NAME

Message::Passing::Role::HasErrorChain - A role for components which can report errors

SYNOPSIS

# Note this is an example package, and does not really exist!
package Message::Passing::Output::ErrorAllMessages;
use Moo;
use namespace::clean -except => 'meta';

with qw/
    Message::Passing::Role::Output
    Message::Passing::Role::HasErrorChain
/;

sub consume {
    my ($self, $message) = @_;
    $self->error->consume($message);
}

DESCRIPTION

Some components can create an error stream in addition to a message stream.

METHODS

error

An attribute containing the error chain.

By default, this is a chain of:

Message::Passing::Filter::Encoder::JSON

Message::Passing::Output::STDOUT

WARNINGS

ERROR CHAINS CAN LOOP

If you override the error chain output, be sure that the error chain does not go into your normal log path! This is because if you suddenly have errors in your normal log path, and you then start logging these errors, this causes more errors - causing you to generate a message loop.

ENCODING IN ERROR CHAINS

If you emit something which cannot be encoded to an error chain then the encoding error will likely be emitted by the error chain - this can again cause loops and other issues.

All components which use error chains should be very careful to output data which they are entirely certain will be able to be encoded.

SPONSORSHIP

This module exists due to the wonderful people at Suretec Systems Ltd. <http://www.suretecsystems.com/> who sponsored its development for its VoIP division called SureVoIP <http://www.surevoip.co.uk/> for use with the SureVoIP API - <http://www.surevoip.co.uk/support/wiki/api_documentation>

AUTHOR, COPYRIGHT AND LICENSE

See Message::Passing.