Add API to find services for a given feature

It's a common pattern to look for all services hosted under the users
service that provide a given feature. Let's provide an API for that and
use that API in the methods that benefit from it.

smack-extensions/src/main/java/org/jivesoftware/smackx/address/MultipleRecipientManager.java

@@ -25,18 +25,13 @@ import org.jivesoftware.smack.XMPPConnection;
 import org.jivesoftware.smack.XMPPException.XMPPErrorException;
 import org.jivesoftware.smack.packet.Message;
 import org.jivesoftware.smack.packet.Packet;
-import org.jivesoftware.smack.util.Cache;
 import org.jivesoftware.smackx.address.packet.MultipleAddresses;
 import org.jivesoftware.smackx.disco.ServiceDiscoveryManager;
-import org.jivesoftware.smackx.disco.packet.DiscoverInfo;
-import org.jivesoftware.smackx.disco.packet.DiscoverItems;
 import org.jxmpp.util.XmppStringUtils;
 
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
-import java.util.logging.Level;
-import java.util.logging.Logger;
 
 /**
  * A MultipleRecipientManager allows to send packets to multiple recipients by making use of
@@ -47,14 +42,6 @@ import java.util.logging.Logger;
  */
 public class MultipleRecipientManager {
 
-    private static final Logger LOGGER = Logger.getLogger(MultipleRecipientManager.class.getName());
-
-    /**
-     * Create a cache to hold the 100 most recently accessed elements for a period of
-     * 24 hours.
-     */
-    private static Cache<String, String> services = new Cache<String, String>(100, 24 * 60 * 60 * 1000);
-
     /**
      * Sends the specified packet to the list of specified recipients using the
      * specified connection. If the server has support for XEP-33 then only one
@@ -295,43 +282,12 @@ public class MultipleRecipientManager {
      * @throws NotConnectedException 
      */
     private static String getMultipleRecipienServiceAddress(XMPPConnection connection) throws NoResponseException, XMPPErrorException, NotConnectedException {
-        String serviceName = connection.getServiceName();
+        ServiceDiscoveryManager sdm = ServiceDiscoveryManager.getInstanceFor(connection);
-        String serviceAddress = (String) services.get(serviceName);
+        List<String> services = sdm.findServices(MultipleAddresses.NAMESPACE, true, true);
-        if (serviceAddress == null) {
+        if (services.size() > 0) {
-            ServiceDiscoveryManager sdm = ServiceDiscoveryManager.getInstanceFor(connection);
+            return services.get(0);
-            // Send the disco packet to the server itself
-            DiscoverInfo info = sdm.discoverInfo(serviceName);
-            // Check if the server supports XEP-33
-            if (info.containsFeature(MultipleAddresses.NAMESPACE)) {
-                serviceAddress = serviceName;
-            }
-            else {
-                // Get the disco items and send the disco packet to each server item
-                DiscoverItems items = sdm.discoverItems(serviceName);
-                for (DiscoverItems.Item item : items.getItems()) {
-                    try {
-                        info = sdm.discoverInfo(item.getEntityID(), item.getNode());
-                    }
-                    catch (XMPPErrorException|NoResponseException e) {
-                        // Don't throw this exceptions if one of the server's items fail
-                        LOGGER.log(Level.WARNING,
-                                        "Exception while discovering info of " + item.getEntityID()
-                                                        + " node: " + item.getNode(), e);
-                        continue;
-                    }
-                    if (info.containsFeature(MultipleAddresses.NAMESPACE)) {
-                        serviceAddress = serviceName;
-                        break;
-                    }
-                }
-            }
-            // Use the empty string to indicate that no service is known for this connection
-            serviceAddress = serviceAddress == null ? "" : serviceAddress;
-            // Cache the discovered information
-            services.put(serviceName, serviceAddress);
         }
-
+        return null;
-        return "".equals(serviceAddress) ? null : serviceAddress;
     }
 
     /**

smack-extensions/src/main/java/org/jivesoftware/smackx/disco/ServiceDiscoveryManager.java

