doc/core/howto/tutorial/backends.html

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   3 <title>Twisted Documentation: The Evolution of Finger: pluggable backends</title>
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   6
   7   <body bgcolor="white">
   8     <h1 class="title">The Evolution of Finger: pluggable backends</h1>
   9     <div class="toc"><ol><li><a href="#auto0">Introduction</a></li><li><a href="#auto1">Another Back-end</a></li><li><a href="#auto2">Yet Another Back-end: Doing the Standard Thing</a></li></ol></div>
  10     <div class="content">
  11
  12 <span/>
  13
  14 <h2>Introduction<a name="auto0"/></h2>
  15
  16 <p> This is the fifth part of the Twisted tutorial <a href="index.html" shape="rect">Twisted from Scratch, or The Evolution of Finger</a>.</p>
  17
  18 <p>In this part we will add new several new backends to our finger service using
  19 the component-based architecture developed in <a href="components.html" shape="rect">The
  20 Evolution of Finger: moving to a component based architecture</a>. This will
  21 show just how convenient it is to implement new back-ends when we move to a
  22 component based architecture. Note that here we also use an interface we
  23 previously wrote, <code>FingerSetterFactory</code>, by supporting one single
  24 method. We manage to preserve the service's ignorance of the network.</p>
  25
  26 <h2>Another Back-end<a name="auto1"/></h2>
  27
  28 <div class="py-listing"><pre><p class="py-linenumber"> 1
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  47 </p><span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">internet</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">protocol</span>, <span class="py-src-variable">reactor</span>, <span class="py-src-variable">defer</span>, <span class="py-src-variable">utils</span>
  48 <span class="py-src-keyword">import</span> <span class="py-src-variable">pwd</span>
  49
  50 <span class="py-src-comment"># Another back-end</span>
  51
  52 <span class="py-src-keyword">class</span> <span class="py-src-identifier">LocalFingerService</span>(<span class="py-src-parameter">service</span>.<span class="py-src-parameter">Service</span>):
  53
  54     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IFingerService</span>)
  55
  56     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
  57     <span class="py-src-comment"># need a local finger daemon running for this to work</span>
  58         <span class="py-src-keyword">return</span> <span class="py-src-variable">utils</span>.<span class="py-src-variable">getProcessOutput</span>(<span class="py-src-string">&quot;finger&quot;</span>, [<span class="py-src-variable">user</span>])
  59
  60     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUsers</span>(<span class="py-src-parameter">self</span>):
  61         <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>([])
  62
  63
  64 <span class="py-src-variable">f</span> = <span class="py-src-variable">LocalFingerService</span>()
  65 </pre><div class="caption">Source listing - <a href="listings/finger/finger19b_changes.py"><span class="filename">listings/finger/finger19b_changes.py</span></a></div></div>
  66 <p>
  67 Full source code here: <div class="py-listing"><pre><p class="py-linenumber">  1
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 358 292
 359 </p><span class="py-src-comment"># Do everything properly, and componentize</span>
 360 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">application</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">internet</span>, <span class="py-src-variable">service</span>
 361 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">internet</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">protocol</span>, <span class="py-src-variable">reactor</span>, <span class="py-src-variable">defer</span>, <span class="py-src-variable">utils</span>
 362 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">words</span>.<span class="py-src-variable">protocols</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">irc</span>
 363 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">protocols</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">basic</span>
 364 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">python</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">components</span>
 365 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">web</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">resource</span>, <span class="py-src-variable">server</span>, <span class="py-src-variable">static</span>, <span class="py-src-variable">xmlrpc</span>
 366 <span class="py-src-keyword">from</span> <span class="py-src-variable">zope</span>.<span class="py-src-variable">interface</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">Interface</span>, <span class="py-src-variable">implements</span>
 367 <span class="py-src-keyword">import</span> <span class="py-src-variable">cgi</span>
 368 <span class="py-src-keyword">import</span> <span class="py-src-variable">pwd</span>
 369
 370 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IFingerService</span>(<span class="py-src-parameter">Interface</span>):
 371
 372     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">user</span>):
 373         <span class="py-src-string">&quot;&quot;&quot;
 374         Return a deferred returning a string.
 375         &quot;&quot;&quot;</span>
 376
 377     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUsers</span>():
 378         <span class="py-src-string">&quot;&quot;&quot;
 379         Return a deferred returning a list of strings.
 380         &quot;&quot;&quot;</span>
 381
 382
 383 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IFingerSetterService</span>(<span class="py-src-parameter">Interface</span>):
 384
 385     <span class="py-src-keyword">def</span> <span class="py-src-identifier">setUser</span>(<span class="py-src-parameter">user</span>, <span class="py-src-parameter">status</span>):
 386         <span class="py-src-string">&quot;&quot;&quot;
 387         Set the user's status to something.
 388         &quot;&quot;&quot;</span>
 389
 390
 391 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IFingerSetterService</span>(<span class="py-src-parameter">Interface</span>):
 392
 393     <span class="py-src-keyword">def</span> <span class="py-src-identifier">setUser</span>(<span class="py-src-parameter">user</span>, <span class="py-src-parameter">status</span>):
 394         <span class="py-src-string">&quot;&quot;&quot;
 395         Set the user's status to something.
 396         &quot;&quot;&quot;</span>
 397
 398
 399 <span class="py-src-keyword">def</span> <span class="py-src-identifier">catchError</span>(<span class="py-src-parameter">err</span>):
 400     <span class="py-src-keyword">return</span> <span class="py-src-string">&quot;Internal error in server&quot;</span>
 401
 402
 403 <span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerProtocol</span>(<span class="py-src-parameter">basic</span>.<span class="py-src-parameter">LineReceiver</span>):
 404
 405     <span class="py-src-keyword">def</span> <span class="py-src-identifier">lineReceived</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
 406         <span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">user</span>)
 407         <span class="py-src-variable">d</span>.<span class="py-src-variable">addErrback</span>(<span class="py-src-variable">catchError</span>)
 408         <span class="py-src-keyword">def</span> <span class="py-src-identifier">writeValue</span>(<span class="py-src-parameter">value</span>):
 409             <span class="py-src-variable">self</span>.<span class="py-src-variable">transport</span>.<span class="py-src-variable">write</span>(<span class="py-src-variable">value</span>+<span class="py-src-string">'\r\n'</span>)
 410             <span class="py-src-variable">self</span>.<span class="py-src-variable">transport</span>.<span class="py-src-variable">loseConnection</span>()
 411         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">writeValue</span>)
 412
 413
 414 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IFingerFactory</span>(<span class="py-src-parameter">Interface</span>):
 415
 416     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">user</span>):
 417         <span class="py-src-string">&quot;&quot;&quot;
