OPeNDAP serving in situ data from relational database (Xenia or others)?

[Emilio]

I've been looking into options for serving NANOOS data from my Xenia
database via OPeNDAP, to make our modelers happy b/c they're very
familiar with that interface (as opposed to SOS). I've read that
others have done it, but some of the code I've found is very old, or
the experiences are not well documented. pydap (a nice python module)
had an rdbms handler in its earlier version (2.x), but the one for the
new version (3.0 beta) is still in the works.

Have any of you set up opendap to read from an rdbms, or know of
someone who has?

BTW, I thought about cc'ing the ioos_tech list as well, but I only
joined that list just now and I wasn't sure that'd be an appropriate
post (probably would).

Thanks. Cheers,

-Emilio Mayorga
NANOOS

[Rob Cermak]

Emilio,

This type of question is good for the ioos_tech list.

Yeah, all three opendap services went through a major upgrade and left
the RDBMS handlers behind: Hyrax, TDS and pydap. I think Rob(pydap)
is going to be rolling out plugins for 3.0 soon. Looks like a very
bare bones SQL handler has been put together.

http://groups.google.com/group/pydap/browse_thread/thread/074a5349f4ef6f98/1c610f72d17cbc35#1c610f72d17cbc35

I used to have time to dink more with pydap than just using the python module.

Rob

[Emilio Mayorga]

Hi Rob,

Thanks for your feedback. I scoured the pydap mailing list and documentation yesterday, but it looks like Rob De Almeida updated the thread you pointed me to exactly at mid-day yesterday, right after I looked at it! So, rdbms access from pydap 3 is looking very promising, which is great for me b/c Python is my preferred language.

If pydap rdbms handlers are usable, I hope to have something by Sept or Oct. If so, I'll report back here and at the ioos_tech list then.

Thanks again. Cheers,

-Emilio

[Jeremy Cothran]

Hey Emilio,

Sorry for the slow post.  We're haven't upgraded from the old, old OPeNDAP RDBMS/JDBC adapter from back in 2004.  Sounds like the pydap modules development might be the next thing to try.

Not sure technically how the python database handler compares to other JDBC implementations, etc and also whether there might be some smarts on the handler to order a request/query the same as the search index(faster processing/return using the index) for the main data table multi_obs which has a unique index in order m_date,m_type,sensor_id.

Thanks

Jeremy

[Emilio Mayorga]

Hi Jeremy,

Thanks for your input. I really can't say how the pydab rdbms handler
compares to JDBC. First, I don't use Java. But isn't JDBC just the
generic Java database access, um, component/scheme/module? From what I
can see, pydap is using the standard DB-API 2 modules to access each
database system (MySQL, Postgresql, possibly SQLite); what it does
with that in handling indices, etc, remains to be seen.

Yeah, all the implementations I saw looked old and unmaintained.

But I'm interested anyways: so, you do have an opendap implementation
on top of an rdbms? Is it public -- and if so, could you point me to
it, so I can explore it a bit?

Thanks. Cheers,

-Emilio

[Jeremy Cothran]

>But isn't JDBC just the generic Java database access, um, component/scheme/module?

Yes, the older OPeNDAP RDBMS solution was just an html query wrapper to a JDBC request. 

The below is it in action against an older database schema, I don't have it running against any xenia schemas although that would not be too difficult - there's just some intermediate files(.dds, .das) that tell the JDBC request the available tables/columns for query.

http://trident.baruch.sc.edu/dods/index.html

Jeremy

[Emilio Mayorga]

Thanks, that's very useful to see in action. Still, it's hard not to
chuckle at this line on the DODS Dataset Access Form:
"Tested on Netscape 4.61 and Internet Explorer 5.00"

Well ... isn't that special ;)

-Emilio

[Jeremy Cothran]

An dap server for TRS-80(4K), TI-994A(16K) or Commodore-64(64K) would be most special ;)
Jeremy