@@ -30,6 +30,7 @@ import org.jivesoftware.smack.packet.IQ;
 import org.jivesoftware.smack.packet.Packet;
 import org.jivesoftware.smack.packet.PacketExtension;
 import org.jivesoftware.smack.packet.XMPPError;
+import org.jivesoftware.smack.util.Cache;
 import org.jivesoftware.smackx.caps.EntityCapsManager;
 import org.jivesoftware.smackx.disco.packet.DiscoverInfo;
 import org.jivesoftware.smackx.disco.packet.DiscoverItems;
@@ -45,6 +46,8 @@ import java.util.Map;
 import java.util.Set;
 import java.util.WeakHashMap;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 /**
  * Manages discovery of services in XMPP entities. This class provides:
@@ -59,6 +62,7 @@ import java.util.concurrent.ConcurrentHashMap;
  */
 public class ServiceDiscoveryManager extends Manager {
 
+    private static final Logger LOGGER = Logger.getLogger(ServiceDiscoveryManager.class.getName());
     private static final String DEFAULT_IDENTITY_NAME = "Smack";
     private static final String DEFAULT_IDENTITY_CATEGORY = "client";
     private static final String DEFAULT_IDENTITY_TYPE = "pc";
@@ -682,6 +686,77 @@ public class ServiceDiscoveryManager extends Manager {
         return result.containsFeature(feature);
     }
 
+    /**
+     * Create a cache to hold the 25 most recently lookup services for a given feature for a period
+     * of 24 hours.
+     */
+    private Cache<String, List<String>> services = new Cache<String, List<String>>(25,
+                    24 * 60 * 60 * 1000);
+
+    /**
+     * Find all services under the users service that provide a given feature.
+     * 
+     * @param feature the feature to search for
+     * @param stopOnFirst if true, stop searching after the first service was found
+     * @param useCache if true, query a cache first to avoid network I/O
+     * @return a possible empty list of services providing the given feature
+     * @throws NoResponseException
+     * @throws XMPPErrorException
+     * @throws NotConnectedException
+     */
+    public List<String> findServices(String feature, boolean stopOnFirst, boolean useCache)
+                    throws NoResponseException, XMPPErrorException, NotConnectedException {
+        List<String> serviceAddresses = null;
+        String serviceName = connection().getServiceName();
+        if (useCache) {
+            serviceAddresses = (List<String>) services.get(feature);
+            if (serviceAddresses != null) {
+                return serviceAddresses;
+            }
+        }
+        serviceAddresses = new LinkedList<String>();
+        // Send the disco packet to the server itself
+        DiscoverInfo info = discoverInfo(serviceName);
+        // Check if the server supports XEP-33
+        if (info.containsFeature(feature)) {
+            serviceAddresses.add(serviceName);
+            if (stopOnFirst) {
+                if (useCache) {
+                    // Cache the discovered information
+                    services.put(feature, serviceAddresses);
+                }
+                return serviceAddresses;
+            }
+        }
+        // Get the disco items and send the disco packet to each server item
+        DiscoverItems items = discoverItems(serviceName);
+        for (DiscoverItems.Item item : items.getItems()) {
+            try {
+                // TODO is it OK here in all cases to query without the node attribute?
+                // MultipleRecipientManager queried initially also with the node attribute, but this
+                // could be simply a fault instead of intentional.
+                info = discoverInfo(item.getEntityID());
+            }
+            catch (XMPPErrorException | NoResponseException e) {
+                // Don't throw this exceptions if one of the server's items fail
+                LOGGER.log(Level.WARNING, "Exception while discovering info for feature " + feature
+                                + " of " + item.getEntityID() + " node: " + item.getNode(), e);
+                continue;
+            }
+            if (info.containsFeature(feature)) {
+                serviceAddresses.add(item.getEntityID());
+                if (stopOnFirst) {
+                    break;
+                }
+            }
+        }
+        if (useCache) {
+            // Cache the discovered information
+            services.put(feature, serviceAddresses);
+        }
+        return serviceAddresses;
+    }
+
     /**
      * Entity Capabilities
      */

smack-extensions/src/main/java/org/jivesoftware/smackx/muc/MultiUserChat.java

@@ -260,16 +260,8 @@ public class MultiUserChat {
      * @throws NotConnectedException 
      */
     public static Collection<String> getServiceNames(XMPPConnection connection) throws NoResponseException, XMPPErrorException, NotConnectedException  {
-        final List<String> answer = new ArrayList<String>();
+        ServiceDiscoveryManager sdm = ServiceDiscoveryManager.getInstanceFor(connection);
-        ServiceDiscoveryManager discoManager = ServiceDiscoveryManager.getInstanceFor(connection);
+        return sdm.findServices(MUCInitialPresence.NAMESPACE, false, false);
-        DiscoverItems items = discoManager.discoverItems(connection.getServiceName());
-        for (DiscoverItems.Item item : items.getItems()) {
-            DiscoverInfo info = discoManager.discoverInfo(item.getEntityID());
-            if (info.containsFeature(MUCInitialPresence.NAMESPACE)) {
-                answer.add(item.getEntityID());
-            }
-        }
-        return answer;
     }
 
