How to read registry items inside a Class Mediator in WSO2 EI

Question

How can we read registry items inside a Class Mediator? We have 100+ proxy services that use a class mediator, and to access a property from a registry, we have to add a property mediator before our class mediator to each proxy service, like this:

<-- load the property via the Property Mediator -->
<property expression="get-property('registry','conf:someProp')" name="SOME_PROP" scope="default" type="STRING"/>

<-- then we access the "SOME_PROP" by using MessageContext#getProperty()
<class name="com.example.project.mediators.SomeMediator"/>

This would be difficult to maintain. Is there a better way?

Answer 1

This is how the get-property function does this, you can replicate this in the class mediator.

String[] regParam = key.split("@");
String regPath = null;
String propName = null;
if (regParam.length == 2) {
    regPath = regParam[0];
    propName = regParam[1];
} else if (regParam.length == 1) {
    regPath = regParam[0];
}

Entry propEntry = synCtx.getConfiguration().getEntryDefinition(regPath);
if (propEntry == null) {
    propEntry = new Entry();
    propEntry.setType(Entry.REMOTE_ENTRY);
    propEntry.setKey(key);
}
Registry registry = synCtx.getConfiguration().getRegistry();
if (registry != null) {
    registry.getResource(propEntry, new Properties());
    if (propName != null) {
        Properties reqProperties = propEntry.getEntryProperties();
        if (reqProperties != null) {
            if (reqProperties.get(propName) != null) {
                return reqProperties.getProperty(propName);
            }
        }
    } else if (propEntry.getValue() != null) {
        if (propEntry.getValue() instanceof OMText) {
            return ((OMText) propEntry.getValue()).getText();
        }
        return propEntry.getValue().toString();
    }
}