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diff --git a/studio/static/doc/flask-docs/patterns/appdispatch.html b/studio/static/doc/flask-docs/patterns/appdispatch.html new file mode 100644 index 0000000..de88a7b --- /dev/null +++ b/studio/static/doc/flask-docs/patterns/appdispatch.html @@ -0,0 +1,273 @@ + +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> + + +<html xmlns="http://www.w3.org/1999/xhtml"> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> + + <title>Application Dispatching — Flask 0.8 documentation</title> + + <link rel="stylesheet" href="../_static/flasky.css" type="text/css" /> + <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> + + <script type="text/javascript"> + var DOCUMENTATION_OPTIONS = { + URL_ROOT: '../', + VERSION: '0.8', + COLLAPSE_INDEX: false, + FILE_SUFFIX: '.html', + HAS_SOURCE: true + }; + </script> + <script type="text/javascript" src="../_static/jquery.js"></script> + <script type="text/javascript" src="../_static/underscore.js"></script> + <script type="text/javascript" src="../_static/doctools.js"></script> + <link rel="top" title="Flask 0.8 documentation" href="../index.html" /> + <link rel="up" title="Patterns for Flask" href="index.html" /> + <link rel="next" title="Using URL Processors" href="urlprocessors.html" /> + <link rel="prev" title="Application Factories" href="appfactories.html" /> + + + <link rel="apple-touch-icon" href="../_static/touch-icon.png" /> + + <link media="only screen and (max-device-width: 480px)" href="../_static/small_flask.css" type= "text/css" rel="stylesheet" /> + + </head> + <body> + <div class="related"> + <h3>Navigation</h3> + <ul> + <li class="right" style="margin-right: 10px"> + <a href="../genindex.html" title="General Index" + accesskey="I">index</a></li> + <li class="right" > + <a href="urlprocessors.html" title="Using URL Processors" + accesskey="N">next</a> |</li> + <li class="right" > + <a href="appfactories.html" title="Application Factories" + accesskey="P">previous</a> |</li> + <li><a href="../index.html">Flask 0.8 documentation</a> »</li> + <li><a href="index.html" accesskey="U">Patterns for Flask</a> »</li> + </ul> + </div> + + <div class="document"> + <div class="documentwrapper"> + <div class="bodywrapper"> + <div class="body"> + + <div class="section" id="application-dispatching"> +<span id="app-dispatch"></span><h1>Application Dispatching<a class="headerlink" href="#application-dispatching" title="Permalink to this headline">¶</a></h1> +<p>Application dispatching is the process of combining multiple Flask +applications on the WSGI level. You can not only combine Flask +applications into something larger but any WSGI application. This would +even allow you to run a Django and a Flask application in the same +interpreter side by side if you want. The usefulness of this depends on +how the applications work internally.</p> +<p>The fundamental difference from the <a class="reference internal" href="packages.html#larger-applications"><em>module approach</em></a> is that in this case you are running the same or +different Flask applications that are entirely isolated from each other. +They run different configurations and are dispatched on the WSGI level.</p> +<div class="section" id="working-with-this-document"> +<h2>Working with this Document<a class="headerlink" href="#working-with-this-document" title="Permalink to this headline">¶</a></h2> +<p>Each of the techniques and examples below results in an <tt class="docutils literal"><span class="pre">application</span></tt> object +that can be run with any WSGI server. For production, see <a class="reference internal" href="../deploying/index.html#deployment"><em>Deployment Options</em></a>. +For development, Werkzeug provides a builtin server for development available +at <a class="reference external" href="http://werkzeug.pocoo.org/docs/serving/#werkzeug.serving.run_simple" title="(in Werkzeug v0.7)"><tt class="xref py py-func docutils literal"><span class="pre">werkzeug.serving.run_simple()</span></tt></a>:</p> +<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">werkzeug.serving</span> <span class="kn">import</span> <span class="n">run_simple</span> +<span class="n">run_simple</span><span class="p">(</span><span class="s">'localhost'</span><span class="p">,</span> <span class="mi">5000</span><span class="p">,</span> <span class="n">application</span><span class="p">,</span> <span class="n">use_reloader</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span> +</pre></div> +</div> +<p>Note that <a class="reference external" href="http://werkzeug.pocoo.org/docs/serving/#werkzeug.serving.run_simple" title="(in Werkzeug v0.7)"><tt class="xref py py-func docutils literal"><span class="pre">run_simple</span></tt></a> is not intended for +use in production. Use a <a class="reference internal" href="../deploying/index.html#deployment"><em>full-blown WSGI server</em></a>.