Perl As A System Glue

Patrick M. BensonUniversity of Washington

Information Systems

http://weber.u.washington.edu/~pbensonemail: pbenson@cac.washington.edu

2

Overview of Examples

File Store-and-ForwardIntroductory Level Example

Perl CGIIntermediate Level ExampleHalf-a-Perl ConceptSQL Development

3

File Store-and-Forward

VAX/VMS with Multinet outside our firewall running FOCUS under DCL

RS-6000 UNIX/AIX inside our firewall with strict security measures

IBM-309x/VM with an unknown Comm System on dedicated RJE line through our firewall

4

File Store-and-Forward

firew

all

firew

all

firew

all

firew

all

.rhost/.netrc .netrc/unknown

file to forward'datafile'

Returned Copyof file

'datafile_check'

DestinationCopy of'datafile'

Return Copy of'datafile'

Send Copy of'datafile'

Local Net VAX/VMS RS-6000/AIX IBM 309x/VMUsers

Xterm, PC, Mac

Create and IssueRSH comands for

FTP process

Display DestinationDirectory, run DIFF

on datafile anddatafile_check

Issue Directory,Get, Put FTP

commands; thenremove datafile(s)

Issue Get.Directory, Delete,

Put FTP commands

Respond to Dir, Put,Get FTP commands

5

File Store-and-Forward

RSH and FTP work because ... I trust you enough to let you talk to me,

I’ll take data files you say are safe. You trust me enough to give me your

account / password and to let me send a copy of your data file back to you.

6

Perl in this process (See Listing 2, RS6000/AIX Perl Script)

IF Statements, Logical Operators, Code Blocks

16. if ($#ARGV != 1) {

17. print “\n\n *******************************************”;

18. print “\n * ARGUMENT MISMATCH ERROR #”, $#ARGV *”;

19. print “\n *******************************************\n”;

20. exit -1;}

Arguments, Array Notation, Concatenation, Constants

23. $infile = $ARGV[0];

24. $chkfile = $infile . ‘_check’;

Back-Tic Execution, Nested Quotes, Imbedded Pipes

43. $get_file = ‘echo “get $outfile $chkfile” | ftp vsvm.dis.wa.gov‘;

File Store-and-Forward

7

Overview of Examples

File Store-and-ForwardIntroductory Level Example

Perl CGIIntermediate Level ExampleHalf-a-Perl ConceptSQL Development

8

Perl CGI

Web Client (PC, Mac, Xterm with Netscape 2.1 or better or similar, marginal HTML 3.0 or better compliant)

Web Server (Perl 4.2 or better) Data Server (Unix Box with Informix,

Sybase, Oracle ISQL or similar)

9

Perl CGI

Hypertext Transfer Protocol(HTTP)

Web Client(Netscape 3.0+ or

similar, HTML 3.0+)

Hard Firewall

HTML and PerlLibrary

WEB SERVER

S

oft

Fire

wal

l

Perl Scripts(Dynamic

HTML)

Static HTMLDEVELOPMENT

SERVERPico, VI, etc.text editors

Static DataServer 'Half-a-Perl' files

RSHCommand

Files

SQL Engine

Soft

Fire

wal

l

Web Side "Half-a-Perl"

Web-Side'Half-a-Perl'

Data ServerResponse

Web Side 'Half-a-Perl'

DS Side 'Half-a-Perl'

Target SQLDatabase

TemporaryDisk Files

UNLOAD Data

UNLOAD Data

Data Server 'Half-a-Perl' Scripts

Hard Firewall

DATA SERVER

SELECT Data

Common GatewayInterface (CGI)

10

Perl CGI

Content, Cache Control, Libraries, Initialization Accept static HTML parameters & Main Driver Construct ISQL command to meet request Copy the ISQL command through the firewall

to a data file Pass filename and CAT statements as a

parameter to ISQL command file Parse returned string into rows Build HTML Page

11

Perl CGI

See Listing 3, Perl CGI Content, Cache Control, Libraries, Initialization

9. print "CONTENT-TYPE: text/html","\n";10. print "Pragma: no-cache","\n\n";12. require "/www/world/cgi-bin/cgi-lib.pl";14. $rcp_user = ‘oasis’;15. $rcp_cmd = ‘/usr/ucb/rcp’;16. $rcp_host = ‘equip.u.washington.edu’;18. $rsh_user = ‘oasis’;19. $rsh_cmd = ‘/usr/ucb/rsh’;21. $sql_host = ‘equip.u.washington.edu’;22. $sql_db = ‘oasisdev@equipdev’;27. $rcp_destination = $rcp_user . ‘\@’ . $rcp_host . ‘:.’;28. $sql_user = $sql_host . ‘ -l ‘ . $rsh_user . ‘ ‘;

12

Perl CGI

See Listing 3, Perl CGI Accept static HTML parameters & Main

Driver

37. &ReadParse;

39. $table_name = $in{'table_name'};

41. $set_extract;42. &run_extract;43. &write_report;

45. exit;

13

Perl CGI

See Listing 3, Perl CGIConstruct ISQL command to meet request

49. sub set_extract {

53. $sellist = ‘name_value, name_full_text’;

