1 files changed, 134 insertions, 0 deletions
diff --git a/tags/java/sca/2.0-M3-RC4/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceDiscovery.java b/tags/java/sca/2.0-M3-RC4/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceDiscovery.java
new file mode 100644
index 0000000000..a5048859f0
--- /dev/null
+++ b/tags/java/sca/2.0-M3-RC4/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ServiceDiscovery.java
@@ -0,0 +1,134 @@
+/*
+ * 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.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * 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.
+ *
+ *
+ * @version $Rev$ $Date$
+ */
+public final class ServiceDiscovery implements ServiceDiscoverer {
+    private final static ServiceDiscovery INSTANCE = new ServiceDiscovery();
+
+    private ServiceDiscoverer discoverer;
+
+    private ServiceDiscovery() {
+        super();
+    }
+    /**
+     * Get an instance of Service discovery, one instance is created per
+     * ClassLoader that this class is loaded from
+     *
+     * @return
+     */
+    public static ServiceDiscovery getInstance() {
+        return INSTANCE;
+    }
+
+    public ServiceDiscoverer getServiceDiscoverer() {
+        if (discoverer != null) {
+            return discoverer;
+        }
+        try {
+            // FIXME: This is a hack to trigger the activation of the extensibility-equinox bundle in OSGi
+            Class.forName("org.apache.tuscany.sca.extensibility.equinox.EquinoxServiceDiscoverer");
+            if (discoverer != null) {
+                return discoverer;
+            }
+        } catch (Throwable e) {
+        }
+        discoverer = new ContextClassLoaderServiceDiscoverer();
+        return discoverer;
+    }
+
+    public void setServiceDiscoverer(ServiceDiscoverer sd) {
+        if (discoverer != null) {
+            throw new IllegalStateException("The ServiceDiscoverer cannot be reset");
+        }
+        discoverer = sd;
+    }
+
+    public Collection<ServiceDeclaration> getServiceDeclarations(String name) throws IOException {
+        return getServiceDeclarations(name, false);
+    }
+
+    public Collection<ServiceDeclaration> getServiceDeclarations(String name, boolean byRanking) throws IOException {
+        Collection<ServiceDeclaration> declarations = getServiceDiscoverer().getServiceDeclarations(name);
+        if (!byRanking) {
+            return declarations;
+        }
+        if (!declarations.isEmpty()) {
+            List<ServiceDeclaration> declarationList = new ArrayList<ServiceDeclaration>(declarations);
+            Collections.sort(declarationList, ServiceComparator.DESCENDING_ORDER);
+            return declarationList;
+        } else {
+            return Collections.emptyList();
+        }
+    }
+
+    /**
+     * Get the service declaration. If there are more than one services, the one with highest ranking will
+     * be returned.
+     */
+    public ServiceDeclaration getServiceDeclaration(final String name) throws IOException {
+        //        ServiceDeclaration service = getServiceDiscoverer().getFirstServiceDeclaration(name);
+        //        return service;
+        Collection<ServiceDeclaration> declarations = getServiceDeclarations(name, true);
+        if (!declarations.isEmpty()) {
+            List<ServiceDeclaration> declarationList = new ArrayList<ServiceDeclaration>(declarations);
+            Collections.sort(declarationList, ServiceComparator.DESCENDING_ORDER);
+            return declarationList.get(0);
+        } else {
+            return null;
+        }
+    }
+
+    /**
+     * Compare service declarations by ranking
+     */
+    private static class ServiceComparator implements Comparator<ServiceDeclaration> {
+        private final static Comparator<ServiceDeclaration> DESCENDING_ORDER = new ServiceComparator();
+
+        public int compare(ServiceDeclaration o1, ServiceDeclaration o2) {
+            int rank1 = 0;
+            String r1 = o1.getAttributes().get("ranking");
+            if (r1 != null) {
+                rank1 = Integer.parseInt(r1);
+            }
+            int rank2 = 0;
+            String r2 = o2.getAttributes().get("ranking");
+            if (r2 != null) {
+                rank2 = Integer.parseInt(r2);
+            }
+            return rank2 - rank1; // descending
+        }
+    }
+
+}