Non-blocking handler code in ratpack not working

Question

I am trying to follow this blogpost that demonstrates blocking handler in ratpack but I could not get it to work. I am getting missing method exception for background.

My build.gradle file is as below from this GitHub directory

buildscript {
    repositories {
    maven { url "http://oss.jfrog.org/artifactory/repo" }
    jcenter()
  }
  dependencies {
    classpath 'io.ratpack:ratpack-gradle:0.9.4'
  }
}

apply plugin: "ratpack-groovy"
apply plugin: "idea"
apply plugin: "eclipse"

repositories {
  maven { url "http://oss.jfrog.org/artifactory/repo" }
  jcenter()
  maven { url "http://repo.springsource.org/repo" }
  maven { url "https://nexus.codehaus.org/content/repositories/snapshots/" }
}

dependencies {
  springloaded "org.springsource.loaded:springloaded:1.1.5.RELEASE"

  testCompile "org.spockframework:spock-core:0.7-groovy-2.0", {
      exclude module: "groovy-all"
  }
}

// The Groovy that rest-assured drags in via ratpack-groovy-test is toxic, prevent it from coming in
// This should be fixed upstream in Ratpack
configurations.testCompile.dependencies.find { it.name == "ratpack-groovy-test" }.exclude(group: "org.codehaus.groovy")

and handler code is as below.

import static ratpack.groovy.Groovy.ratpack

    ratpack {
        handlers {
            get("non-blocking") {
                background {
                    Thread.sleep(10000)
                }.then{
                    response.send()
                }
            }
        }
    }

I am getting missing method exception for background.

groovy.lang.MissingMethodException: No signature of method: nonBlocking.background() is applicable for argument types: (nonBlocking$_run_closure1$_closure2$_closure3$_closure4) values: [nonBlocking$_run_closure1$_closure2$_closure3$_closure4@497352d0]
    at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:58)
    at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:81)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:52)
    at 

Answer 1

background has since been replaced with Blocking.get

https://ratpack.io/manual/current/api/ratpack/exec/Blocking.html#get-ratpack.func.Factory-

Answer 2

What is Gradle version you use? Keep in mind that this example is already almost 4 years old and it uses old versions of tools like Gradle. If I use for example Gradle 3.5-rc-2 version and do

./gradlew test

it gonna fail with following error:

FAILURE: Build failed with an exception.

* Where:
Build file '/home/wololock/workspace/idea/stackoverflow-answers/46009278/build.gradle' line: 11

* What went wrong:
A problem occurred evaluating root project '46009278'.
> Failed to apply plugin [id 'ratpack-groovy']
   > Could not find method groovy() for arguments [DefaultExternalModuleDependency{group='io.ratpack', name='ratpack-groovy', version='0.9.4', configuration='default'}] on object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

Now if we take a look what Gradle version was used when this example was developed we will find out that it uses Gradle 1.10 according to project's gradle-wrapper.properties file:

#Sun Jul 21 19:00:37 CDT 2013
distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists
distributionUrl=http\://services.gradle.org/distributions/gradle-1.10-bin.zip

If you define same Gradle wrapper version and do:

./gradlew test

or

./gradlew runFatJar

to run application, it should work:

10:39:44: Executing external task 'runFatJar'...
The groovy configuration has been deprecated and is scheduled to be removed in Gradle 2.0. Typically, usages of 'groovy' can simply be replaced with 'compile'. In some cases, it may be necessary to additionally configure the 'groovyClasspath' property of GroovyCompile and Groovydoc tasks.
:compileJava UP-TO-DATE
:compileGroovy UP-TO-DATE
:processResources UP-TO-DATE
:classes UP-TO-DATE
:fatJar
wrz 02, 2017 10:39:48 AM ratpack.server.internal.NettyRatpackServer start
INFO: Ratpack started for http://localhost:5050
:runFatJar
Sat Sep 02 10:40:40 CEST 2017 - received blocking request
Sat Sep 02 10:40:50 CEST 2017 - replying blocking request
Sat Sep 02 10:40:50 CEST 2017 - received non-blocking request
Sat Sep 02 10:41:00 CEST 2017 - replying non-blocking request