Dynamic Languages on USS Matthew Finlayson IBM 8.13.2008 2927 

Who’s presenting? • Matthew Finlayson • IT Architect • @ IBM Design Center • 10 Years Experience in Open Source • 5 Years Experience on System Z 

What are dynamic languages? 

4 Dynamic Languages Characteristics of Dynamic Languages • High level programming language • Dynamic typing rather than Static typing • Strong and weak typing do not matter • Executes at runtime rather than at compilation • Generally Interpreted • Automatic memory management – That’s right, no malloc! • Some dynamic languages – Perl – Python – Ruby – Javascript – Tcl – Smalltalk – Lisp 

5 Dynamic Languages Dynamic vs. Static Typing • With Static Typed languages checking is done at compile time • Variables know the type of their objects • “Unsafe” operations rejected at compile time • Objects have one immutable type and must be cast to change type • Languages • C, C++, Java • With Dynamic Typed languages checking is done at run time • Objects know their types; variables don't care • “Unsafe” operations rejected at runtime • Objects can change type • Languages • PHP, Perl, Python 

6 Dynamic Languages Dynamic Languages: Some Strong Typing • Strong Typing • Not associated with static typing • Python Code Example >>> 1 + “1” Traceback (most recent call last): File “”, line 1, in? TypeError: unsupported operand type(s) for +: 'int' and 'str' >>> 1 + 1 2 >>> “1” + “1” '11' >>> 1 + int(“1”) 2 >>> “1” + str(1) '11' 

7 Dynamic Languages Dynamic Languages: Some Weak Typing • Weak Typing • Not associated with dynamic typing • PHP Code Example 

8 Dynamic Languages Where does your language fall? Static Dynamic Strong Weak Java Python PHP C++ C Perl Haskell 

9 Dynamic Languages Pros and cons of static typing • Pros • IDEs can be more helpful: code completion, refactoring • Avoid errors due to mismatched types • May run faster because the compiler can optimize for types • Cons • Lots of machinery to put in place to get a program moving • Code is verbose: you have to manually specify types for variables 

10 Dynamic Languages Pros and cons of dynamic typing • Pros • Code is less verbose • Faster development cycle edit -> compile -> test -> debug • Since the compiler is not doing error checks and errors must be run explicitly testing is part of development • Cons • Code completion is harder • No type checking at compile time • TESTING IS MORE IMPORTANT • May be lots of implicit code 

Why use Dynamic Languages on USS? 

Dynamic Languages Open Source projects on Freshmeat.net 

Dynamic Languages Book Sales on Programming Languages O‘Reilly book sales in 2007 

14 Dynamic Languages What work do they do well? • Probably not going to scale to an enterprise level tool • Eg: not for handling banking transactions • Perl good for: • Batch processing • Report generation • Small to midsize projects • PHP is good for: • Web Applications • Easier to maintain code • Small -> Large projects • Python is good for: • All of these things … just not on USS • from gluing together backend systems • to network-aware applications to • desktop and web user interfaces. • embedded devices • controlling large manufacturing systems. 

Where can I get them? 

3 Dynamic Languages available on USS • PHP, Perl, and Python • Usually the ‘P’ in Lamp • All three are popular dynamic open source languages • PHP and Perl are both ‘supported’ by IBM 

17 PHP Getting Perl for z/OS Unix System Services • IBM Ported Tools for z/OS: PHP for z/OS • Provides PHP 5.1.2 for USS • PHP (PHP: Hypertext Preprocessor) is a general purpose language well suited to web development. • Preconfigured / Precompiled to address ASCII/EBCDIC conversion • Unpriced feature of IBM Ported Tools for z/OS • Requires z/OS.e V1.6 or higher • Using IBM's version saves you the pain of compiling it yourself • http://www- 03.ibm.com/servers/eserver/zseries/zos/unix/ported/php/index.ht ml 

