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<h1>Lifetime Of An Object Container</h1>
<p>The main interface to your database is the <a href="../basics/object_container.htm">object container</a>. You do all major operations with a object container instance. Now how long should you keep a object container open? Is it better to close the object container after each operation. Or keep the object container open? This topic is a small guideline on the lifetime of an object container. </p>
<h2>Understanding Object Containers</h2>
<p>The lifetime of a object container heavily depends on your application scenario. Therefore it's vital to understand what a object container represents. A object container consist of a <a href="../basics/acid_and_transactions.htm">transaction</a> and a <a href="../basics/indentity_concept/reference_cache.htm">reference</a> cache and is thread safe. This means that a object container is isolated from other containers. Furthermore an object container has a cache, so you don't want to throw a object container away if you don't have to. </p>
<h2>One Object Container Per Unit Of Work</h2>
<p>This means in fact that you should use one object container per unit of work. You can use a object container for succeeding units of work. But you should never use the same object container for concurrent or independent units of work. You can create <a href="../advanced_topics/session_containers.htm">new object containers at any time</a>. </p>
<h2>Desktop Application</h2>
<p>What does this mean for a desktop application? Well in a simple desktop application you might can use only one object container. Since there only one user doing something at a time you can use the same object container for all operations.</p>
<p>For complexes desktop application multiple object container can be an option. For example a object container per tab, per wizard etc. </p>
<p>Be aware only because object container is thread safe it doesn't make your object model thread safe. If multiple threads are using the same object container they will use the same objects and modify the same object concurrently. You need to use an appropriate model for the concurrent access.</p>
<h2>Web Application</h2>
<p>In a web application you should use a <a href="../platform_specific_issues/web/web_isolation.htm">object container per request</a>. Each request is it unit of work. Maybe there are multiple unit of work successively in a request, but a request represents the top level unit of work. </p>
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