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| <h1>ProbeGuide</h1> |
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| <h1 id="developping-probes-for-mosgi-framework">Developping probes for MOSGi framework<a class="headerlink" href="#developping-probes-for-mosgi-framework" title="Permanent link">¶</a></h1> |
| <p>{quote}</p> |
| <p>{quote} |
| MOSGi is a management infrastructure for OSGi gateways remote management. The architecture relies on JMX management infrastructure and is classically build on a three layered system:</p> |
| <p>!ManagementLayers.png! |
| <em> The probe layer: are low layer elements that drive the gateway. They can either get information from the gateway (gateway status) or set information on it (install a bundle), |
| </em> The Agent layer: there is one agent per gateway and is responsible for maintaining access to a list of available probes, |
| * The Manager layer is the remote environment that can communicate with the agent to get information from the gateway through the probes</p> |
| <p>There are various way to implements this architecture (CIM/Wbem, Snmp, JMX). We have choose to use the JMX proposal because it is standardized in the java virtual machine since jdk1.5.</p> |
| <h1 id="jmx-management-infrastructure-synthesis">JMX management infrastructure synthesis<a class="headerlink" href="#jmx-management-infrastructure-synthesis" title="Permanent link">¶</a></h1> |
| <p>Sun JMX proposal defines the following elements :</p> |
| <p>!JMXLayers.png! |
| <em> The agent is the registry for probes called MBeans and is accessed through connectors. |
| </em> MBeans are java objects that register themselves to the agent under some name |
| * Connectors are end points were external managers can communicate with. There are currently two available connectors : an xml/http connector and a rmi based connector. We are using the rmi connector (JSR160).</p> |
| <p>In the JMX world probes are represented as MBeans. They are java singleton object that declare a single interface to the agent. This interface is registered under a unique name within the agent namespace. The JMX namespace is structured as a domainname:mbeanname unique name. The following html page represents an example of this kind of namespace (we use the httpconnector connector with the agent to get this information).</p> |
| <p>!jmxmx4jhtml.png!</p> |
| <p>These are various mbeans deployed on a specific gateway. We can identify 4 columns : the mbean registered name (and domain), its implementation, a comment and a function to unregister it.</p> |
| <p>Mbeans are component that declare a management interface that should have a syntactic name similar to the class they instrument. For instance the class foo.Test should implement a management interface whose name is foo.TestMBean. The registration mechanism associates a implementation (conform to the management interface) with an objectName (a unique identifier). The corresponding call is something like :aMbeanServer.register(aMBeanImplementation, anObjectName);. There are many kinds of MBeans (standard, dynamic, model and simple) but their description is out of the scope of this document.</p> |
| <h1 id="mosgi-probe-developpement">MOSGi probe developpement<a class="headerlink" href="#mosgi-probe-developpement" title="Permanent link">¶</a></h1> |
| <p>Our management infrastructure proposes a framework for deploying standard mbean within OSGi gateways. It also embeds a reference to a graphical part (manager view) directly in the Mbean itself. Thus the management console is automatically populated with client part of the management system.</p> |
| <h2 id="gateway-probes">Gateway probes<a class="headerlink" href="#gateway-probes" title="Permanent link">¶</a></h2> |
| <p>These probes are developed in conformance to the following elements. |
| <em> A probe must be registered under the domain TabUI. It means that they will have a corresponding tab in our management console. |
| </em> A probe must implement a management interface conform to the JMX specification (ie : foo.LinuxProbe --> foo.LinuxProbeMBean) |
| <em> The management interface must extend TabIfc (which declares a single method : getBundleName()). This methods returns an url were the management console should find a tab that can establish a management dialog with the probe. |
| </em> The probe is made available as a standard OSGi Mbean that will make its registration during the bundleActivator start method.</p> |
| <p>The following picture illustrates relations between these elements.</p> |
| <p>!MOSGiProbeClasses.png!</p> |
| <p>For instance a Probe that declares a single management function <em>int getValue()</em>;should provide the following interface:</p> |
| <div class="codehilite"><pre><span class="n">package</span> <span class="n">foo</span><span class="p">;</span> |
