Обсуждение: Re: [HACKERS] Re: XML (was: 2 patches)
The Hermit Hacker wrote: > On Sat, 2 Jan 1999, Goran Thyni wrote: > > Bruce Momjian wrote: > > > I vote against it. Maybe nice to have as an extra, but the base > > > protocol seems to work well, and is fast. > > > > You are right, > > let me rephrase myself: > > - the "base protocol" might become obsolite if and when we have > > a better object base alternative (CORBA and/or XML). > > - this might be the case for v. 7.0 or later. > > Okay, we have to sides to the coin here...Bruce, who feels that our > current protocol is both good and fast, and you, who wants to replace it > :) > > My question is simple...what benefit is gained by replacing current > protocol? And, what cons? > > Replacing something is great, if there is a reason...what is that reason > and how does that improve us? Marc, The pros, IMHO: * XML interfaces better to the object model of pgsql itself * XML interfaces better to XML-viewer, like next generation of web browsers. With a little imagination we can at some point in the future forget about making clients for the databases, just point your webbrowser at the serverport a make both SELECTs (displays) and INSERT/UPDATE (forms) with a few lines of javascript. The con: * We have a good stable protocol but a little simplistic. Anything new is not as good until it has matured. Thus I not suggesting replacing it until we have something better, sound resonable? mvh, -- ----------------- Göran Thyni This is Penguin Country. On a quiet night you can hear Windows NT reboot!
> The pros, IMHO: > * XML interfaces better to the object model of pgsql itself > * XML interfaces better to XML-viewer, like next generation of > web browsers. > > With a little imagination we can at some point in the future forget > about making clients for the databases, just point your webbrowser > at the serverport a make both SELECTs (displays) and INSERT/UPDATE > (forms) with a few lines of javascript. > > The con: > * We have a good stable protocol but a little simplistic. > Anything new is not as good until it has matured. > > Thus I not suggesting replacing it until we have something > better, sound resonable? It is appealing to be able to talk to the database via some sgml/html/xml format. A proxy would allow this too, and it certainly something that would be nice. Certainly no reason we can't add it, and if we start out as a proxy, we don't have to add it to the backend itself. -- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610) 853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania19026
On Fri, 1 Jan 1999, Bruce Momjian wrote:
> > The pros, IMHO:
> > * XML interfaces better to the object model of pgsql itself
> > * XML interfaces better to XML-viewer, like next generation of
> > web browsers.
> >
> > With a little imagination we can at some point in the future forget
> > about making clients for the databases, just point your webbrowser
> > at the serverport a make both SELECTs (displays) and INSERT/UPDATE
> > (forms) with a few lines of javascript.
> >
> > The con:
> > * We have a good stable protocol but a little simplistic.
> > Anything new is not as good until it has matured.
> >
> > Thus I not suggesting replacing it until we have something
> > better, sound resonable?
>
> It is appealing to be able to talk to the database via some
> sgml/html/xml format. A proxy would allow this too, and it certainly
> something that would be nice. Certainly no reason we can't add it, and
> if we start out as a proxy, we don't have to add it to the backend
> itself.
And, of course, as it matures, its something we can always roll
into the backend :)
Marc G. Fournier
Systems Administrator @ hub.org
primary: scrappy@hub.org secondary: scrappy@{freebsd|postgresql}.org
Goran Thyni <goran@kirra.net> writes:
> The pros, IMHO:
> * XML interfaces better to the object model of pgsql itself
CORBA does that as well or better, I suspect.
> * XML interfaces better to XML-viewer, like next generation of
> web browsers.
So? I can't get excited about being able to view raw server output in
a web browser --- it seems to me that any interesting web application
of Postgres is going to involve an intermediate layer of code anyway
(to convert client actions into SQL commands, adorn the output with page
headers and buttons and so forth, etc etc). I don't see anything about
XML that eliminates the need for that intermediate layer, and I don't
see much about XML that makes that layer easier to write.
