Problem:
Is there a way to download web pages via HTTP from a COBOL program under UNIX ?
Resolution:
This can be done via calls to the libcurl library.
Libcurl is a library for transfering data with URL syntax, supporting FTP, FTPS, HTTP, HTTPS, TFTP, GOPHER, TELNET, DICT, FILE and LDAP.
Here is an example of calling libcurl functions:
*
* Demo showing how to make an http request from a COBOL program
* using libcurl.
* libcurl can be found at http://sourceforge.net/projects/curl/
* libcurl documentation can be found at http://curl.haxx.se/libcurl/
*
* compile as follows:
* cob -x urltest.cbl -L/usr/lib -lcurl -L/usr/ssl/lib -lssl
* -lcrypto -ldl
*
Program-ID. urltest.
Working-Storage Section.
01 Curl-Handle pointer.
01 Bad-Handle pointer.
78 CURLOPT-NOTHING value 0.
78 CURLOPT-FILE value 10001.
78 CURLOPT-URL value 10002.
78 CURLOPT-PORT value 3.
78 CURLOPT-ERRORBUFFER value 10010.
78 CURLOPT-WRITEFUNCTION value 20011.
78 CURLOPT-CRLF value 27.
78 CURLOPT-VERBOSE value 41.
78 CURLOPT-HEADER value 42.
78 CURLOPT-NOPROGRESS value 43.
78 CURLOPT-NOBODY value 44.
78 CURLOPT-HEADER-YES value 1.
78 CURLOPT-HEADER-NO value 0.
01 Curl-URL pic x(256).
01 Writefunction-Ptr procedure-pointer.
01 Curl-Error-Text pic x(256).
01 Ws-Error pic x(40).
01 Web-Data pic x(65536).
01 Web-Data-Len pic x(04) comp-5 value 0.
01 Web-Data-Max pic x(04) comp-5.
01 Total-Size pic x(04) comp-5.
01 Bytes-Read pic x(04) comp-5.
Linkage Section.
01 Data-In pic x(04) comp-5.
01 Data-Elem-Size pic x(04) comp-5.
01 Data-Elem-Num pic x(04) comp-5.
01 Unused-Ptr pointer.
Procedure Division.
0000-Main.
perform 1000-Init.
perform 2000-Setup.
perform 3000-Get-URL.
perform 9999-Cleanup.
display "Received " Web-Data-Len " bytes from " Curl-URL.
display " ".
display "First 80 characters:".
display Web-Data(1:80).
display " ".
display "Last 80 characters:".
display Web-Data(Web-Data-Len - 80:80).
stop run.
1000-Init.
set Curl-Handle to null.
set Bad-Handle to null.
call "curl_easy_init"
returning Curl-Handle.
if Curl-Handle = Bad-Handle
move "Easy Init Error" to Ws-Error
perform 9000-Error
end-if.
2000-Setup.
call "curl_easy_setopt"
using by value Curl-Handle
by value CURLOPT-ERRORBUFFER size 4
by reference Curl-Error-Text.
if Return-Code not = 0
move "Set Option ErrorBuffer Error" to Ws-Error
perform 9000-Error
end-if.
call "curl_easy_setopt"
using by value Curl-Handle
by value CURLOPT-HEADER size 4
by value CURLOPT-HEADER-NO size 4.
if Return-Code not = 0
move "Set Option Header Error" to Ws-Error
perform 9000-Error
end-if.
set Writefunction-Ptr to entry "curl-callback".
call "curl_easy_setopt"
using by value Curl-Handle
by value CURLOPT-WRITEFUNCTION size 4
by value Writefunction-Ptr.
if Return-Code not = 0
move "Set Option Writefunction Error" to Ws-Error
perform 9000-Error
end-if.
move z"http://www.microfocus.com" to Curl-URL.
call "curl_easy_setopt"
using by value Curl-Handle
by value CURLOPT-URL size 4
by reference Curl-URL.
if Return-Code not = 0
move "Set Option URL Error" to Ws-Error
perform 9000-Error
end-if.
3000-Get-URL.
call "curl_easy_perform"
using by value Curl-Handle.
if Return-Code not = 0
move "Perform Error" to Ws-Error
perform 9000-Error
end-if.
9000-Error.
display Ws-Error.
display "Return-Code: " Return-Code.
display "Error Text: " Curl-Error-Text.
perform 9999-Cleanup.
goback.
9999-Cleanup.
call "curl_easy_cleanup"
using by value Curl-Handle.
Program-Termination.
entry "curl-callback"
using by reference Data-In
by value Data-Elem-Size
by value Data-Elem-Num
by value Unused-Ptr.
E1000-Buffer-Data.
compute Total-Size = (Data-Elem-Size * Data-Elem-Num).
compute Web-Data-Max = (length of Web-Data - Web-Data-Len).
if Total-Size > Web-Data-Max
move Web-Data-Max to Total-Size
end-if.
move Data-In(1:Total-Size)
to Web-Data(Web-Data-Len 1:Total-Size).
add Total-Size to Web-Data-Len.
move Total-Size to Bytes-Read.
goback returning Bytes-Read.
Entry-Termination.