18 Perl Getting Perl for z/OS Unix System Services • IBM Ported Tools for z/OS: Perl for z/OS • Provides Perl 5.8.7 for USS • Perl (Practical Extraction and Report Language) is a popular general purpose language widely used in UNIX environments • Preconfigured / Precompiled to address ASCII/EBCDIC conversion • Unpriced feature of IBM Ported Tools for z/OS • Requires z/OS.e V1.4 or higher • Using IBM's version saves you the pain of compiling it yourself • http://www- 03.ibm.com/servers/eserver/zseries/zos/unix/ported/perl/index.ht ml 

19 Python Python-Mvs: Z/OS Python Ports • Python 1.4 (old) version was available from IBM • Current version 2.4.1 is available from a third party • Major port issues were due to classic EBCDIC / ASCII pitfalls • Binary and source packages available, no need to build yourself • Not a complete port • Mostly addresses explicit conversion between ASCII/Unicode and EBCDIC • http://www.teaser.fr/~jymengant/mvspython/mvsPythonPort.html 

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21 Perl Features of Perl on z/OS USS • Perl syntax is similar to the bad parts of C, making it familiar for people with C programming skills to learn • Particularly suited for text / batch processing • AMAZINGLY Rich set of API's available • I would love to fill out a bulleted list but it would be huge • Perl for z/OS includes an extension to access DB2 for z/OS via standard perl modules allowing access to DB2 data on z/OS 

22 Perl Path Considerations for Perl on z/OS • Typically the first line of a php script looks like this: • #!/usr/bin/perl • However the default installation path of php is /usr/lpp/perl/bin/perl • Create a symbolic link from /usr/bin/perl to the default installation path • to ensure compatibility • to prevent script changes between systems 

23 Perl Running Perl from JCL • JCL, the Job Control Language is the heart of every job running on a z/OS system • Even if a Perl program is running on USS it is quite likely that it will be controlled from within a JCL environment • Running such a program involves more than just starting a task: • Execute the Perl program in the USS environment with output redirection using BPXBATCH • Define characteristics of datasets to hold stdout and stderr, so that these will be available on the z/OS side. • Copy the redirected output to the datasets defined before • Interpret the return code and take appropriate actions 

Perl Example JCL (1 of 2) //PERLTEST JOB ’TEST’,’USER’,MSGCLASS=M,MSGLEVEL=(1,1), // USER=&SYSUID,NOTIFY=&SYSUID,CLASS=T //***************************************************************** //* // SET SYS=’development’ // SET DIR=’test’ // SET PRG=’db2_test.pl’ //* //***************************************************************** //* //RUNPERL EXEC PGM=BPXBATCH, // PARM=’sh perl /usr/local/&SYS/&DIR/&PRG..pl &SYS..ini’ //* //* Set environment variables //STDOUT DD PATH=’/tmp/&PRG..out’, // PATHOPTS=(OCREAT,OTRUNC,OWRONLY),PATHMODE=SIRWXU //STDERR DD PATH=’/tmp/&PRG..err’, // PATHOPTS=(OCREAT,OTRUNC,OWRONLY),PATHMODE=SIRWXU //* //* Since BPXBATCH can only redirect stdout and stderr into //* HFS-files these will now be copied back to the MVS environment //CPOUT EXEC PGM=IKJEFT01,DYNAMNBR=300,COND=EVEN //SYSTSPRT DD SYSOUT=* 

Perl Example JCL (2 of 2) //HFSOUT DD PATH=’/tmp/&PRG..out’ //HFSERR DD PATH=’/tmp/&PRG..err’ //STDOUTL DD SYSOUT=*,DCB=(RECFM=VB,LRECL=133,BLKSIZE=137) //STDERRL DD SYSOUT=*,DCB=(RECFM=VB,LRECL=133,BLKSIZE=137) //STDOUTLF DD DSN=&&STDOUTLF, // DISP=(NEW,PASS), // SPACE=(CYL,(20,10),RLSE), // DCB=(RECFM=FB,LRECL=80,BLKSIZE=0) //STDERRLF DD DSN=&&STDERRLF, // DISP=(NEW,PASS), // SPACE=(CYL,(20,10),RLSE), // DCB=(RECFM=FB,LRECL=80,BLKSIZE=0) //SYSPRINT DD SYSOUT=* //SYSTSIN DD * OCOPY INDD(HFSOUT) OUTDD(STDOUTL) OCOPY INDD(HFSOUT) OUTDD(STDOUTLF) OCOPY INDD(HFSERR) OUTDD(STDERRL) OCOPY INDD(HFSERR) OUTDD(STDERRLF) //* //* If something went wrong, perform some recovery actions. // IF RC NE 0 THEN ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... // ENDIF 

