NAME

DBD::Gofer::Transport::Base - base class for DBD::Gofer client transports

SYNOPSIS

  my $remote_dsn = "..."
  DBI->connect("dbi:Gofer:transport=...;url=...;timeout=...;retry_limit=...;dsn=$remote_dsn",...)

or, enable by setting the DBI_AUTOPROXY environment variable:

  export DBI_AUTOPROXY='dbi:Gofer:transport=...;url=...'

which will force all DBI connections to be made via that Gofer server.

DESCRIPTION

This is the base class for all DBD::Gofer client transports.

ATTRIBUTES

Gofer transport attributes can be specified either in the attributes parameter of the connect() method call, or in the DSN string. When used in the DSN string, attribute names don't have the go_ prefix.

go_dsn

The full DBI DSN that the Gofer server should connect to on your behalf.

When used in the DSN it must be the last element in the DSN string.

go_timeout

A time limit for sending a request and receiving a response. Some drivers may implement sending and receiving as separate steps, in which case (currently) the timeout applies to each separately.

If a request needs to be resent then the timeout is restarted for each sending of a request and receiving of a response.

go_retry_limit

The maximum number of times an request may be retried. The default is 2.

go_retry_hook

This subroutine reference is called, if defined, for each response received where $response->err is true.

The subroutine is pass three parameters: the request object, the response object, and the transport object.

If it returns an undefined value then the default retry behaviour is used. See RETRY ON ERROR below.

If it returns a defined but false value then the request is not resent.

If it returns true value then the request is resent, so long as the number of retries does not exceed go_retry_limit.

RETRY ON ERROR

The default retry on error behaviour is:

 - Retry if the error was due to DBI_GOFER_RANDOM. See L<DBI::Gofer::Execute>.

 - Retry if $request->is_idempotent returns true. See L<DBI::Gofer::Request>.

A retry won't be allowed if the number of previous retries has reached go_retry_limit.

TRACING

Tracing of gofer requests and reponses can be enabled by setting the DBD_GOFER_TRACE environment variable. A value of 1 gives a reasonably compact summary of each request and response. A value of 2 or more gives a detailed, and voluminous, dump.

The trace is written using DBI->trace_msg() and so is written to the default DBI trace output, which is usually STDERR.

AUTHOR

Tim Bunce, http://www.tim.bunce.name

LICENCE AND COPYRIGHT

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