[sldev] message_template.msg ordering and packing : attention LLfolks

Adam Frisby adam at gwala.net
Fri Mar 16 00:41:50 PDT 2007


Here's a curious experiment:

1. Use alphabetical ordering on keywords
2. Attach a [8/16-bit?] checksum to each packet, with the checksum 
representing the original msg_template definition for that unique packet.

End result is, we can spot modified versions of each packet and handle 
them appropriately (since getting a collision with so little data that 
is modifyable should be an interesting exercise) with maybe one or two 
"cemented" standard versions that will always be recognised.

It leaves room for screwing around and at the same time allows 
interoperability between different versions of the same packets on the 
same grid/servers at once (if packet type = X and msg checksum = Y then 
do Z)

Adam

John Hurliman wrote:

> Tleiades wrote:
> 
>> I have a hard time accepting this as a bug, I do agree that it really 
>> isn't elegant, and makes things more complicated than it really needs 
>> to be, without any gains.
> 
> 
>> Yes, I agree, it could have been implemented differently, and the 
>> results would be easier to understand, but is it really a bug?
> 
> 
> 
> Since we are down to semantics now, lets replace the word "bug" with 
> "bad" and move on. It would certainly make third party implementations 
> of the networking library easier to write without the hashing and 
> reordering mess, and should make clients more resilient to future 
> changes in the protocol (where adding a single field won't reorder the 
> entire template). If something like alphabetical ordering was used it 
> would significantly change the protocol ordering one time, but this 
> probably isn't much different than a normal protocol-breaking release. 
> Any thoughts?
> 
> John Hurliman
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