</p> +</div> +<div class="section" id="combining-applications"> +<h2>Combining Applications<a class="headerlink" href="#combining-applications" title="Permalink to this headline">¶</a></h2> +<p>If you have entirely separated applications and you want them to work next +to each other in the same Python interpreter process you can take +advantage of the <a class="reference external" href="http://werkzeug.pocoo.org/docs/middlewares/#werkzeug.wsgi.DispatcherMiddleware" title="(in Werkzeug v0.7)"><tt class="xref py py-class docutils literal"><span class="pre">werkzeug.wsgi.DispatcherMiddleware</span></tt></a>. The idea +here is that each Flask application is a valid WSGI application and they +are combined by the dispatcher middleware into a larger one that +dispatched based on prefix.</p> +<p>For example you could have your main application run on <cite>/</cite> and your +backend interface on <cite>/backend</cite>:</p> +<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">werkzeug.wsgi</span> <span class="kn">import</span> <span class="n">DispatcherMiddleware</span> +<span class="kn">from</span> <span class="nn">frontend_app</span> <span class="kn">import</span> <span class="n">application</span> <span class="k">as</span> <span class="n">frontend</span> +<span class="kn">from</span> <span class="nn">backend_app</span> <span class="kn">import</span> <span class="n">application</span> <span class="k">as</span> <span class="n">backend</span> + +<span class="n">application</span> <span class="o">=</span> <span class="n">DispatcherMiddleware</span><span class="p">(</span><span class="n">frontend</span><span class="p">,</span> <span class="p">{</span> + <span class="s">'/backend'</span><span class="p">:</span> <span class="n">backend</span> +<span class="p">})</span> +</pre></div> +</div> +</div> +<div class="section" id="dispatch-by-subdomain"> +<h2>Dispatch by Subdomain<a class="headerlink" href="#dispatch-by-subdomain" title="Permalink to this headline">¶</a></h2> +<p>Sometimes you might want to use multiple instances of the same application +with different configurations. Assuming the application is created inside +a function and you can call that function to instanciate it, that is +really easy to implement. In order to develop your application to support +creating new instances in functions have a look at the +<a class="reference internal" href="appfactories.html#app-factories"><em>Application Factories</em></a> pattern.</p> +<p>A very common example would be creating applications per subdomain. For +instance you configure your webserver to dispatch all requests for all +subdomains to your application and you then use the subdomain information +to create user-specific instances. Once you have your server set up to +listen on all subdomains you can use a very simple WSGI application to do +the dynamic application creation.</p> +<p>The perfect level for abstraction in that regard is the WSGI layer. You +write your own WSGI application that looks at the request that comes and +and delegates it to your Flask application. If that application does not +exist yet, it is dynamically created and remembered:</p> +<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">threading</span> <span class="kn">import</span> <span class="n">Lock</span> + +<span class="k">class</span> <span class="nc">SubdomainDispatcher</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span> + + <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">domain</span><span class="p">,</span> <span class="n">create_app</span><span class="p">):</span> + <span class="bp">self</span><span class="o">.</span><span class="n">domain</span> <span class="o">=</span> <span class="n">domain</span> + <span class="bp">self</span><span class="o">.</span><span class="n">create_app</span> <span class="o">=</span> <span class="n">create_app</span> + <span class="bp">self</span><span class="o">.</span><span class="n">lock</span> <span class="o">=</span> <span class="n">Lock</span><span class="p">()</span> + <span class="bp">self</span><span class="o">.</span><span class="n">instances</span> <span class="o">=</span> <span class="p">{}</span> + + <span class="k">def</span> <span class="nf">get_application</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">host</span><span class="p">):</span> + <span class="n">host</span> <span class="o">=</span> <span class="n">host</span><span class="o">.</span><span class="n">split</span><span class="p">(</span><span class="s">':'</span><span class="p">)[</span><span class="mi">0</span><span class="p">]</span> + <span class="k">assert</span> <span class="n">host</span><span class="o">.</span><span class="n">endswith</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">domain</span><span class="p">),</span> <span class="s">'Configuration error'</span> + <span class="n">subdomain</span> <span class="o">=</span> <span class="n">host</span><span class="p">[:</span><span class="o">-</span><span class="nb">len</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">domain</span><span class="p">)]</span><span class="o">.</span><span class="n">rstrip</span><span class="p">(</span><span class="s">'.'