RPyC

Architecture

RPyC gives the programmer a slave python interpreter at his or her control. In this essence, RPyC is different from other RPCs, that require registration of resources prior to accessing them. As a result, using RPyC is much more straightforward, but this comes at the expense of security (you cannot limit access). RPyC is intended to be used within a trusted network, there are various schemes including VPN for achieving this.

Once a client is connected to the server, it has one of two ways to perform remote operations:

• The modules property, that exposes the server's modules namespace: doc = conn.modules.sys.path or conn.modules["xml.dom.minidom"].parseString("<some>xml</some>").
• The execute function, that executes the given code on the server: conn.execute("print 'hello world'")

Remote operations return something called a NetProxy, which is an intermediate object that reflects any operation performed locally on it to the remote object. For example, conn.modules.sys.path is a NetProxy for the sys.path object of the server. Any local changes done to conn.modules.sys.path are reflected immediately on the remote object. Note: NetProxies are not used for simple objects, such as numbers and strings, which are immutable.

Async is a proxy wrapper, meaning, it takes a NetProxy and returns another that wraps it with asynchronous functionality. Operations done to an AsyncNetProxy return something called AsyncResult. These objects have a '.is_ready' predicate, '.result' property that holds the result (or blocks until it arrives), and '.on_ready' callback, which will be called when the result arrives.

Usage

Originally, RPyC was developed for managing distributed testing of products over a range of different platforms (all capable of running python). However, RPyC has evolved since then, and now its use cases include:

• Distributed computing (splitting workload between machines)
• Distributed testing (running tests that connect multiple platforms and abstracting hardware resources)
• Remote administration (tweaking config files from one central place, etc.)
• Tunneling or chaining (crossing over routable network boundaries)

