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Sub-Spec-HTTP-Server-0.12
++
/ Sub::Spec::HTTP::Server

NAME

Sub::Spec::HTTP::Server - PSGI application to serve remote (HTTP) subroutine call requests

VERSION

version 0.12

SYNOPSIS

Suppose you want to expose functions in My::API::Adder and My::API::Adder::Array as HTTP API functions, using URL http://<host>/api/<module>/<func>:

 package My::API::Adder;
 our %SPEC;
 $SPEC{add} = {args => {a=>["float*"=>{arg_pos=>0}],
                        b=>["float*"=>{arg_pos=>1}]}};
 sub add { my %args=@_; [200, "OK", $args{a}+$args{b}] }
 1;

 package My::API::Adder::Array;
 $SPEC{add_array} = {

     summary => 'Concatenate two arrays together',
     args => {a1=>["array*" => {summary => 'First array'}],
              a2=>["array*" => {summary => 'Second array'}]},
 };
 sub add { my %args=@_; [200, "OK", [@{$args{a1}}, @{$args{a2}}]] }
 1;

 # or just write any normal Perl module without any specs

Then:

 $ servepm My::API::Adder My::API::Adder::Array

Then call your functions over HTTP(S)?:

 % curl http://localhost:5000/api/My::API::Adder/add/2/3
 [200,"OK",6]

 % curl -H 'X-SS-Req-Log-Level: trace' \
   'http://localhost:5000/api/My::API::Adder::Array/add?a1:j=[1]&a2:j=[2,3]'
 [200,"OK",[1,2,3]]

Request help/usage information:

 % curl -H 'X-SS-Req-Command: help' \
   'http://localhost:5000/api/My::API::Adder::Array/add'
 My::API::Adder::Array::add - Concatenate two arrays together

 Arguments:
   a1   (array, required) First array
   a2   (array, required) Second array

List available function in a module (request key 'command' given in request variable):

 % curl 'http://localhost:5000/api/My::API::Adder?-ss-req-command=list_subs'
 ['add']

List available modules:

 % curl -H 'X-SS-Req-Command: list_mods' \
   'http://localhost:5000/api/'
 ['My::API::Adder','My::API::Adder::Array']

DESCRIPTION

NOTICE: This module and the Sub::Spec standard is deprecated as of Jan 2012. Rinci is the new specification to replace Sub::Spec, it is about 95% compatible with Sub::Spec, but corrects a few issues and is more generic. Perinci::* is the Perl implementation for Rinci and many of its modules can handle existing Sub::Spec sub specs. Serabi (Perinci::HTTP::Server) supersedes this module.

Sub::Spec::HTTP::Server is a PSGI application to serve remote (HTTP) subroutine call requests. It is suitable for serving remote API. (Sorry for the slight confusion between "server" and "application"; this module was not originally PSGI-based.)

As the case with any PSGI application, you can use any PSGI server to run it with. But you might want to consider Gepok, which has built-in HTTPS support.

This PSGI application is actually a set of modular middlewares (Plack::Middleware::SubSpec::*) which you can compose in your app.psgi, configuring each one and including only the ones you need. The Synopsis shows one such basic composition. There are more middlewares to do custom stuffs. See each middleware's documentation for details.

This module uses Log::Any for logging.

This module uses Moo for object system.

FAQ

How can I customize URL?

For example, instead of:

 http://localhost:5000/api/My::API::Adder/func

you want:

 http://localhost:5000/adder/func

or perhaps (if you only have one module to expose):

 http://localhost:5000/func

You can do this by customizing uri_pattern when enabling SubSpec::ParseRequest middleware (see servepm source code). You just need to make sure that you produce $env->{"ss.request"}{uri} (and other necessary SS request keys).

I want to let user specify output format from URI (e.g. /api/json/... or /api/v1/yaml/...)

Again, this can be achieved by customizing the SubSpec::ParseRequest middleware. You can do something like:

 enable "SubSpec::ParseRequest"
     uri_pattern => qr!^/api/v1/(?<output_format>json|yaml)/
                       (?<module>[^?/]+)?
                       (?:/(?<sub>[^?/]+)?)!x;

or:

 enable "SubSpec::ParseRequest"
     uri_pattern => qr!^/api/v1/(?<fmt>j|y)/
                       (?<module>[^?/]+)?
                       (?:/(?<sub>[^?/]+)?)!x,
     after_parse => sub {
         my $env = shift;
         my $fmt = $env->{"ss.uri_pattern_matches"}{fmt};
         $env->{"ss.request"}{output_format} = $fmt =~ /j/ ? 'json' : 'yaml';
     };

I need even more custom URI syntax

You can leave uri_pattern empty and perform your custom URI parsing in after_parse. For example:

 enable "SubSpec::ParseRequest"
     after_parse => sub {
         my $env = shift;
         # parse $env->{REQUEST_URI} on your own and put the result in
         # $env->{"ss.request"}{uri}
     };

Or alternatively you can write your own request parser to replace ParseRequest.

I want to enable HTTPS.

Supply --https_ports, --ssl_key_file and --ssl_cert_file options in servepm.

I don't want to expose my subroutines and module structure directly!

Well, isn't exposing functions the whole point of API?

If you have modules that you do not want to expose as API, simply exclude it (e.g. using allowed_modules configuration in SubSpec::ParseRequest middleware. Or, create a set of wrapper modules to expose only the functionalities that you want to expose.

Or, if you have a custom mapping of "modules" and "subs" that are different than Perl's, I recommend you create a new Sub::Spec::URI::xxx implementation.

I want to support another output format (e.g. XML, MessagePack, etc).

Add a format_<fmtname> method to Plack::Middleware::SubSpec::HandleCommand. The method accepts sub response and is expected to return a tuplet ($output, $content_type).

Note that you do not have to modify the Plack/Middleware/SubSpec/HandleCommand.pm file itself. You can inject the method from another file.

Also make sure that the output format is allowed (see configuration allowed_output_formats in the command handler middleware).

I want to automatically reload modules that changed on disk.

Use one of the module-reloading module on CPAN, e.g.: Module::Reload or Module::Reload::Conditional.

I want to authenticate clients.

Enable Plack::Middleware::Auth::Basic (or other authen middleware you prefer) before SubSpec::ParseRequest.

I want to authorize clients.

Take a look at Plack::Middleware::SubSpec::Authz::ACL which allows authorization based on various conditions. Normally this is put after authentication and before command handling.

I want to support new commands.

Write Sub::Spec::HTTP::Server::Command::<cmdname>, and include the command in SubSpec::ParseRequest's allowed_commands configuration.

But first consider if that is really what you want. If you want to serve static files or do stuffs unrelated to calling subroutines or subroutine spec, you ought to put it somewhere else, e.g.:

 my $app = builder {
     mount "/api" => builder {
         enable "SubSpec::ParseRequest", ...;
         ...
     },
     mount "/static" => ...
 };

TIPS AND TRICKS

Proxying API server

Not only can you serve local modules ("pm://" URIs), you can serve remote modules ("http://" or "https://" URIs) making your API server a proxy for another.

Performance tuning

To be written.

TODO

* Improve performance.

SEE ALSO

Sub::Spec::HTTP

AUTHOR

Steven Haryanto <stevenharyanto@gmail.com>

COPYRIGHT AND LICENSE

This software is copyright (c) 2012 by Steven Haryanto.

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