| <span class="n">import</span> <span class="n">insa</span><span class="p">.</span><span class="n">jmxconsole</span><span class="p">.</span><span class="n">gui</span><span class="p">.</span><span class="n">service</span><span class="p">.</span><span class="n">TabIfc</span><span class="p">;</span> |
| <span class="n">public</span> <span class="n">interface</span> <span class="n">ProbeMBean</span> <span class="n">extends</span> <span class="n">TabIfc</span> <span class="p">{</span> |
| <span class="n">public</span> <span class="n">int</span> <span class="n">getValue</span><span class="p">();</span> |
| <span class="p">}</span> |
| </pre></div> |
| |
| |
| <p>And the following class:</p> |
| <div class="codehilite"><pre><span class="n">package</span> <span class="n">foo</span><span class="p">;</span> |
| <span class="n">import</span> <span class="n">org</span><span class="p">.</span><span class="n">osgi</span><span class="p">.</span><span class="n">framework</span><span class="p">.</span><span class="n">BundleActivator</span><span class="p">;</span> |
| <span class="n">import</span> <span class="n">org</span><span class="p">.</span><span class="n">osgi</span><span class="p">.</span><span class="n">framework</span><span class="p">.</span><span class="n">BundleContext</span><span class="p">;</span> |
| <span class="n">import</span> <span class="n">org</span><span class="p">.</span><span class="n">osgi</span><span class="p">.</span><span class="n">framework</span><span class="p">.</span><span class="n">ServiceReference</span><span class="p">;</span> |
| <span class="n">import</span> <span class="n">insa</span><span class="p">.</span><span class="n">jmxconsole</span><span class="p">.</span><span class="n">gui</span><span class="p">.</span><span class="n">service</span><span class="p">.</span><span class="n">TabIfc</span><span class="p">;</span> |
| <span class="n">import</span> <span class="n">javax</span><span class="p">.</span><span class="n">management</span><span class="p">.</span><span class="n">MBeanServer</span><span class="p">;</span> |
| <span class="n">public</span> <span class="n">class</span> <span class="n">Probe</span> <span class="n">implements</span> <span class="n">BundleActivator</span><span class="p">,</span><span class="n">ProbeMBean</span><span class="p">{</span> |
| <span class="o">//////////////////////////////////////////</span> |
| <span class="o">//</span> <span class="n">BundleActivator</span> <span class="n">Interface</span> <span class="o">//</span> |
| <span class="o">//////////////////////////////////////////</span> |
| <span class="o">/*</span> <span class="n">The</span> <span class="n">probe</span> <span class="n">lifecycle</span> <span class="n">is</span> <span class="n">linked</span> <span class="n">to</span> <span class="n">the</span> <span class="n">bundle</span> <span class="n">lifecycle</span> <span class="o">*/</span> |
| <span class="n">public</span> <span class="n">void</span> <span class="n">start</span><span class="p">(</span><span class="n">BundleContext</span> <span class="n">bc</span><span class="p">){</span> |
| <span class="o">/*</span> <span class="n">Here</span> <span class="n">we</span> <span class="n">register</span> <span class="n">the</span> <span class="n">Mbean</span> <span class="n">within</span> <span class="n">the</span> <span class="n">agent</span> <span class="o">*/</span> |
| <span class="n">ServiceReference</span> <span class="n">sr</span> <span class="p">=</span> <span class="n">context</span><span class="p">.</span><span class="n">getServiceReference</span><span class="p">(</span><span class="n">MBeanServer</span><span class="p">.</span><span class="n">class</span><span class="p">.</span><span class="n">getName</span><span class="p">());</span> |
| <span class="k">if</span> <span class="p">(</span><span class="n">sr</span>!<span class="p">=</span><span class="n">null</span><span class="p">){</span> |
| <span class="n">MBeanServer</span> <span class="n">server</span> <span class="p">=</span> <span class="p">(</span><span class="n">MbeanServer</span><span class="p">)</span><span class="n">this</span><span class="p">.</span><span class="n">bc</span><span class="p">.</span><span class="n">getService</span><span class="p">(</span><span class="n">sr</span><span class="p">);</span> |
| <span class="n">server</span><span class="p">.</span><span class="n">registerMBean</span><span class="p">(</span><span class="n">this</span><span class="p">,</span> <span class="n">new</span> <span class="n">ObjectName</span><span class="p">(</span>"<span class="n">TabUI</span><span class="p">:</span><span class="n">name</span><span class="p">=</span><span class="n">Probe</span>"<span class="p">);</span> |
| <span class="p">}</span> |
| <span class="p">}</span> |
| <span class="n">public</span> <span class="n">void</span> <span class="n">stop</span><span class="p">(</span><span class="n">BundleContext</span> <span class="n">bc</span><span class="p">){...}</span> |
| <span class="o">///////////////////////////</span> |