</span><span class="p">)</span> + <span class="k">with</span> <span class="bp">self</span><span class="o">.</span><span class="n">lock</span><span class="p">:</span> + <span class="n">app</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">instances</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="n">subdomain</span><span class="p">)</span> + <span class="k">if</span> <span class="n">app</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span> + <span class="n">app</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">create_app</span><span class="p">(</span><span class="n">subdomain</span><span class="p">)</span> + <span class="bp">self</span><span class="o">.</span><span class="n">instances</span><span class="p">[</span><span class="n">subdomain</span><span class="p">]</span> <span class="o">=</span> <span class="n">app</span> + <span class="k">return</span> <span class="n">app</span> + + <span class="k">def</span> <span class="nf">__call__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">environ</span><span class="p">,</span> <span class="n">start_response</span><span class="p">):</span> + <span class="n">app</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_application</span><span class="p">(</span><span class="n">environ</span><span class="p">[</span><span class="s">'HTTP_HOST'</span><span class="p">])</span> + <span class="k">return</span> <span class="n">app</span><span class="p">(</span><span class="n">environ</span><span class="p">,</span> <span class="n">start_response</span><span class="p">)</span> +</pre></div> +</div> +<p>This dispatcher can then be used like this:</p> +<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">myapplication</span> <span class="kn">import</span> <span class="n">create_app</span><span class="p">,</span> <span class="n">get_user_for_subdomain</span> +<span class="kn">from</span> <span class="nn">werkzeug.exceptions</span> <span class="kn">import</span> <span class="n">NotFound</span> + +<span class="k">def</span> <span class="nf">make_app</span><span class="p">(</span><span class="n">subdomain</span><span class="p">):</span> + <span class="n">user</span> <span class="o">=</span> <span class="n">get_user_for_subdomain</span><span class="p">(</span><span class="n">subdomain</span><span class="p">)</span> + <span class="k">if</span> <span class="n">user</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span> + <span class="c"># if there is no user for that subdomain we still have</span> + <span class="c"># to return a WSGI application that handles that request.</span> + <span class="c"># We can then just return the NotFound() exception as</span> + <span class="c"># application which will render a default 404 page.</span> + <span class="c"># You might also redirect the user to the main page then</span> + <span class="k">return</span> <span class="n">NotFound</span><span class="p">()</span> + + <span class="c"># otherwise create the application for the specific user</span> + <span class="k">return</span> <span class="n">create_app</span><span class="p">(</span><span class="n">user</span><span class="p">)</span> + +<span class="n">application</span> <span class="o">=</span> <span class="n">SubdomainDispatcher</span><span class="p">(</span><span class="s">'example.com'</span><span class="p">,</span> <span class="n">make_app</span><span class="p">)</span> +</pre></div> +</div> +</div> +<div class="section" id="dispatch-by-path"> +<h2>Dispatch by Path<a class="headerlink" href="#dispatch-by-path" title="Permalink to this headline">¶</a></h2> +<p>Dispatching by a path on the URL is very similar. Instead of looking at +the <cite>Host</cite> header to figure out the subdomain one simply looks at the +request path up to the first slash:</p> +<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">threading</span> <span class="kn">import</span> <span class="n">Lock</span> +<span class="kn">from</span> <span class="nn">werkzeug.wsgi</span> <span class="kn">import</span> <span class="n">pop_path_info</span><span class="p">,</span> <span class="n">peek_path_info</span> + +<span class="k">class</span> <span class="nc">PathDispatcher</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span> + + <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">default_app</span><span class="p">,</span> <span class="n">create_app</span><span class="p">):</span> + <span class="bp">self</span><span class="o">.</span><span class="n">default_app</span> <span class="o">=</span> <span class="n">default_app</span> + <span class="bp">self</span><span class="o">.</span><span class="n">create_app</span> <span class="o">=</span> <span class="n">create_app</span> + <span class="bp">self</span><span class="o">.</span><span class="n">lock</span> <span class="o">=</span> <span class="n">Lock</span><span class="p">()</span> + <span class="bp">self</span><span class="o">.