core.html

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layout: layout
title: "Core features"
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<section class="content core">
		
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	<h1>Core Features</h1>
  	<p>Elementary entities manipulated in Kevoree models</p>
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	<!-- Common Type Definition -->
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	        <h3>TypeDefinition</h3>
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	        <h5>TypeDefinition/Instance separation</h5>

	        <p>Every Kevoree features follow a type/instance design pattern. Similarly to Class and Object separation in OO
	            programmation, Kevoree type definitions define <code>what</code> is available in the system, while instances
	            define <code>how/where</code> each functionality is used.</p>
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	<!-- Dictionary Definition -->
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	        <h3>Dictionary</h3>
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	        <h5>Dictionaries define parameters</h5>

	        <p>Each type may define a DictionaryType that identify the set of parameters of the component. 
	        Parameters can be optional, can have default values or can provide a finite list of choice.
	        Described at the component TypeDefinition level, parameters are however specific to each instance created.
	        </p>
	        <!-- TODO INSERT FIGURE -->

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	        <!-- Model Example -->
	        <pre class="code-box prettyprint lang-java">
	@NodeType
	@DictionaryType({
	    @DictionaryAttribute(name = "logLevel",
	            defaultValue = "INFO", optional = true,
	            vals = {"INFO","WARN","DEBUG","ERROR"})
	})
	public class JavaSENode extends AbstractNodeType {
	}</pre>
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	<!-- Component Definition -->
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	        <h3>Component</h3>
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	        <h5>Components encapsulate business functionalities</h5>

	        <p>Each component provides a set of functionalities exposed to others. A component also requires functionalities
	            to achieve their own ones. All these functionalities are
	            identified by a port (required or provided) on the component.</p>

	        <p>Components communicates only through their ports.</p>

	        <p></p>
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	        <pre class="code-box prettyprint">
	@ComponentType
	public class FakeConsole
	            extends AbstractComponentType {
	}</pre>
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	</div>
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	<!-- Channel Definition -->
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	    <div class="span2 heading-box">
	        <h3>Channel</h3>
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	    <div class="span4">
	        <h5>Channel entity encapsulate business communication semantics</h5>

	        <p>An application also defines how components are bound to exchange data. These bindings are done with channels
	            that encapsulate inter-component communication semantics. For instance such
	            channel semantics can encapsulate broadcast diffusion or distributed transaction, etc.
	        </p>
	        <!-- TODO INSERT FIGURE -->

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	        <!-- Model Example -->
	        <pre class="code-box prettyprint">
	@ChannelTypeFragment
	public class defMSG extends AbstractChannelFragment {
	}</pre>
	    </div>
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	<!-- Node Definition -->
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	    <div class="span2 heading-box">
	        <h3>Node</h3>
	    </div>
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	        <h5>Nodes encapsulate adaptation semantics</h5>

	        <p>Distributed systems are composed by computation node instances related to a NodeType. A NodeType host
	            specific adaptation semantics which is composed by a list of managed AdaptationPrimitive types and a
	            planning algorithm</p>
	        <!-- TODO INSERT FIGURE -->

	    </div>
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	        <!-- Model Example -->
	        <pre class="code-box prettyprint">
	@NodeType
	public class JavaSENode extends AbstractNodeType {
	}</pre>
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	</div>

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	<!-- Group Definition -->
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	        <h3>Groups</h3>
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	        <h5>Groups encapsulate node synchronisation and communication semantic</h5>

	        <p>In a nutshell, groups are channels dedicated to inter-nodes communications. These entity encapsulate also
	            synchronisation semantics such as groups synchronisation in total or partial order,
	            etc ....</p>
	        <!-- TODO INSERT FIGURE -->
	    </div>
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	        <!-- Model Example -->
	        <pre class="code-box prettyprint">
	@ChannelTypeFragment
	public class GossiperGroup extends AbstractGroupType {
	}</pre>
	    </div>
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	<!-- Adaptation -->
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	        <h3>Adaptation Primitive</h3>
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	        <h5>Adaptation primitives define adaptation capabilities for a NodeType</h5>

	        <p>A node instance can be viewed as a container which provides an isolation level and has responsibility to
	            ensure the synchronization between model and runtime. This responsibility is
	            represented by the adaptation capabilities the node has and these adaptation capabilities are provided by
	            adaptation primitives to perform migration actions between two configurations (two
	            models).
	        </p>
	        <!-- TODO INSERT FIGURE -->

	    </div>
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	        <!-- Model Example -->
	        <pre class="code-box prettyprint">
	@NodeType
	@PrimitiveCommands(
	    values = {"UpdateType", "UpdateDeployUnit", "AddType", "AddDeployUnit",
	            "AddThirdParty", "RemoveType", "RemoveDeployUnit",
	            "UpdateInstance", "UpdateBinding", "UpdateDictionaryInstance",
	            "AddInstance", "RemoveInstance", "AddBinding",
	            "RemoveBinding", "AddFragmentBinding", "RemoveFragmentBinding",
	            "UpdateFragmentBinding", "StartInstance",
	            "StopInstance", "StartThirdParty","RemoveThirdParty"})
	public class JavaSENode extends AbstractNodeType {
	}</pre>
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	</div>

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