Java tutorial
/* * RHQ Management Platform * Copyright (C) 2005-2008 Red Hat, Inc. * All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation version 2 of the License. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ package org.rhq.plugins.agent; import java.io.File; import java.util.HashSet; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.mc4j.ems.connection.bean.attribute.EmsAttribute; import org.rhq.core.domain.configuration.Configuration; import org.rhq.core.domain.configuration.PropertySimple; import org.rhq.core.pluginapi.inventory.DiscoveredResourceDetails; import org.rhq.core.pluginapi.inventory.ResourceDiscoveryComponent; import org.rhq.core.pluginapi.inventory.ResourceDiscoveryContext; import org.rhq.core.system.OperatingSystemType; import org.rhq.core.system.SystemInfo; import org.rhq.enterprise.agent.Version; /** * This is the discovery component for the agent launcher script. * This launcher script is for UNIX and is not to be found on a * Windows platform. See {@link AgentJavaServiceWrapperDiscoveryComponent} * for the analogous Windows component. * * @author John Mazzitelli */ public class AgentLauncherScriptDiscoveryComponent implements ResourceDiscoveryComponent<AgentServerComponent<?>> { private final Log log = LogFactory.getLog(AgentLauncherScriptDiscoveryComponent.class); /** * The name of the plugin configuration simple property whose value is the launcher script file path. * Package scoped so the component can use this. */ static final String PLUGINCONFIG_PATHNAME = "Pathname"; /** * Simply returns the service resource. * * @see ResourceDiscoveryComponent#discoverResources(ResourceDiscoveryContext) */ public Set<DiscoveredResourceDetails> discoverResources( ResourceDiscoveryContext<AgentServerComponent<?>> context) { log.info("Discovering RHQ Agent's launcher script service..."); HashSet<DiscoveredResourceDetails> set = new HashSet<DiscoveredResourceDetails>(); try { String baseName = getBaseName(context.getSystemInformation()); if (baseName != null) { EmsAttribute attrib = context.getParentResourceComponent().getAgentBean().getAttribute("Version"); attrib.refresh(); String version; if (attrib.getValue() != null) { version = attrib.getValue().toString(); } else { version = Version.getProductVersion(); // just use the one we can get statically, its probably the correct version } // we know our agent plugin is running in the same process as our agent // so the script must be on the same box that we are running on. // try to find the file in one of several ways - but once we find it, stop (there is only ever one of them) if (!findInAgentHome(context, version, baseName, set)) { log.warn("Could not find the agent's launcher script anywhere"); } } } catch (Exception e) { log.error("An error occurred while attempting to auto-discover the agent's launcher script", e); } return set; } /** * Looks for the launcher script relative to the agent home directory. * * @param context * @param version * @param baseName * @param discoveries where the new details are stored if the script is discovered * * @return <code>true</code> if this method discovers the launcher script; <code>false</code> if not */ private boolean findInAgentHome(ResourceDiscoveryContext<AgentServerComponent<?>> context, String version, String baseName, HashSet<DiscoveredResourceDetails> discoveries) { try { EmsAttribute home = context.getParentResourceComponent().getAgentBean() .getAttribute("AgentHomeDirectory"); home.refresh(); Object agentHome = home.getValue(); if (agentHome != null) { File file = new File(agentHome.toString(), baseName); if (file.exists()) { discoveries.add(createDetails(context, version, file)); } } return discoveries.size() > 0; } catch (Exception e) { log.debug("Cannot use agent home to find launcher script. Cause: " + e); return false; } } private DiscoveredResourceDetails createDetails(ResourceDiscoveryContext<AgentServerComponent<?>> context, String version, File discoveredLocation) { String key = "launcherscript"; // this is a singleton resource; only ever one of these String name = "RHQ Agent Launcher Script"; String description = "A script that can start the agent and manage its lifecycle as a service"; String location; try { location = discoveredLocation.getCanonicalPath(); // try to get the canonical path but... } catch (Exception e) { location = discoveredLocation.getAbsolutePath(); // ...if we can't, use absolute path } File launcher = new File(new File(location), "rhq-agent-wrapper.sh"); DiscoveredResourceDetails details = new DiscoveredResourceDetails(context.getResourceType(), key, name, version, description, null, null); Configuration pc = details.getPluginConfiguration(); pc.put(new PropertySimple(PLUGINCONFIG_PATHNAME, launcher.getAbsoluteFile())); return details; } /** * Returns the base filename where the launcher script is to be found. * This is dependent on the platform we are running on. * UNIX machines will return a non-<code>null</code> string but because the * launcher script is not used by the agent on Windows machines, <code>null</code> will be returned * when running on Windows machines. * * @param sysInfo used to determine what platform we are on * * @return the location of the launcher script that we are trying to discover, or <code>null</code> if we * should not try to discovery the launcher script. The returned location is relative to agent home. */ private String getBaseName(SystemInfo sysInfo) { String location = null; try { OperatingSystemType osType = sysInfo.getOperatingSystemType(); if (osType == OperatingSystemType.JAVA) { String osName = System.getProperty("os.name", "").toLowerCase(); osType = osName.contains("windows") ? OperatingSystemType.WINDOWS : OperatingSystemType.LINUX; } if (osType != OperatingSystemType.WINDOWS) { location = "bin"; } } catch (Exception e) { // can't determine os type, assume windows } return location; } }