DDevelopment & Design

Multi module Gradle project with IDE support

This article is a short how-to about multi-module project setup with usage of the Gradle automation build tool. Here’s how Rich Seller, a StackOverflow user, describes Gradle: Gradle promises to hit the sweet spot between Ant and Maven. It uses Ivy’s approach for dependency resolution. It allows for convention over configuration but also includes Ant tasks as first class citizens. It also wisely allows you to use existing Maven/Ivy repositories. So why would one use yet another JVM build tool such as Gradle? The answer is simple: to avoid frustration involved by Ant or Maven. Short story I was fooling around with some fresh proof of concept and needed a build tool. I’m pretty familiar with Maven so created project from an artifact, and opened the build file, pom.xml for further tuning. I had been using Grails with its own build system (similar to Gradle, btw) already for some time up then, so after quite a time without Maven, I looked on the pom.xml and found it to be really repulsive. Once again I felt clearly: XML is not for humans. After quick googling I found Gradle. It was still in beta (0.8 version) back then, but it’s configured with Groovy DSL and that’s what a human likes :) Where are we In the time Ant can be met but among IT guerrillas, Maven is still on top and couple of others like for example Ivy conquer for the best position, Gradle smoothly went into its mature age. It’s now available in 1.3 version, released at 20th of November 2012. I’m glad to recommend it to anyone looking for relief from XML configured tools, or for anyone just looking for simple, elastic and powerful build tool. Lets build I have already written about basic project structure so I skip this one, reminding only the basic project structure: <project root> │ ├── build.gradle └── src ├── main │ ├── java │ └── groovy │ └── test ├── java └── groovy Have I just referred myself for the 1st time? Achievement unlocked! ;) Gradle as most build tools is run from a command line with parameters. The main parameter for Gradle is a ‘task name’, for example we can run a command: gradle build. There is no ‘create project’ task, so the directory structure has to be created by hand. This isn’t a hassle though. Java and groovy sub-folders aren’t always mandatory. They depend on what compile plugin is used. Parent project Consider an example project ‘the-app’ of three modules, let say: database communication layer domain model and services layer web presentation layer Our project directory tree will look like: the-app │ ├── dao-layer │ └── src │ ├── domain-model │ └── src │ ├── web-frontend │ └── src │ ├── build.gradle └── settings.gradle the-app itself has no src sub-folder as its purpose is only to contain sub-projects and build configuration. If needed it could’ve been provided with own src though. To glue modules we need to fill settings.gradle file under the-app directory with a single line of content specifying module names: include 'dao-layer', 'domain-model', 'web-frontend' Now the gradle projects command can be executed to obtain such a result: :projects ------------------------------------------------------------ Root project ------------------------------------------------------------ Root project 'the-app' +--- Project ':dao-layer' +--- Project ':domain-model' \--- Project ':web-frontend' …so we know that Gradle noticed the modules. However gradle build command won’t run successful yet because build.gradle file is still empty. Sub project As in Maven we can create separate build config file per each module. Let say we starting from DAO layer. Thus we create a new file the-app/dao-layer/build.gradle with a line of basic build info (notice the new build.gradle was created under sub-project directory): apply plugin: 'java' This single line of config for any of modules is enough to execute gradle build command under the-app directory with following result: :dao-layer:compileJava :dao-layer:processResources UP-TO-DATE :dao-layer:classes :dao-layer:jar :dao-layer:assemble :dao-layer:compileTestJava UP-TO-DATE :dao-layer:processTestResources UP-TO-DATE :dao-layer:testClasses UP-TO-DATE :dao-layer:test :dao-layer:check :dao-layer:build BUILD SUCCESSFUL Total time: 3.256 secs To use Groovy plugin slightly more configuration is needed: apply plugin: 'groovy' repositories { mavenLocal() mavenCentral() } dependencies { groovy 'org.codehaus.groovy:groovy-all:2.0.5' } At lines 3 to 6 Maven repositories are set. At line 9 dependency with groovy library version is specified. Of course plugin as ‘java’, ‘groovy’ and many more can be mixed each other. If we have settings.gradle file and a build.gradle file for each module, there is no need for parent the-app/build.gradle file at all. Sure that’s true but we can go another, better way. One file to rule them all Instead of creating many build.gradle config files, one per each module, we can use only the parent’s one and make it a bit more juicy. So let us move the the-app/dao-layer/build.gradle a level up to the-app/build-gradle and fill it with new statements to achieve full project configuration: def langLevel = 1.7 allprojects { apply plugin: 'idea' group = 'com.tamashumi' version = '0.1' } subprojects { apply plugin: 'groovy' sourceCompatibility = langLevel targetCompatibility = langLevel repositories { mavenLocal() mavenCentral() } dependencies { groovy 'org.codehaus.groovy:groovy-all:2.0.5' testCompile 'org.spockframework:spock-core:0.7-groovy-2.0' } } project(':dao-layer') { dependencies { compile 'org.hibernate:hibernate-core:4.1.7.Final' } } project(':domain-model') { dependencies { compile project(':dao-layer') } } project(':web-frontend') { apply plugin: 'war' dependencies { compile project(':domain-model') compile 'org.springframework:spring-webmvc:3.1.2.RELEASE' } } idea { project { jdkName = langLevel languageLevel = langLevel } } At the beginning simple variable langLevel is declared. It’s worth knowing that we can use almost any Groovy code inside build.gradle file, statements like for example if conditions, for/while loops, closures, switch-case, etc… Quite an advantage over inflexible XML, isn’t it? Next the allProjects block. Any configuration placed in it will influence – what a surprise – all projects, so the parent itself and sub-projects (modules). Inside of the block we have the IDE (Intellij Idea) plugin applied which I wrote more about in previous article (look under “IDE Integration” heading). Enough to say that with this plugin applied here, command gradle idea will generate Idea’s project files with modules structure and dependencies. This works really well and plugins for other IDEs are available too. Remaining two lines at this block define group and version for the project, similar as this is done by Maven. After that subProjects block appears. It’s related to all modules but not the parent project. So here the Groovy language plugin is applied, as all modules are assumed to be written in Groovy. Below source and target language level are set. After that come references to standard Maven repositories. At the end of the block dependencies to groovy version and test library – Spock framework. Following blocks, project(‘:module-name’), are responsible for each module configuration. They may be omitted unless allProjects or subProjects configure what’s necessary for a specific module. In the example per module configuration goes as follow: Dao-layer module has dependency to an ORM library – Hibernate Domain-model module relies on dao-layer as a dependency. Keyword project is used here again for a reference to other module. Web-frontend applies ‘war’ plugin which build this module into java web archive. Besides it referes to domain-model module and also use Spring MVC framework dependency. At the end in idea block is basic info for IDE plugin. Those are parameters corresponding to the Idea’s project general settings visible on the following screen shot. jdkName should match the IDE’s SDK name otherwise it has to be set manually under IDE on each Idea’s project files (re)generation with gradle idea command. Is that it? In the matter of simplicity – yes. That’s enough to automate modular application build with custom configuration per module. Not a rocket science, huh? Think about Maven’s XML. It would take more effort to setup the same and still achieve less expressible configuration quite far from user-friendly. Check the online user guide for a lot of configuration possibilities or better download Gradle and see the sample projects. As a tasty bait take a look for this short choice of available plugins: java groovy scala cpp eclipse netbeans ida maven osgi war ear sonar project-report signing and more, 3rd party plugins…