Perl Accessing DB2 from Perl on USS • Accessing DB2 • All in all accessing DB2 from within a Perl program running in the USS environment is very straightforward. #!/usr/bin/perl use DBI; use DBD::DB2::Constants; use DBD::DB2; my ($username, $password) = (’DB2USR’, ’SOMEPASSWORD’); my $dbh = DBI -> connect ("dbi:DB2:ENV", $username, $password) or die "Could not connect to database! $!\n" if !defined ($dbh); my $sth = $dbh -> prepare (...); $sth -> execute (...) or die "PANIC!\n"; $sth -> finish; $dbh -> disconnect; 

27 Perl Finding more information • General Information on PHP • http://www.perl.org • Perl core user documentation • http://www.perl.org/docs.html • Perl user mailing lists • http://lists.cpan.org • Perl-MVS List – General discussion on perl MVS • http://lists.perl.org/showlist.cgi?name=perl-mvs • z/OS Unix Implementation of PHP • http://www- 03.ibm.com/servers/resources/servers_eserver_zseries_zos_unix_perl_pdf_ hpeza200.pdf 

I wish I had a better picture… 

29 PHP Features of PHP on z/OS USS • PHP's syntax is similar to C and Perl, making it easy for people with basic programming skills to learn • Particularly suited for web development and can be embedded directly in HTML • Rich set of API's available, including Perl compatible regular expression library • PHP for z/OS includes an extension to access DB2 for z/OS via ODBC allowing access to DB2 data on z/OS 

30 PHP Path Considerations for PHP on z/OS • Typically the first line of a php script looks like this: • #!/usr/bin/php • However the default installation path of php is /usr/lpp/php/5.1.2/bin/php • Create a symbolic link from /usr/bin/php to the default installation path • to ensure compatibility • to prevent script changes between systems 

31 PHP Running PHP under IBM HTTP Server (IHS) • Enable .IHS to execute a CGI application • Configure a directory in httpd.conf to allow execution • Exec /cgi-bin/* /usr/lpp/internet/server_root/cgi-bin/* • If not set scripts will be displayed as normal files • Set the PHPRC environment variable • Makes the php.ini file accessable to the .IHS server • Set in .IHS configuration file httpd.envvars • PHPRC=/etc • Restart .IHS server • Set permissions of the php file to 0755 

32 PHP Using PHP PDO wrapper with DB2 ODBC • z/OS DB2 Version 8.1 is the recommended version for PHP use • PDO provides a data-access abstraction layer • First set up the two following items • z/OS DB2 userid and password • DSNAOINI (DB2 ODBC initialization file) • Set the environment variable DSNAOINI like so: • putenv(“DSNAOINI=user_dir/DSNAOINI”); • user_dir is the directory where you place the DSNAOINI file • Make the following change to /etc/php.ini • [PDO] • pdo.dsn.yourdsnname=”odbc:DSN=DBW9L0C1;UID=userid;PWD=password 

33 PHP Accessing DB2 through web applications # File: pdo_conn.inc false)); $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } catch(Exception $e) { echo “FAILED: “ . $e->getMessage(); exit(0); } ?> 

34 PHP Query records through PDO w/ Php # File: pdo_conn.inc setAttribute(PDO::ARRT_ERRMODE, PDO::ERRMODE_WARNING); $statement = $dbconn->prepare(“select * from Cust “); $statement->execute(); $response = $statement->fetchAll(); var_dump($response); } catch(PDOException $e) { echo “FAILED: “ . $e->getMessage(); } ?> 

35 PHP Update records through PDO w/ Php # File: pdo_conn.inc setAttribute(PDO::ARRT_ERRMODE, PDO::ERRMODE_WARNING); $statement = $dbconn->prepare(“update Cust set CustomerTel=? “); $statement->bindValue(1, “98765”); $statement->execute(); } catch(PDOException $e) { echo “FAILED: “ . $e->getMessage(); } ?> 

