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Middleware in PAGI

A port of the sample app from What Is Middleware? — which builds the same three-layer stack in Plack/PSGI (Perl) and Starlette/ASGI (Python) — to PAGI, an async, ASGI-style application interface for Perl.

The app is deliberately tiny but exercises the three things middleware exists to do:

1. Logger — wrap the request, time it, log method/path in and status/duration out.
2. Authenticator — inspect a header, inject context for downstream layers on

jjn1056

#!/usr/bin/env perl
# future-io-cancel-bug.pl
#
# Demonstrates a bug in Future::IO::Impl::IOAsync where cancelling a future
# that's waiting on a socket read doesn't properly clean up internal state.
#
# This is SELF-CONTAINED - no Redis or external server required.
#
# Run with different backends:
#   perl future-io-cancel-bug.pl              # defaults to IOAsync

jjn1056

Sketch to see if we can just use AUTOLOAD to inject into the
display object methods as needed ad hoc

# in this approach you have some named methods like $args
# and other methods use AUTOLOAD, defautl behavior is to call
# resolve_method_for_proxy($method) or if that doesn't exist
# dfaults to $obj->method.

# if you pass args to an AUTOLOADED method, that sets that
# method to have that value.

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use Future::AsyncAwait;

# Define an ASGI-like application as an anonymous async sub.
# This app checks the request scope and sends a response.

my $asgi_app = async sub ($scope, $receive, $send) {
    if ($scope->{type} eq 'http') {
        # Send the response start message.
        await $send->({
            type    => "http.response.start",

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#!/usr/bin/env perl

use strictures;
use PSGI::Syntax; #(signatures, etc. for example code)
use Future::AsyncAwait;
use Future;

### Basic ASGI App Implementation
async sub app($scope, $receive, $send) {
    if ($scope->{type} eq 'http') {

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import asyncio

# A simple logging middleware
class LoggingMiddleware:
    def __init__(self, app):
        self.app = app

    async def __call__(self, scope, receive, send):
        # Only handle HTTP requests for this example.
        if scope["type"] == "http":

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package MyApp::Model::Components::Counter;

use Moose;
extends 'CatalystX::Components:::DisplayModel';

has count => (is=>'rw', required=>1, default=>0, live=>1); #lifecycle=>'request|session'
  
sub increment($self) {
  my $current = $self->count;
  $self->count($current++);

jjn1056

Enhancing Perl Method Signatures with Attributes

Extending Perl to support attributes in method signatures, similar to frameworks like Java Spring, offers numerous benefits. This document details three well-detailed examples illustrating the advantages and use cases for this syntax extension, compares it to Spring's approach, and contrasts the two methodologies. Additionally, we include curl commands to demonstrate example requests and what the Perl code would do in response.

Improved Code Readability and Maintainability

Example: Automatically Binding Path Parameters

Current Approach in Perl: In frameworks like Mojolicious, routing and parameter extraction are typically separate.

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package Example::Web::Controller::TodoList;

use Moose;
use Example::Syntax;
use Modulo::PageController;  #  to get attributes, etc

has 'people' => (is=>'rw', context=>1);
has 'person' => (is=>'rw');

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my $ua = Mojo::UserAgent->new(max_response_size => 0);
	my $tx = $ua->build_tx(
		POST => 'https://api.openai.com/v1/chat/completions',
		+{
			Authorization => "Bearer $ENV{OPENAI_API_KEY}",
		},
		json => {
			model => "gpt-3.5-turbo",
			stream => \1,
   		messages => [