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<h1>Accessing Persistent Classes From Different .NET Applications</h1><div id="TOC"><div id="TOCinner"><span class="TOCtitle">Contents</span><div class="TOCcontents"><ul><li><a href ="#Problem">Problem</a></li><li><a href ="#Reason">Reason</a></li><li><a href ="#Solution">Solution</a></li></ul></li></ul></div></div></div><p><font color="#990000">This topic applies to .NET version only</font> </p><a name="Problem"></a><h2>Problem</h2>
<p>Accessing db4o database created and filled in with a .NET
application or library from another .NET application or library shows an empty
database.</p><a name="Reason"></a><h2>Reason</h2>
<p>db4o class name format in db4o consists of the full class
name and assembly name:</p>
<p><code>Namespace.ClassName, AssemblyName</code></p>
<p>Two different .NET applications (libraries) usually have
different assembly names. If you do not use
<a href="../implementation_strategies/aliases.html" class="wikiLink">aliasing</a>, the class name will be appended
with the current application assembly name.</p><a name="Solution"></a><h2>Solution</h2>
<p>In order to access db4o persistent classes from different
applications (libraries) you will need to use an
<a href="../implementation_strategies/aliases.html" class="wikiLink">Alias</a>. For example:</p>
<p><b>Application1.exe ("Application1" assembly):</b></p>
<p><code>objectContainer.Set(new MyClasses.Pilot("David
Barrichello",99))</code></p>
<p><code>// internally the class is saved as "MyClasses.Pilot,
Application1".</code></p>
<p><b>Application2.exe ("Application2" assembly):</b></p>
<span name="cs_wiki_filter" csw_filters="cs">
<p>c#:</p>
<p><code>// create an Alias for the MyClasses.Pilot,
Application1:</code></p>
<p><code>IConfiguration configuration =
Db4oFactory.NewConfiguration();</code></p>
<p><code>configuration.AddAlias(new
TypeAlias("MyClasses.Pilot, Application1", " MyClasses.Pilot, Application2"));</code></p>
<p><code>IObjectContainer container =
Db4oFactory.OpenFile(configuration, "reference.db4o");</code></p>
<p><code>// now you query as usual</code></p>
<p><code>IObjectSet result = container.Get(new
Test());</code></p>
</span>
<span name="cs_wiki_filter" csw_filters="vb">
<p>VB:</p>
<p><code>// create an Alias for the MyClasses.Pilot,
Application1:</code></p>
<p><code>Dim configuration As IConfiguration = Db4oFactory.NewConfiguration()</code></p>
<p><code>configuration.AddAlias(new
TypeAlias("MyClasses.Pilot, Application1", " MyClasses.Pilot, Application2"))</code></p>
<p><code>Dim container As IObjectContainer =
Db4oFactory.OpenFile(configuration, "reference.db4o")</code></p>
<p><code>// now you query as usual</code></p>
<p><code>Dim result As IObjectSet = container.Get(New
Test())</code></p>
</span>
<p>For more information see
<a href="../object_lifecycle/class_name_format_in_.net.html" class="wikiLink">Class Name Format In .NET</a> and
<a href="../implementation_strategies/aliases.html" class="wikiLink">Aliases</a>.</p></div>
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This revision (7) was last Modified 2007-05-09T07:20:53 by Tetyana.
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