java server library
James Gallagher
jhrg at mac.com
Thu Mar 16 08:49:01 PST 2006
On Mar 15, 2006, at 10:14 AM, Thomas LOUBRIEU wrote:
> Hi Peter,
>
> Thanks you for you help.
> We will consider the pyDAP option but we do not have any python
> skills in our team so we would prefer to use the Java DRDS API.
> That way we will be able to easily improve our server as our
> database or the openDAP API is updated.
Thomas,
My initial take on your question was that the pyDAP code would be
easier to work with because it is so much smaller. Also, there's an
outside chance that pyDAP can handle nested sequences already, which
would save you from having to add features to the DRDS.
Roberto, Any comments?
Regarding the DRDS, we do plan to support it and would welcome any
contributions you can make to increasing its functionality! We can
answer questions and the like, but right now we're 'booked solid' on
projects, so we can't do any of the coding. I'll include some more
comments below...
>
> Bye,
>
> Thomas
>
>
>
> Peter Cornillon wrote:
>> Hi Thomas,
>>
>> We discussed your message today. The upshot of our discussion is
>> that you should consider pyDAP first and if that doesn't meet your
>> needs, then the DRDS. James, Dan and Nathan each have specific
>> comments that they will send you in reply to your message. I would
>> however like to send it to dods-tech so that others on the e-mail
>> list, e.g., Roberto, can also chime in. Do you have any problem
>> with me fowarding your e-mail to the dods-tech list or would you
>> prefer that we reply to your without posting the message? If you
>> have no problems with airing your questions on dods-tech, either I
>> can forward the message to the list, or you can send it to the
>> list. Your choice.
>>
>> Peter
>>
>> On Mar 2, 2006, at 9:43 AM, Thomas LOUBRIEU wrote:
>>
>>> Dear Peter,
>>>
>>> At CORIOLIS in-situ data center, we are starting to develop an
>>> opendap server directly connected on our ORACLE RDBMS which
>>> contains the full profiles (date, position, measurements...)
>>> managed by the CORIOLIS data center.
>>>
>>> We would like to disseminate the profile datasets, as DAPPER
>>> does : a sequence of location (position + date) containing
>>> sequence of profiles (parameter list) containing sequence of
>>> measurement (for each vertical level).
>>>
>>> Our server has to be a web application which is easy to deploy on
>>> existing tomcat server.
>>>
>>> We're now looking for the best framework to start with :
>>>
>>> 1) Java-DAP 1.1.7 (http://www.opendap.org/download/java-
>>> dap.html) : seems to be the good one but it's source content
>>> seems to be the same as DRDS.
>>>
>>> 2) DRDS (http://www.opendap.org/download/drds_server.html) : it
>>> is a good model for us because it is easy to connect to a RDBMS
>>> but it doesn't seems to handle sequence of sequence ? We could
>>> add that function to DRDS but we would like to be sure the DRDS
>>> release will benefits of the future improvments of Java-DAP.
Nathan Potter is author of the DRDS, as well as significant part of
the Java implementation of the DAP2 and supporting code. He's the
real authority on the DRDS, but I'll try to give you some background
and hopefully he will correct my errors.
The DRDS is designed so that there is a one-to-one correspondence
between database tables and DAP datasets and only those tables that
are configured to be DAP datasets are visible to outside users. That
means that you have complete control over what users coming in from
outside see, but also that you have to do some configuration work to
serve data once the DRDS is installed in TomCat. One basic feature of
the DRDS is that it does not provide a way for outside uses to
perform join operations since without detailed knowledge of the
database's internals it is hard to do those sorts of operations well.
To join two or more tables and make them appear as a single DAP
dataset, use a view. So in the end it _is_ possible to serve, as a
single dataset, information stored in multiple tables, but you will
have to add the appropriate view to the database. This is generally
not a problem, but it's an additional configuration issue to consider.
>>>
>>> 3) With Dapper we should set up and maintain a mysql server
>>> containing information copied from our Oracle Database. Moreover,
>>> we will not benefit from the indexation of our data in Oracle
>>> (qualitiy flags, vertical levels...) to improve the performance
>>> of the request (dapper reads netCDF files).
>>>
>>> 4) Anagram seems to be a good candidate but, firstly, we are a
>>> little bit afraid because only GDS (GrADS-server) seems to be
>>> made from that framework. Secondly, we will need specific filters
>>> at the upper layer of the Anagram architecture (in order to
>>> prevent overload by counting the requested record in the database).
I believe that people at PMEL have used Anagram, too.
James
>>>
>>> What would you recommend in our case ?
>>>
>>> Thanks for your help,
>>>
>>> Bye,
>>>
>>>
>>> Thomas and Arnaud.
>>>
>>> --
>>>
>>>
>>> -------------------------------------------------------------
>>> Thomas LOUBRIEU
>>> IFREMER IDM/ISI
>>> BP70
>>> 29280 Plouzane
>>> FRANCE
>>> email: Thomas.Loubrieu at ifremer.fr
>>> WWW : http://www.coriolis.eu.org/cdc
>>> Tel.: (+33) (0)2 98 22 48 53
>>> Fax: (+33) (0)2 98 22 46 44
>>> -------------------------------------------------------------
>>>
>>
>> --
>> Peter Cornillon
>> Graduate School of Oceanography - Telephone: (401) 874-6283
>> University of Rhode Island -
>> Fax: (401) 874-6728
>> Narragansett, RI 02882 - E-
>> mail: pcornillon at gso.uri.edu
>>
>
> --
>
>
> -------------------------------------------------------------
> Thomas LOUBRIEU
> IFREMER IDM/ISI
> BP70
> 29280 Plouzane
> FRANCE
>
> email: Thomas.Loubrieu at ifremer.fr
> WWW : http://www.coriolis.eu.org/cdc
> Tel.: (+33) (0)2 98 22 48 53
> Fax: (+33) (0)2 98 22 46 44
>
> -------------------------------------------------------------
>
--
James Gallagher jgallagher at opendap.org
OPeNDAP, Inc 406.723.8663
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