In Wcf REST, is it better to return larger models with less requests, or smaller models with more requests

Question

I have an SOA app, and have started to run into some performance issues.

I have models coming OUT of REST that look similar to...

public class Person
{
    public Guid Id { get; set; } 
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public Address Address { get; set; }
    public IEnumerable<Hobby> Hobbies { get; set; }
    public IEnumerable<Interests> Interests { get; set; }
    public IEnumerable<Friends> Friends { get; set; }
}

This turns into a pretty large model pretty quickly when it is being returned via REST with all of those fields populated.

So, my basic question is...Is it better to transfer large models such as above, and use FEWER Rest calls, or transfer smaller objects and use more Rest calls to retrieve the other pieces of data. I.E. have a model like this...

public class Person
{
    public Guid Id { get; set; } 
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public AddressId AddressId { get; set; }
    public IEnumerable<Guid> Hobbies { get; set; }
    public IEnumerable<Guid> Interests { get; set; }
    public IEnumerable<Guid> Friends { get; set; }
}

And now go an grab the other properties as needed...

Thoughts?

I'm curious - what are your performance problems? Is it taking too long to construct the response, or is the problem with the size of the response taking too long to transfer? Also, is `Friends` a collection of `Person`? — Jeff Ogata, Nov 21 '11 at 16:48
I did a test with retrieving 500 "Persons" and the page took quite a while to return (12s+). And more even than the performance issues, I just want to architect the thing in a smart way... :) — jcreamer898, Nov 21 '11 at 16:49

score 4 · Accepted Answer · answered Nov 21 '11 at 16:32

Personally, I prefer a lighter object be returned. I could elaborate as to why, but this article does a pretty good job of doing it for me:

http://davybrion.com/blog/2010/05/why-you-shouldnt-expose-your-entities-through-your-services/

Now, in your case, you can return lists inside of your objects, and then have REST calls that will accept a list of IDs (in your case Guids) and then returns a list of objects, themselves being lightweight. This would give you the best of both worlds - lighter objects and a reduced number of REST calls.

score 1 · Answer 2 · answered Nov 21 '11 at 16:49

General wisdom for rpc calls is to make them chunkier, but like everythign else it all depends on your sitiuation. IMO you should try to make it as chunkier as possible, without pulling too much data :-) so if you have a ui or something, you should focus on user tasks, instead of data, and see which tasks is user going to do on that ui, and how much data does it need. You should them have dtos that are task related, and pull those dtos explicitly, but the bottom line being that DTOs are task related, and business model lives on the server ( which is more business related).

In Wcf REST, is it better to return larger models with less requests, or smaller models with more requests

2 Answers2