1 files changed, 310 insertions, 0 deletions
diff --git a/sandbox/axis2-1.4/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceDiscovery.java b/sandbox/axis2-1.4/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceDiscovery.java
new file mode 100644
index 0000000000..fcf7843fa9
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+++ b/sandbox/axis2-1.4/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceDiscovery.java
@@ -0,0 +1,310 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.    
+ */
+
+package org.apache.tuscany.sca.extensibility;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.URL;
+import java.security.AccessController;
+import java.security.PrivilegedActionException;
+import java.security.PrivilegedExceptionAction;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Hashtable;
+import java.util.Map;
+import java.util.Set;
+import java.util.StringTokenizer;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * Service discovery for Tuscany based on J2SE Jar service provider spec.
+ * Services are described using configuration files in META-INF/services.
+ * Service description specifies a class name followed by optional properties.
+ * Multi-ClassLoader environments are supported through a ClassLoader
+ * registration API
+ *
+ * @version $Rev$ $Date$
+ */
+public class ServiceDiscovery {
+    private static final Logger logger = Logger.getLogger(ServiceDiscovery.class.getName());
+
+    private static ServiceDiscovery instance;
+
+    private HashSet<ClassLoader> registeredClassLoaders;
+
+    /**
+     * Get an instance of Service discovery, one instance is created per
+     * ClassLoader that this class is loaded from
+     * 
+     * @return
+     */
+    public static ServiceDiscovery getInstance() {
+
+        if (instance == null) {
+            instance = new ServiceDiscovery();
+            instance.registeredClassLoaders = new HashSet<ClassLoader>();
+            instance.registeredClassLoaders.add(ServiceDiscovery.class.getClassLoader());
+        }
+        return instance;
+    }
+
+    /**
+     * Register a ClassLoader with this discovery mechanism. Tuscany extension
+     * ClassLoaders are registered here.
+     * 
+     * @param classLoader
+     */
+    public synchronized void registerClassLoader(ClassLoader classLoader) {
+        registeredClassLoaders.add(classLoader);
+    }
+    
+    /**
+     * Unregister a ClassLoader with this discovery mechanism. 
+     * 
+     * @param classLoader
+     */
+    public synchronized void unregisterClassLoader(ClassLoader classLoader) {
+        registeredClassLoaders.remove(classLoader);
+    }
+
+    /**
+     * Get all service declarations for this name
+     * 
+     * @param name
+     * @return set of service declarations
+     * @throws IOException
+     */
+    public Set<ServiceDeclaration> getServiceDeclarations(String name) throws IOException {
+
+        Set<ServiceDeclaration> classSet = new HashSet<ServiceDeclaration>();
+
+        for (ClassLoader classLoader : registeredClassLoaders) {
+            getServiceClasses(classLoader, name, classSet, true);
+        }
+        return classSet;
+    }
+
+    /**
+     * Get all service declarations for this interface
+     * 
+     * @param serviceInterface
+     * @return set of service declarations
+     * @throws IOException
+     */
+    public Set<ServiceDeclaration> getServiceDeclarations(Class<?> serviceInterface) throws IOException {
+
+        return getServiceDeclarations(serviceInterface.getName());
+    }
+
+    /**
+     * Load one service implementation class for this interface
+     * 
+     * @param serviceInterface
+     * @return service implementation class
+     * @throws IOException
+     * @throws ClassNotFoundException
+     */
+    public Class<?> loadFirstServiceClass(Class<?> serviceInterface) throws IOException, ClassNotFoundException {
+
+        Set<ServiceDeclaration> classSet = new HashSet<ServiceDeclaration>();
+
+        for (ClassLoader classLoader : registeredClassLoaders) {
+            getServiceClasses(classLoader, serviceInterface.getName(), classSet, false);
+            if (classSet.size() > 0)
+                break;
+        }
+        if (classSet.size() > 0)
+            return classSet.iterator().next().loadClass();
+        else
+            return null;
+
+    }
+
+    /**
+     * Returns a unique list of resource URLs of name META-INF/services/<name>
+     * Each URL is associated with the first ClassLoader that it was visible
+     * from
+     * 
+     * @param name Name of resource
+     * @return Table of URLs with associated ClassLoaders
+     * @throws IOException
+     */
+    public Hashtable<ClassLoader, Set<URL>> getServiceResources(final String name) throws IOException {
+
+        Hashtable<ClassLoader, Set<URL>> resourceTable = new Hashtable<ClassLoader, Set<URL>>();
+
+        HashSet<URL> allURLs = new HashSet<URL>();
+        for (final ClassLoader classLoader : registeredClassLoaders) {
+            HashSet<URL> urls = new HashSet<URL>();
+            resourceTable.put(classLoader, urls);
+            boolean debug = logger.isLoggable(Level.FINE);
+            if (debug) {
+                logger.fine("Discovering service resources using class loader " + classLoader);
+            }
+            // Allow privileged access to read META-INF/services/*. Add FilePermission to added to security policy file.
