RE: DB Alternatives to DODS

Hi David,

We _don't_ use DODS. I've never been much impressed with it (and I did a
fair amount of work with the newest version of it while I was still at
Lutris)...just not how I like to approach OR mapping. There are a number of
other OR mapping packages out there, but most of them were heavier weight
than what we wanted, so we ended up rolling our own solution, and at some
point when it gets a little further along (and I get a little less busy), we
may make it publically available.

What we really wanted something lightweight to map the JDBC result sets into
nested list/map data structures. Specifically, we thought the data layer
should
a) make no requirements of the SQL DB structure
b) give us complete access to the SQL layer - we write it, rather than
letting the tool do it for us
c) give us the ability to easily write test cases for the sql layer (so we
can validate all the SQL in the app at any given point)
d) automatically support the lazy loading of data (so that nested data
wasn't actually loaded until it was needed) and nested transactions (save
the data at any point in the hierarchy and everything below it gets saved)
e) support different keying mechanisms - simple surrogate keys vs complex
aggregate keys; self assigned identity keys vs. autocreated identity keys
f) be very easy to program against

As an example of what we came up with, consider the following table
structure:



Let's say I want to iterate through all the Terminals for Business ATMR. I
would simply do this:

BusinessList list = new BusinessList();
list.putKey(BusinessMap.COMPANY_ID, Companies.ATMR);
list.load();
for (int i=0; i<list.size(); i++) {
    BusinessMap map = (BusinessMap) list.get(i);
    String descr = (String) map.get(BusinessMap.DESCR);
    TerminalList tlist = (TerminalList) map.get(BusinessMap.TERMINAL_LIST);

    ...iterate through tlist...

}

The key thing to observe here is that the properties are accessed just as if
this was a regular list/map structure. As I'm looping through terminals, I
can set properties as needed, then when I'm all done issue a list.save() and
the whole thing will be automatically wrapped in a trx. Or I could load an
individual Terminal all by itself and work with that:

TerminalMap tm = new TerminalMap();
tm.putKey(TerminalMap.COMPANY_ID, Companies.ATMR);
tm.putKey(TerminalMap.BUSINESS_ID, ...);
tm.putKey(TerminalMap.TERMINAL_ID, ...);
tm.load();
...modify props...
tm.save();

The whole thing is quite flexible. Not entirely automated (in the sense that
we have to write the sql code and manually create the map/list objects, but
that's how we wanted it, so that we could have complete control over the
thing.

So that's how we do OR mapping...

Christian
----------------------------------------------
Christian Cryder [[email protected]]
Internet Architect, ATMReports.com
Barracuda - http://barracudamvc.org
----------------------------------------------
"Coffee? I could quit anytime, just not today"
  -----Original Message-----
  From: [email protected]
[mailto:[email protected]]On Behalf Of David R Robison
  Sent: Thursday, February 27, 2003 7:26 PM
  To: [email protected]
  Subject: [Barracuda] DB Alternatives to DODS


  In the past I've used DODS for my database access in my Barracuda
applications. It integrates well with Enhydra and is easy to use when
creating a new database. However, I have had trouble getting it to work with
legacy databases (tables w/o the version and objected fields). Has anyone
used any other tools besides DODS for database access within
Enhydra/Barracuda?



  David R Robison

  Open Roads Consulting, Inc.

  http://www.openroadsconsulting.com