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7.3. Using an Advanced Externalizer
Using a customized advanced externalizer helps optimize performance in Red Hat JBoss Data Grid.
- Define and implement the
readObject()andwriteObject()methods. - Link externalizers with marshaller classes.
- Register the advanced externalizer.
7.3.1. Implement the Methods
To use advanced externalizers, define and implement the
readObject() and writeObject() methods. The following is a sample definition:
Example 7.2. Define and Implement the Methods
import org.infinispan.commons.marshall.AdvancedExternalizer;
public class Person {
final String name;
final int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public static class PersonExternalizer implements AdvancedExternalizer<Person> {
@Override
public void writeObject(ObjectOutput output, Person person)
throws IOException {
output.writeObject(person.name);
output.writeInt(person.age);
}
@Override
public Person readObject(ObjectInput input)
throws IOException, ClassNotFoundException {
return new Person((String) input.readObject(), input.readInt());
}
@Override
public Set<Class<? extends Person>> getTypeClasses() {
return Util.<Class<? extends Person>>asSet(Person.class);
}
@Override
public Integer getId() {
return 2345;
}
}
}Note
This method does not require annotated user classes. As a result, this method is valid for classes where the source code is not available or cannot be modified.
7.3.2. Link Externalizers with Marshaller Classes
Use an implementation of
getTypeClasses() to discover the classes that this externalizer can marshall and to link the readObject() and writeObject() classes.
The following is a sample implementation:
import org.infinispan.util.Util;
<!-- Additional configuration information here -->
@Override
public Set<Class<? extends ReplicableCommand>> getTypeClasses() {
return Util.asSet(LockControlCommand.class, GetKeyValueCommand.class,
ClusteredGetCommand.class, MultipleRpcCommand.class,
SingleRpcCommand.class, CommitCommand.class,
PrepareCommand.class, RollbackCommand.class,
ClearCommand.class, EvictCommand.class,
InvalidateCommand.class, InvalidateL1Command.class,
PutKeyValueCommand.class, PutMapCommand.class,
RemoveCommand.class, ReplaceCommand.class);
}
In the provided sample, the
ReplicableCommandExternalizer indicates that it can externalize several command types. This sample marshalls all commands that extend the ReplicableCommand interface but the framework only supports class equality comparison so it is not possible to indicate that the classes marshalled are all children of a particular class or interface.
In some cases, the class to be externalized is private and therefore the class instance is not accessible. In such a situation, look up the class with the provided fully qualified class name and pass it back. An example of this is as follows:
@Override
public Set<Class<? extends List>> getTypeClasses() {
return Util.<Class<? extends List>>asSet(
Util.<List>loadClass("java.util.Collections$SingletonList", null));
}7.3.3. Register the Advanced Externalizer (Programmatically)
After the advanced externalizer is set up, register it for use with Red Hat JBoss Data Grid. This registration is done programmatically as follows:
Example 7.3. Registering the Advanced Externalizer Programmatically
GlobalConfigurationBuilder builder = ... builder.serialization() .addAdvancedExternalizer(new Person.PersonExternalizer());
Enter the desired information for the GlobalConfigurationBuilder in the first line.
7.3.4. Register Multiple Externalizers
Alternatively, register multiple advanced externalizers because
GlobalConfiguration.addExternalizer() accepts varargs. Before registering the new externalizers, ensure that their IDs are already defined using the @Marshalls annotation.
Example 7.4. Registering Multiple Externalizers
builder.serialization()
.addAdvancedExternalizer(new Person.PersonExternalizer(),
new Address.AddressExternalizer());