Return a structure by rpc that contains different objects

Hi,

I need to return all messages associated with each user (UserProfile) to the client side by rpc in one shot. So, I need a structure. The structure may be able to expand easily in the future because I may have the third or forth class to include.

Message | UserProfile

Message and UserProfile are serializable objects, and are retrieved from different tables. The Message and UserProfile are many-to-one, but they are not related explicitly in database. I will use mysql join to put them together.

Class Message

{

long oid,

long acctOid

String messageText

}

Class UserProfile

{

long oid,

long acctOid

String email

....

}

What is the simplest way to implement it?

Thanks