This article is a short how-to about multi-module project setup with usage of the Gradle automation build tool.

Here’s how Rich Seller, a StackOverflow user, describes Gradle:

Gradle promises to hit the sweet spot between Ant and Maven. It uses Ivy’s approach for dependency resolution. It allows for convention over configuration but also includes Ant tasks as first class citizens. It also wisely allows you to use existing Maven/Ivy repositories.

So why would one use yet another JVM build tool such as Gradle? The answer is simple: to avoid frustration involved by Ant or Maven.

Short story

I was fooling around with some fresh proof of concept and needed a build tool. I’m pretty familiar with Maven so created project from an artifact, and opened the build file, pom.xml for further tuning.
I had been using Grails with its own build system (similar to Gradle, btw) already for some time up then, so after quite a time without Maven, I looked on the pom.xml and found it to be really repulsive.

Once again I felt clearly: XML is not for humans.

After quick googling I found Gradle. It was still in beta (0.8 version) back then, but it’s configured with Groovy DSL and that’s what a human likes :)

Where are we

In the time Ant can be met but among IT guerrillas, Maven is still on top and couple of others like for example Ivy conquer for the best position, Gradle smoothly went into its mature age. It’s now available in 1.3 version, released at 20th of November 2012. I’m glad to recommend it to anyone looking for relief from XML configured tools, or for anyone just looking for simple, elastic and powerful build tool.

Lets build

I have already written about basic project structure so I skip this one, reminding only the basic project structure:

<project root>
│
├── build.gradle
└── src
    ├── main
    │   ├── java
    │   └── groovy
    │
    └── test
        ├── java
        └── groovy

Have I just referred myself for the 1st time? Achievement unlocked! ;)

Gradle as most build tools is run from a command line with parameters. The main parameter for Gradle is a ‘task name’, for example we can run a command: gradle build.
There is no ‘create project’ task, so the directory structure has to be created by hand. This isn’t a hassle though.
Java and groovy sub-folders aren’t always mandatory. They depend on what compile plugin is used.

Parent project

Consider an example project ‘the-app’ of three modules, let say:

  1. database communication layer
  2. domain model and services layer
  3. web presentation layer

Our project directory tree will look like:

the-app
│
├── dao-layer
│   └── src
│
├── domain-model
│   └── src
│
├── web-frontend
│   └── src
│
├── build.gradle
└── settings.gradle

the-app itself has no src sub-folder as its purpose is only to contain sub-projects and build configuration. If needed it could’ve been provided with own src though.

To glue modules we need to fill settings.gradle file under the-app directory with a single line of content specifying module names:

include 'dao-layer', 'domain-model', 'web-frontend'

Now the gradle projects command can be executed to obtain such a result:

:projects
------------------------------------------------------------
Root project
------------------------------------------------------------
Root project 'the-app'
+--- Project ':dao-layer'
+--- Project ':domain-model'
\--- Project ':web-frontend'

…so we know that Gradle noticed the modules. However gradle build command won’t run successful yet because build.gradle file is still empty.

Sub project

As in Maven we can create separate build config file per each module. Let say we starting from DAO layer.
Thus we create a new file the-app/dao-layer/build.gradle with a line of basic build info (notice the new build.gradle was created under sub-project directory):

apply plugin: 'java'

This single line of config for any of modules is enough to execute gradle build command under the-app directory with following result:

:dao-layer:compileJava
:dao-layer:processResources UP-TO-DATE
:dao-layer:classes
:dao-layer:jar
:dao-layer:assemble
:dao-layer:compileTestJava UP-TO-DATE
:dao-layer:processTestResources UP-TO-DATE
:dao-layer:testClasses UP-TO-DATE
:dao-layer:test
:dao-layer:check
:dao-layer:build

BUILD SUCCESSFUL

Total time: 3.256 secs

To use Groovy plugin slightly more configuration is needed:

apply plugin: 'groovy'

repositories {
    mavenLocal()
    mavenCentral()
}

dependencies {
    groovy 'org.codehaus.groovy:groovy-all:2.0.5'
}

At lines 3 to 6 Maven repositories are set. At line 9 dependency with groovy library version is specified. Of course plugin as ‘java’, ‘groovy’ and many more can be mixed each other.

If we have settings.gradle file and a build.gradle file for each module, there is no need for parent the-app/build.gradle file at all. Sure that’s true but we can go another, better way.

One file to rule them all

Instead of creating many build.gradle config files, one per each module, we can use only the parent’s one and make it a bit more juicy. So let us move the the-app/dao-layer/build.gradle a level up to the-app/build-gradle and fill it with new statements to achieve full project configuration:

pipeline {
    agent any
    stages {
        stage('Unit Test') {
            steps {
                sh 'mvn clean test'
            }
        }
        stage('Deploy Standalone') {
            steps {
                sh 'mvn deploy -P standalone'
            }
        }
        stage('Deploy AnyPoint') {
            environment {
                ANYPOINT_CREDENTIALS = credentials('anypoint.credentials')
            }
            steps {
                sh 'mvn deploy -P arm -Darm.target.name=local-4.0.0-ee -Danypoint.username=${ANYPOINT_CREDENTIALS_USR}  -Danypoint.password=${ANYPOINT_CREDENTIALS_PSW}'
            }
        }
        stage('Deploy CloudHub') {
            environment {
                ANYPOINT_CREDENTIALS = credentials('anypoint.credentials')
            }
            steps {
                sh 'mvn deploy -P cloudhub -Dmule.version=4.0.0 -Danypoint.username=${ANYPOINT_CREDENTIALS_USR} -Danypoint.password=${ANYPOINT_CREDENTIALS_PSW}'
            }
        }
    }
}

At the beginning simple variable langLevel is declared. It’s worth knowing that we can use almost any Groovy code inside build.gradle file, statements like for example if conditions, for/while loops, closures, switch-case, etc… Quite an advantage over inflexible XML, isn’t it?

