[haiku-appserver] Re: communication

  • From: "Stephan Assmus" <superstippi@xxxxxx>
  • To: haiku-appserver@xxxxxxxxxxxxx
  • Date: Sat, 04 Jun 2005 22:38:58 +0200 CEST

Hi DarkWyrm,

> PortLink was the first code that I wrote for Haiku, and not long 
> after 
> then entire project was founded. At that point I only had had about 
> 1.5 
> years of experience writing code. Being I'm self-taught, I didn't 
> have 
> any training in good program design. I originally had intended to use 
> BMessages for all communications, but when Erik said that we needed a 
> messaging class which was as lightweight as possible, I wrote 
> PortLink. 
> A while after Adi came on, he found that we needed to have some 
> message 
> caching on the client side, so the whole PortLink vs Session thing 
> came 
> about. Pahtz eventually resolved it by integrating both classes into 
> something which at least in concept would work well. It's only been 
> since probably last summer that the server has been at a point where 
> stability in the BPortLink class has really been an issue - 
> everything 
> else was so unstable that it was hard to notice. ;D In short, chalk 
> it 
> up to inexperience. It probably sounds like a lame excuse, but it's 
> what happened. :(

No need for _any_ excuses! I'm sorry if I came across like pointing 
fingers or anything. Sometimes, this stuff has to be done in order to 
learn how to do it better. Some problems don't reveal themselves at 
first. So really, there is no problem! All the hard work that has been 
done was necessary, even if some of it gets replaced later.

> AFAICT, the message format is really what is at issue and the reason 
> for all the instability.

Yes, I'm also not against using the port link style messaging. I would 
only like to introduce ways into the implementation that make it very 
error resistent. The app_server design will have to hold up against 
running for at least months straight without a restart. So in the end, 
every part of the server needs to have that level of robustness. In my 
original mail, I just ment to draw some attention to this problem with 
the fragility in the current messaging implementation. I just wanted to 
hear what other like you have to say about this.

Best regards,

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