Oracle External Table PREPROCESSOR :: Loading first n lines from datafile.

This is based on one of the thread in OTN where user wants to load first 100 lines from the data file. Of course this does not make much sense, because you can load the whole file as an external table without preporcessor complexity and then just use a WHERE clause with rownum <=100.
But, for some reason if you must have to do this, then there is a workaround.
 My source file emp_csv.txt has 14 lines, emp_ext.sh is my shell file used in the table definition.

[oracle@localhost saubhik]$ pwd
/home/oracle/saubhik
[oracle@localhost saubhik]$ cat emp_csv.txt
7369,"SMITH","CLERK",7902,17-DEC-80 00:00:00,800,,20
7499,"ALLEN","SALESMAN",7698,20-FEB-81 00:00:00,1600,300,30
7521,"WARD","SALESMAN",7698,22-FEB-81 00:00:00,1250,500,30
7566,"JONES","MANAGER",7839,02-APR-81 00:00:00,2975,,20
7654,"MARTIN","SALESMAN",7698,28-SEP-81 00:00:00,1250,1400,30
7698,"BLAKE","MANAGER",7839,01-MAY-81 00:00:00,2850,,30
7782,"CLARK","MANAGER",7839,09-JUN-81 00:00:00,2450,,10
7788,"SCOTT","ANALYST",7566,19-APR-87 00:00:00,3000,,20
7839,"KING","PRESIDENT",,17-NOV-81 00:00:00,5000,,10
7844,"TURNER","SALESMAN",7698,08-SEP-81 00:00:00,1500,0,30
7876,"ADAMS","CLERK",7788,23-MAY-87 00:00:00,1100,,20
7900,"JAMES","CLERK",7698,03-DEC-81 00:00:00,950,,30
7902,"FORD","ANALYST",7566,03-DEC-81 00:00:00,3000,,20
7934,"MILLER","CLERK",7782,23-JAN-82 00:00:00,1300,,10
[oracle@localhost saubhik]$ cat emp_csv.txt|wc -l
14
[oracle@localhost saubhik]$ cat emp_ext.sh
#!/bin/bash  
  
# Listing the first 10 lines  
/usr//bin/head -10 $1 
exit 
[oracle@localhost saubhik]$ 

Now the table creation and testing:

SCOTT@orclSB 27-FEB-17>  --My database version
SCOTT@orclSB 27-FEB-17> select * from v$version; 

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production

SCOTT@orclSB 27-FEB-17> -- External table definition which will read first 10 lines.
SCOTT@orclSB 27-FEB-17> ed
Wrote file afiedt.buf

  1  create table emp_ext
  2         (       empno varchar2(30),
  3            ename varchar2(30),
  4            job varchar2(30),
  5            mgr varchar2(30),
  6            hiredate varchar2(30),
  7            sal varchar2(30),
  8            comm varchar2(30),
  9            deptno varchar2(30)
 10        )
 11        ORGANIZATION EXTERNAL
 12         ( TYPE ORACLE_LOADER
 13           DEFAULT DIRECTORY SAUBHIK
 14           ACCESS PARAMETERS
 15           ( records delimited by newline
 16         preprocessor saubhik: 'emp_ext.sh'
 17         badfile saubhik:'emp_ext%a_%p.bad'
 18         logfile saubhik:'emp_ext%a_%p.log'
 19         fields terminated by ","
 20          optionally enclosed by '"'
 21          missing field values are null
 22          (empno,ename,job,mgr,hiredate ,sal,comm,deptno
 23          )
 24             )
 25           location
 26            ( SAUBHIK:'emp_csv.txt'
 27            )
 28         )
 29        reject limit unlimited
 30*     PARALLEL 2
SCOTT@orclSB 27-FEB-17> /

Table created.

SCOTT@orclSB 27-FEB-17> select * from emp_ext;

EMPNO                          ENAME                          JOB                            MGR                            HIREDATE                       SAL
------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------
COMM                           DEPTNO
------------------------------ ------------------------------
7369                           SMITH                          CLERK                          7902                           17-DEC-80 00:00:00             800
                               20

7499                           ALLEN                          SALESMAN                       7698                           20-FEB-81 00:00:00             1600
300                            30

7521                           WARD                           SALESMAN                       7698                           22-FEB-81 00:00:00             1250
500                            30


EMPNO                          ENAME                          JOB                            MGR                            HIREDATE                       SAL
------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------
COMM                           DEPTNO
------------------------------ ------------------------------
7566                           JONES                          MANAGER                        7839                           02-APR-81 00:00:00             2975
                               20