 418         Return a deferred returning a string.
 419         &quot;&quot;&quot;</span>
 420
 421     <span class="py-src-keyword">def</span> <span class="py-src-identifier">buildProtocol</span>(<span class="py-src-parameter">addr</span>):
 422         <span class="py-src-string">&quot;&quot;&quot;
 423         Return a protocol returning a string.
 424         &quot;&quot;&quot;</span>
 425
 426
 427 <span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerFactoryFromService</span>(<span class="py-src-parameter">protocol</span>.<span class="py-src-parameter">ServerFactory</span>):
 428
 429     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IFingerFactory</span>)
 430
 431     <span class="py-src-variable">protocol</span> = <span class="py-src-variable">FingerProtocol</span>
 432
 433     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
 434         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
 435
 436     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
 437         <span class="py-src-keyword">return</span> <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">user</span>)
 438
 439 <span class="py-src-variable">components</span>.<span class="py-src-variable">registerAdapter</span>(<span class="py-src-variable">FingerFactoryFromService</span>,
 440                            <span class="py-src-variable">IFingerService</span>,
 441                            <span class="py-src-variable">IFingerFactory</span>)
 442
 443
 444 <span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerSetterProtocol</span>(<span class="py-src-parameter">basic</span>.<span class="py-src-parameter">LineReceiver</span>):
 445
 446     <span class="py-src-keyword">def</span> <span class="py-src-identifier">connectionMade</span>(<span class="py-src-parameter">self</span>):
 447         <span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span> = []
 448
 449     <span class="py-src-keyword">def</span> <span class="py-src-identifier">lineReceived</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">line</span>):
 450         <span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span>.<span class="py-src-variable">append</span>(<span class="py-src-variable">line</span>)
 451
 452     <span class="py-src-keyword">def</span> <span class="py-src-identifier">connectionLost</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">reason</span>):
 453         <span class="py-src-keyword">if</span> <span class="py-src-variable">len</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span>) == <span class="py-src-number">2</span>:
 454             <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">setUser</span>(*<span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span>)
 455
 456
 457 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IFingerSetterFactory</span>(<span class="py-src-parameter">Interface</span>):
 458
 459     <span class="py-src-keyword">def</span> <span class="py-src-identifier">setUser</span>(<span class="py-src-parameter">user</span>, <span class="py-src-parameter">status</span>):
 460         <span class="py-src-string">&quot;&quot;&quot;
 461         Return a deferred returning a string.
 462         &quot;&quot;&quot;</span>
 463
 464     <span class="py-src-keyword">def</span> <span class="py-src-identifier">buildProtocol</span>(<span class="py-src-parameter">addr</span>):
 465         <span class="py-src-string">&quot;&quot;&quot;
 466         Return a protocol returning a string.
 467         &quot;&quot;&quot;</span>
 468
 469
 470 <span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerSetterFactoryFromService</span>(<span class="py-src-parameter">protocol</span>.<span class="py-src-parameter">ServerFactory</span>):
 471
 472     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IFingerSetterFactory</span>)
 473
 474     <span class="py-src-variable">protocol</span> = <span class="py-src-variable">FingerSetterProtocol</span>
 475
 476     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
 477         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
 478
 479     <span class="py-src-keyword">def</span> <span class="py-src-identifier">setUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>, <span class="py-src-parameter">status</span>):
 480         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">setUser</span>(<span class="py-src-variable">user</span>, <span class="py-src-variable">status</span>)
 481
 482
 483 <span class="py-src-variable">components</span>.<span class="py-src-variable">registerAdapter</span>(<span class="py-src-variable">FingerSetterFactoryFromService</span>,
 484                            <span class="py-src-variable">IFingerSetterService</span>,
 485                            <span class="py-src-variable">IFingerSetterFactory</span>)
 486
 487 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IRCReplyBot</span>(<span class="py-src-parameter">irc</span>.<span class="py-src-parameter">IRCClient</span>):
 488
 489     <span class="py-src-keyword">def</span> <span class="py-src-identifier">connectionMade</span>(<span class="py-src-parameter">self</span>):
 490         <span class="py-src-variable">self</span>.<span class="py-src-variable">nickname</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">nickname</span>
 491         <span class="py-src-variable">irc</span>.<span class="py-src-variable">IRCClient</span>.<span class="py-src-variable">connectionMade</span>(<span class="py-src-variable">self</span>)
 492
 493     <span class="py-src-keyword">def</span> <span class="py-src-identifier">privmsg</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>, <span class="py-src-parameter">channel</span>, <span class="py-src-parameter">msg</span>):
 494         <span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>.<span class="py-src-variable">split</span>(<span class="py-src-string">'!'</span>)[<span class="py-src-number">0</span>]
 495         <span class="py-src-keyword">if</span> <span class="py-src-variable">self</span>.<span class="py-src-variable">nickname</span>.<span class="py-src-variable">lower</span>() == <span class="py-src-variable">channel</span>.<span class="py-src-variable">lower</span>():
 496             <span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">msg</span>)
 497             <span class="py-src-variable">d</span>.<span class="py-src-variable">addErrback</span>(<span class="py-src-variable">catchError</span>)
 498             <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">m</span>: <span class="py-src-string">&quot;Status of %s: %s&quot;</span> % (<span class="py-src-variable">msg</span>, <span class="py-src-variable">m</span>))
 499             <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">m</span>: <span class="py-src-variable">self</span>.<span class="py-src-variable">msg</span>(<span class="py-src-variable">user</span>, <span class="py-src-variable">m</span>))
 500
 501
 502 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IIRCClientFactory</span>(<span class="py-src-parameter">Interface</span>):
 503
 504     <span class="py-src-string">&quot;&quot;&quot;
 505     @ivar nickname
 506     &quot;&quot;&quot;</span>
 507
 508     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">user</span>):
 509         <span class="py-src-string">&quot;&quot;&quot;
 510         Return a deferred returning a string.
 511         &quot;&quot;&quot;</span>
 512
 513     <span class="py-src-keyword">def</span> <span class="py-src-identifier">buildProtocol</span>(<span class="py-src-parameter">addr</span>):
 514         <span class="py-src-string">&quot;&quot;&quot;