| <span class="o">//</span> <span class="n">Management</span> <span class="n">interface</span> <span class="o">//</span> |
| <span class="o">///////////////////////////</span> |
| <span class="n">public</span> <span class="n">int</span> <span class="n">getValue</span><span class="p">(){</span><span class="k">return</span> 10<span class="p">;}</span> |
| |
| <span class="o">/*</span> <span class="n">A</span> <span class="n">getIfc</span> <span class="k">function</span> <span class="n">comes</span> <span class="n">from</span> <span class="n">RemoteIfc</span> <span class="n">interface</span> <span class="n">that</span> <span class="n">enable</span> <span class="n">the</span> <span class="n">manager</span> <span class="p">(</span><span class="n">remote</span> <span class="n">console</span><span class="p">)</span> <span class="n">to</span> |
| <span class="n">a</span> <span class="n">bundle</span> <span class="n">that</span> <span class="n">can</span> <span class="n">communicate</span> <span class="n">whith</span> <span class="n">this</span> <span class="n">probe</span> <span class="n">from</span> <span class="n">a</span> <span class="n">remote</span> <span class="n">URL</span> <span class="o">*/</span> |
| <span class="n">public</span> <span class="n">String</span> <span class="n">getBundleName</span><span class="p">(){</span> |
| <span class="k">return</span> "<span class="n">http</span><span class="p">:</span><span class="o">//</span><span class="n">somewhere</span><span class="o">/</span><span class="n">agraphicaltab</span><span class="p">.</span><span class="n">jar</span>" |
| <span class="p">}</span> |
| <span class="p">}</span> |
| </pre></div> |
| |
| |
| <p>Once the probe is made as a bundle it can be deployed on the remote gateway. Then a manager (management console) can ask communicate with the gateway agent to manage the probe.</p> |
| <h2 id="mosgi-jmxconsole-architecture">MOSGi JmxConsole architecture<a class="headerlink" href="#mosgi-jmxconsole-architecture" title="Permanent link">¶</a></h2> |
| <p>When a probe is deployed on a remote gateway it is manageable by standard management consoles like JConsole, MC4J... We have developed our own management console that is able to manage probe in a more dedicated approach.</p> |
| <p>The management console is based on a plugin mechanism. Each plugin is represented as a tab and each tab manages a probe. The console is launched with two bundles. Remotegui.jar is the execution framework and remotecomponent.jar contains a sole remote logger service that gets remote notification from gateways. The screen represented the gateway status after it has been launched.!EmptyConsole.png! |
| The left panel identifies connected gateways, |
| The upper center panel is an container for tabs from managed gateways,</p> |
| <p>The lower center panel contains the remote logger display that shows notifications from remote gateways. |
| When the user selects a gateway (green flag) the console will do the following actions : |
| 1. Ask all MBeans in the TabUI domain. |
| 1. For each of these MBean, get the URL of bundle that provides the tab. This is done through the call to getBundleName( ) method in RemoteIfc interface. |
| 1. Install the bundle on the gateway</p> |
| <p>For instance if the user selects the green point he gets the following tabs.</p> |
| <p>!TabbedConsole.png!</p> |
| <p>4 probes have been deployed on the remote gateway and 4 graphical tabs have been installed.</p> |
| <h2 id="graphical-tab-integration">Graphical tab integration<a class="headerlink" href="#graphical-tab-integration" title="Permanent link">¶</a></h2> |
| <p>When developing a probe one shall provide a corresponding MOSGi tab. It should follow these guidelines. |
| <em> It should be a bundle in order to be remotely installed on the console |
| </em> It should implement Plugin interface with is the jmxconsole container interface specification.</p> |
| <p>The plugin is mainly conform to the java beans specification development. The jmxconsole acts as a bean container and each tab is a bean in this infrastructure. This is the general architecture of a Tab class.!MOSGiConsoleTabClasses.png!</p> |
| <p>The plugin interface has the following structure:</p> |
| <div class="codehilite"><pre><span class="n">package</span> <span class="n">insa</span><span class="p">.</span><span class="n">jmxconsole</span><span class="p">.</span><span class="n">gui</span><span class="p">.</span><span class="n">service</span><span class="p">;</span> |
| <span class="n">import</span> <span class="n">java</span><span class="p">.</span><span class="n">awt</span><span class="p">.</span><span class="n">Component</span><span class="p">;</span> |
| <span class="n">import</span> <span class="n">java</span><span class="p">.</span><span class="n">beans</span><span class="p">.</span><span class="n">PropertyChangeListener</span><span class="p">;</span> |
