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NAME
Event::RPC - Event based transparent Client/Server RPC framework
SYNOPSIS
#-- Server Code
use Event::RPC::Server;
use My::TestModule;
my $server = Event::RPC::Server->new (
port => 5555,
classes => { "My::TestModule" => { ... } },
);
$server->start;
----------------------------------------------------------
#-- Client Code
use Event::RPC::Client;
my $client = Event::RPC::Client->new (
server => "localhost",
port => 5555,
);
$client->connect;
#-- Call methods of My::TestModule on the server
my $obj = My::TestModule->new ( foo => "bar" );
my $foo = $obj->get_foo;
ABSTRACT
Event::RPC supports you in developing Event based networking
client/server applications with transparent object/method access from
the client to the server. Network communication is optionally encrypted
using IO::Socket::SSL. Several event loop managers are supported due to
an extensible API. Currently Event, Glib and AnyEvent are implemented.
The latter lets you use nearly every event loop implementation available
for Perl. AnyEvent was invented after Event::RPC was created and thus
Event::RPC started using it's own abstraction model.
DESCRIPTION
Event::RPC consists of a server and a client library. The server exports
a list of classes and methods, which are allowed to be called over the
network. More specific it acts as a proxy for objects created on the
server side (on demand of the connected clients) which handles client
side methods calls with transport of method arguments and return values.
The object proxy handles refcounting and destruction of objects created
by clients properly. Objects as method parameters and return values are
handled as well (although with some limitations, see below).
For the client the whole thing is totally transparent - once connected
to the server it doesn't know whether it calls methods on local or
remote objects.
Also the methods on the server newer know whether they are called
locally or from a connected client. Your application logic is not
affected by Event::RPC at all, at least if it has a rudimentary clean OO
design.
For details on implementing servers and clients please refer to the man
pages of Event::RPC::Server and Event::RPC::Client.
REQUIREMENTS
Event::RPC needs either one of the following modules on the server
(they're not necessary on the client):
Event
Glib
AnyEvent
They're needed for event handling resp. mainloop implementation. If you
like to use SSL encryption you need to install
IO::Socket::SSL
Event::RPC needs minimum one of the following modules for data
serialisation:
Sereal (::Decoder and ::Encoder)
CBOR::XS
JSON::XS
Storable
Server and client negotiate automatically which serialiser to use to
achieve maximum compatibility.
Some words about the Storable module: it's known to be insecure, so
Event::RPC uses it as the last option. You can even prevent Event::RPC
from using it at all (even when it's installed, which is the case for
nearly every Perl installation) - check manpages of Event::Server and
Event::Client about the details.
In case you use Storable take care that both client and server use
exactly the same version of the Storable module! Otherwise Event::RPC
client/server communication will fail badly.
INSTALLATION
You get the latest installation tarballs and online documentation at
this location:
http://www.exit1.org/Event-RPC/
If your system meets the requirements mentioned above, installation is
just:
perl Makefile.PL
make test
make install
To test a specific Event loop implementation, export the variable
EVENT_RPC_LOOP:
export EVENT_RPC_LOOP=Event::RPC::Loop::Glib
make test
Otherwise Event::RPC will fallback to the most appropriate module
installed on your system.
EXAMPLES
The tarball includes an examples/ directory which contains two programs:
server.pl
client.pl
Just execute them with --help to get the usage. They do some very simple
communication but are good to test your setup, in particular in a mixed
environment.
LIMITATIONS
Although the classes and objects on the server are accessed
transparently by the client there are some limitations should be aware
of. With a clean object oriented design these should be no problem in
real applications:
Direct object data manipulation is forbidden
All objects reside on the server and they keep there! The client just
has specially wrapped proxy objects, which trigger the necessary magic
to access the object's methods on the server. Complete objects are never
transferred from the server to the client, so something like this does
not work:
$object->{data} = "changed data";
(assuming $object is a hash ref on the server).
Only method calls are transferred to the server, so even for "simple"
data manipulation a method call is necessary:
$object->set_data ("changed data");
As well for reading an object attribute. Accessing a hash key will fail:
my $data = $object->{data};
Instead call a method which returns the 'data' member:
my $data = $object->get_data;
Methods may exchange objects, but not in a too complex structure
Event::RPC handles methods which return objects. The only requirement is
that they are declared as a Object returner on the server (refer to
Event::RPC::Server for details), but not if the object is hidden inside
a deep complex data structure.
An array or hash ref of objects is Ok, but not more. This would require
to much expensive runtime data inspection.
Object receiving parameters are more restrictive, since even hiding them
inside one array or hash ref is not allowed. They must be passed as a
direkt argument of the method subroutine.
AUTHORS
Jörn Reder <joern AT zyn.de>
COPYRIGHT AND LICENSE
Copyright (C) 2005-2015 by Jörn Reder <joern AT zyn.de>.
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
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