 515         Return a protocol.
 516         &quot;&quot;&quot;</span>
 517
 518
 519 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IRCClientFactoryFromService</span>(<span class="py-src-parameter">protocol</span>.<span class="py-src-parameter">ClientFactory</span>):
 520
 521     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IIRCClientFactory</span>)
 522
 523     <span class="py-src-variable">protocol</span> = <span class="py-src-variable">IRCReplyBot</span>
 524     <span class="py-src-variable">nickname</span> = <span class="py-src-variable">None</span>
 525
 526     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
 527         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
 528
 529     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
 530         <span class="py-src-keyword">return</span> <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">user</span>)
 531
 532 <span class="py-src-variable">components</span>.<span class="py-src-variable">registerAdapter</span>(<span class="py-src-variable">IRCClientFactoryFromService</span>,
 533                            <span class="py-src-variable">IFingerService</span>,
 534                            <span class="py-src-variable">IIRCClientFactory</span>)
 535
 536
 537 <span class="py-src-keyword">class</span> <span class="py-src-identifier">UserStatusTree</span>(<span class="py-src-parameter">resource</span>.<span class="py-src-parameter">Resource</span>):
 538
 539     <span class="py-src-variable">implements</span>(<span class="py-src-variable">resource</span>.<span class="py-src-variable">IResource</span>)
 540
 541     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
 542         <span class="py-src-variable">resource</span>.<span class="py-src-variable">Resource</span>.<span class="py-src-variable">__init__</span>(<span class="py-src-variable">self</span>)
 543         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
 544         <span class="py-src-variable">self</span>.<span class="py-src-variable">putChild</span>(<span class="py-src-string">'RPC2'</span>, <span class="py-src-variable">UserStatusXR</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>))
 545
 546     <span class="py-src-keyword">def</span> <span class="py-src-identifier">render_GET</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">request</span>):
 547         <span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUsers</span>()
 548         <span class="py-src-keyword">def</span> <span class="py-src-identifier">formatUsers</span>(<span class="py-src-parameter">users</span>):
 549             <span class="py-src-variable">l</span> = [<span class="py-src-string">'&lt;li&gt;&lt;a href=&quot;%s&quot;&gt;%s&lt;/a&gt;&lt;/li&gt;'</span> % (<span class="py-src-variable">user</span>, <span class="py-src-variable">user</span>)
 550                  <span class="py-src-keyword">for</span> <span class="py-src-variable">user</span> <span class="py-src-keyword">in</span> <span class="py-src-variable">users</span>]
 551             <span class="py-src-keyword">return</span> <span class="py-src-string">'&lt;ul&gt;'</span>+<span class="py-src-string">''</span>.<span class="py-src-variable">join</span>(<span class="py-src-variable">l</span>)+<span class="py-src-string">'&lt;/ul&gt;'</span>
 552         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">formatUsers</span>)
 553         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">request</span>.<span class="py-src-variable">write</span>)
 554         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">_</span>: <span class="py-src-variable">request</span>.<span class="py-src-variable">finish</span>())
 555         <span class="py-src-keyword">return</span> <span class="py-src-variable">server</span>.<span class="py-src-variable">NOT_DONE_YET</span>
 556
 557     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getChild</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">path</span>, <span class="py-src-parameter">request</span>):
 558         <span class="py-src-keyword">if</span> <span class="py-src-variable">path</span>==<span class="py-src-string">&quot;&quot;</span>:
 559             <span class="py-src-keyword">return</span> <span class="py-src-variable">UserStatusTree</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>)
 560         <span class="py-src-keyword">else</span>:
 561             <span class="py-src-keyword">return</span> <span class="py-src-variable">UserStatus</span>(<span class="py-src-variable">path</span>, <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>)
 562
 563 <span class="py-src-variable">components</span>.<span class="py-src-variable">registerAdapter</span>(<span class="py-src-variable">UserStatusTree</span>, <span class="py-src-variable">IFingerService</span>,
 564                            <span class="py-src-variable">resource</span>.<span class="py-src-variable">IResource</span>)
 565
 566
 567 <span class="py-src-keyword">class</span> <span class="py-src-identifier">UserStatus</span>(<span class="py-src-parameter">resource</span>.<span class="py-src-parameter">Resource</span>):
 568
 569     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>, <span class="py-src-parameter">service</span>):
 570         <span class="py-src-variable">resource</span>.<span class="py-src-variable">Resource</span>.<span class="py-src-variable">__init__</span>(<span class="py-src-variable">self</span>)
 571         <span class="py-src-variable">self</span>.<span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>
 572         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
 573
 574     <span class="py-src-keyword">def</span> <span class="py-src-identifier">render_GET</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">request</span>):
 575         <span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">user</span>)
 576         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">cgi</span>.<span class="py-src-variable">escape</span>)
 577         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">m</span>:
 578                       <span class="py-src-string">'&lt;h1&gt;%s&lt;/h1&gt;'</span>%<span class="py-src-variable">self</span>.<span class="py-src-variable">user</span>+<span class="py-src-string">'&lt;p&gt;%s&lt;/p&gt;'</span>%<span class="py-src-variable">m</span>)
 579         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">request</span>.<span class="py-src-variable">write</span>)
 580         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">_</span>: <span class="py-src-variable">request</span>.<span class="py-src-variable">finish</span>())
 581         <span class="py-src-keyword">return</span> <span class="py-src-variable">server</span>.<span class="py-src-variable">NOT_DONE_YET</span>
 582
 583
 584 <span class="py-src-keyword">class</span> <span class="py-src-identifier">UserStatusXR</span>(<span class="py-src-parameter">xmlrpc</span>.<span class="py-src-parameter">XMLRPC</span>):
 585
 586     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
 587         <span class="py-src-variable">xmlrpc</span>.<span class="py-src-variable">XMLRPC</span>.<span class="py-src-variable">__init__</span>(<span class="py-src-variable">self</span>)
 588         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
 589
 590     <span class="py-src-keyword">def</span> <span class="py-src-identifier">xmlrpc_getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
 591         <span class="py-src-keyword">return</span> <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">user</span>)
 592
 593
 594 <span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerService</span>(<span class="py-src-parameter">service</span>.<span class="py-src-parameter">Service</span>):
 595
 596     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IFingerService</span>)
 597