Next the allProjects block. Any configuration placed in it will influence – what a surprise – all projects, so the parent itself and sub-projects (modules). Inside of the block we have the IDE (Intellij Idea) plugin applied which I wrote more about in previous article (look under “IDE Integration” heading). Enough to say that with this plugin applied here, command gradle idea will generate Idea’s project files with modules structure and dependencies. This works really well and plugins for other IDEs are available too.
Remaining two lines at this block define group and version for the project, similar as this is done by Maven.

After that subProjects block appears. It’s related to all modules but not the parent project. So here the Groovy language plugin is applied, as all modules are assumed to be written in Groovy.
Below source and target language level are set.
After that come references to standard Maven repositories.
At the end of the block dependencies to groovy version and test library – Spock framework.

Following blocks, project(‘:module-name’), are responsible for each module configuration. They may be omitted unless allProjects or subProjects configure what’s necessary for a specific module. In the example per module configuration goes as follow:

  • Dao-layer module has dependency to an ORM library – Hibernate
  • Domain-model module relies on dao-layer as a dependency. Keyword project is used here again for a reference to other module.
  • Web-frontend applies ‘war’ plugin which build this module into java web archive. Besides it referes to domain-model module and also use Spring MVC framework dependency.

At the end in idea block is basic info for IDE plugin. Those are parameters corresponding to the Idea’s project general settings visible on the following screen shot.

jdkName should match the IDE’s SDK name otherwise it has to be set manually under IDE on each Idea’s project files (re)generation with gradle idea command.

Is that it?

In the matter of simplicity – yes. That’s enough to automate modular application build with custom configuration per module. Not a rocket science, huh? Think about Maven’s XML. It would take more effort to setup the same and still achieve less expressible configuration quite far from user-friendly.

Check the online user guide for a lot of configuration possibilities or better download Gradle and see the sample projects.
As a tasty bait take a look for this short choice of available plugins:

  • java
  • groovy
  • scala
  • cpp
  • eclipse
  • netbeans
  • ida
  • maven
  • osgi
  • war
  • ear
  • sonar
  • project-report
  • signing

and more, 3rd party plugins…

— Previous article

WHUG 8. Beyond Hadoop - checking other options

Next article —

Use XMLs not groovy scripts with db migration plugin!

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Using WsLite in practice

TL;DR

There is a example working GitHub project which covers unit testing and request/response logging when using WsLite.

Why Groovy WsLite ?

I’m a huge fan of Groovy WsLite project for calling SOAP web services. Yes, in a real world you have to deal with those - big companies have huge amount of “legacy” code and are crazy about homogeneous architecture - only SOAP, Java, Oracle, AIX…

But I also never been comfortable with XFire/CXF approach of web service client code generation. I wrote a bit about other posibilites in this post. With JAXB you can also experience some freaky classloading errors - as Tomek described on his blog. In a large commercial project the “the less code the better” principle is significant. And the code generated from XSD could look kinda ugly - especially more complicated structures like sequences, choices, anys etc.

Using WsLite with native Groovy concepts like XmlSlurper could be a great choice. But since it’s a dynamic approach you have to be really careful - write good unit tests and log requests. Below are my few hints for using WsLite in practice.

