Desperately Seeking a lightweight Perl web framework

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Desperately Seekinga lightweight Perl web
framework

• Peter Edwards

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Introduction

• Peter Edwards background

Subject

• Explain about the processes and decision making
  involved in assessing, selecting and using a Perl
  web framework

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Aims

• Learn what frameworks are out there
• Technical considerations
• Business tools for decision-making
• Audience What is your background and interest?

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Topics

• Define the problem
• Example requirements
• Attributes of frameworks
• Business decision making tools
• Architecture
• Application components
• Perl application frameworks
• Roll your own
• Summary

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Define the Problem

• Why do you need a web app?
• What functionality / how complex?no. screens,
  other features, e.g. search engine, integration
  to other apps/components/company infrastructure,
  server platform
• Business settingProject length, size Developer
  expertise, skill sets Integration to network,
  database type, existing frameworks e.g. ADS
  authentication Capacity plan - no. of users and
  required performance

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Example

• http//merlinfootball.com
• ComponentsFlash front end, sending XML
  transactions toPerl back endPerl XHTML admin
  system
• ElementsHuge volume of users and
  transactionsStreaming videoPicture upload and
  approval to galleryFAQ submission, approval and
  editing into FAQ list

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Attributes of Frameworks

• Size -gt complexity
• Learning curve
• Vertical vs. horizontal
• Functionality, flexibility
• Monotheistic/"One True Way" vs. agnostic
• Increased power, reduced performance
• Cost of testing new code 50 of time
• By extension DRY KISS

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Business Decision Making Tools

• The point of businessIncreased shareholder value
  - cash
• William of Occam, 14th century logician and
  Franciscan friarentia non sunt multiplicanda
  praeter necessitatementities should not be
  multiplied beyond necessity"All things being
  equal, the simplest solution tends to be the best
  one.It often happens that the best explanation
  is much more complicated than the simplest
  possible explanation because it requires fewer
  assumptions.
• Pareto Principle, by Joseph M. Juran named after
  Vilfredo Pareto, Italian economist"for many
  phenomena, 80 of the consequences stem from 20
  of the causes-- en.wikipedia.org
• Cost Benefit AnalysisEstimate days for
  developmentEstimate hidden costs and benefits
  e.g. of more stable frameworkCost comparison -gt
  decisionPerfection vs. pragmatism

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Architecture I

• Web ProtocolHTTP request/responseURI, REST, URL
  parameters http//server.com/client/view/FRED?vie
  wxmltabsallWeb 2.0, AJAX
• Web ServerApache, IIS, lighttpdCGI/mod_perl,
  FastCGI
• Controller ProcessingApache registry style
  stacked phase handlersMVC Model View
  ControllerSingle entry point vs. separate CGI

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Architecture II

• SessionCGISessionApacheSessionCatalystPlu
  ginSession -gt CacheFastMMap
• Security AuthenticationGroup permission
  rolesHTML field and SQL field encoding
• Database layerDirect DBISimple ClassDBIORM
  Object Relational Mapper DBIxClass
  RoseDBPerformance considerations - DBI 10-100x
  fasterData object attributes - data dictionary -
  screen dictionary

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Architecture III

• TemplatesTemplateToolkit (TT2) variable
  merge, not too complex, encourages using Perl in
  app modulesHTMLMason inline codePersonal
  preference understandable by Web
  designersXHTML, accessibility,
  internationalisation LocaleMaketextForm
  handling, CRUD from db object, validation
  DataFormValidatorRich components
  http//script.aculo.us/ http//dojotoolkit.org/
• Testingmodule unit test, business data object
  tests, Javascript/browser compatability
  checksTestMore TestWWWMechanize
  TestWWWSelenium

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Application Components

• Pre-built componentssave time in short term on
  testing may cost more long term integration
  costsPHPSession
• Language Repository Template ComponentPerl CPAN T
  T2 BricolagePHP PEAR Smarty CMSMSPython Built-i
  n Clearsilver Trac

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Perl Application Frameworks

• CGIApplication CGISession lightweight,
  easy to use, reliable, full control, open
• Watch out for CGIBuilder, based on CGIApp
  but used to have Makefile.PL that downloaded and
  eval'd code, also bizarre "Perlish" coding style
  use 5.006_001 use Carp
  CarpInternal__PACKAGE__
  CarpInternal__PACKAGE__.'_' use
  IOUtil
• CGIFrameworkfixed - glue between
  HTMLTemplate, CGISession, CGI,
  LocaleMaketext last release 11-Oct-2005
• Jifty one true way database mapper, template,
  web services, AJAX toolkit, handlers for FastCGI
  continuations, form-based dispatch "Jifty is the
  only web application framework that comes with a
  pony
• Gantry Bigtop Apache/mod_perl, MVC Bigtop -
  web application data language processor, app
  generator
• OpenInteract SPOPS Complex, slow, powerful,
  CMS-oriented permissions last release
  18-Mar-2005
• Catalystagnostic, MVC, complex, magic, powerful,
  slow (third time in NEXT/C3 OO extension), well
  tested Works well with DBIxClass and TT2 can
  also use ClassDBI, HTMLMason Many plugins for
  auth, XML etc.
• Maypole (ancestor of Catalyst) similar approach
  ClassDBI, TT2

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Roll Your Own

• "Not invented here" syndrome, AKA submitting a
  module to CPAN with "Lite" or "Plus" in the name.
• Can base on CGIApplication CGISession
• Or write one yourself. Easier than you'd think.
  Here's one written in a week, not pretty but
  delivered a project delivered fast and on time
  http//perl.dragonstaff.co.uk/app.zip

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Summary

• Processes and decision making
• requirements
• business context
• CBA decision basis
• technical considerations, architecture,
  constraints and features
• application components
• Perl application frameworks

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Where to Get More Information

• CPAN http//search.cpan.org
• Books
• Any Questions
• These slides are at http//perl.dragonstaff.co.uk/