! How are you today?. endif::[] // ================================================================================================= // Testing the web application // =================================================================================================
== Testing the web application
One of the benefits of building an application with Maven is that Maven can be configured to run a set of tests. You can write tests for the individual units of code outside of a running Liberty instance (unit tests), or you can write them to call the Liberty instance directly (integration tests). In this example you will create a simple integration test that checks that the web page opens and that the correct response is returned when the link is clicked.
EndpointIT class.src/test/java/io/openliberty/guides/hello/it/EndpointIT.java The test class name ends in IT to indicate that it contains an integration test.
Maven is configured to run the integration test using the [hotspot=maven-failsafe-plugin file=1]maven-failsafe-plugin. The [hotspot=system-property-variables file=1]systemPropertyVariables section defines some variables that the test class uses. The test code needs to know where to find the application that it is testing. While the port number and context root information can be hardcoded in the test class, it is better to specify it in a single place like the Maven [hotspot file=1]pom.xml file because this information is also used by other files in the project. The [hotspot=system-property-variables file=1]systemPropertyVariables section passes these details to the Java test program as a series of system properties, resolving the [hotspot=http-port file=1]http.port and [hotspot=war-name file=1]war.name variables.
The following lines in the [hotspot=URL file=0]EndpointIT test class uses these system variables to build up the URL of the application.
In the test class, after defining how to build the application URL, the [hotspot=Test file=0]@Test annotation indicates the start of the test method.
In the [hotspot=link file=0]try block of the test method, an HTTP GET request to the URL of the application returns a status code. If the response to the request includes the string Hello! How are you today?, the test passes. If that string is not in the response, the test fails. The HTTP client then disconnects from the application.
In the [hotspot=import file=0]import statements of this test class, you'll notice that the test has some new dependencies. Before the test can be compiled by Maven, you need to update the [hotspot file=1]pom.xml to include these dependencies.
The Apache [hotspot=commons-httpclient file=1]httpclient and [hotspot=junit file=1]junit-jupiter-engine dependencies are needed to compile and run the integration test [hotspot=EndpointIT file=0]EndpointIT class. The scope for each of the dependencies is set to [hotspot=test1 hotspot=test2 file=1]test because the libraries are needed only during the Maven build and do not needed to be packaged with the application.
Now, the created WAR file contains the web application, and dev mode can run any integration test classes that it finds. Integration test classes are classes with names that end in IT.
The directory structure of the project should now look like this:
└── src
├── main
│ └── java
│ └── resources
│ └── webapp
│ └── liberty
│ └── config
└── test
└── java// ================================================================================================= // Running the tests // =================================================================================================
[role='command'] include::{common-includes}/devmode-test.adoc[]
You see the following output:
Running io.openliberty.guides.hello.it.EndpointIT Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.255 sec - in io.openliberty.guides.hello.it.EndpointIT
Results :
To see whether the test detects a failure, change the [hotspot=responseString file=0]response string in the servlet [hotspot]src/main/java/io/openliberty/guides/hello/HelloServlet.java so that it doesn't match the string that the test is looking for. Then re-run the tests and check that the test fails.
[role='command'] include::{common-includes}/devmode-quit-ctrlc.adoc[]
== Great work! You're done!
You built and tested a web application project with an Open Liberty instance using Maven.
include::{common-includes}/attribution.adoc[subs="attributes"]