DDevelopment & Design

Classloader problem with Java 7 and WebServices in Grails

Our Grails 2.1 application communicates with external SOAP WebServices. It worked fine as we follow Software Guy’s advices from this blog post. Recently, our client required new functionality – export to Excel. We’ve used Apache POI libraries for expor…

Our Grails 2.1 application communicates with external SOAP WebServices. It worked fine as we follow Software Guy’s advices from this blog post.

Recently, our client required new functionality – export to Excel. We’ve used Apache POI libraries for export. And our web service communication died. All it gave us was:

Caused by: java.lang.LinkageError: loader constraint violation: when resolving field "DATETIME" the class loader (instance of org/codehaus/groovy/grails/cli/support/GrailsRootLoader) of the referring class, javax/xml/datatype/DatatypeConstants, and the class loader (instance of <bootloader>) for the field's resolved type, ants, have different Class objects for that type</bootloader>

This message is strange, LinkageError can give you creeps. But read carefully: resolved type, ants? Something is definitely wrong here. After many searches it turned out that Java 7 already contains some conflicting classes from stax-api.jar. To solve this problem there are two thing you need to do:

  1. Ensure that your jaxws-rt dependency is runtime, not compile! // http://asoftwareguy.com/2012/02/25/web-service-clients-where-grails-lost-its-mojo/
    // Do not remove this dependency. Web services need this to work flawlessly.
    runtime (‘com.sun.xml.ws:jaxws-rt:2.1.4’)
  2. Create dependency report (grails dependency-report), search and exclude all stax-api dependencies other than jaxws-rt like this example: 
    compile ('org.apache.poi:poi-ooxml-3.7') {
    excludes 'stax-api'
}
compile ('org.apache.poi:poi-ooxml-schemas:3.7') {
    excludes 'stax-api'
}

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Grails with Spock unit test + IntelliJ IDEA = No thread-bound request found

During my work with Grails project using Spock test in IntelliJ IDEA I've encountered this error:

java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
 at org.springframework.web.context.request.RequestContextHolder.currentRequestAttributes(RequestContextHolder.java:131)
 at org.codehaus.groovy.grails.plugins.web.api.CommonWebApi.currentRequestAttributes(CommonWebApi.java:205)
 at org.codehaus.groovy.grails.plugins.web.api.CommonWebApi.getParams(CommonWebApi.java:65)
... // and few more lines of stacktrace ;)

It occurred when I tried to debug one of test from IDEA level. What is interesting, this error does not happen when I'm running all test using grails test-app for instance.

So what was the issue? With little of reading and tip from Tomek Kalkosiński (http://refaktor.blogspot.com/) it turned out that our test was missing @TestFor annotation and adding it solved all problems.

This annotation, according to Grails docs (link), indicates Spock what class is being tested and implicitly creates field with given type in test class. It is somehow strange as problematic test had explicitly and "manually" created field with proper controller type. Maybe there is a problem with mocking servlet requests?