--- /dev/null
+---
+layout: default
+title: SimpleRPC Introduction
+toc: false
+---
+[WritingAgents]: /mcollective/reference/basic/basic_agent_and_client.html
+[SimpleRPCAgents]: /mcollective/simplerpc/agents.html
+[SimpleRPCClients]: /mcollective/simplerpc/clients.html
+[SimpleRPCAuditing]: /mcollective/simplerpc/auditing.html
+[SimpleRPCAuthorization]: /mcollective/simplerpc/authorization.html
+[DDL]: /mcollective/reference/plugins/ddl.html
+[SimpleRPCMessageFormat]: /mcollective/simplerpc/messageformat.html
+[RPCUtil]: /mcollective/reference/plugins/rpcutil.html
+[WritingAgentsScreenCast]: http://mcollective.blip.tv/file/3808928/
+[RestGateway]: http://github.com/puppetlabs/marionette-collective/blob/master/ext/mc-rpc-restserver.rb
+
+MCollective is a framework for writing feature full agents and clients and provides a [rich system to do that][WritingAgents]. MCollective's native Client though is very low level, a bit like TCP/IP is to HTTP. Like TCP/IP the native client does not provide any Authentication, Authorization etc.
+
+MCollective Simple RPC is a framework on top of the standard client that abstracts away a lot of the complexity and provides a lot of convention and standards. It's a bit like using HTTP ontop of TCP/IP to create REST services.
+
+SimpleRPC is a framework that provides the following:
+
+ * Provide simple conventions for writing [agents][SimpleRPCAgents] and [clients][SimpleRPCClients], favoring convention over custom design
+ * Very easy to write agents including input validation and a sensible feedback mechanism in case of error
+ * Provide [audit logging][SimpleRPCAuditing] abilities of calls to agents
+ * Provide the ability to do [fine grain Authorization][SimpleRPCAuthorization] of calls to agents and actions.
+ * Has a [Data Definition Language][DDL] used to describe agents and assist in giving hints to auto generating user interfaces.
+ * The provided generic calling tool should be able to speak to most compliant agents
+ * Should you need to you can still write your own clients, this should be very easy too
+ * Return data should be easy to print, in most cases the framework should be able to print a sensible output with a single, provided, function. The [DDL] is used here to improve the standard one-size-fits-all methods.
+ * The full capabilities of the standard Client classes shouldddl still be exposed in case you want to write advanced agents and clients
+ * A documented [standard message format][SimpleRPCMessageFormat] built ontop of the core format.
+
+
+We've provided full tutorials on [Writing Simple RPC Agents][SimpleRPCAgents] and [Clients][SimpleRPCClients]. There is also a [screencast that will give you a quick look at what is involved in writing agents][WritingAgentsScreenCast].
+
+
+A bit of code probably says more than lots of English, so here's a simple hello world Agent, it just echo's back everything you send it in the _:msg_ argument:
+
+{% highlight ruby linenos %}
+module MCollective
+ module Agent
+ class Helloworld<RPC::Agent
+ # Basic echo server
+ def echo_action
+ validate :msg, String
+
+ reply.data = request[:msg]
+ end
+ end
+ end
+end
+{% endhighlight %}
+
+The nice thing about using a standard abstraction for clients is that you often won't even need to write a client for it, we ship a standard client that you can use to call the agent above:
+
+{% highlight console %}
+ % mco rpc helloworld echo msg="Welcome to MCollective Simple RPC"
+ Determining the amount of hosts matching filter for 2 seconds .... 1
+
+ devel.your.com : OK
+ "Welcome to MCollective Simple RPC"
+
+
+
+ ---- rpctest#echo call stats ----
+ Nodes: 1
+ Start Time: Wed Dec 23 20:49:14 +0000 2009
+ Discovery Time: 0.00ms
+ Agent Time: 54.35ms
+ Total Time: 54.35ms
+{% endhighlight %}
+
+Note: This example is not complete. Please see the [agents][SimpleRPCAgents] and [clients][SimpleRPCClients] pages for a walkthrough.
+
+You could also use *mco rpc* like this and achieve the same result:
+
+{% highlight console %}
+ % mco rpc helloworld echo msg="Welcome to MCollective Simple RPC"
+{% endhighlight %}
+
+For multiple options just add more *key=val* pairs at the end
+
+But you can still write your own clients, it's incredibly simple, full details of a client is out of scope for the introduction - see the [SimpleRPCClients] page instead for full details - but here is some sample code to do the same call as above including full discovery and help output:
+
+{% highlight ruby linenos %}
+#!/usr/bin/ruby
+
+require 'mcollective'
+
+include MCollective::RPC
+
+mc = rpcclient("helloworld")
+
+printrpc mc.echo(:msg => "Welcome to MCollective Simple RPC")
+
+printrpcstats
+{% endhighlight %}
+
+With a standard interface come a lot of possibilities, just like the standard one-size-fits-all CLI client above you can make web interfaces, there's a [simple MCollective <-> REST bridge in the ext directory][RestGateway].
+
+A helper agent called [_rpcutil_][RPCUtil] is included that helps you gather stats, inventory etc about the running daemon.
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