<lang:groovy> tag in version 2.5 and higher doesn't work for refreshable Spring MVC endpoints [SPR-10689]

[spring-projects-issues]

Dhaval Powar opened SPR-10689 and commented

THIS BUG LIES IN SPRING 2.5 AND HIGHER

---

Dynamic language support is added to Spring by using the <lang:> namespace.
For eg. for a groovy script, the following xml should handle dynamic language support in Spring.

<lang:groovy id="refreshableMessenger" 
    script-source="classpath:org/fw/scripting/groovy/Messenger.groovy"> 
    <lang:property name="message" value="Hello World!"/> 
</lang:groovy>

How this functions under the hood is:

1. The <lang:groovy> instantiates the LangNamespaceHandler class which parses the xml and identifies the type of dynamic language ie. groovy, JRuby or BSH.

2. LangNamespaceHandler then calls the registerScriptBeanDefinitionParser method which in turn, makes a call to registerBeanDefinitionParser to register the bean. The call to this method instantiates a ScriptBeanDefinitionParser object which does the following:

a. Resolve the script source
b. Set up infrastructure
c. Create script factory bean definition
d. and many more other specific functionalities....

In step (b.), to setup the architecture, the LangNamespaceUtils class sets up the scriptFactoryPostProcessor object. This object handles ScriptFactory definitions, replacing each factory with the actual scripted Java object generated by it.

The bug lies in the LangNamespaceUtils class due to an invalid variable initialization.

This class contains a variable name

SCRIPT_FACTORY_POST_PROCESSOR_BEAN_NAME="org.springframework.scripting.config.ScriptFactoryPostProcessor"

The value of this variable is invalid because the full qualified name of the ScriptFactoryPostProcessor class is org.springframework.scripting.support.ScriptFactoryPostProcessor.

This means that ScriptFactoryPostProcessor lies in the package org.springframework.scripting.support and NOT org.springframework.scripting.config. Due to this the ScriptFactoryPostProcessor bean does not get instantiated and the dynamic language support does not work.

However, this issue did not exist in Spring 2.0 & earlier since the <lang:grovy> xml namespace and tag were handled in a different way. Please fix the bug.

---

Affects: 3.1.2

Reference URL: http://grepcode.com/file/repo1.maven.org/maven2/org.springframework/spring-context/2.5/org/springframework/scripting/config/LangNamespaceUtils.java?av=f

Attachments:

• LangNamespaceUtils.java (2.25 kB)
• scripting.zip (34.00 kB)

Issue Links:

• Annotated Groovy controllers don't work properly [SPR-6268] #10935 Annotated Groovy controllers don't work properly

3 votes, 5 watchers

[spring-projects-issues]

Phil Webb commented

The SCRIPT_FACTORY_POST_PROCESSOR_BEAN_NAME provides the bean name of the ScriptFactoryPostProcessor, not the actual bean class. It is prefixed with org.springframework.scripting.config because that is the package where LangNamespaceUtils resides. If you looks at line 52 you should see that the bean class is org.springframework.scripting.support.ScriptFactoryPostProcessor.

There are also some tests that should verify <lang:groovy> support.

Are you experiencing an actual problem with the tag? Would you be able to submit a issue project that can reproduce your problem?

[spring-projects-issues]

Dhaval Powar commented

Hi Phil,

Thanks for the quick reply. Yes, sorry, I seem to have missed that. You are right as far as the definition of the LangNamespaceUtils class. But this does not reflect well when it comes to processing the groovy script dynamically at runtime using the <lang:groovy> tag.

I am currently developing a Web application which makes RESTful calls using Spring annotations such as @RequestMapping etc.
So I am using groovy scripts which contains methods to which URLs are mapped using the Spring annotations. Now, I want to dynamically load the groovy scripts at runtime. The main reason of using groovy with spring is to implement HOT DEPLOYMENT. Having this, I can make changes to my groovy scripts while the server is running, and the changes will be caught at runtime and the script will be recompiled and reloaded without restarting the server.

So I first tried to use the lang:groovy notation in the applicationContext.xml but my scripts just do not get loaded at runtime and the URLs are not mapped to the respective handler methods.

However, then I created beans for the actual classes which makes load the groovy scripts, namely, org.springframework.scripting.support.ScriptFactoryPostProcessor and org.springframework.scripting.groovy.GroovyScriptFactory.

So I implemented the following beans..

<bean class="org.springframework.scripting.support.ScriptFactoryPostProcessor" />

<bean id ="User" class="org.springframework.scripting.groovy.GroovyScriptFactory">
     <constructor-arg value="classpath:controller/UserController.groovy" />
</bean>

And with this definition, these beans do load the groovy scripts at runtime and the URLs are mapped to their respective handler methods. But using this definition, I am unable to implement the 'dynamic bean refresh' functionality. This can be done easily using the refresh-check-delay attribute in the lang:groovy tag.
I have provided detailed explanation of the problem at the following link. Please have a look and let me know as it has been almost a month that I am trying to get the dynamic functionality working.

http://stackoverflow.com/questions/17286333/spring-rest-application-with-hot-deployment-groovy-script-does-not-load-dynamic

[spring-projects-issues]

Seamus McMorrow commented

Is this something that is being worked on, or any update on it?

[spring-projects-issues]

Juergen Hoeller commented

Does this refer to the same scenario as #10935? In that case, setting proxy-target-class="true" on your lang:groovy tag should help...

Otherwise, target class annotations will not get exposed through the proxy and therefore not discovered by the MVC DispatcherServlet.

Juergen

[spring-projects-issues]

venkata narayana commented

Any update on this as I am holding off upgrading my Spring version from 2.5.6 (this feature works on this version) to the latest and Java from 1.7 to 1.8. 

I recently tested on 5.0.8.RELEASE and no luck. I tried all the attribute combinations as per the doc:(

<lang:groovy id="nnService" script-source="classpath:com/vnn/apps/reload/ServiceImpl.groovy" scope="prototype" proxy-target-class="true" refresh-check-delay="1000"/>

 

 

 

 

[spring-projects-issues]

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