Creating dll for executing external procedure('c' language)", version Version 8i

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Hi Tom,
      I am using Wint NT,Oracle 8i(server) and C language.
      My goal is calling 'c' routine thru stored procedure.
      For that I had made neccesary steps.I had modified Tnsnames and listener 
entry as follows.

      Tnsnames entry
------------------------
extproc_connection_data = 
   (DESCRIPTION = 
       (ADDRESS = 
          (PROTOCOL=IPC) 
      (KEY=extproc_key) )
      (CONNECT_DATA = 
          (SID = extproc_agent)
     ) 


Listener entry
-------------------
EXTERNAL_PROCEDURE_LISTENER = 

(ADDRESS_LIST =
    (ADDRESS = (PROTOCOL=ipc)
               (KEY=extproc_key)
     )
)

SID_LIST_EXTERNAL_PROCEDURE_LISTENER =

(SID_LIST =
     (SID_DESC = (SID_NAME=extproc_agent)
                 (ORACLE_HOME=d:/oracle8i)
                 (PROGRAM=extproc)
      )
)

Then I want to create the dll.Here I have a doubt how to use the dll.Any my 'C' 
routine is
/*This program will gives square the number*/
/*square.c*/
#include <stdio.h>
main(int argc,char *argv[])
{
  int no;
  no = argv[1];
  return no*no;
}
My next question is "Would I need to include any OCI statements inside of 'C' 
routines?".If say yes,Please tell me how to I do it?.
 

and we said...

You do not create a DDL with a main.  You create an EXE with a main.

You do not *need* to have OCI in your extproc.  Many (most) do however -- to 
handle errors and such.

Look in $ORACLE_HOME/plsql/demo for ext*.*.  There is a full example of an 
extproc routine there including the C code for you to review.

It is recommended to test the installation of external procedures with the 
demonstration programs.  The reason for this is twofold

ć Oracle support is aware of and can help setup/configure the demonstration 
program.  If we work with an example they know about ¡V we¡¦ll be able to 
resolve any issues that much faster

ć The supplied demonstration program will illustrate the correct approach for 
compiling and linking on your platform

The demonstration program is found in your $ORACLE_HOME/plsql/demo directory on 
all releases of Oracle8i.  The steps we should follow to make the demonstration 
are:

Compile the extproc.c code into a DLL or .so/.sl/.a file.  

The process for doing that on NT is to simply cd to the ORACLE_HOME/plsql/demo 
directory and type make (they have supplied a Make.BAT file in that directory):

C:/oracle/plsql/demo>make
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 10.00.5270 for 80x86
Copyright (C) Microsoft Corp 1984-1995. All rights reserved.

extproc.c
Microsoft (R) 32-Bit Incremental Linker Version 3.00.5270
Copyright (C) Microsoft Corp 1992-1995. All rights reserved.

/out:extproc.dll
/dll
/implib:extproc.lib
/debug
../../oci/lib/msvc/oci.lib
msvcrt.lib
/nod:libcmt
/DLL
/EXPORT:UpdateSalary
/EXPORT:PercentComm
/EXPORT:PercentComm_ByRef
/EXPORT:EmpExp
/EXPORT:CheckEmpName
/EXPORT:LobDemo
extproc.obj
C:/oracle/plsql/demo>

In Unix, you will do much the same but the command to compile is different.  
There it will look like:


$ make -f demo_plsql.mk extproc.so
/usr/ccs/bin/make -f /export/home/ora816/rdbms/demo/demo_rdbms.mk 
extproc_callback SHARED_LIBNAME=extproc.so OBJS="extproc.o"
¡K..

After that command completes, you will have a .DLL file on NT or a .so/.sl/.a 
file on Unix (extension depends on platform.  For example, Solaris is .so, HP/UX 
will be .sl).

