How to build cache mechanism

Question

Hello all
i have application that basically loading very big object that contains sub objects and
doing dynamic lookup by name of the object and the method i like to invoke and then invoke it
everything done ofcorce with reflection .
now this application will be called handeret times per minute .
some questions .
first of all do i need caching mechanism? for saving the subobject that had bean called in some kind of vector in memory for example or if i use reflection , i dont need caching mechanism .
second question is do i need threads here ? if i do , how i buid some kind of locks to this threads ?
thanks

Answer 1

I'd use the Flyweight pattern here. It sounds like you're retrieving a lot of data that's related to other data through some kind of index. A Data Transfer Object (DTO) is a Flyweight class that could hold all of the information required to retrieve the "sub-objects" as you call them, but not until they're needed. It's a little more detailed to make sure that the objects are available when you need them, but obviously the network bandwidth/latency issues are causing a severe performance impact. I'm using EJBs in this example, but it will apply to anything where large amounts of related data are used in the application.
// EJB Entity bean
public abstract class EJBEntity extends EJBObject {
    public abstract Integer getId();
    public abstract String getStringData();
    public abstract Collection getChildObjects(); // "heavyweight" data
// Data Transfer Object
public class EJBEntityDTO {
   private int id;
   private String stringData;
   private int[] childIds;
// some application code
id = ...
EJBEntityDTO dto = transferEJBData(id);
EJBEntityDTO childDTO = transferEJBData(dto.childIds[0]);
...It's definitely more work to do it this way, but it's the only way to avoid fetching the entire collection when you only need one child object.
Brian