Support for ZK custom scopes: "desktop", etc.

[gushakov]

Hello,

Thank you for creating this very useful starter.

In our team we've noticed that, apparently, custom scopes ("desktop", etc.) are not yet supported.

Example:

Declare a converter bean.

@Scope("desktop")
@Component
public class CustomConverter implements Converter<String, String, org.zkoss.zk.ui.Component> {
   // implementation omitted 
}

Register it with a view-model.

<label value="@load('hello world') @converter(vm.customConverter)"/>

Try to use it, there is an exception.

Caused by: java.lang.IllegalStateException: No Scope registered for scope name 'desktop'
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:347) ~[spring-beans-5.0.8.RELEASE.jar:5.0.8.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.8.RELEASE.jar:5.0.8.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1089) ~[spring-context-5.0.8.RELEASE.jar:5.0.8.RELEASE]
	at org.zkoss.spring.init.CoreVariableResolver.resolveVariable(CoreVariableResolver.java:61) ~[zkspring-core-3.2.0.jar:3.0]
	at org.zkoss.zkplus.spring.DelegatingVariableResolver.resolveVariable(DelegatingVariableResolver.java:100) ~[zkplus-8.5.2.1-Eval.jar:8.5.2.1]
	at org.zkoss.xel.util.Evaluators.resolveVariable(Evaluators.java:200) ~[zcommon-8.5.2.1-Eval.jar:8.5.2.1]
	at org.zkoss.zk.ui.impl.PageImpl.getXelVariable(PageImpl.java:648) ~[zk-8.5.2.1-Eval.jar:8.5.2.1]

Workaround

The way we are working around this is to do what the old <zk-config/> XML configuration was doing.

1. For this we specify the dependency for zkspring-core-3.2.0 in our POM.
2. Then use a custom application initializer

public class ZkConfigRegisteringApplicationContextInitializer implements ApplicationContextInitializer<AnnotationConfigServletWebServerApplicationContext> {

    @Override
    public void initialize(AnnotationConfigServletWebServerApplicationContext applicationContext) {
        applicationContext.addBeanFactoryPostProcessor(beanFactory -> {
            // we just need an instance of XmlBeanDefinitionReader configured with this bean factory
            // since the zk-config element is not actually used by ZkConfigDefinitionParser
            final XmlReaderContext xmlReaderContext = new XmlReaderContext(null, null, null, null,
                    new XmlBeanDefinitionReader((BeanDefinitionRegistry) beanFactory), null);
            final ParserContext pc = new ParserContext(xmlReaderContext, null);
            new ZkConfigDefinitionParser().parse(null, pc);
            // custom beans from zk-config are registered at this point
        });
    }
}

3. And finally use the initializer when running our Boot application

@SpringBootApplication
public class ZkBootApplication {

    public static void main(String[] args) {

        new SpringApplicationBuilder(ZkBootApplication.class)
                .initializers(new ZkConfigRegisteringApplicationContextInitializer())
                .run(args);

    }

}

This way we are able to use the beans with the custom scopes.

Question

This does not seem like a long-term solution since it depends on the old dependency zkspring-core. Would you please consider adding support for custom scoped beans.

Thank you,

George

[cor3000]

sorry about the delay ... we were busy with the ZK 8.6.0 release, I'll get back to you soon

[cor3000]

I tested the "old-dependency" zkspring-core:3.2.0 and it still works as before. No workaround was needed on my side. I agree a Java configuration approach would be preferable and we'll consider it when upgrading the dependencies for spring 4/5.

For now spring 4/5 still support XML configuration as before ... (especially for legacy libraries)
The simplest config I came up with was the following:

As you did: add the dependency and exclude the obsolete versions (this should be improved on our side in the next release)

	<dependency>
		<groupId>org.zkoss.zk</groupId>
		<artifactId>zkspring-core</artifactId>
		<version>3.2.0</version>
		<exclusions>
			<exclusion>
				<groupId>org.springframework</groupId>
				<artifactId>spring-beans</artifactId>
			</exclusion>
			<exclusion>
				<groupId>org.springframework</groupId>
				<artifactId>spring-context</artifactId>
			</exclusion>
			<exclusion>
				<groupId>org.springframework</groupId>
				<artifactId>spring-web</artifactId>
			</exclusion>
			<exclusion>
				<groupId>org.reflections</groupId>
				<artifactId>reflections</artifactId>
			</exclusion>
		</exclusions>
	</dependency>

Then create a small XML config file - XML does not bite ;)

e.g. /resources/zkscopes-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	   xmlns:zksp="http://www.zkoss.org/2008/zkspring/core"
	   xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
            http://www.zkoss.org/2008/zkspring/core http://www.zkoss.org/2008/zkspring/core/zkspring-core.xsd">
	<!-- Enables ZK custom scopes for Spring Beans -->
	<zksp:zk-config/>
</beans>

And then import it in the application.

@SpringBootApplication
@Controller
@ImportResource("classpath:zkscopes-config.xml")
public class DemoApplication {
...

When starting spring boot it picks up the config file.

2018-11-14 12:35:24.153 INFO 13272 --- [ main] o.s.b.f.xml.XmlBeanDefinitionReader : Loading XML bean definitions from class path resource [zkscopes-config.xml]

After that I was able to annotate and use beans with @Scope("desktop")

I agree this is quite ugly but still works without any change from the documented usage.

[cor3000]

Also I think a java config options should be provided from zkspring-core before adding a config property to the zkspringboot autoconfig project. I created the FR
ZKSPRING-57 to allow simpler configuration.

[cor3000]

@gushakov which custom zk scopes are you still using... I assume only desktop and maybe application

The others (idspace, page, component, execution) seem obsolete to me
(even application is somewhat redundant as that is already provided by spring anyway)

I am planning to clean up trying to remove deprecated and obsolete configuration classes

[cor3000]

I added a simple version to add the most common ZK scopes webapp/desktop/execution

currently just in a branch 'development'

https://github.com/zkoss/zkspringboot/blob/development/zkspringboot-autoconfig/src/main/java/org/zkoss/zkspringboot/scopes/ZkScopeConfigurer.java

@SpringBootApplication
@Import(ZkScopeConfigurer.class)
public class DemoApplication {

If you needed you can also implement your own CustomScopeConfigurer adding the other scope classes from zkspring-core. Often that's not necessary so I just provided them here.

Would does this work?

[cor3000]

zkspring-core 4.0.0 has been released (compatible with spring 4/5) providing a java config option
https://github.com/zkoss/zkspring/releases (maven)

@Import(ZkScopesConfigurer.class)

see:
https://github.com/zkoss/zkspring/blob/master/zkspringessentials/zkspringcoresec/src/main/java/org/zkoss/zkspringessentials/config/ApplicationConfig.java