On 12/12/11 15:43, Pierre Y. wrote:
> Hi All,
>
> Thanks to Vlad, we achieved the translation of the FB3 OO API in UIB
> Components for Delphi.
>
> You can checkout the code from SourceForge repository :
>
> https://uib.svn.sourceforge.net/svnroot/uib/trunk
>
> Now, we only miss hints to deal with FbMessage, it seems that the
> examples (fbstuff on github) made by Adriano heavily relies on BOOST
> and as we don't have such possibilities with Delphi we must understand
> what is exactly an FbMessage and see what we can do.
I've reordered filed in struct in order to put them in logically correct
order. [One really present is OK from alignment POV]
struct FbMessage
{
unsigned char* buffer; // contains data and NULL flags to
be transfered to/from engine.
unsigned int bufferLength; // length of that buffer
const unsigned char* blr; // describes format of data in a
form, easily understood by engine
unsigned int blrLength; // length of that format description
};
A sample. Imagine you
create table test (a int, f double precision);
and after some inserts want to
select a, f from test;
Buffer should have following data:
4 bytes for integer 'a'
2 bytes for it's NULL flag (NULL flag is always 2-byte integer)
2 bytes - alignment to 8-bytes boundary for next floating point value,
unused
8 bytes for floating point 'f'
2 bytes for it's NULL flag
Therefore the length of buffer is 18 bytes.
BLR is actually binary language representation for engine. All
procedures, view, etc. a first translated to BLR. BLR in FbMessage is
used to transfer data to/from message's buffer. Both BLR generation and
rules how to align data in buffer correctly can be found in
src/yvalve/why.cpp, function sqldaParse. Let me not try to repeat that C
code here in plain english - I'm afraid this can be buggy process :)
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