[mythtv] Protocol negotiation?

[Paul Bender]

Geoffrey Kruse wrote:
> 
> On Sep 29, 2006, at 11:53 AM, Paul Bender wrote:
> 
>> Michael Tiller wrote:
>>
>>  From experience, I can tell you that it is often a lot of effort to
>> make sure that older protocol versions still work when you extend or
>> replace protocols. I would much rather MythTV developers spend time  move
>> things forward than looking back.
>>
> I think it could be done quite simply...
> The myth protocol is basically a series of strings separated by a  token 
> ([[::]] if I remember correctly).  Why not just add the  protocol 
> version of each token to the separator ( [[::30::]]Some Data 
> [[::31::]]New Data ...)  That way, the parser just simply throws out  
> any tokens that have a number higher than it understands in the  
> separator.  I think this would be fairly straight forward to  
> implement.  Of course, there would have to be tolerance for missing  
> fields if a newer version of the protocol were to remove elements,  but 
> this also should be trivial.  Since the myth protocol is already  very 
> string heavy and not very efficient, I think adding a few  characters to 
> each separator would not be much of a performance hit.

The easy part is making the over-the-wire protocol extensible. The hard 
part is making sure the software for the older protocol versions works 
after modifying the software to add the newer protocol.