Re: Creating db front end or middleware.

tobiah wrote:
Let's say I want to write a new tool to do
something to, or report on people in a database.
Each tool is going to have to have all sorts of
routines that know about the relationship between
the data. The first thought is to write a library
of routines that do things like, change_address(),
or fire_employee() or whatever.
Whoops, now we've decided to move to python. I
have to write all of that again.

So I thought, shouldn't there be a cloud that sits
in front of the database to which I can ask these
services of? Some process that awaits requests for
information, or handles new incoming data. Now new
apps written in any language should be able to use a basic protocol in
order to get the work done.

The question then, is what the best way to do this is.

The first question then is: do you really need a middleware ? Most
RDBMSs are already full-blown server applications - with support for
authentification, permissions, triggers and stored procedures - that can
be accessed by client programs in almost any language.

Now if you effectively want/need a web service, it seems that the
canonical solutions are XMLRPC and SOAP. But if you already use a RDBMS,
this web service should IMHO mostly be designed as an higher-level
interface to the RDBMS, not as a full-blown app managing domain/business
rules (which is the job of the RDBMS). IOW, it should be still possible
for applications to directly interact with the RDBMS.

First I thought of using cherrypy to sit and listen to
POST requests, but this would make passing complex structures
extremely inconvenient.

There are XMLRPC packages for most languages, that knows how to do the
native data structure <-> XMLRPC translation. Python has both client and
server packages in the standard lib.

Then I thought about WSDL.
Would this be the next logical step, or is this more for
allowing different companies to communicate with each other
when there needs to be a broadcast description of the interface?

As the name implies, W(eb) S(ervice) D(escription) L(anguage) is meant
to describe a given web service - and says nothing about implementation.

My 2 cents
--
bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in 'onurb@xxxxxxxxxxx'.split('@')])"
.

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