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Subject: [Pljava-dev] UDT send and receive
Date: Mon, 25 Sep 2006 17:05:29 +0200
Message-ID: <4517F039.6050709@logix-tt.com> (raw)
In-Reply-To: <45150E10.8030907@logix-tt.com>
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	<45150E10.8030907@logix-tt.com>

Hi, Thomas,

Markus Schaber wrote:

> I'm definitely planning to look into the C code. However, I might need
> some time to understand the "inner workings", and there's some higher
> priority work on my table, so it might take a few days.

I'm currently stuck in the C code in UDT.h.

From looking at the code, it seems to assume that the send and receive
code assumes that the internal (on-disk) representation is the same than
the one used for binary I/O, rather than relying on the send and receive
functions. Also, there are CREATE FUNCTION calls in the example on
http://wiki.tada.se/wiki/display/pljava/Creating+a+Scalar+UDT+in+Java
but the java code does not actually define them.

Is that assumption correct?

At least PostGIS currently uses a slightly different internal
representation internally compared to what send/receive use. The
internal on-disk format is optimized, the external representation is an
upwards compatible extension to the OpenGIS standardized WKB format.

So, from my understanding of the code, it's currently impossible to
implement an 1:1 replacement for PostGIS in pljava. (Not that I
seriously plan to do this.)

Btw, I have the impression that I'm the first one actually trying VARLEN
UDT mapping with pljava :-)

Thanks,
Markus
-- 
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

Fight against software patents in Europe! www.ffii.org
www.nosoftwarepatents.org

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