 598     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">filename</span>):
 599         <span class="py-src-variable">self</span>.<span class="py-src-variable">filename</span> = <span class="py-src-variable">filename</span>
 600         <span class="py-src-variable">self</span>.<span class="py-src-variable">users</span> = {}
 601
 602     <span class="py-src-keyword">def</span> <span class="py-src-identifier">_read</span>(<span class="py-src-parameter">self</span>):
 603         <span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>.<span class="py-src-variable">clear</span>()
 604         <span class="py-src-keyword">for</span> <span class="py-src-variable">line</span> <span class="py-src-keyword">in</span> <span class="py-src-variable">file</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">filename</span>):
 605             <span class="py-src-variable">user</span>, <span class="py-src-variable">status</span> = <span class="py-src-variable">line</span>.<span class="py-src-variable">split</span>(<span class="py-src-string">':'</span>, <span class="py-src-number">1</span>)
 606             <span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>.<span class="py-src-variable">strip</span>()
 607             <span class="py-src-variable">status</span> = <span class="py-src-variable">status</span>.<span class="py-src-variable">strip</span>()
 608             <span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>[<span class="py-src-variable">user</span>] = <span class="py-src-variable">status</span>
 609         <span class="py-src-variable">self</span>.<span class="py-src-variable">call</span> = <span class="py-src-variable">reactor</span>.<span class="py-src-variable">callLater</span>(<span class="py-src-number">30</span>, <span class="py-src-variable">self</span>.<span class="py-src-variable">_read</span>)
 610
 611     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
 612         <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>.<span class="py-src-variable">get</span>(<span class="py-src-variable">user</span>, <span class="py-src-string">&quot;No such user&quot;</span>))
 613
 614     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUsers</span>(<span class="py-src-parameter">self</span>):
 615         <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>.<span class="py-src-variable">keys</span>())
 616
 617     <span class="py-src-keyword">def</span> <span class="py-src-identifier">startService</span>(<span class="py-src-parameter">self</span>):
 618         <span class="py-src-variable">self</span>.<span class="py-src-variable">_read</span>()
 619         <span class="py-src-variable">service</span>.<span class="py-src-variable">Service</span>.<span class="py-src-variable">startService</span>(<span class="py-src-variable">self</span>)
 620
 621     <span class="py-src-keyword">def</span> <span class="py-src-identifier">stopService</span>(<span class="py-src-parameter">self</span>):
 622         <span class="py-src-variable">service</span>.<span class="py-src-variable">Service</span>.<span class="py-src-variable">stopService</span>(<span class="py-src-variable">self</span>)
 623         <span class="py-src-variable">self</span>.<span class="py-src-variable">call</span>.<span class="py-src-variable">cancel</span>()
 624
 625
 626 <span class="py-src-comment"># Another back-end</span>
 627
 628 <span class="py-src-keyword">class</span> <span class="py-src-identifier">LocalFingerService</span>(<span class="py-src-parameter">service</span>.<span class="py-src-parameter">Service</span>):
 629
 630     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IFingerService</span>)
 631
 632     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
 633     <span class="py-src-comment"># need a local finger daemon running for this to work</span>
 634         <span class="py-src-keyword">return</span> <span class="py-src-variable">utils</span>.<span class="py-src-variable">getProcessOutput</span>(<span class="py-src-string">&quot;finger&quot;</span>, [<span class="py-src-variable">user</span>])
 635
 636     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUsers</span>(<span class="py-src-parameter">self</span>):
 637         <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>([])
 638
 639
 640 <span class="py-src-variable">application</span> = <span class="py-src-variable">service</span>.<span class="py-src-variable">Application</span>(<span class="py-src-string">'finger'</span>, <span class="py-src-variable">uid</span>=<span class="py-src-number">1</span>, <span class="py-src-variable">gid</span>=<span class="py-src-number">1</span>)
 641 <span class="py-src-variable">f</span> = <span class="py-src-variable">LocalFingerService</span>()
 642 <span class="py-src-variable">serviceCollection</span> = <span class="py-src-variable">service</span>.<span class="py-src-variable">IServiceCollection</span>(<span class="py-src-variable">application</span>)
 643 <span class="py-src-variable">internet</span>.<span class="py-src-variable">TCPServer</span>(<span class="py-src-number">79</span>, <span class="py-src-variable">IFingerFactory</span>(<span class="py-src-variable">f</span>)
 644                    ).<span class="py-src-variable">setServiceParent</span>(<span class="py-src-variable">serviceCollection</span>)
 645 <span class="py-src-variable">internet</span>.<span class="py-src-variable">TCPServer</span>(<span class="py-src-number">8000</span>, <span class="py-src-variable">server</span>.<span class="py-src-variable">Site</span>(<span class="py-src-variable">resource</span>.<span class="py-src-variable">IResource</span>(<span class="py-src-variable">f</span>))
 646                    ).<span class="py-src-variable">setServiceParent</span>(<span class="py-src-variable">serviceCollection</span>)
 647 <span class="py-src-variable">i</span> = <span class="py-src-variable">IIRCClientFactory</span>(<span class="py-src-variable">f</span>)
 648 <span class="py-src-variable">i</span>.<span class="py-src-variable">nickname</span> = <span class="py-src-string">'fingerbot'</span>
 649 <span class="py-src-variable">internet</span>.<span class="py-src-variable">TCPClient</span>(<span class="py-src-string">'irc.freenode.org'</span>, <span class="py-src-number">6667</span>, <span class="py-src-variable">i</span>
 650                    ).<span class="py-src-variable">setServiceParent</span>(<span class="py-src-variable">serviceCollection</span>)
 651 </pre><div class="caption">Source listing - <a href="listings/finger/finger19b.tac"><span class="filename">listings/finger/finger19b.tac</span></a></div></div>
 652 </p>
 653
 654 <p>We've already written this, but now we get more for less work:
 655 the network code is completely separate from the back-end.</p>
 656
 657
 658 <h2>Yet Another Back-end: Doing the Standard Thing<a name="auto2"/></h2>
 659
 660 <div class="py-listing"><pre><p class="py-linenumber"> 1
 661  2
 662  3
 663  4
 664  5
 665  6
 666  7
 667  8
 668  9
 669 10
 670 11
 671 12
 672 13
 673 14
 674 15
 675 16
 676 17
 677 18
 678 19
 679 20
 680 21
 681 22
 682 23
 683 24
 684 25
 685 26
 686 27
 687 28
 688 29
 689 30
 690 31
 691 32
 692 </p><span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">internet</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">protocol</span>, <span class="py-src-variable">reactor</span>, <span class="py-src-variable">defer</span>, <span class="py-src-variable">utils</span>
 693 <span class="py-src-keyword">import</span> <span class="py-src-variable">pwd</span>
 694 <span class="py-src-keyword">import</span> <span class="py-src-variable">os</span>
 695
 696
 697 <span class="py-src-comment"># Yet another back-end</span>
 698
 699 <span class="py-src-keyword">class</span> <span class="py-src-identifier">LocalFingerService</span>(<span class="py-src-parameter">service</span>.<span class="py-src-parameter">Service</span>):