     /**

smack-extensions/src/main/java/org/jivesoftware/smackx/search/UserSearch.java

@@ -23,6 +23,7 @@ import org.jivesoftware.smack.XMPPException.XMPPErrorException;
 import org.jivesoftware.smack.packet.IQ;
 import org.jivesoftware.smack.provider.IQProvider;
 import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smack.util.XmlStringBuilder;
 import org.jivesoftware.smackx.xdata.Form;
 import org.jivesoftware.smackx.xdata.FormField;
 import org.jivesoftware.smackx.xdata.packet.DataForm;
@@ -40,18 +41,23 @@ import org.xmlpull.v1.XmlPullParser;
  */
 public class UserSearch extends IQ {
 
+    public static final String NAMESPACE = "jabber:iq:search";
+
     /**
      * Creates a new instance of UserSearch.
      */
     public UserSearch() {
     }
 
-    public String getChildElementXML() {
+    @Override
-        StringBuilder buf = new StringBuilder();
+    public XmlStringBuilder getChildElementXML() {
-        buf.append("<query xmlns=\"jabber:iq:search\">");
+        XmlStringBuilder xml = new XmlStringBuilder();
-        buf.append(getExtensionsXML());
+        xml.halfOpenElement(IQ.QUERY_ELEMENT);
-        buf.append("</query>");
+        xml.xmlnsAttribute(NAMESPACE);
-        return buf.toString();
+        xml.rightAngelBracket();
+        xml.append(getExtensionsXML());
+        xml.closeElement(IQ.QUERY_ELEMENT);
+        return xml;
     }
 
     /**

smack-extensions/src/main/java/org/jivesoftware/smackx/search/UserSearchManager.java

@@ -19,16 +19,11 @@ package org.jivesoftware.smackx.search;
 import org.jivesoftware.smack.SmackException.NoResponseException;
 import org.jivesoftware.smack.SmackException.NotConnectedException;
 import org.jivesoftware.smack.XMPPConnection;
-import org.jivesoftware.smack.XMPPException;
 import org.jivesoftware.smack.XMPPException.XMPPErrorException;
 import org.jivesoftware.smackx.disco.ServiceDiscoveryManager;
-import org.jivesoftware.smackx.disco.packet.DiscoverInfo;
-import org.jivesoftware.smackx.disco.packet.DiscoverItems;
 import org.jivesoftware.smackx.xdata.Form;
 
-import java.util.ArrayList;
 import java.util.Collection;
-import java.util.List;
 
 /**
  * The UserSearchManager is a facade built upon Jabber Search Services (XEP-055) to allow for searching
@@ -101,29 +96,7 @@ public class UserSearchManager {
      * @throws NotConnectedException 
      */
     public Collection<String> getSearchServices() throws NoResponseException, XMPPErrorException, NotConnectedException  {
-        final List<String> searchServices = new ArrayList<String>();
         ServiceDiscoveryManager discoManager = ServiceDiscoveryManager.getInstanceFor(con);
-        DiscoverItems items = discoManager.discoverItems(con.getServiceName());
+        return discoManager.findServices(UserSearch.NAMESPACE, false, false);
-        for (DiscoverItems.Item item : items.getItems()) {
-            try {
-                DiscoverInfo info;
-                try {
-                    info = discoManager.discoverInfo(item.getEntityID());
-                }
-                catch (XMPPException e) {
-                    // Ignore Case
-                    continue;
-                }
-
-                if (info.containsFeature("jabber:iq:search")) {
-                    searchServices.add(item.getEntityID());
-                }
-            }
-            catch (Exception e) {
-                // No info found.
-                break;
-            }
-        }
-        return searchServices;
     }
 }