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| <h1>Apache Felix Serialization Framework</h1> |
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| <h1 id="problem">Problem<a class="headerlink" href="#problem" title="Permanent link">¶</a></h1> |
| <p>When you have an object graph that consists of objects that were created by different bundles, serializing and deserializing such a graph becomes a problem, since there is no single bundle that can "see" all (implementation) objects in the graph.</p> |
| <p>The problem manifests itself for example in Apache Wicket, but also in other applications. The serialization framework is a solution to this problem.</p> |
| <h1 id="design-discussion-sketch">Design discussion sketch<a class="headerlink" href="#design-discussion-sketch" title="Permanent link">¶</a></h1> |
| <p>Made at ApacheCon EU 2009, Robert, Martijn, Felix and Marcel produced the following design on the flipover:</p> |
| <p>!sf_design.jpg|thumbnail!</p> |
| <h1 id="service-design">Service design<a class="headerlink" href="#service-design" title="Permanent link">¶</a></h1> |
| <p>Basically, we need two services: |
| 1. The serialization service, that can serialize and deserialize an object graph to an output or input stream. |
| 1. Helpers that are used to (de)serialize specific objects.</p> |
| <h2 id="serialization-service">Serialization Service<a class="headerlink" href="#serialization-service" title="Permanent link">¶</a></h2> |
| <div class="codehilite"><pre><span class="n">interface</span> <span class="n">SerializationService</span> <span class="p">{</span> |
| <span class="n">void</span> <span class="n">serialize</span><span class="p">(</span><span class="n">Object</span> <span class="n">o</span><span class="p">,</span> <span class="n">OutputStream</span> <span class="n">s</span><span class="p">)</span> <span class="n">throws</span> <span class="n">IOException</span><span class="p">,</span> <span class="n">UnknownObjectException</span><span class="p">;</span> |
| <span class="n">Object</span> <span class="n">deserialize</span><span class="p">(</span><span class="n">InputStream</span> <span class="n">s</span><span class="p">)</span> <span class="n">throws</span> <span class="n">IOException</span><span class="p">,</span> <span class="n">UnknownObjectException</span><span class="p">;</span> |
| <span class="p">}</span> |
| </pre></div> |
| |
| |
| <p>The actual implementation of this service determines how objects are serialized.</p> |
| <h2 id="serialization-helper">Serialization Helper<a class="headerlink" href="#serialization-helper" title="Permanent link">¶</a></h2> |
| <div class="codehilite"><pre><span class="n">interface</span> <span class="n">SerializationHelper</span> <span class="p">{</span> |
| <span class="o">//</span> <span class="n">TODO</span> |
| <span class="p">}</span> |
| </pre></div> |
| |
| |
| <p>We also discussed adding a special manifest header to a bundle to create a sort of declarative serialization helper. That way the bundle does not need to implement and register the service (if all of them use the same helper anyway).</p> |
| <p>Helpers in some way need to be linked to a specific serialization service (using an XML serialization with a JSON helper will probably not be what you want).</p> |
| <div class="timestamp" style="margin-top: 30px; font-size: 80%; text-align: right;"> |
| Rev. 1700393 by cziegeler on Tue, 1 Sep 2015 06:04:06 +0000 |
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