 700
 701     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IFingerService</span>)
 702
 703     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
 704         <span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>.<span class="py-src-variable">strip</span>()
 705         <span class="py-src-keyword">try</span>:
 706             <span class="py-src-variable">entry</span> = <span class="py-src-variable">pwd</span>.<span class="py-src-variable">getpwnam</span>(<span class="py-src-variable">user</span>)
 707         <span class="py-src-keyword">except</span> <span class="py-src-variable">KeyError</span>:
 708             <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-string">&quot;No such user&quot;</span>)
 709         <span class="py-src-keyword">try</span>:
 710             <span class="py-src-variable">f</span> = <span class="py-src-variable">file</span>(<span class="py-src-variable">os</span>.<span class="py-src-variable">path</span>.<span class="py-src-variable">join</span>(<span class="py-src-variable">entry</span>[<span class="py-src-number">5</span>],<span class="py-src-string">'.plan'</span>))
 711         <span class="py-src-keyword">except</span> (<span class="py-src-variable">IOError</span>, <span class="py-src-variable">OSError</span>):
 712             <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-string">&quot;No such user&quot;</span>)
 713         <span class="py-src-variable">data</span> = <span class="py-src-variable">f</span>.<span class="py-src-variable">read</span>()
 714         <span class="py-src-variable">data</span> = <span class="py-src-variable">data</span>.<span class="py-src-variable">strip</span>()
 715         <span class="py-src-variable">f</span>.<span class="py-src-variable">close</span>()
 716         <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-variable">data</span>)
 717
 718     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUsers</span>(<span class="py-src-parameter">self</span>):
 719         <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>([])
 720
 721
 722
 723 <span class="py-src-variable">f</span> = <span class="py-src-variable">LocalFingerService</span>()
 724 </pre><div class="caption">Source listing - <a href="listings/finger/finger19c_changes.py"><span class="filename">listings/finger/finger19c_changes.py</span></a></div></div>
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1031 </p><span class="py-src-comment"># Do everything properly, and componentize</span>
1032 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">application</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">internet</span>, <span class="py-src-variable">service</span>
1033 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">internet</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">protocol</span>, <span class="py-src-variable">reactor</span>, <span class="py-src-variable">defer</span>, <span class="py-src-variable">utils</span>
1034 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">words</span>.<span class="py-src-variable">protocols</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">irc</span>
1035 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">protocols</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">basic</span>
1036 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">python</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">components</span>
1037 <span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">web</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">resource</span>, <span class="py-src-variable">server</span>, <span class="py-src-variable">static</span>, <span class="py-src-variable">xmlrpc</span>
1038 <span class="py-src-keyword">from</span> <span class="py-src-variable">zope</span>.<span class="py-src-variable">interface</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">Interface</span>, <span class="py-src-variable">implements</span>
1039 <span class="py-src-keyword">import</span> <span class="py-src-variable">cgi</span>
1040 <span class="py-src-keyword">import</span> <span class="py-src-variable">pwd</span>
1041 <span class="py-src-keyword">import</span> <span class="py-src-variable">os</span>
1042
1043 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IFingerService</span>(<span class="py-src-parameter">Interface</span>):
1044
1045     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">user</span>):
1046         <span class="py-src-string">&quot;&quot;&quot;
1047         Return a deferred returning a string.
1048         &quot;&quot;&quot;</span>
1049
1050     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUsers</span>():
1051         <span class="py-src-string">&quot;&quot;&quot;
1052         Return a deferred returning a list of strings.
1053         &quot;&quot;&quot;</span>
1054
1055
1056 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IFingerSetterService</span>(<span class="py-src-parameter">Interface</span>):
1057
1058     <span class="py-src-keyword">def</span> <span class="py-src-identifier">setUser</span>(<span class="py-src-parameter">user</span>, <span class="py-src-parameter">status</span>):
1059         <span class="py-src-string">&quot;&quot;&quot;
1060         Set the user's status to something.
1061         &quot;&quot;&quot;</span>
1062
1063
1064 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IFingerSetterService</span>(<span class="py-src-parameter">Interface</span>):
1065
1066     <span class="py-src-keyword">def</span> <span class="py-src-identifier">setUser</span>(<span class="py-src-parameter">user</span>, <span class="py-src-parameter">status</span>):
1067         <span class="py-src-string">&quot;&quot;&quot;
1068         Set the user's status to something.
1069         &quot;&quot;&quot;</span>
1070
1071
1072 <span class="py-src-keyword">def</span> <span class="py-src-identifier">catchError</span>(<span class="py-src-parameter">err</span>):
1073     <span class="py-src-keyword">return</span> <span class="py-src-string">&quot;Internal error in server&quot;</span>
1074
1075
1076 <span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerProtocol</span>(<span class="py-src-parameter">basic</span>.<span class="py-src-parameter">LineReceiver</span>):
1077
1078     <span class="py-src-keyword">def</span> <span class="py-src-identifier">lineReceived</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
1079         <span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">user</span>)
1080         <span class="py-src-variable">d</span>.<span class="py-src-variable">addErrback</span>(<span class="py-src-variable">catchError</span>)
1081         <span class="py-src-keyword">def</span> <span class="py-src-identifier">writeValue</span>(<span class="py-src-parameter">value</span>):
1082             <span class="py-src-variable">self</span>.<span class="py-src-variable">transport</span>.<span class="py-src-variable">write</span>(<span class="py-src-variable">value</span>+<span class="py-src-string">'\r\n'</span>)
1083             <span class="py-src-variable">self</span>.<span class="py-src-variable">transport</span>.<span class="py-src-variable">loseConnection</span>()
1084         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">writeValue</span>)
1085
1086
1087 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IFingerFactory</span>(<span class="py-src-parameter">Interface</span>):
1088
1089     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">user</span>):
1090         <span class="py-src-string">&quot;&quot;&quot;
1091         Return a deferred returning a string.
1092         &quot;&quot;&quot;</span>
1093
1094     <span class="py-src-keyword">def</span> <span class="py-src-identifier">buildProtocol</span>(<span class="py-src-parameter">addr</span>):
1095         <span class="py-src-string">&quot;&quot;&quot;