| <span class="n">public</span> <span class="n">interface</span> <span class="n">Plugin</span> <span class="n">extends</span> <span class="n">PropertyChangeListener</span><span class="p">{</span> |
| <span class="n">public</span> <span class="n">String</span> <span class="n">getName</span><span class="p">();</span> <span class="o">/*</span> <span class="n">The</span> <span class="n">name</span> <span class="n">of</span> <span class="n">the</span> <span class="n">tab</span> <span class="o">*/</span> |
| <span class="n">public</span> <span class="n">Component</span> <span class="n">getGUI</span><span class="p">();</span> <span class="o">/*</span> <span class="n">This</span> <span class="n">is</span> <span class="n">called</span> <span class="n">by</span> <span class="n">the</span> <span class="n">container</span> <span class="n">to</span> <span class="n">get</span> <span class="n">the</span> <span class="n">graphical</span> <span class="n">component</span> <span class="o">*/</span> |
| <span class="n">public</span> <span class="n">void</span> <span class="n">registerServicePlugin</span><span class="p">();</span> <span class="o">/*</span> <span class="n">This</span> <span class="n">is</span> <span class="n">called</span> <span class="n">by</span> <span class="n">the</span> <span class="n">framework</span> <span class="n">when</span> <span class="n">a</span> <span class="n">new</span> <span class="n">gateway</span> <span class="n">is</span> <span class="n">selected</span> <span class="o">*/</span> |
| <span class="n">public</span> <span class="n">void</span> <span class="n">unregisterServicePlugin</span><span class="p">();</span> |
| <span class="o">/*</span> <span class="n">see</span> <span class="n">before</span> <span class="o">*/</span> |
| <span class="n">public</span> <span class="n">String</span> <span class="n">pluginLocation</span><span class="p">();</span> <span class="o">/*</span> <span class="n">This</span> <span class="n">a</span> <span class="n">unique</span> <span class="n">identifier</span> <span class="n">of</span> <span class="n">the</span> <span class="n">plugin</span> <span class="o">*/</span> |
| <span class="o">/*</span> <span class="n">These</span> <span class="n">are</span> <span class="n">constants</span> <span class="n">that</span> <span class="n">enable</span> <span class="n">communication</span> <span class="n">between</span> <span class="n">container</span> <span class="n">and</span> <span class="n">plugins</span><span class="p">.</span> <span class="n">They</span> <span class="n">are</span> <span class="n">treated</span> <span class="n">in</span> <span class="n">the</span> |
| <span class="n">propertyChange</span> <span class="k">function</span> <span class="n">brought</span> <span class="n">by</span> <span class="n">the</span> <span class="n">javabean</span> <span class="n">API</span> <span class="o">*/</span> |
| <span class="n">public</span> <span class="n">static</span> <span class="n">final</span> <span class="n">String</span> <span class="n">NEW_NODE_SELECTED</span><span class="p">=</span>"<span class="n">newNodeSelected</span>"<span class="p">;</span> |
| <span class="n">public</span> <span class="n">static</span> <span class="n">final</span> <span class="n">String</span> <span class="n">NEW_NODE_READY</span><span class="p">=</span>"<span class="n">newNodeReady</span>"<span class="p">;</span> |
| <span class="n">public</span> <span class="n">static</span> <span class="n">final</span> <span class="n">String</span> <span class="n">NEW_NODE_CONNECTION</span><span class="p">=</span>"<span class="n">newNodeConnection</span>"<span class="p">;</span> |
| <span class="n">public</span> <span class="n">static</span> <span class="n">final</span> <span class="n">String</span> <span class="n">EMPTY_NODE</span><span class="p">=</span>"<span class="n">emptyNode</span>"<span class="p">;</span> |
| <span class="n">public</span> <span class="n">static</span> <span class="n">final</span> <span class="n">String</span> <span class="n">PLUGIN_ADDED</span><span class="p">=</span>"<span class="n">pluggin_added</span>"<span class="p">;</span> |
| <span class="n">public</span> <span class="n">static</span> <span class="n">final</span> <span class="n">String</span> <span class="n">PLUGIN_REMOVED</span><span class="p">=</span>"<span class="n">pluggin_removed</span>"<span class="p">;</span> |
| <span class="p">}</span> |
| </pre></div> |
| |
| |
| <p>Implementation tabs are provided as open-source code. You can find various implementation of this interface in felix repository in the <em>mosgi.managedelements.xxx.tab</em> elements.</p> |
| <h2 id="function-call-sequence">Function call sequence<a class="headerlink" href="#function-call-sequence" title="Permanent link">¶</a></h2> |
| <p>The next figure presents a function call sequence when using MOSGi framework.</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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