Set up the scott/tiger account

For this demonstration program to work correct, we will need a scott/tiger demo 
account.  If your database does not have a scott/tiger account, you can set one 
up by issuing:

   SQL> grant connect, resource to scott identified by tiger;

That will create the scott user and give it the ability to connect to the 
database and create objects like tables and packages.  You will most like want 
to assign this use a default tablespace other then SYSTEM and a temporary 
tablespace as well.  

Given that we have the scott/tiger account, we must provide it with one 
additional grant before proceeding.  The SCOTT user will need the ¡§CREATE 
LIBRARY¡¨ privilege.  This privilege will allow SCOTT to issue the create 
library statement needed for external procedures (more on that in a moment).  As 
this is a fairly powerful privilege ¡V you will want to consider revoking it 
from SCOTT after running the example.  To accomplish this you will:

   SQL> grant create library to SCOTT;

When connected as someone who has the CREATE LIBRARY privilege with the ADMIN 
option themselves (eg: SYSTEM or some DBA account).

Lastly, you will want to ensure the EMP/DEPT demo tables are in the scott schema 
and populated with data.  You can verify this via:

SQL> select count(*) from emp;

  COUNT(*)
----------
        14

SQL> select count(*) from dept;

  COUNT(*)
----------
         4

If these tables do not exist or do not have any data ¡V you can rebuild them by 
executing demodrop.sql (to remove them) and demobld.sql (to create and populate 
them).  These scripts are found in $ORACLE_HOME/sqlplus/demo and are meant to be 
executed via sqlplus when logged in as SCOTT.

Create the demolib LIBRARY

The next step in the demonstration is to create the library object in Oracle.  
This object is simply a mapping of a library name (some 30 character name you 
choose) to a physical operating system file.  This OS file is your compiled 
binary we made in the first step.  The user who issues the create library 
statement must have the CREATE LIBRARY privilege granted to them either via a 
ROLE or directly.  This privilege is considered a fairly powerful one and should 
be given out only to those accounts you trust with the privilege.  It will allow 
them to execute any arbitrary C code they wish on your server machine using the 
account the extproc service executes with.  This is one of the reasons you would 
want to configure the extproc service to execute under some account other then 
the Oracle software owner (to avoid the inadvertent or malicious overwriting of 
your System tablespace for example).

In order to accomplish this step, you use SQLPlus and execute:

SQL> connect scott/tiger
Connected.
SQL> create or replace library demolib as 'c:/oracle/plsql/demo/extproc.dll';
  2  /

Library created.

The name DEMOLIB is what the developers of the demo chose as the name of their 
library ¡V you must use DEMOLIB.  The file name c:/oracle/plsql/demo/extproc.dll 
may be different for you ¡V I built the example directly in the demo directory 
of my Oracle_Home.  You may have a different Oracle_Home then I do or you might 
have built the demo in some other directory entirely ¡V you should use the 
actual path name of the extproc.dll you built in the first step.

Installing and running  the demo packages

The last step in the demo is to install the PLSQL code that maps to routines in 
the demolib library.  We are not interested at this point in what they look like 
as much as we are what they output ¡V we are using this demo to test external 
procedures, we¡¦ll look at how we code them in a bit.

Now we will simply execute:

SQL> connect scott/tiger
Connected.
SQL> @extproc

When in the $ORACLE_HOME/plsql/demo directory.  What we expect to see is:

SQL> @extproc

Package created.

No errors.

Package body created.

No errors.
ENAME      : ALLEN
JOB        : SALESMAN
SALARY     : 1600
COMMISSION : 300
Percent Commission : 18.75
ENAME      : MARTIN
JOB        : SALESMAN
SALARY     : 1250
COMMISSION : 1400
Percent Commission : 112
Return value from CheckEmpName : 0
old_ename value on return      : ANIL
ENAME      : 7369
HIREDATE   : 17-DEC-80
Employee Experience Test Passed.
***************************************

PL/SQL procedure successfully completed.
¡K. (other feedback would be here as well)¡K.

