oracular (3) Web::Machine::Manual.3pm.gz

Provided by: libweb-machine-perl_0.17-4_all bug

NAME
       Web::Machine::Manual - Learn how to use Web::Machine


VERSION
       version 0.17


Web::Machine IN A NUTSHELL
       The basic idea behind "Web::Machine" is that the handling of a web request is implemented as a state
       machine. If you're not familiar with state machines, think of a flowchart. We look at the request and the
       resource we provide and ask questions about them. Is our service available? Is this a GET, POST, PUT,
       etc.? Does the request ask for a content type our resource provides?

       The result of each question leads us to the next state (or flowchart box). Eventually we reach a point
       where we have a response for the client. Since this is all built on top of Plack and PSGI
       <http://plackperl.org/>, the response consists of a status code, some headers, and an optional body.

       The best way to understand the full request/response cycle is to look at the original Erlang webmachine
       state diagram <https://github.com/basho/webmachine/wiki/Diagram>. Each diamond in that diagram
       corresponds to a method that your Web::Machine::Resource subclass can implement. The return value from
       your method determines what method to call next.

       However, unlike on that diagram, we often support return values beyond simple true/false values for
       methods. The Web::Machine::Resource documentation describes what each method can return.


Web::Machine and Plack
       "Web::Machine" is built on top of Plack and follows the PSGI <http://plackperl.org/> spec. You can mix
       "Web::Machine" applications with other Plack applications using standard Plack tools like Plack::Builder.

   Web::Machine and Plack Middleware
       Since "Web::Machine" implements the complete request and response cycle, some Plack middleware is not
       really needed with "Web::Machine". For example, it wouldn't make sense to use something like
       "Plack::Middleware::XSLT" with "Web::Machine". "Web::Machine" implements the full content negotiation
       process, so if you want to handle requests for "text/html" it probably makes more sense to do this in
       your resources. The benefit of doing so is that with "Web::Machine" you can easily ensure that you return
       a proper "406 Not Acceptable" status for content types you can't handle.

       There are still many pieces of Plack middleware that are useful with "Web::Machine", such as logging
       middleware, debugging/linting middleware, etc.

       That all said, "Web::Machine" won't break if you use an inappropriate middleware; you'll just lose some
       of the benefits you get from implementing things the "Web::Machine" way.

   Bodies Must be Bytes
       The PSGI spec requires that the body you return contain bytes, not Perl characters. In other words,
       strings you return must be passed through "Encode::encode" so that Perl interprets their contents as
       bytes.

       If your data is not binary or ASCII, your resource should make sure to provide charset_provided() and
       default_charset() methods. This will make sure that "Web::Machine" knows how to turn your response bodies
       into bytes.

       CAVEAT: Note that currently "Web::Machine" does not provide full charset or encoding support when the
       body is returned as a CODE ref. This is a bug to be remedied in the future, but currently you are
       responsible for making sure this code ref returns bytes.


SUPPORT
       bugs may be submitted through <https://github.com/houseabsolute/webmachine-perl/issues>.


AUTHORS
       •   Stevan Little <stevan@cpan.org>

       •   Dave Rolsky <autarch@urth.org>


       This software is copyright (c) 2016 by Infinity Interactive, Inc.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
       programming language system itself.