Using Laszlo javarpc approach + Spring Managed beans….

Off late, I am involved in porting some screens of an application built using Wicket + Spring + Hibernate
to Laszlo + Spring + Hibernate. To suggest that I would have been hesitant about it would not be
very far from truth..mainly because I love wicket.

However, as I checked out some sites built using Laszlo , my interest really grew.
In the past few days, I have playing around with javarpc part of Laszlo – since it gives
one the ability to use the service layer developed as is – all that is required is to build
a pojo which will access the service and return a list of java objects for example.

But as I started developing in OpenLaszlo javarpc approach, I thought I hit a dead
end regarding the approach to take to get my spring managed beans.After all that
was critical to invoke the service layer calls.Keep in mind that my remote pojo
was just really an ordinary java object.

The solution occurred when I was discussing this with my lead and it came to light
that Spring 2.0 has a lot of new features like @Configurable approach. However this
simply uses AspectJ under the hood. Also this approach suited me because
as we all know its all about getting beans injected instead of pulling explicitly.

With this in mind, I decided to implement using AspectJ. AspectJ is really powerful.
One is able to write fine-grained expressions to capture joinpoints.

So this is code that I finally got to use to make my javarpc approach working…

The base handler which stores reference to service – this is what needs to get injected…public abstract class BaseRemoteHandler implements Serializable { private IService service; private String serviceNameInContextFile; public IService getService() { return service; } public void setService(IService serive) { this.service = serive; } public abstract String getServiceNameInContextFile() ; public void setServiceNameInContextFile(String serviceNameInContextFile) { this.serviceNameInContextFile = serviceNameInContextFile; } }

This is the ACTUAL remote handler – which laszlo will access public class AttributeRemoteHandler extends BaseRemoteHandler{ public AttributeRemoteHandler() { super(); } @Override public String getServiceNameInContextFile() { return “attributeServiceManager”; // The name of service in the context file used by Spring. } public List getListAtrributes(int start,int count,String column,boolean ascending){ return ((AttributeService)getService()).getSortedAttributes(0, count, column, ascending); } }

Finally THE aspectj ASPECT – which does the magic required …. public aspect ServiceInjector { public pointcut instanceIdentifier(): execution(*.new(..)); before(): instanceIdentifier(){ Object thisobject = thisJoinPoint.getThis(); if(thisobject instanceof BaseRemoteHandler){ BaseRemoteHandler basehandler =((BaseRemoteHandler)thisobject); String managedServiceName = basehandler.getServiceNameInContextFile(); if(managedServiceName == null){ throw new IllegalStateException(“Serive name not implemented in handler “+basehandler.getClass().getName()); } org.springframework.context.ApplicationContext context = ApplicationContextFetcher.getContext(); // ApplicationContextFetcher – My Util class to get ApplicationContext Object service = context.getBean(managedServiceName); basehandler.setService((IService)service); } } }