Unit testing

Suppose you have some invocation of WsLite SOAPClient (original WsLite example):

def getMothersDay(long _year) {
    def response = client.send(SOAPAction: action) {
       body {
           GetMothersDay('xmlns':'http://www.27seconds.com/Holidays/US/Dates/') {
              year(_year)
           }
       }
    }
    response.GetMothersDayResponse.GetMothersDayResult.text()
}

How can the unit test like? My suggestion is to mock SOAPClient and write a simple helper to test that builded XML is correct. Example using great SpockFramework: 

void setup() {
   client = Mock(SOAPClient)
   service.client = client
}

def "should pass year to GetMothersDay and return date"() {
  given:
      def year = 2013
  when:
      def date = service.getMothersDay(year)
  then:
      1 * client.send(_, _) >> { Map params, Closure requestBuilder ->
            Document doc = buildAndParseXml(requestBuilder)
            assertXpathEvaluatesTo("$year", '//ns:GetMothersDay/ns:year', doc)
            return mockResponse(Responses.mothersDay)
      }
      date == "2013-05-12T00:00:00"
}

This uses a real cool feature of Spock - even when you mock the invocation with “any mark” (_), you are able to get actual arguments. So we can build XML that would be passed to SOAPClient's send method and check that specific XPaths are correct:

void setup() {
    engine = XMLUnit.newXpathEngine()
    engine.setNamespaceContext(new SimpleNamespaceContext(namespaces()))
}

protected Document buildAndParseXml(Closure xmlBuilder) {
    def writer = new StringWriter()
    def builder = new MarkupBuilder(writer)
    builder.xml(xmlBuilder)
    return XMLUnit.buildControlDocument(writer.toString())
}

protected void assertXpathEvaluatesTo(String expectedValue,
                                      String xpathExpression, Document doc) throws XpathException {
    Assert.assertEquals(expectedValue,
            engine.evaluate(xpathExpression, doc))
}

protected Map namespaces() {
    return [ns: 'http://www.27seconds.com/Holidays/US/Dates/']
}

The XMLUnit library is used just for XpathEngine, but it is much more powerful for comparing XML documents. The NamespaceContext is needed to use correct prefixes (e.g. ns:GetMothersDay) in your Xpath expressions.

Finally - the mock returns SOAPResponse instance filled with envelope parsed from some constant XML:

protected SOAPResponse mockResponse(String resp) {
    def envelope = new XmlSlurper().parseText(resp)
    new SOAPResponse(envelope: envelope)
}

Request and response logging

The WsLite itself doesn’t use any logging framework. We usually handle it by adding own sendWithLogging method:

private SOAPResponse sendWithLogging(String action, Closure cl) {
    SOAPResponse response = client.send(SOAPAction: action, cl)
    log(response?.httpRequest, response?.httpResponse)
    return response
}

private void log(HTTPRequest request, HTTPResponse response) {
    log.debug("HTTPRequest $request with content:\n${request?.contentAsString}")
    log.debug("HTTPResponse $response with content:\n${response?.contentAsString}")
}

This logs the actual request and response send through SOAPClient. But it logs only when invocation is successful and errors are much more interesting… So here goes withExceptionHandler method:

private SOAPResponse withExceptionHandler(Closure cl) {
    try {
        cl.call()
    } catch (SOAPFaultException soapEx) {
        log(soapEx.httpRequest, soapEx.httpResponse)
        def message = soapEx.hasFault() ? soapEx.fault.text() : soapEx.message
        throw new InfrastructureException(message)
    } catch (HTTPClientException httpEx) {
        log(httpEx.request, httpEx.response)
        throw new InfrastructureException(httpEx.message)
    }
}
def send(String action, Closure cl) {
    withExceptionHandler {
        sendWithLogging(action, cl)
    }
}

XmlSlurper gotchas

Working with XML document with XmlSlurper is generally great fun, but is some cases could introduce some problems. A trivial example is parsing an id with a number to Long value:

def id = Long.valueOf(edit.'@id' as String)

The Attribute class (which edit.'@id' evaluates to) can be converted to String using as operator, but converting to Long requires using valueOf.

The second example is a bit more complicated. Consider following XML fragment:

<edit id="3">
   <params>
      <param value="label1" name="label"/>
      <param value="2" name="param2"/>
   </params>
   <value>123</value>
</edit>
<edit id="6">
   <params>
      <param value="label2" name="label"/>
      <param value="2" name="param2"/>
   </params>
   <value>456</value>
</edit>

We want to find id of edit whose label is label1. The simplest solution seems to be:

def param = doc.edit.params.param.find { it['@value'] == 'label1' }
def edit = params.parent().parent()

But it doesn’t work! The parent method returns multiple edits, not only the one that is parent of given param…

Here’s the correct solution:

doc.edit.find { edit ->
    edit.params.param.find { it['@value'] == 'label1' }
}

Example

The example working project covering those hints could be found on GitHub.