There's a neat option in protobuf-net ver 2 called [ProtoMember(2,AsReference=true)]. For the most part, this is a follow up question to:
I started wondering if reference integrity is always maintained irrespective of when serialization / deserialization occurs. Is protobuf-net already doing this when you use the AsReference option?
I threw together a basic code example for illustration purposes, and then thought, "perhaps I need to borrow some ideas from the ORM world?" Should I be implementing an identity map? Should I somehow tell protobuf (via a delegates?) to resolve references to/from foreign key values instead.
The answer I'd like to hear is that somehow protobuf-net can maintain reference integrity across assembly boundaries, even with types that just look like each other.
However, here's an alternative sequence just-in-case:
a => 1. resolve a reference to a primary key int, 2. serialize
b => 3. deserialize, 4. resolve primary key int to a reference
Notes/Constraints:
classes are a mirror image of each other, but are recompiled in each assembly.
the object graph needs to be the same irrespective of when the objects gets serialized. i.e. A.ref=B (serialize / deserialize). C.ref=B (serialize / deserialize).
Example for discussion:
using System;
using System.Collections.Generic;
using ProtoBuf;
namespace protobuf_question
{
class Program
{
static void Main(string[] args)
{
var a = new A() { key = 1 };
var b = new B() { A = a, key = 2 };
}
}
[ProtoContract]
public class A
{
[ProtoMember(1)]
public int key { get; set; }
}
[ProtoContract]
public class B
{
[ProtoMember(1)]
public int key { get; set; }
[ProtoMember(2,AsReference=true)]
public A A { get; set; } // a reference
}
[ProtoContract]
public class IdentityMap<T,TKey>
{
public static readonly IdentityMap<T,TKey> instance = new IdentityMap<T,TKey>(); // singleton
private Dictionary<string, T> identitySpace { get; set; }
public IEnumerable<string> GetIdentitySet (/* some criteria */)
{
// used for serializing with reference safety between assemblies.
throw new NotImplementedException();
}
public TKey GetKey(T reference)
{
// map object reference to identity map; return identity.
throw new KeyNotFoundException();
}
}
}
