Subject: Re: OT: XML Server dream From: Eric van der Vlist <vdv@xxxxxxxxxxxx> Date: Sun, 24 Oct 1999 16:33:25 +0200 |
Hi Stefano, Stefano Mazzocchi wrote: > > Eric van der Vlist wrote: > > > > Hi, > > > > I have been playing with XSL for a couple of months now. > > > > I store an increasing volume of information in XML files which are > > formatted into HTML through XSL-T and can be edited either with a text > > editor or using php scripts. > > > > The benefit is obvious and I will continue on this path. > > > > However, I am losing some of the benefits I had using a RDBMS > > (PostgreSQL) and I wonder if it wouldn't be possible to combine XML/XSL > > with a server approach. > > Many people are concerned about how to combine legacy stuff with the new > XML/XSL model. This is a key issue for XML wep publishing and clearly > understood. Nice to know I am not the only one :=) ! It's not only what I meant : for me it's not only a matter of combining legacy stuff (personally I have started my company less than 1 year ago and I don't have that much legacy :=)) I am afraid of increasing the amount of XML data since I do not know how I'll manage all these files and I don't know either how I'll manage files which DOMs do not fit in memory. I have been working during 6 for a RDBMS vendor and it may be why I tend to like servers ;=) , but I'd like to be able to rely on a server to handle this kind of issues. It may not be a complete physical server but some glue between other projects and products, but I'd like to have "something" on which to rely to manage my XML information as I used to rely on a RDBMS to manage by SQL information... > > By server, I mean a process which would store XML documents not I shouldn't have say "process" here... > > necessarily in their text format, cache a domlike structure and manage > > all the concurrency issues (yes, I mean transactional XML...). > > I think you're saying too many things at once. > > 1) persistent storing methodology > 2) concurrency issues. > > I don't have to rethink the "ACID" properties of transactions: all good > DBMS implement them. No need to reinvent the wheel. No, but we need ACID properties on part of XML trees if we want to update them in a transactional way. > What you need is a powerful way to combine your existing DBMS with your > XML publishing framework and yes, a smarter way would be to store a > "serialized" version of your classes to "compile" XML parsing in the > serialized memory structure (and all you need is a serializable DOM > implementation a little JDBC glue logic and a well known database > schema) If it be done by adding some glue, let's do it ! > > This server should be capable to process queries written in XSL-T, but > > also to process update statements (maybe as XSL extensions) and > > administration commands. > > ? what for? Do you want to manage your database with XSLT commands? > weird idea... databases already have their tools for management. Is it so weird ? How do you manage complex or huge XML documents ? How, for instance, do you update a node in such a document like an ODP (http://dmoz.org) RDF dump ? > > It would be for XML data and XSL processing, what RDBMS are for > > relational data and SQL. > > I think you might end up loosing focus: you should try to use what's > available and find useful ways to combine them. It's easier to code, > faster to get out, easier to users to use (since this doesn't impact > their systems). My goal is on the contrary to define a features list and to search which products can be used to meet this list. > > I have done some research on the web and I have found many documents > > about "XML servers", but none of them seems to match with what I mean. > > > > Is my dream stupid or not feasible ? > > Not stupid, a smart one. Feasible? sure, almost anything is, even > starting an operating system from scratch and get much of the UNIX > market :) Or building a Java publishing framework in less than one year :) > The question is: do you really want to do it? I don't know yet ;=) I'd like first to see the "state of the art"... and to share the effort and the result of my researches. > > If not, are you aware of any Open Source project going in this direction > > ? > > The new release of Cocoon (due early next week) has a new Processor that > expands XML tags into their data meaning. An example for this will make > things clearer. You write the following page (that of course, you keep > well protected or use external entities to include your passwords) > > <?xml version="1.0"?> > <page> > <connectiondefs> > <connection name="foo_connection"> > <driver>org.gjt.mm.mysql.Driver</driver> > <dburl>jdbc:mysql://mysql.example.com/foo_database</dburl> > <username>foo_user</username> > <password>foo_password</password> > </connection> > </connectiondefs> > > <query connection="foo_connection"> > select name,number,message from foo_table order by name > </query> > </page> > > and the processors transforms it into something like > > <?xml version="1.0"?> > <page> > <result-set> > <tuple id="0"> > <name>Donald Ball</name> > <number>23</number> > <message>The Illuminati do not exist. This message paid for by the > Illuminati.</message> > </tuple> > ... other tuples ... > </result-set> > </page> > > the result tag set can be defined to match your exisings stylesheets or > your DTD preferences. (The DTD used in the SQLProcessor is compatible > with the Oracle XSQL Servlet which implements the exact same design > pattern) > > This is (IMO) a great way to "glue" RDBMS and XML web publishing. I agree. > Another component that is being created will be able to store XML in a > parsed-serialized state in DMBS as BLOB or text (depending on databases > used). This won't be available in Cocoon 1.5 as it's being worked on but > will probably in Cocoon 1.6. It will probably coupled by a file-upload > tool that will perform XML validation and database insertion. Any help > on this will be very appreciated. It looks like a big piece of what I have called XML Server. > So, to sum up, I don't see the need for an XML server. I see the need > for logic glue between existing database systems and XML publishing > systems. > > The Cocoon Project is already covering part of that ground and will > follow that path in the future. I was expecting an answer like this one and that's why I had also posted my "dream" on the Cocoon list. It's definitely a direction to evaluate. I have played with Cocoon (1.3) for a while and the only point which has disappointed me (but it may be the way I was using it) was performance. I have never been able to get under 800 ms for the generation of simple page on my test server. This test server is only a small machine (Intel i586 150 MHz, 64 M RAM), but with plain HTML Apache is incredibly fast. > Needless to say, any contribution (either with code, ideas, bugfixes or > anything) will be of great help and much appreciated. It would be sad to > have more and more projects going to cover up the same ground. I agree. > Quoting something I read somewhere :) ... > > "E Pluribus Unum" > > Take care. Thanks for your feedback. Eric XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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