FreeTDS Development Group

[Frediano Ziglio <freddyz77 AT tin.it>]

Il sab, 2002-11-23 alle 07:28, James K. Lowden ha scritto:
> Hello everyone, 
> 
> Frediano told me rpc is "quite done" in libtds, but I think we're speaking
> of different things that might overlap somewhat.  I've been reading about
> the dblib rpc fuctions, trying to mate them to the TDS documentation, and
> AFAICT, what I'm trying to do is quite different from "dynamic SQL".  What
> I'm doing has no placeholders.  
> 

Yesterday tds_submit_rpc was just empty. Today it should work on TDS7+.
The reason is that call to dynamic and RPC are very similar, so a bit of
cut&paste is sufficient.

> This message is an outline of what I think is needed.  Please chime in to
> keep me on track. 
> 
> What I have done so far is define the data structures to hold what the
> client application passes to db-lib.  I'm now wrestling with dbrpcsend(),
> which dereferences all those captured values and sends the appropriate
> packets to the server.  
> 
> I propose a 1:1 mapping of TDS token to libtds function, passing a data
> structure/parameters sufficient to construct the packet.  In fact, I'd
> like to divide libtds along those very lines: a "token layer" to be called
> by the client APIs, one per token, and a "wire layer" of internal
> functions to support the token layer.  
> 
> Toward that end, I see flow control like this:
> 
> 1.  dbrpcinit
> 2.  dbrpcparam
>       [repeat 2 as for each param]
>       [repeat 1, 2 for each proc]
> 3.  dbrpcsend
>    ^^-dblib-^^
>    vv--tds--vv
> 4.  TDS_DBRPC     (sends proc name)
> 5.  TDS_PARAMFMT  (sends param types)
> 6.  TDS_PARAMS    (sends param data)
> 7.  TDS_DONE_[MORE|FINAL]
>       [repeat 4..7 for each proc]
>       [return status to dbrpcsend]
>    ^^--tds--^^

RPC in mssql and Sybase are quite different... The best thing to to is
to send RPC request calling a unique function (is what do now
tds_submit_rpc)

Params can be stored in a TDSPARAMINFO (there are functions for
allocating and adding a column at a time, so you can add a column at
time and finally allocate row, fill it and call tds_submit_rpc, this is
why I indicate dynamic1 as an example).


>    vv-dblib-vv
> 8.  dbsqlok       (waits for first result set)
> 
> Thenceforward, process results as usual, including output parameters.  
> 
> There's no TDS_DBRPC definition in tds.h, leading me to think I'm the
> first guy to work on this.  If I'm going down the wrong path, though, I'd
> sure appreciate a map.  
> 

>From the Sybase manuals there are some way do do a RPC:
- use header 3 (same method of mssql, perhaps this work even on tds4.2 and 
tds5, not tested)
- use TDS_RPC (old and deprecated)
- use TDS_DBRPC (TDS5)

freddy77