Demo

<span id="mwSA"></span><span class="kn" id="mwSQ">import</span><span class="w" id="mwSg"> </span><span class="nn" id="mwSw">rpyc</span> <span class="n" id="mwTA">conn</span> <span class="o" id="mwTQ">=</span> <span class="n" id="mwTg">rpyc</span><span class="o" id="mwTw">.</span><span class="n" id="mwUA">classic</span><span class="o" id="mwUQ">.</span><span class="n" id="mwUg">connect</span><span class="p" id="mwUw">(</span><span class="s2" id="mwVA">"hostname"</span><span class="p" id="mwVQ">)</span> <span class="c1" id="mwVg"># assuming a classic server is running on 'hostname'</span> <span class="nb" id="mwVw">print</span><span class="p" id="mwWA">(</span><span class="n" id="mwWQ">conn</span><span class="o" id="mwWg">.</span><span class="n" id="mwWw">modules</span><span class="o" id="mwXA">.</span><span class="n" id="mwXQ">sys</span><span class="o" id="mwXg">.</span><span class="n" id="mwXw">path</span><span class="p" id="mwYA">)</span> <span class="n" id="mwYQ">conn</span><span class="o" id="mwYg">.</span><span class="n" id="mwYw">modules</span><span class="o" id="mwZA">.</span><span class="n" id="mwZQ">sys</span><span class="o" id="mwZg">.</span><span class="n" id="mwZw">path</span><span class="o" id="mwaA">.</span><span class="n" id="mwaQ">append</span><span class="p" id="mwag">(</span><span class="s2" id="mwaw">"lucy"</span><span class="p" id="mwbA">)</span> <span class="nb" id="mwbQ">print</span><span class="p" id="mwbg">(</span><span class="n" id="mwbw">conn</span><span class="o" id="mwcA">.</span><span class="n" id="mwcQ">modules</span><span class="o" id="mwcg">.</span><span class="n" id="mwcw">sys</span><span class="o" id="mwdA">.</span><span class="n" id="mwdQ">path</span><span class="p" id="mwdg">[</span><span class="o" id="mwdw">-</span><span class="mi" id="mweA">1</span><span class="p" id="mweQ">])</span> <span class="c1" id="mweg"># a version of 'ls' that runs remotely</span> <span class="k" id="mwew">def</span><span class="w" id="mwfA"> </span><span class="nf" id="mwfQ">remote_ls</span><span class="p" id="mwfg">(</span><span class="n" id="mwfw">path</span><span class="p" id="mwgA">):</span> <span class="n" id="mwgQ">ros</span> <span class="o" id="mwgg">=</span> <span class="n" id="mwgw">conn</span><span class="o" id="mwhA">.</span><span class="n" id="mwhQ">modules</span><span class="o" id="mwhg">.</span><span class="n" id="mwhw">os</span> <span class="k" id="mwiA">for</span> <span class="n" id="mwiQ">filename</span> <span class="ow" id="mwig">in</span> <span class="n" id="mwiw">ros</span><span class="o" id="mwjA">.</span><span class="n" id="mwjQ">listdir</span><span class="p" id="mwjg">(</span><span class="n" id="mwjw">path</span><span class="p" id="mwkA">):</span> <span class="n" id="mwkQ">stats</span> <span class="o" id="mwkg">=</span> <span class="n" id="mwkw">ros</span><span class="o" id="mwlA">.</span><span class="n" id="mwlQ">stat</span><span class="p" id="mwlg">(</span><span class="n" id="mwlw">ros</span><span class="o" id="mwmA">.</span><span class="n" id="mwmQ">path</span><span class="o" id="mwmg">.</span><span class="n" id="mwmw">join</span><span class="p" id="mwnA">(</span><span class="n" id="mwnQ">path</span><span class="p" id="mwng">,</span> <span class="n" id="mwnw">filename</span><span class="p" id="mwoA">))</span> <span class="nb" id="mwoQ">print</span><span class="p" id="mwog">(</span><span class="s2" id="mwow">"</span><span class="si" id="mwpA">%d</span><span class="se" id="mwpQ">\t</span><span class="si" id="mwpg">%d</span><span class="se" id="mwpw">\t</span><span class="si" id="mwqA">%s</span><span class="s2" id="mwqQ">"</span> <span class="o" id="mwqg">%</span> <span class="p" id="mwqw">(</span><span class="n" id="mwrA">stats</span><span class="o" id="mwrQ">.</span><span class="n" id="mwrg">st_size</span><span class="p" id="mwrw">,</span> <span class="n" id="mwsA">stats</span><span class="o" id="mwsQ">.</span><span class="n" id="mwsg">st_uid</span><span class="p" id="mwsw">,</span> <span class="n" id="mwtA">filename</span><span class="p" id="mwtQ">))</span> <span class="n" id="mwtg">remote_ls</span><span class="p" id="mwtw">(</span><span class="s2" id="mwuA">"/usr/bin"</span><span class="p" id="mwuQ">)</span> <span class="c1" id="mwug"># and exceptions...</span> <span class="k" id="mwuw">try</span><span class="p" id="mwvA">:</span> <span class="n" id="mwvQ">f</span> <span class="o" id="mwvg">=</span> <span class="n" id="mwvw">conn</span><span class="o" id="mwwA">.</span><span class="n" id="mwwQ">builtin</span><span class="o" id="mwwg">.</span><span class="n" id="mwww">open</span><span class="p" id="mwxA">(</span><span class="s2" id="mwxQ">"/non/existent/file/name"</span><span class="p" id="mwxg">)</span> <span class="k" id="mwxw">except</span> <span class="ne" id="mwyA">IOError</span><span class="p" id="mwyQ">:</span> <span class="k" id="mwyg">pass</span>

History

RPyC is based on the work of Eyal Lotem (a.k.a. Lotex) on PyInvoke, which is no longer maintained. The first public release was 1.20, which allowed for symmetric and transparent RPC, but not for asynchronous operation. Version 1.6, while never publicly released, added the concept of 'events', as a means for the server to inform the client. Version 2.X, the first release of which was 2.2, added thread synchronization and the Async concept, which can be used as a superset of events. Version 2.40 adds the execute method, that can be used to execute code on the other side of the connection directly. RPyC 3 is a complete rewrite of the library, adding a capability-based security model, explicit services, and various other improvements.