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27 lines
994 B
Plaintext
27 lines
994 B
Plaintext
This is a very simple example of using binary cursors to move binary data from
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the server to the client.
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We convert the GEOMETRY to the OpenGIS Well Known Binary (WKB) format before
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sending it to the client.
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The WKB format contains information about the endian of the data, so it can be
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used for transfer between servers and clients that are not the same endian
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(ie. between i386 and sparc)
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See http://www.opengis.org/techno/specs/99-049.rtf page 3-24 for the WKB
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specification.
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Z and M coordinates presence is encoded by or'ing WKBZOFFSET (0x80000000)
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and WKBMOFFSET (0x40000000) to the type.
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Points can then be 24 bytes (XYZ,XYM) or 32 bytes (XYZM)
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You can force geometries to be returned as 2d using the force_2d()
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function. For example:
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select asBinary(force_2d(geom)) from mytable;
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If the client is running on a i386, you should use asBinary(geom, 'NDR')
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and on a sparc you should use asBinary(geom, 'XDR') so you do not causes
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an endian shift on both the server and client.
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