That shows that external procedures are correctly configured and ready to be 
used on our system ¡V the first procedure executes many of the routines in the 
extproc.dll we created.  This shows conclusively that all is configured 
correctly.

In the event of an incorrectly configured system, you would expect to see:

SQL> @extproc

Package created.

No errors.

Package body created.

No errors.
BEGIN demopack.demo_procedure; END;

*
ERROR at line 1:
ORA-28575: unable to open RPC connection to external procedure agent
ORA-06512: at "SCOTT.DEMOPACK", line 61
ORA-06512: at "SCOTT.DEMOPACK", line 103
ORA-06512: at line 1

That implies that it is time to revisit your tnsnames and listener.ora 
configuration.


 

	Reviews
GOTO a page to Bookmark Review | Bottom | Top November 21, 2001 Reviewer: Areader hi tom i don't have make.bat in %oracle_home%/plsql/demo directoty it's prcmake.bat i read the text in side and it is telling -- ----------------- Rem Use this script to create executables for the demo scripts with PL/SQL Rem blocks embedded in C code. To create all executables, at the prompt type: if (%1) == () goto usage Rem MSVCDir is defined by running a batch file, vcvars32.bat, Rem in Microsoft Visual Studio directory. You can find it using Rem Windows Explorer. Rem Environment Check: if (%MSVCDir%) == () goto msvcdir_error -- --------- i don't have visual studio I am running personal oracle 8.1.7 on windows 98 i want to call executable from pl/sql at my work. so please respond as soon as possible Followup: If you don't have MAKE.BAT you don't have a version of Oracle with extprocs. prcmake.bat doesn't make the extprocs. you need make.bat. if you dir ext* in that directory -- you should see: Directory of C:/oracle/plsql/demo 02/29/2000 02:03p 17,853 extproc.c 02/29/2000 02:03p 15,779 extproc.sql if not, you don't have the extproc stuff. I've never installed Personal Oracle -- I suppose there is a chance its "not there". try downloading http://asktom.oracle.com/~tkyte/extproc.tar I've tarred up (winzip will extract it) the source and make.bat. Lets start there and see what happens. <script language="JavaScript1.1" type="text/javascript"> document.getElementById("latestLink").style.display = "inline" </script> GOTO a page to Bookmark Review | Bottom | Top November 21, 2001 Reviewer: Areader Tom So FAST REPLY!!!!!!!!!!!!!!!!!!!!!!!!!!! IT REALLY HELPS ME A LOT CAN'T BELIEVE IT I REALLY APPRICIATE IT YOU ARE REALLY BOON TO DEVLOPER COMMUNITY HAVE NICE THANKSGIVING GOTO a page to Bookmark Review | Bottom | Top November 21, 2001 Reviewer: Areader Another question. External procedure in C is better OR java stored procedure is better (Consider Resources and perfomance of database) Followup: It is a double edged sword. C will be faster, its closer to the machine. Java will be a little slower but it is approaching the speed of C with regards to performance when NCOMP'ed (natively compiled) C will run outside the address space of the server -- it will take another process. Java runs inside the database, in the same address space. No extra process. Calling a java stored procedure for the first time in a session takes a bit of time (jvm startup). Its getting better with each release but its still rather large the first time. A C extproc is not. This mostly counts in a stateless environment where "for the first time in a session" happens very often. My mantra in general is: o if you can do it in SQL, do it o if not, do it in PLSQL, if you cannot do it there (eg: ftp'ing a file, writing a binary file, etc) o do it in Java in a simple stored procedure o if Java won't do it (you have a 3rd party api, existing C code) do it in C as an extproc. <script language="JavaScript1.1" type="text/javascript"> document.getElementById("latestLink").style.display = "inline" </script> GOTO a page to Bookmark Review | Bottom | Top make.bat and MS .netJune 18, 2003 Reviewer: Jeff Yuan from AZ USA First of all, thank you very much for your excellent coverings on extproc in your book and here. I believe the existing make.bat (from Oracle 9.0.1 installation) works with MS Visual Studio. Now in my box, I have only MS Visual Studio .NET installed, including MS Visual C++ .NET. I can not have MS Visaul C++ in same box.