</span><span class="n">instances</span> <span class="o">=</span> <span class="p">{}</span> + + <span class="k">def</span> <span class="nf">get_application</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">prefix</span><span class="p">):</span> + <span class="k">with</span> <span class="bp">self</span><span class="o">.</span><span class="n">lock</span><span class="p">:</span> + <span class="n">app</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">instances</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="n">prefix</span><span class="p">)</span> + <span class="k">if</span> <span class="n">app</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span> + <span class="n">app</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">create_app</span><span class="p">(</span><span class="n">prefix</span><span class="p">)</span> + <span class="k">if</span> <span class="n">app</span> <span class="ow">is</span> <span class="ow">not</span> <span class="bp">None</span><span class="p">:</span> + <span class="bp">self</span><span class="o">.</span><span class="n">instances</span><span class="p">[</span><span class="n">prefix</span><span class="p">]</span> <span class="o">=</span> <span class="n">app</span> + <span class="k">return</span> <span class="n">app</span> + + <span class="k">def</span> <span class="nf">__call__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">environ</span><span class="p">,</span> <span class="n">start_response</span><span class="p">):</span> + <span class="n">app</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_application</span><span class="p">(</span><span class="n">peek_path_info</span><span class="p">(</span><span class="n">environ</span><span class="p">))</span> + <span class="k">if</span> <span class="n">app</span> <span class="ow">is</span> <span class="ow">not</span> <span class="bp">None</span><span class="p">:</span> + <span class="n">pop_path_info</span><span class="p">(</span><span class="n">environ</span><span class="p">)</span> + <span class="k">else</span><span class="p">:</span> + <span class="n">app</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">default_app</span> + <span class="k">return</span> <span class="n">app</span><span class="p">(</span><span class="n">environ</span><span class="p">,</span> <span class="n">start_response</span><span class="p">)</span> +</pre></div> +</div> +<p>The big difference between this and the subdomain one is that this one +falls back to another application if the creator function returns <cite>None</cite>:</p> +<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">myapplication</span> <span class="kn">import</span> <span class="n">create_app</span><span class="p">,</span> <span class="n">default_app</span><span class="p">,</span> <span class="n">get_user_for_prefix</span> + +<span class="k">def</span> <span class="nf">make_app</span><span class="p">(</span><span class="n">prefix</span><span class="p">):</span> + <span class="n">user</span> <span class="o">=</span> <span class="n">get_user_for_prefix</span><span class="p">(</span><span class="n">prefix</span><span class="p">)</span> + <span class="k">if</span> <span class="n">user</span> <span class="ow">is</span> <span class="ow">not</span> <span class="bp">None</span><span class="p">:</span> + <span class="k">return</span> <span class="n">create_app</span><span class="p">(</span><span class="n">user</span><span class="p">)</span> + +<span class="n">application</span> <span class="o">=</span> <span class="n">PathDispatcher</span><span class="p">(</span><span class="n">default_app</span><span class="p">,</span> <span class="n">make_app</span><span class="p">)</span> +</pre></div> +</div> +</div> +</div> + + + </div> + </div> + </div> + <div class="sphinxsidebar"> + <div class="sphinxsidebarwrapper"><p class="logo"><a href="../index.html"> + <img class="logo" src="../_static/flask.png" alt="Logo"/> +</a></p> + <h3><a href="../index.html">Table Of Contents</a></h3> + <ul> +<li><a class="reference internal" href="#">Application Dispatching</a><ul> +<li><a class="reference internal" href="#working-with-this-document">Working with this Document</a></li> +<li><a class="reference internal" href="#combining-applications">Combining Applications</a></li> +<li><a class="reference internal" href="#dispatch-by-subdomain">Dispatch by Subdomain</a></li> +<li><a class="reference internal" href="#dispatch-by-path">Dispatch by Path</a></li> +</ul> +</li> +</ul> +<h3>Related Topics</h3> +<ul> + <li><a href="../index.html">Documentation overview</a><ul> + <li><a href="index.html">Patterns for Flask</a><ul> + <li>Previous: <a href="appfactories.html" title="previous chapter">Application Factories</a></li> + <li>Next: <a href="urlprocessors.html" title="next chapter">Using URL Processors</a></li> + </ul></li> + </ul></li> +</ul> + <h3>This Page</h3> + <ul class="this-page-menu"> + <li><a href="../_sources/patterns/appdispatch.txt" + rel="nofollow">Show Source</a></li> + </ul> +<div id="searchbox" style="display: none"> + <h3>Quick search</h3> + <form class="search" 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