7654                           MARTIN                         SALESMAN                       7698                           28-SEP-81 00:00:00             1250
1400                           30

7698                           BLAKE                          MANAGER                        7839                           01-MAY-81 00:00:00             2850
                               30


EMPNO                          ENAME                          JOB                            MGR                            HIREDATE                       SAL
------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------
COMM                           DEPTNO
------------------------------ ------------------------------
7782                           CLARK                          MANAGER                        7839                           09-JUN-81 00:00:00             2450
                               10

7788                           SCOTT                          ANALYST                        7566                           19-APR-87 00:00:00             3000
                               20

7839                           KING                           PRESIDENT                                                     17-NOV-81 00:00:00             5000
                               10


EMPNO                          ENAME                          JOB                            MGR                            HIREDATE                       SAL
------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------
COMM                           DEPTNO
------------------------------ ------------------------------
7844                           TURNER                         SALESMAN                       7698                           08-SEP-81 00:00:00             1500
0                              30


10 rows selected.

Calling Web Service From PL/SQL : Temperature Converter Using 1. UTL_HTTP 2. UTL_DBWS

This is part II of my earlier post of Calling Webservice through pl/sql. This post is also based on one of the threads in OTN.
I will demonstrate calling free Web-services available in http://www.webservicex.net/new/Home/Index  using two methods: 1. UTL_HTTP 2. UTL_DBWS and both are working perfectly.

SCOTT@orclSB 27-FEB-17> -- My database version.
SCOTT@orclSB 27-FEB-17> select * from v$version;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production

SCOTT@orclSB 27-FEB-17> ed
Wrote file afiedt.buf

  1  create or replace function ConvertTemperature( Temperature integer, FromUnit varchar2, ToUnit varchar2 ) return integer is
  2              --// URL to call
  3              SOAP_URL        constant varchar2(1000) := 'http://www.webservicex.net/ConvertTemperature.asmx';
  4              --// SOAP envelope template, containing $ substitution variables
  5              SOAP_ENVELOPE   constant varchar2(32767) :=
  6      '
  7  
  8    
  9      
 10        $TEMPERATURE
 11        $FROMUNIT
 12        $TOUNIT
 13      
 14    
 15  ';
 16             --// we ll identify ourselves using an IE9/Windows7 generic browser signature
 17             C_USER_AGENT    constant varchar2(4000) := 'Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)';
 18             --// these variables need to be set if web access
 19             --// is via a proxy server
 20             proxyServer varchar2(20) default null;
 21             proxyUser varchar2(20) default null;
 22             proxyPass varchar2(20) default null;
 23             --// our local variables
 24             soapEnvelope    varchar2(32767);
 25             proxyURL        varchar2(4000);
 26             request         utl_http.req;
 27             response        utl_http.resp;
 28             buffer          varchar2(32767);
 29             soapResponse    clob;
 30             xmlResponse     XmlType;
 31             eof             boolean;
 32             lResponse integer;
 33     begin
 34             --// create the SOAP envelope
 35             soapEnvelope := replace( SOAP_ENVELOPE, '$TEMPERATURE', Temperature );
 36             soapEnvelope := replace( soapEnvelope, '$FROMUNIT', FromUnit );
 37             soapEnvelope := replace( soapEnvelope, '$TOUNIT', ToUnit );
 38             --// our "browser" settings
 39             utl_http.set_response_error_check( true );
 40             utl_http.set_detailed_excp_support( true );
 41             utl_http.set_cookie_support( true );
 42             utl_http.set_transfer_timeout( 10 );
 43             utl_http.set_follow_redirect( 3 );
 44             utl_http.set_persistent_conn_support( true );
 45             --// configure for web proxy access if applicable
 46             if proxyServer is not null then
 47                     proxyURL := 'http://'||proxyServer;
 48                     if (proxyUser is not null) and (proxyPass is not null) then
 49                             proxyURL := Replace( proxyURL, 'http://',  'http://'||proxyUser||':'||proxyPass||'@' );
 50                     end if;
 51                      utl_http.set_proxy( proxyURL, null );
 52             end if;
 53             --// make the POST call to the web service
 54             request := utl_http.begin_request( SOAP_URL, 'POST', utl_http.HTTP_VERSION_1_1 );
 55             utl_http.set_header( request, 'User-Agent', C_USER_AGENT );
 56             utl_http.set_header( request, 'Content-Type', 'text/xml; charset=utf-8' );
 57             utl_http.set_header( request, 'Content-Length', length(soapEnvelope) );
 58             utl_http.set_header( request, 'SoapAction', 'http://www.webserviceX.NET/ConvertTemp' );
 59             utl_http.write_text( request, soapEnvelope );
 60             --// read the web service HTTP response
 61             response := utl_http.get_response( request );
 62             dbms_lob.CreateTemporary( soapResponse, true );
 63             eof := false;
 64             loop
 65                     exit when eof;
 66                     begin
 67                             utl_http.read_line( response, buffer, true );
 68                             if length(buffer) > 0 then
 69                                     dbms_lob.WriteAppend(
 70                                             soapResponse,
 71                                             length(buffer),
 72                                             buffer
 73                                     );
 74                             end if;
 75                     exception when utl_http.END_OF_BODY then
 76                             eof := true;
 77                     end;
 78             end loop;
 79             utl_http.end_response( response );
 80             --// as the SOAP responds with XML, we convert
 81             --// the response to XML
 82             xmlResponse := XmlType( soapResponse );
 83             dbms_lob.freetemporary( soapresponse );
 84             select extractvalue(xmlResponse,'/soap:Envelope/soap:Body/ns0:ConvertTempResponse/ns0:ConvertTempResult'
 85  ,'xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/", xmlns:ns0="http://www.webserviceX.NET/"')
 86   into lResponse
 87   from dual;
 88             return( lResponse );
 89     exception when OTHERS then
 90             if soapResponse is not null then
 91                     dbms_lob.FreeTemporary( soapResponse );
 92             end if;
 93             raise;
 94*   end;
 95  /