36 PHP Finding more information • General Information on PHP • http://www.php.net • PHP core user documentation • http://www.php.net/docs.php • PHP user mailing lists • http://www.php.net/mailing-lists.php • MVS-OE Forum – General discussion on z/OS Unix • http://www-03.ibm.com/servers/eserver/zseries/zos/unix/bpxa1dis.html • z/OS Unix Implementation of PHP • http://www- 03.ibm.com/servers/resources/servers_eserver_zseries_zos_unix_PHP_pdf _hphza200.pdf 

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38 Python Features of Python on z/OS USS • Python syntax is somewhat similar to the others, there are core differences like whitespace delimitation, no braces, etc • Normally well suited to most any task, however on USS only the CORE functionality has been ported. This is due to ASCII EBCIDIC issues • Rich set of API's unavailable, batteries not included… • Can access DB2, only sniff tested, at this point it can only be considered a toy 

39 Python Accessing DB2 on USS with Python #!/usr/bin/python import DB2 conn = DB2.connect(dsn='sample', uid='db2inst1', pwd='ibmdb2') curs = conn.cursor() curs.execute('select fname, lname from contacts where id=%s'%(id),) one_row = curs.fetchone() many_rows = curs.fetchmany(3) many_rows = curs.fetchall() curs.execute("insert into contacts values (?, ?, ?)", (fname, lname, addr curs.close() conn.close() 

40 Python Some Discourse • “How important is z/OS? I'm very skeptical of the viability of any OS that uses an encoding that is not a superset of ASCII.” - Guido Van Rossum • “As a non-ASCII platform, z/OS is certainly challenging for people used to modern conventions, and that is exactly why a familiar and easy-to-use tool like Python is so valuable there.” - Lauri Alanko 

41 Python Finding more information • General Information on Python • http://www.python.org • Python core user documentation • http://www.python.org/doc • Python user user lists • http://python.org/community/lists • z/OS Unix Implementation of Python • http://www.teaser.fr/~jymengant/mvspython/mvsPythonPort.html 

Conclusion Ready for the enterprise? 

Dynamic Languages Do they scale? • Size of project eg. lines of code • You can only manage so much complexity in a project • Many dynamic languages hide complexity in the language • The hidden cost here is the level of abstraction • So yes, you’ll have less lines of code for a ‘bigger’ project • IF YOU DO IT THE LANGUAGES WAY • Capacity handling, it needs to scale to X requests per second • Well, it depends on X … • Terrible answer but use it • If you need a certain functionality with a lower upfront cost • You don’t have time to develop scaffolding • Batteries Included comes at the cost of speed – just measure that cost 

Which should I choose? • Personal preference is a strong factor between these languages • When it comes to core qualities they all add, subtract, divide and fetch URLs for you • Structure and style of the code does vary • Some languages do have features that make them more suited for particular tasks • Bigger differences often come in the libraries and frameworks (quantity and quality) that are available for the language. • A developer must weigh their project needs against the available frameworks, along with their personal preferences 

Final Thought "From each language, according to its abilities, to each project, according to its needs.*“ – Karl Marx *Oh, except Perl. Perl just sucks, period. 

Other Materials • PHP • http://www- 03.ibm.com/servers/resources/servers_eserver_zseries_zos_unix_PHP_pdf_hphza2 00.pdf • PERL • http://www- 03.ibm.com/servers/resources/servers_eserver_zseries_zos_unix_perl_pdf_hpeza2 00.pdf • Background Materials • (zAMP presentation) • http://www.share.org/EventDocuments/tabid/323/Default.aspx?document=proceedings/SHARE_in_Orlando/ S8524XX153116.pdf • (open source presentation) • http://ew.share.org/client_files/callpapers/attach/SHARE_in_San_Jose/S9200JE141546.pdf • Dynamic vs. Static • http://townx.org/files/dynamic_languages.pdf 

Delicious Links • http://delicious.com/mattfinlayson • All my references are publicly available on this page • Feel free to follow up with questions, if I don’t know I’ll try to find someone who does • [email protected] • Thank You! 

Questions