1096         Return a protocol returning a string.
1097         &quot;&quot;&quot;</span>
1098
1099
1100 <span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerFactoryFromService</span>(<span class="py-src-parameter">protocol</span>.<span class="py-src-parameter">ServerFactory</span>):
1101
1102     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IFingerFactory</span>)
1103
1104     <span class="py-src-variable">protocol</span> = <span class="py-src-variable">FingerProtocol</span>
1105
1106     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
1107         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
1108
1109     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
1110         <span class="py-src-keyword">return</span> <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">user</span>)
1111
1112 <span class="py-src-variable">components</span>.<span class="py-src-variable">registerAdapter</span>(<span class="py-src-variable">FingerFactoryFromService</span>,
1113                            <span class="py-src-variable">IFingerService</span>,
1114                            <span class="py-src-variable">IFingerFactory</span>)
1115
1116
1117 <span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerSetterProtocol</span>(<span class="py-src-parameter">basic</span>.<span class="py-src-parameter">LineReceiver</span>):
1118
1119     <span class="py-src-keyword">def</span> <span class="py-src-identifier">connectionMade</span>(<span class="py-src-parameter">self</span>):
1120         <span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span> = []
1121
1122     <span class="py-src-keyword">def</span> <span class="py-src-identifier">lineReceived</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">line</span>):
1123         <span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span>.<span class="py-src-variable">append</span>(<span class="py-src-variable">line</span>)
1124
1125     <span class="py-src-keyword">def</span> <span class="py-src-identifier">connectionLost</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">reason</span>):
1126         <span class="py-src-keyword">if</span> <span class="py-src-variable">len</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span>) == <span class="py-src-number">2</span>:
1127             <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">setUser</span>(*<span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span>)
1128
1129
1130 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IFingerSetterFactory</span>(<span class="py-src-parameter">Interface</span>):
1131
1132     <span class="py-src-keyword">def</span> <span class="py-src-identifier">setUser</span>(<span class="py-src-parameter">user</span>, <span class="py-src-parameter">status</span>):
1133         <span class="py-src-string">&quot;&quot;&quot;
1134         Return a deferred returning a string.
1135         &quot;&quot;&quot;</span>
1136
1137     <span class="py-src-keyword">def</span> <span class="py-src-identifier">buildProtocol</span>(<span class="py-src-parameter">addr</span>):
1138         <span class="py-src-string">&quot;&quot;&quot;
1139         Return a protocol returning a string.
1140         &quot;&quot;&quot;</span>
1141
1142
1143 <span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerSetterFactoryFromService</span>(<span class="py-src-parameter">protocol</span>.<span class="py-src-parameter">ServerFactory</span>):
1144
1145     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IFingerSetterFactory</span>)
1146
1147     <span class="py-src-variable">protocol</span> = <span class="py-src-variable">FingerSetterProtocol</span>
1148
1149     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
1150         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
1151
1152     <span class="py-src-keyword">def</span> <span class="py-src-identifier">setUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>, <span class="py-src-parameter">status</span>):
1153         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">setUser</span>(<span class="py-src-variable">user</span>, <span class="py-src-variable">status</span>)
1154
1155
1156 <span class="py-src-variable">components</span>.<span class="py-src-variable">registerAdapter</span>(<span class="py-src-variable">FingerSetterFactoryFromService</span>,
1157                            <span class="py-src-variable">IFingerSetterService</span>,
1158                            <span class="py-src-variable">IFingerSetterFactory</span>)
1159
1160
1161 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IRCReplyBot</span>(<span class="py-src-parameter">irc</span>.<span class="py-src-parameter">IRCClient</span>):
1162
1163     <span class="py-src-keyword">def</span> <span class="py-src-identifier">connectionMade</span>():
1164         <span class="py-src-variable">self</span>.<span class="py-src-variable">nickname</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">nickname</span>
1165         <span class="py-src-variable">irc</span>.<span class="py-src-variable">IRCClient</span>.<span class="py-src-variable">connectionMade</span>(<span class="py-src-variable">self</span>)
1166
1167     <span class="py-src-keyword">def</span> <span class="py-src-identifier">privmsg</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>, <span class="py-src-parameter">channel</span>, <span class="py-src-parameter">msg</span>):
1168         <span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>.<span class="py-src-variable">split</span>(<span class="py-src-string">'!'</span>)[<span class="py-src-number">0</span>]
1169         <span class="py-src-keyword">if</span> <span class="py-src-variable">self</span>.<span class="py-src-variable">nickname</span>.<span class="py-src-variable">lower</span>() == <span class="py-src-variable">channel</span>.<span class="py-src-variable">lower</span>():
1170             <span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">msg</span>)
1171             <span class="py-src-variable">d</span>.<span class="py-src-variable">addErrback</span>(<span class="py-src-variable">catchError</span>)
1172             <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">m</span>: <span class="py-src-string">&quot;Status of %s: %s&quot;</span> % (<span class="py-src-variable">msg</span>, <span class="py-src-variable">m</span>))
1173             <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">m</span>: <span class="py-src-variable">self</span>.<span class="py-src-variable">msg</span>(<span class="py-src-variable">user</span>, <span class="py-src-variable">m</span>))
1174
1175
1176 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IIRCClientFactory</span>(<span class="py-src-parameter">Interface</span>):
1177
1178     <span class="py-src-string">&quot;&quot;&quot;
1179     @ivar nickname
1180     &quot;&quot;&quot;</span>
1181
1182     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">user</span>):
1183         <span class="py-src-string">&quot;&quot;&quot;
1184         Return a deferred returning a string.
1185         &quot;&quot;&quot;</span>
1186
1187     <span class="py-src-keyword">def</span> <span class="py-src-identifier">buildProtocol</span>(<span class="py-src-parameter">addr</span>):
1188         <span class="py-src-string">&quot;&quot;&quot;