+            ArrayList<URL> urlList;
+            try {
+                // FIXME J2 Security - promote this to callers of this method
+                urlList = AccessController.doPrivileged(new PrivilegedExceptionAction<ArrayList<URL>>() {
+                    public ArrayList<URL> run() throws IOException {
+                        return Collections.list(classLoader.getResources("META-INF/services/" + name));
+                    }
+                });
+            } catch (PrivilegedActionException e) {
+                throw (IOException)e.getException();
+            }
+            
+            for (URL url : urlList) {
+                if (allURLs.contains(url))
+                    continue;
+                urls.add(url);
+            }
+            allURLs.addAll(urls);
+        }
+        return resourceTable;
+    }
+
+    /**
+     * Parse a service declaration in the form class;attr=value,attr=value and
+     * return a map of attributes
+     * 
+     * @param declaration
+     * @return a map of attributes
+     */
+    private Map<String, String> parseServiceDeclaration(String declaration) {
+        Map<String, String> attributes = new HashMap<String, String>();
+        int index = declaration.indexOf(';');
+        if (index != -1) {
+            attributes.put("class", declaration.substring(0, index).trim());
+            declaration = declaration.substring(index);
+        } else {
+            int j = declaration.indexOf('=');
+            if (j == -1) {
+                attributes.put("class", declaration.trim());
+                return attributes;
+            } else {
+                declaration = ";" + declaration;
+            }
+        }
+        StringTokenizer tokens = new StringTokenizer(declaration);
+        for (; tokens.hasMoreTokens();) {
+            String key = tokens.nextToken("=").substring(1).trim();
+            if (key == null)
+                break;
+            String value = tokens.nextToken(",").substring(1).trim();
+            if (value == null)
+                break;
+            attributes.put(key, value);
+        }
+        return attributes;
+    }
+
+    /**
+     * Load the service class whose name specified in a configuration file
+     * 
+     * @param classLoader
+     * @param name The name of the service class
+     * @param classSet Populate this set with classes extends/implements the
+     *                service class
+     * @throws IOException
+     */
+    private void getServiceClasses(final ClassLoader classLoader,
+                                   final String name,
+                                   Set<ServiceDeclaration> classSet,
+                                   boolean findAllClasses) throws IOException {
+
+        boolean debug = logger.isLoggable(Level.FINE);
+        if (debug) {
+            logger.fine("Discovering service providers using class loader " + classLoader);
+        }
+        // Allow privileged access to read META-INF/services/*. Add FilePermission to added to
+        // security policy file.
+        ArrayList<URL> urlList;
+        try {
+            urlList = AccessController.doPrivileged(new PrivilegedExceptionAction<ArrayList<URL>>() {
+                public ArrayList<URL> run() throws IOException {
+                    return Collections.list(classLoader.getResources("META-INF/services/" + name));
+                }
+            });
+        } catch (PrivilegedActionException e) {
+            throw (IOException)e.getException();
+        }
+        
+        for (final URL url : urlList) {
+            if (debug) {
+                logger.fine("Reading service provider file: " + url.toExternalForm());
+            }
+
+            // Allow privileged access to open URL stream. Add FilePermission to added to security
+            // policy file.
+            InputStream is;
+            try {
+                is = AccessController.doPrivileged(new PrivilegedExceptionAction<InputStream>() {
+                    public InputStream run() throws IOException {
+                        return url.openStream();
+                    }
+                });
+            } catch (PrivilegedActionException e) {
+                throw (IOException)e.getException();
+            }
+            BufferedReader reader = null;
+            try {
+                reader = new BufferedReader(new InputStreamReader(is));
+                while (true) {
+                    String line = reader.readLine();
+                    if (line == null)
+                        break;
+                    line = line.trim();
+                    if (!line.startsWith("#") && !"".equals(line)) {
+                        String reg = line.trim();
+                        if (debug) {
+                            logger.fine("Registering service provider: " + reg);
+                        }
+
+                        Map<String, String> attributes = parseServiceDeclaration(reg);
+                        String className = attributes.get("class");
+                        ServiceDeclaration serviceClass = new ServiceDeclaration(className, classLoader, attributes);
+                        classSet.add(serviceClass);
+
+                        if (!findAllClasses)
+                            break;
+                    }
+                }
+            } finally {
+                if (reader != null)
+                    reader.close();
+                if (is != null) {
+                    try {
+                        is.close();
+                    } catch (IOException ioe) {
+                    }
+                }
+            }
+            if (!findAllClasses && classSet.size() > 0)
+                break;
+        }
+    }
+
+}