OK, I made the system far more complex than necessary; your comments about the suitability of MagmaCollection made everything clear. It'll work fine now.
Actually, I started this simply enough, in exactly the way you suggested, but using OrderedCollection - and when it didn't work properly I complicated everything instead of simply using a MagmaCollection.
Thanks for your help Chris!
And, of course, thanks for your comments Facu.
Amir
On Mon, 3 Jan 2011 12:33:11 -0600 Chris Muller asqueaker@gmail.com wrote:
I originally thought to create a mailbox for each user in a MagmaPreallocatedDictionary, with the association User -> OrderedCollection (where 'User' is an instance of class 'User', so each item would be unique).
Why are you wanting to use a MagmaPreallocatedDictionary to hold Users? How many users are in the system and how fast do they need access to their list of new messages?
When I pull up my mail client, it takes a couple of seconds for my Inbox to be displayed. This is analagous to using a MagmaCollection for each user's message.
Recall what I said MagmaCollections were designed for: For end-user query requirements, which is exactly the case you've stated: A user comes to check on their messages. So a MagmaCollection is perfectly appropriate for that, not a MagmaPreallocatedDictionary.
I don't know how many users you will have, but given the extremely simple access requirements, you could put htem into a MagmaCollection as well.
So, you have one MC for "AllUsers" and then one MC for each user containing that users messages.
So, checking up on one's own mailbox would simply entail finding oneself's User in the Dictionary and reading the associated collection of messages.
However, if another user were to drop a message into this collection, the same OrderedCollection would have to be accessed by another session. Isn't this a no-no, even with refreshing a session?
I'm wondering what you mean by "the same OrderedCollection". The same one in the database? Or the same one in image memory?
Yes, it will be the same one in the database, but it will be different ones in image memory if they are retrieved by different sessions.
Are you suggesting to use MagmaCollections instead of OrderedCollections? Isn't that far more 'expensive', especially since each user on the system would be assigned such a collection just to hold their messages?
MagmaCollections consume more resources than a OrderedCollection, yes, but the reason I stated was that it would allow multiple messages to come into the same user and avoid a commit-conflict.
- Chris