NAME¶
Event::RPC::Client - Client API to connect to Event::RPC Servers
SYNOPSIS¶
use Event::RPC::Client;
my $rpc_client = Event::RPC::Client->new (
#-- Required arguments
host => "localhost",
port => 5555,
#-- Optional arguments
classes => [ "Event::RPC::Test" ],
class_map => { "Event::RPC::Test" => "My::Event::RPC::Test" },
ssl => 1,
ssl_ca_file => "some/ca.crt",
ssl_ca_path => "some/ca/dir",
timeout => 10,
auth_user => "fred",
auth_pass => Event::RPC->crypt("fred",$password),
error_cb => sub {
my ($client, $error) = @_;
print "An RPC error occured: $error\n";
$client->disconnect;
exit;
},
);
$rpc_client->set_max_packet_size(2*1024*1024*1024);
$rpc_client->connect;
#-- And now use classes and methods to which the
#-- server allows access via RPC, here My::TestModule
#-- from the Event::RPC::Server manpage SYNPOSIS.
my $obj = My::TestModule->new( data => "foobar" );
print "obj says hello: ".$obj->hello."\n";
$obj->set_data("new foobar");
print "updated data: ".$obj->get_data."\n";
$rpc_client->disconnect;
DESCRIPTION¶
Use this module to write clients accessing objects and methods exported by a
Event::RPC driven server.
Just connect to the server over the network, optionally with SSL and user
authentication, and then simply use the exported classes and methods like
having them locally in the client.
General information about the architecture of Event::RPC driven applications is
collected in the Event::RPC manpage.
The following documentation describes the client connection options in detail.
CONFIGURATION OPTIONS¶
You need to specify at least the server hostname and TCP port to connect a
Event::RPC server instance. If the server requires a SSL connection or user
authentication you need to supply the corresponding options as well, otherwise
connecting will fail.
All options described here may be passed to the
new() constructor of
Event::RPC::Client. As well you may set or modify them using set_OPTION style
mutators, but not after
connect() was called! All options may be read
using get_OPTION style accessors.
REQUIRED OPTIONS¶
These are necessary to connect the server:
- server
- This is the hostname of the server running Event::RPC::Server. Use a IP
address or DNS name here.
- port
- This is the TCP port the server is listening to.
NETWORK OPTIONS¶
- timeout
- Specify a timeout (in seconds), which is applied when connecting the
server.
CLASS IMPORT OPTION¶
- classes
- This is reference to a list of classes which should be imported into the
client. You get a warning if you request a class which is not exported by
the server.
By default all server classes are imported. Use this feature if your server
exports a huge list of classes, but your client doesn't need all of them.
This saves memory in the client and connect performance increases.
- class_map
- Optionally you can map the class names from the server to a different name
on the local client using the class_map hash.
This is necessary if you like to use the same classes locally and remotely.
Imported classes from the server are by default registered under the same
name on the client, so this conflicts with local classes named
identically.
On the client you access the remote classes under the name assigned in the
class map. For example with this map
class_map => { "Event::ExecFlow::Job" => "_srv::Event::ExecFlow::Job" }
you need to write this on the client, if you like to create an object
remotely on the server:
my $server_job = _srv::Event::ExecFlow::Job->new ( ... );
and this to create an object on the client:
my $client_job = Event::ExecFlow::Job->new ( ... );
The server knows nothing of the renaming on client side, so you still write
this on the server to create objects there:
my $job = Event::ExecFlow::Job->new ( ... );
SSL OPTIONS¶
If the server accepts only SSL connections you need to enable ssl here in the
client as well. By default the SSL connection will be established without any
peer verification, which makes Man-in-the-Middle attacks possible. If you want
to prevent that, you need to set either
ssl_ca_file or
ssl_ca_path option.
- ssl
- Set this option to 1 to encrypt the network connection using SSL.
- ssl_ca_file
- Path to the the Certificate Authority's certificate file (ca.crt), your
server key was signed with.
- ssl_ca_path
- Path of a directory containing several trusted certificates with a proper
index. Please refer to the OpenSSL documentation for details about setting
up such a directory.
AUTHENTICATION OPTIONS¶
If the server requires user authentication you need to set the following
options:
- auth_user
- A valid username.
- auth_pass
- The corresponding password, encrypted using Perl's crypt()
function, using the username as the salt.
Event::RPC has a convenience function for generating such a crypted
password, although it's currently just a wrapper around Perl's builtin
crypt() function, but probably this changes someday, so better use
this method:
$crypted_pass = Event::RPC->crypt($user, $pass);
If the passed credentials are invalid the Event::RPC::Client->
connect() method throws a correspondent exception.
ERROR HANDLING¶
Any exceptions thrown on the server during execution of a remote method will
result in a corresponding exception on the client. So you can use normal
exception handling with eval {} when executing remote methods.
But besides this the network connection between your client and the server may
break at any time. This raises an exception as well, but you can override this
behaviour with the following attribute:
- error_cb
- This subroutine is called if any error occurs in the network communication
between the client and the server. The actual Event::RPC::Client object
and an error string are passed as arguments.
This is no generic exception handler for exceptions thrown from the
executed methods on the server! If you like to catch such exceptions you
need to put an eval {} around your method calls, as you would do for local
method calls.
If you don't specify an error_cb an exception is thrown instead.
METHODS¶
- $rpc_client->connect
- This establishes the configured connection to the server. An exception is
thrown if something goes wrong, e.g. server not available, credentials are
invalid or something like this.
- $rpc_client->disconnect
- Closes the connection to the server. You may omit explicit disconnecting
since it's done automatically once the Event::RPC::Client object gets
destroyed.
- $rpc_client->set_max_packet_size ( $bytes )
- By default Event::RPC does not handle network packages which exceed 2 GB
in size (was 4 MB with version 1.04 and earlier).
You can change this value using this method at any time, but 4 GB is the
maximum. An attempt of the server to send a bigger packet will be aborted
and reported as an exception on the client and logged as an error message
on the server.
Note: you have to set the same value on client and server side!
- $rpc_client->get_max_packet_size
- Returns the currently active max packet size.
READY ONLY ATTRIBUTES¶
- $rpc_client->get_server_version
- Returns the Event::RPC version number of the server after connecting.
- $rpc_client->get_server_protocol
- Returns the Event::RPC protocol number of the server after
connecting.
- $rpc_client->get_client_version
- Returns the Event::RPC version number of the client.
- $rpc_client->get_client_protocol
- Returns the Event::RPC protocol number of the client.
AUTHORS¶
Joern Reder <joern at zyn dot de>
COPYRIGHT AND LICENSE¶
Copyright (C) 2002-2006 by Joern Reder, All Rights Reserved.
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.