1189         Return a protocol.
1190         &quot;&quot;&quot;</span>
1191
1192
1193 <span class="py-src-keyword">class</span> <span class="py-src-identifier">IRCClientFactoryFromService</span>(<span class="py-src-parameter">protocol</span>.<span class="py-src-parameter">ClientFactory</span>):
1194
1195     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IIRCClientFactory</span>)
1196
1197     <span class="py-src-variable">protocol</span> = <span class="py-src-variable">IRCReplyBot</span>
1198     <span class="py-src-variable">nickname</span> = <span class="py-src-variable">None</span>
1199
1200     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
1201         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
1202
1203     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
1204         <span class="py-src-keyword">return</span> <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">user</span>)
1205
1206 <span class="py-src-variable">components</span>.<span class="py-src-variable">registerAdapter</span>(<span class="py-src-variable">IRCClientFactoryFromService</span>,
1207                            <span class="py-src-variable">IFingerService</span>,
1208                            <span class="py-src-variable">IIRCClientFactory</span>)
1209
1210
1211 <span class="py-src-keyword">class</span> <span class="py-src-identifier">UserStatusTree</span>(<span class="py-src-parameter">resource</span>.<span class="py-src-parameter">Resource</span>):
1212
1213     <span class="py-src-variable">implements</span>(<span class="py-src-variable">resource</span>.<span class="py-src-variable">IResource</span>)
1214
1215     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
1216         <span class="py-src-variable">resource</span>.<span class="py-src-variable">Resource</span>.<span class="py-src-variable">__init__</span>(<span class="py-src-variable">self</span>)
1217         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
1218         <span class="py-src-variable">self</span>.<span class="py-src-variable">putChild</span>(<span class="py-src-string">'RPC2'</span>, <span class="py-src-variable">UserStatusXR</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>))
1219
1220     <span class="py-src-keyword">def</span> <span class="py-src-identifier">render_GET</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">request</span>):
1221         <span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUsers</span>()
1222         <span class="py-src-keyword">def</span> <span class="py-src-identifier">formatUsers</span>(<span class="py-src-parameter">users</span>):
1223             <span class="py-src-variable">l</span> = [<span class="py-src-string">'&lt;li&gt;&lt;a href=&quot;%s&quot;&gt;%s&lt;/a&gt;&lt;/li&gt;'</span> % (<span class="py-src-variable">user</span>, <span class="py-src-variable">user</span>)
1224                  <span class="py-src-keyword">for</span> <span class="py-src-variable">user</span> <span class="py-src-keyword">in</span> <span class="py-src-variable">users</span>]
1225             <span class="py-src-keyword">return</span> <span class="py-src-string">'&lt;ul&gt;'</span>+<span class="py-src-string">''</span>.<span class="py-src-variable">join</span>(<span class="py-src-variable">l</span>)+<span class="py-src-string">'&lt;/ul&gt;'</span>
1226         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">formatUsers</span>)
1227         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">request</span>.<span class="py-src-variable">write</span>)
1228         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">_</span>: <span class="py-src-variable">request</span>.<span class="py-src-variable">finish</span>())
1229         <span class="py-src-keyword">return</span> <span class="py-src-variable">server</span>.<span class="py-src-variable">NOT_DONE_YET</span>
1230
1231     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getChild</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">path</span>, <span class="py-src-parameter">request</span>):
1232         <span class="py-src-keyword">if</span> <span class="py-src-variable">path</span>==<span class="py-src-string">&quot;&quot;</span>:
1233             <span class="py-src-keyword">return</span> <span class="py-src-variable">UserStatusTree</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>)
1234         <span class="py-src-keyword">else</span>:
1235             <span class="py-src-keyword">return</span> <span class="py-src-variable">UserStatus</span>(<span class="py-src-variable">path</span>, <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>)
1236
1237 <span class="py-src-variable">components</span>.<span class="py-src-variable">registerAdapter</span>(<span class="py-src-variable">UserStatusTree</span>, <span class="py-src-variable">IFingerService</span>,
1238                            <span class="py-src-variable">resource</span>.<span class="py-src-variable">IResource</span>)
1239
1240
1241 <span class="py-src-keyword">class</span> <span class="py-src-identifier">UserStatus</span>(<span class="py-src-parameter">resource</span>.<span class="py-src-parameter">Resource</span>):
1242
1243     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>, <span class="py-src-parameter">service</span>):
1244         <span class="py-src-variable">resource</span>.<span class="py-src-variable">Resource</span>.<span class="py-src-variable">__init__</span>(<span class="py-src-variable">self</span>)
1245         <span class="py-src-variable">self</span>.<span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>
1246         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
1247
1248     <span class="py-src-keyword">def</span> <span class="py-src-identifier">render_GET</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">request</span>):
1249         <span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">user</span>)
1250         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">cgi</span>.<span class="py-src-variable">escape</span>)
1251         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">m</span>:
1252                       <span class="py-src-string">'&lt;h1&gt;%s&lt;/h1&gt;'</span>%<span class="py-src-variable">self</span>.<span class="py-src-variable">user</span>+<span class="py-src-string">'&lt;p&gt;%s&lt;/p&gt;'</span>%<span class="py-src-variable">m</span>)
1253         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">request</span>.<span class="py-src-variable">write</span>)
1254         <span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">_</span>: <span class="py-src-variable">request</span>.<span class="py-src-variable">finish</span>())
1255         <span class="py-src-keyword">return</span> <span class="py-src-variable">server</span>.<span class="py-src-variable">NOT_DONE_YET</span>
1256
1257
1258 <span class="py-src-keyword">class</span> <span class="py-src-identifier">UserStatusXR</span>(<span class="py-src-parameter">xmlrpc</span>.<span class="py-src-parameter">XMLRPC</span>):
1259
1260     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
1261         <span class="py-src-variable">xmlrpc</span>.<span class="py-src-variable">XMLRPC</span>.<span class="py-src-variable">__init__</span>(<span class="py-src-variable">self</span>)
1262         <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
1263
1264     <span class="py-src-keyword">def</span> <span class="py-src-identifier">xmlrpc_getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
1265         <span class="py-src-keyword">return</span> <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">user</span>)
1266
1267
1268 <span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerService</span>(<span class="py-src-parameter">service</span>.<span class="py-src-parameter">Service</span>):
1269
1270     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IFingerService</span>)
1271
1272     <span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">filename</span>):
1273         <span class="py-src-variable">self</span>.<span class="py-src-variable">filename</span> = <span class="py-src-variable">filename</span>