> With a little imagination we can at some point in the future forget
> about making clients for the databases, just point your webbrowser
> at the serverport a make both SELECTs (displays) and INSERT/UPDATE
> (forms) with a few lines of javascript.
I think you drastically underestimate the amount of glue code that will
be needed, and overestimate the advantage of having the results come
back already formatted in an HTML-like fashion. (OK, it'd make direct
display a little easier, but what if you have to extract some data for
processing? Writing an XML parser in Javascript doesn't sound like a
piece of cake to me.)
If XML had big benefits for non-web-browser front ends, it might still
be a win, but I'm not seeing anything much there either.
It should also be pointed out that XML isn't a *protocol*, just a
data representation. If you choose to represent the results of SELECTs
in XML, that still leaves you with all the other aspects of FE/BE
communication yet to be designed.
I thought the proposal to build a CORBA-based interface for Postgres
was pretty interesting and worthy of further study ... I'd rather see
us put our time into that. (I am certainly not wedded to the current
FE/BE protocol; it gets the job done, but it's crufty and has
performance limitations.)
regards, tom lane
Tom Lane wrote: > > Goran Thyni <goran@kirra.net> writes: > > The pros, IMHO: > > * XML interfaces better to the object model of pgsql itself > > CORBA does that as well or better, I suspect. > > > * XML interfaces better to XML-viewer, like next generation of > > web browsers. > > So? I can't get excited about being able to view raw server output in > a web browser --- it seems to me that any interesting web application > of Postgres is going to involve an intermediate layer of code anyway > (to convert client actions into SQL commands, adorn the output with page > headers and buttons and so forth, etc etc). I don't see anything about > XML that eliminates the need for that intermediate layer, and I don't > see much about XML that makes that layer easier to write. This is what DOM is for, read on. > > With a little imagination we can at some point in the future forget > > about making clients for the databases, just point your webbrowser > > at the serverport a make both SELECTs (displays) and INSERT/UPDATE > > (forms) with a few lines of javascript. > > I think you drastically underestimate the amount of glue code that will > be needed, and overestimate the advantage of having the results come > back already formatted in an HTML-like fashion. (OK, it'd make direct > display a little easier, but what if you have to extract some data for > processing? Writing an XML parser in Javascript doesn't sound like a > piece of cake to me.) The XML parser is in the browser. It parses to XML-code into a DOM which is easily accessed from javascript. The step are: 1/ a DTD defines the parsing of our document type into the DOM 2/ a style sheet determines the layout on our output device 3/ javascript access to the DOM for making tweak to layout and functions. The client side is still immature and some parts are in still flux. > If XML had big benefits for non-web-browser front ends, it might still > be a win, but I'm not seeing anything much there either. This is a chicken-egg problem, we must have data to make clients interesting and we must have clients to make server output interesting CORBA has the same problem, we must start somewhere. As I am a "server-side kind of guy", I will start there and hope clients catch up. On the client side I put most faith in "Gecko" the new layout engine from mozilla.org. > It should also be pointed out that XML isn't a *protocol*, just a > data representation. If you choose to represent the results of SELECTs > in XML, that still leaves you with all the other aspects of FE/BE > communication yet to be designed. HTTP and/or IIOP/CORBA is useable for that. > I thought the proposal to build a CORBA-based interface for Postgres > was pretty interesting and worthy of further study ... I'd rather see > us put our time into that. One does not rule out the other, I think that much of the object functionality of both ideas has much in common with seperate output mechanisms, like: ---------------------------------------| PgSQL Core | ---------------------------------------| Object Data Access | Base |---------------------------- || CORBA | XML | protocol |---------------------------------------| Clients | --------------------------------------- Anyway, thanks for your input Tom. Questioning my ideas, forces me to develop them and fill in the blanks, which is "good thing(tm)". Keep arguments, ideas and questions coming! mvh, -- ----------------- Göran Thyni This is Penguin Country. On a quiet night you can hear Windows NT reboot!