Editing Portal:SaaS and Web Development (section)

=== PSGI and Plack ===

A major modernization of Perl web deployment came with '''PSGI''' and '''Plack'''. The official Plack site describes PSGI as an interface between Perl web applications and web servers, and Plack as a Perl module and toolkit containing PSGI middleware, helpers, and adapters to web servers. It also notes that PSGI and Plack were inspired by Python’s WSGI and Ruby’s Rack.<ref>Plack/PSGI, https://plackperl.org/, accessed July 3, 2026.</ref>

Perl.org describes Plack as “Perl superglue for web frameworks and web servers,” sitting between application code and the web server so that applications and frameworks do not need to worry about server-specific details.<ref>Perl.org, “Perl web development - Plack/PSGI,” https://www.perl.org/about/whitepapers/perl-plack.html, accessed July 3, 2026.</ref>

PSGI changed Perl web development by creating a common deployment interface. A PSGI application could run under different servers and environments without being rewritten. Plack middleware could add behavior such as sessions, debugging, logging, static-file handling, authentication layers, error pages, and testing support.

This was an important correction to the fragmentation of earlier Perl web deployment. CGI, mod_perl, FastCGI, standalone servers, and framework-specific servers all had different expectations. PSGI gave Perl web applications a more portable target.

PSGI also made testing and development easier. A developer could run an application locally with `plackup`, test it as a Perl object, wrap it with middleware, and deploy it behind a real server later.