1274         <span class="py-src-variable">self</span>.<span class="py-src-variable">users</span> = {}
1275
1276     <span class="py-src-keyword">def</span> <span class="py-src-identifier">_read</span>(<span class="py-src-parameter">self</span>):
1277         <span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>.<span class="py-src-variable">clear</span>()
1278         <span class="py-src-keyword">for</span> <span class="py-src-variable">line</span> <span class="py-src-keyword">in</span> <span class="py-src-variable">file</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">filename</span>):
1279             <span class="py-src-variable">user</span>, <span class="py-src-variable">status</span> = <span class="py-src-variable">line</span>.<span class="py-src-variable">split</span>(<span class="py-src-string">':'</span>, <span class="py-src-number">1</span>)
1280             <span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>.<span class="py-src-variable">strip</span>()
1281             <span class="py-src-variable">status</span> = <span class="py-src-variable">status</span>.<span class="py-src-variable">strip</span>()
1282             <span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>[<span class="py-src-variable">user</span>] = <span class="py-src-variable">status</span>
1283         <span class="py-src-variable">self</span>.<span class="py-src-variable">call</span> = <span class="py-src-variable">reactor</span>.<span class="py-src-variable">callLater</span>(<span class="py-src-number">30</span>, <span class="py-src-variable">self</span>.<span class="py-src-variable">_read</span>)
1284
1285     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
1286         <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>.<span class="py-src-variable">get</span>(<span class="py-src-variable">user</span>, <span class="py-src-string">&quot;No such user&quot;</span>))
1287
1288     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUsers</span>(<span class="py-src-parameter">self</span>):
1289         <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>.<span class="py-src-variable">keys</span>())
1290
1291     <span class="py-src-keyword">def</span> <span class="py-src-identifier">startService</span>(<span class="py-src-parameter">self</span>):
1292         <span class="py-src-variable">self</span>.<span class="py-src-variable">_read</span>()
1293         <span class="py-src-variable">service</span>.<span class="py-src-variable">Service</span>.<span class="py-src-variable">startService</span>(<span class="py-src-variable">self</span>)
1294
1295     <span class="py-src-keyword">def</span> <span class="py-src-identifier">stopService</span>(<span class="py-src-parameter">self</span>):
1296         <span class="py-src-variable">service</span>.<span class="py-src-variable">Service</span>.<span class="py-src-variable">stopService</span>(<span class="py-src-variable">self</span>)
1297         <span class="py-src-variable">self</span>.<span class="py-src-variable">call</span>.<span class="py-src-variable">cancel</span>()
1298
1299
1300 <span class="py-src-comment"># Yet another back-end</span>
1301
1302 <span class="py-src-keyword">class</span> <span class="py-src-identifier">LocalFingerService</span>(<span class="py-src-parameter">service</span>.<span class="py-src-parameter">Service</span>):
1303
1304     <span class="py-src-variable">implements</span>(<span class="py-src-variable">IFingerService</span>)
1305
1306     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
1307         <span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>.<span class="py-src-variable">strip</span>()
1308         <span class="py-src-keyword">try</span>:
1309             <span class="py-src-variable">entry</span> = <span class="py-src-variable">pwd</span>.<span class="py-src-variable">getpwnam</span>(<span class="py-src-variable">user</span>)
1310         <span class="py-src-keyword">except</span> <span class="py-src-variable">KeyError</span>:
1311             <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-string">&quot;No such user&quot;</span>)
1312         <span class="py-src-keyword">try</span>:
1313             <span class="py-src-variable">f</span> = <span class="py-src-variable">file</span>(<span class="py-src-variable">os</span>.<span class="py-src-variable">path</span>.<span class="py-src-variable">join</span>(<span class="py-src-variable">entry</span>[<span class="py-src-number">5</span>],<span class="py-src-string">'.plan'</span>))
1314         <span class="py-src-keyword">except</span> (<span class="py-src-variable">IOError</span>, <span class="py-src-variable">OSError</span>):
1315             <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-string">&quot;No such user&quot;</span>)
1316         <span class="py-src-variable">data</span> = <span class="py-src-variable">f</span>.<span class="py-src-variable">read</span>()
1317         <span class="py-src-variable">data</span> = <span class="py-src-variable">data</span>.<span class="py-src-variable">strip</span>()
1318         <span class="py-src-variable">f</span>.<span class="py-src-variable">close</span>()
1319         <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-variable">data</span>)
1320
1321     <span class="py-src-keyword">def</span> <span class="py-src-identifier">getUsers</span>(<span class="py-src-parameter">self</span>):
1322         <span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>([])
1323
1324
1325 <span class="py-src-variable">application</span> = <span class="py-src-variable">service</span>.<span class="py-src-variable">Application</span>(<span class="py-src-string">'finger'</span>, <span class="py-src-variable">uid</span>=<span class="py-src-number">1</span>, <span class="py-src-variable">gid</span>=<span class="py-src-number">1</span>)
1326 <span class="py-src-variable">f</span> = <span class="py-src-variable">LocalFingerService</span>()
1327 <span class="py-src-variable">serviceCollection</span> = <span class="py-src-variable">service</span>.<span class="py-src-variable">IServiceCollection</span>(<span class="py-src-variable">application</span>)
1328 <span class="py-src-variable">internet</span>.<span class="py-src-variable">TCPServer</span>(<span class="py-src-number">79</span>, <span class="py-src-variable">IFingerFactory</span>(<span class="py-src-variable">f</span>)
1329                    ).<span class="py-src-variable">setServiceParent</span>(<span class="py-src-variable">serviceCollection</span>)
1330 <span class="py-src-variable">internet</span>.<span class="py-src-variable">TCPServer</span>(<span class="py-src-number">8000</span>, <span class="py-src-variable">server</span>.<span class="py-src-variable">Site</span>(<span class="py-src-variable">resource</span>.<span class="py-src-variable">IResource</span>(<span class="py-src-variable">f</span>))
1331                    ).<span class="py-src-variable">setServiceParent</span>(<span class="py-src-variable">serviceCollection</span>)
1332 <span class="py-src-variable">i</span> = <span class="py-src-variable">IIRCClientFactory</span>(<span class="py-src-variable">f</span>)
1333 <span class="py-src-variable">i</span>.<span class="py-src-variable">nickname</span> = <span class="py-src-string">'fingerbot'</span>
1334 <span class="py-src-variable">internet</span>.<span class="py-src-variable">TCPClient</span>(<span class="py-src-string">'irc.freenode.org'</span>, <span class="py-src-number">6667</span>, <span class="py-src-variable">i</span>
1335                    ).<span class="py-src-variable">setServiceParent</span>(<span class="py-src-variable">serviceCollection</span>)
1336 </pre><div class="caption">Source listing - <a href="listings/finger/finger19c.tac"><span class="filename">listings/finger/finger19c.tac</span></a></div></div>
1337 </p>
1338
1339 <p>Not much to say except that now we can be churn out backends like crazy. Feel
1340 like doing a back-end for <a href="http://www.advogato.org/" shape="rect">Advogato</a>, for
1341 example? Dig out the XML-RPC client support Twisted has, and get to work!</p>
1342
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