(?) When I try to run make.bat, I doesn't work. I don't know much about .NET. Could you please look into this? Is some modification on the make.bat necessary to find the C++ compiler? Regards, Jeff ~~~~~~~~~~~~~~ C:/oracle/plsql/demo>make.bat . Environment variable MSVCDIR must be set before running this batch file. Please run vcvars32.bat from MS Visual Studio directory. . C:/>cd program files/microsoft visual studio .net C:/Program Files/Microsoft Visual Studio .NET>cd vc7/bin C:/Program Files/Microsoft Visual Studio .NET/Vc7/bin>vcvars32.bat C:/Program Files/Microsoft Visual Studio .NET/Vc7/bin>"C:/Program Files/Microsof t Visual Studio .NET/Common7/Tools/"vsvars32.bat Setting environment for using Microsoft Visual Studio .NET tools. (If you also have Visual C++ 6.0 installed and wish to use its tools from the command line, run vcvars32.bat for Visual C++ 6.0.) C:/>cd oracle/plsql/demo C:/oracle/plsql/demo>make Files/Microsoft was unexpected at this time. Followup: looks like there might be an issue with spaces in the filenames. maybe you can use the 8.3 filenames instead. I don't have access to any windows machines, sorry. <script language="JavaScript1.1" type="text/javascript"> document.getElementById("latestLink").style.display = "inline" </script> GOTO a page to Bookmark Review | Bottom | Top vcSeptember 17, 2003 Reviewer: Aladdin from india sir how could i use external dll files not made by c language but with visual c ++ or vb Followup: you just need to know the "c prototype" they use. then you can map to it. <script language="JavaScript1.1" type="text/javascript"> document.getElementById("latestLink").style.display = "inline" </script> GOTO a page to Bookmark Review | Bottom | Top Need a clarificationOctober 08, 2003 Reviewer: Sanjay Jha from Toronto For using External Proc..do we need any additional piece of software? I am not able to run make.bat. It complains: C:/oracle/ora81/plsql/demo>make 'cl' is not recognized as an internal or external command, operable program or batch file. I referred metalink doc id (70110.1)and it says, I need to run vcvars32.bat before running make.bat: ********************************************************** 3. Use the make.bat available in the %ORACLE_HOME%/rdbms/extproc directory. You need to run vcvars32.bat file before running this batch file. This will create a dll file. ********************************************************** However, I did not see that step mentioned in your book, nor do I see a mention of the fact that I need any extra piece of software than Oracle RDBMS. Do I need Visual Studio to be installed, since I did not see vcvars32.bat, cl.exe etc. anywhere in my Oracle folder? Followup: you need a C compiler, yes. In order to compile C, you need a C compiler. You do not need a C compiler if you have a DLL already. You do need a C compiler to turn C into a DLL on windows. <script language="JavaScript1.1" type="text/javascript"> document.getElementById("latestLink").style.display = "inline" </script> GOTO a page to Bookmark Review | Bottom | Top Demo C-Based External Procedure -- Error ORA-03114January 25, 2005 Reviewer: Cheema from Toronto Hi Tom, I followed Chapter 18 of your "One-on_One" and was able to compile and link the demo program. However, when I call it from demopack.demo_procedure I get the following errors: SQL> @extproc Package created. No errors. Package body created. No errors. ERROR: ORA-03114: not connected to ORACLE BEGIN demopack.demo_procedure; END; * ERROR at line 1: ORA-03113: end-of-file on communication channel Is there anything which I may have missed out. Thanks Followup: please contact support -- that is the sample that is shipped with the server, if you followed the setup exactly and that happens -- there is a problem.... (the reason I put the shipping example in the book like that is -- in the event of somehting going horribly wrong -- support would be able to work with you, you are using the standard sample....)