Function created.

SCOTT@orclSB 27-FEB-17> select converttemperature(68,'degreeFahrenheit','degreeCelsius') from dual; 

CONVERTTEMPERATURE(68,'DEGREEFAHRENHEIT','DEGREECELSIUS')
---------------------------------------------------------
                                                       20

SCOTT@orclSB 27-FEB-17> ed
Wrote file afiedt.buf

  1  create or replace function ConvertTemperature_dbws( Temperature integer, FromUnit varchar2, ToUnit varchar2 ) return integer is
  2              --// URL to call
  3              SOAP_URL        constant varchar2(1000) := 'http://www.webservicex.net/ConvertTemperature.asmx';
  4              --// SOAP envelope template, containing $ substitution variables
  5  SOAP_ENVELOPE   constant varchar2(32767) :=
  6      '
  7        $TEMPERATURE
  8        $FROMUNIT
  9        $TOUNIT
 10      ';
 11    lservice           sys.utl_dbws.service;
 12    DBWScall             sys.utl_dbws.CALL;
 13    serviceQname      sys.utl_dbws.QNAME;
 14    port_qname         sys.utl_dbws.QNAME;
 15    xmlResponse           sys.xmltype;
 16    request            sys.xmltype;
 17    lResponse integer;
 18    soapEnvelope    varchar2(32767);
 19     begin
 20             --// create the SOAP envelope
 21             soapEnvelope := replace( SOAP_ENVELOPE, '$TEMPERATURE', Temperature );
 22             soapEnvelope := replace( soapEnvelope, '$FROMUNIT', FromUnit );
 23             soapEnvelope := replace( soapEnvelope, '$TOUNIT', ToUnit );
 24             serviceQname := sys.utl_dbws.to_qname(null, 'ConvertTemp');
 25    lservice := sys.utl_dbws.create_service(serviceQname);
 26    DBWScall := sys.utl_dbws.create_call(lservice);
 27    sys.utl_dbws.set_target_endpoint_address(DBWScall, SOAP_URL);
 28    sys.utl_dbws.set_property( DBWScall, 'SOAPACTION_USE', 'TRUE');
 29    sys.utl_dbws.set_property( DBWScall, 'SOAPACTION_URI', 'http://www.webserviceX.NET/ConvertTemp');
 30    xmlResponse :=sys. utl_dbws.invoke(DBWScall, xmltype(soapenvelope));
 31   select extractvalue(xmlresponse,'ConvertTempResponse/ConvertTempResult','xmlns:="http://www.webserviceX.NET/"')
 32   into lresponse
 33  from dual;
 34    return (lresponse);
 35*   end ConvertTemperature_dbws;
 36  /

Function created.

SCOTT@orclSB 27-FEB-17> select converttemperature_dbws(68,'degreeFahrenheit','degreeCelsius') from dual; 

CONVERTTEMPERATURE_DBWS(68,'DEGREEFAHRENHEIT','DEGREECELSIUS')
--------------------------------------------------------------
                                                            20

SCOTT@orclSB 27-FEB-17> l