---
name: "LWP::Protocol"
section: "3pm"
platform: "linux"
package: "perl-libwww"
version: "6.83-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/LWP::Protocol"
---

# LWP::Protocol(3pm)

Base class for LWP protocols

## NAME

LWP::Protocol - Base class for LWP protocols

## SYNOPSIS

```
 package LWP::Protocol::foo;
 use parent qw(LWP::Protocol);
```

## DESCRIPTION

This class is used as the base class for all protocol implementations supported by the LWP library.

When creating an instance of this class using `LWP::Protocol::create($url)`, and you get an initialized subclass appropriate for that access method. In other words, the "create" in LWP::Protocol function calls the constructor for one of its subclasses.

All derived `"LWP::Protocol"` classes need to override the `request()` method which is used to service a request. The overridden method can make use of the `collect()` method to collect together chunks of data as it is received.

## METHODS

The following methods and functions are provided:

### new

```
    my $prot = LWP::Protocol->new();
```

The LWP::Protocol constructor is inherited by subclasses. As this is a virtual base class this method should **not** be called directly.

### create

```
    my $prot = LWP::Protocol::create($scheme)
```

Create an object of the class implementing the protocol to handle the given scheme. This is a function, not a method. It is more an object factory than a constructor. This is the function user agents should use to access protocols.

### implementor

```
    my $class = LWP::Protocol::implementor($scheme, [$class])
```

Get and/or set implementor class for a scheme.  Returns `''` if the specified scheme is not supported.

### request

```
    $response = $protocol->request($request, $proxy, undef);
    $response = $protocol->request($request, $proxy, '/tmp/sss');
    $response = $protocol->request($request, $proxy, \&callback, 1024);
    $response = $protocol->request($request, $proxy, $fh);
```

Dispatches a request over the protocol, and returns a response object. This method needs to be overridden in subclasses.  Refer to LWP::UserAgent for description of the arguments.

### collect

```
    my $res = $prot->collect(undef, $response, $collector); # stored in $response
    my $res = $prot->collect($filename, $response, $collector);
    my $res = $prot->collect(sub { ... }, $response, $collector);
```

Collect the content of a request, and process it appropriately into a scalar, file, or by calling a callback. If the first parameter is undefined, then the content is stored within the `$response`. If it's a simple scalar, then it's interpreted as a file name and the content is written to this file.  If it's a code reference, then content is passed to this routine. If it is a filehandle, or similar, such as a File::Temp object, content will be written to it.

The collector is a routine that will be called and which is responsible for returning pieces (as ref to scalar) of the content to process.  The `$collector` signals `"EOF"` by returning a reference to an empty string.

The return value is the HTTP::Response object reference.

**Note:** We will only use the callback or file argument if `"$response->is_success()"`.  This avoids sending content data for redirects and authentication responses to the callback which would be confusing.

### collect\_once

```
    $prot->collect_once($arg, $response, $content)
```

Can be called when the whole response content is available as content. This will invoke "collect" in LWP::Protocol with a collector callback that returns a reference to `$content` the first time and an empty string the next.

## SEE ALSO

Inspect the *LWP/Protocol/file.pm* and *LWP/Protocol/http.pm* files for examples of usage.

## COPYRIGHT

Copyright 1995-2001 Gisle Aas.

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