54. $passlist = “'$table_name'”;

55. $sql_tables = ‘UNLOAD TO TEMPTBL SELECT ‘ . $sellist

56. . ‘ FROM names’

57. . ‘ WHERE name_type = ‘ . $passlist

58. . ‘\n’;

59. }

14

Perl CGI

See Listing 3, Perl CGICopy the ISQL command through the firewall to a data file

76. $info_time = `$rsh_cmd $sql_user "/bin/date "`;

77. if ($info_time eq '') {

78. print "<P>Database Server not responding ... try again later.";

79. exit;

80. }

85. $d = `rcp isql_tables.sql $rcp_destination`;

15

Perl CGI

See Listing 3, Perl CGI Pass filename and CAT statements as a

parameter to ISQL command file

94. $info = `rsh $sql_user "$rsh_file $sql_db isql_tables.sql; cat -e -v TEMPTBL ; rm TEMPTBL"`;

16

Perl CGI

See Listing 3, Perl CGI Parse Returned String into Rows

100. @table_data = split('\|\$',$info);

101. $row_count = $#table_data;

102. @row_data = split('\|',$table_data[0]);

103. $col_count = $#row_data + 1;

17

Perl CGI

See Listing 3, Perl CGIBuild HTML Page

108. sub write_report {

110 &build_headers;

111. &write_header;

112. &write_body

113 &write_footers;

114. }

18

Perl CGI

See Listing 3, Perl CGIBuild HTML Page - Build Headers122. $table_title[0] = ‘Column 1’;

123. $table_title[1] = ‘Column 2’;

125. if ($table_name eq “class”) {

126. $table_title[0] = ‘Class Code’;

127. $table_title[1] = ‘Class of Equipment’;

128. elsif ($table_name eq "cond") {

129. $table_title[0] = ‘Condition Code’;

130. $table_title[1] = ‘Asset's Present Condition’;}

(and so on until all possible table column titles are set)

140. }

19

Perl CGI

See Listing 3, Perl CGIBuild HTML Page - Write Header144. sub write_header {

148. print <<end_of_header;

149. <HTML>

150. <HEAD><TITLE>

151. Table Contents Inquiry

152. </TITLE></HEAD>

153. <BODY

161. end_of_header

162. }

20

Perl CGI

See Listing 3, Perl CGIBuild HTML Page - Write Body - Table Header175. print "<P> <TABLE COL=$col_count BORDER=\"1\" ";

176. for ($i = 0; $i < $row_count; $i++) {

180. if ($i == 0) {

181. print "<THEAD><TR>";

182. for ($j = 0; $j < $col_count; $j++) {

183. print "<TD ALIGN=\"CENTER\"> $table_title[$j] </TD>";

184. }

185. print "</THEAD><TBODY>";

186. }

21

Perl CGI

See Listing 3, Perl CGI Build HTML Page - Write Body - Table Rows195. @row_data = split('\|',$table_data[$i]);

196. for ($j = 0; $j < $col_count; $j++) {

197. if ($j == 0) {

198. $row_data[0] =~ s/\xA//g;

199. print "<TR><TD><FORMMETHOD=\"GET\"ACTION=\"./update_table.cgi\">

200. <INPUT TYPE=\"hidden\" NAME=\"$table_name\"

201. VALUE=\"$row_data[0]\">

202. <INPUT TYPE=\"SUBMIT\" VALUE=\"$row_data[0]\"></FORM></TD>";

203. } else {

204. print "<TD> $row_data[$j] </TD>";

205. }

206. }

22

Perl CGI

Hypertext Transfer Protocol(HTTP)

Web Client(Netscape 3.0+ or

similar, HTML3.0+)

OASIS HTML, Perl and Utilities

Library

Web Server

Sof

t

Fire

wal

lUtilities ("C"

and Perl)

Perl Scripts(Dynamic

HTML)

StaticFASTRANS

HTML

Pico, VI, etc texteditors

BrowserPrinted Output

Sof

t

F

irew

all

Time Request

CGI GeneratedSQL Cmd FIles

CAT'd SQLUNLOAD Files

Timestamp

Execute the Web"Half a Perl" Cmd

Hard Firewall

FASData Tables

PASData Tables

SQL Engine

SQL Engine

Hard Firewall

RSHCommand

Files

Data ServerTemp Disk

Storage

OASISData Tables

SQL Engine(Informix)

OASIS Data Server

Web Side "Half-a-Perl"

SQL UNLOAD'edData

CGI Generated SQLCommad FIles

FAS Data Server

PAS Data Server

Web Side "Half-a-Perl" for FAS Data

Web Side "Half-a-Perl" for PAS Data

FAS DataServer

Temp DiskStorage

PAS DataServer

Temp DiskStorage

Static DataServer "Half-

a-Perl"

Data Server Side"Half-a-Perl"

23

Perl As A System Glue

Pluses Cost effective cross platform superglue. Efficient and Structured code possible 1 hour of Perl = 8 hours of COBOLMinuses 10 ways to mess up maintenance staff Difficult post-implementation support

environment All the HTML Bandwagon problems