> -------- Original Message -------- > Subject: Re: [sqlite] uSQLiteServer Source code available > From: John Stanton <[EMAIL PROTECTED]> > Date: Mon, November 14, 2005 9:47 pm > To: sqlite-users@sqlite.org > > [EMAIL PROTECTED] wrote: > >>I like your concept and agree with your design choices, so much in fact > >>that I independently implemented a very similar system. In my case I > >>packaged the responses in XML, > > > > > > Difficult isn't it, XML or no XML :-) I had also considered XML, if > > nothing else it is the 'in thing'. But the other side of the coin is > > that if your XML replies do not comply to a recognised dictionary, the > > only advantage is that ready made parsers are available. > > > > Apart from the horrendous overhead of XML, it is not necessarily easier > > to incorporate a ready made but complex library than it is to implement > > a very simple parser from scratch. But when I factored in the > > possibilities of connecting from environments like PLC's and scripting > > environments where an XML parser is not necessarily available it became > > a no brainer. My underlying philosophy was KISS, and perhaps a better > > name for the techfell protocol (which is historic and pre dates > > uSQLite) would be SPP, Simplest Possible Protocol. > > > > > >>parser for flexibility. Even with the added overhead it is fast enough > >>to get comments from users. Don't be discouraged. > > > > > > You mean it was allready available? > > > I wrote it. I used XML in the end because it can map a complex data > structure into a single document. In that case what you lose on the > swings (XML) you gain on the roundabouts (TCP/IP), particularly if you > use HTTP for transport. At the client end it requires a rather complex > parser, a mindless overhead for an embedded system but no sweat for a > modern PC. I use a client parser based around a transformed DTD driving > our old friend "expat".
I wish I had seen this before I started. Of course parsing the XML would be a very heavy task if you have to roll your on client, so it would not have fullt satisfied my criteria. Also, as I generally don't use HTTP (I deal with industrial systems which tend to be closed to the internet) perhaps I would have more to lose than gain. So perhaps it is a good thing I did not see it, or I might have taken th 'lazy way out'. But what I have been thinking is what about merging the technology, you send a #PPRAGMA XML and wham, you get an XML reply. I know little about the details of implementing XML, and nothing about using it over http, so I don't know how feasible this would actually be. It would be possible to have the #PPRAGMA XML command as the first string sent to the server.....but how do you send commands? If they can just be sent as query string as on uSQLite then it would be easy. When switching to XML mode you would supply a different callback function to the sqlite3_exec command and that would generate XML replies. Presumably it would also be necessary to modify the :Err and :OK replies as well, but that is no big deal. That would make it possible to put the XML capability in a conditional compile (allthougth I expect the **generation** does not take up that much space anyway). > A general comment. KISS, or Occam's Razor for us diplomats, is sadly I thought it was philosophers who reffered to Occams razor? OTOH using the term Occam's razor instead of KISS would seem to be a contradiction in terms ;-) Then again, perhaps not......I would like to think that keeping it simple is synonymous with 'refined' and 'elegant', not 'crude' and 'coarse'.
