GMSClient.java

/*
 ************************************************************************
 *******************  CANADIAN ASTRONOMY DATA CENTRE  *******************
 **************  CENTRE CANADIEN DE DONNÉES ASTRONOMIQUES  **************
 *
 *  (c) 2014.                            (c) 2014.
 *  Government of Canada                 Gouvernement du Canada
 *  National Research Council            Conseil national de recherches
 *  Ottawa, Canada, K1A 0R6              Ottawa, Canada, K1A 0R6
 *  All rights reserved                  Tous droits réservés
 *
 *  NRC disclaims any warranties,        Le CNRC dénie toute garantie
 *  expressed, implied, or               énoncée, implicite ou légale,
 *  statutory, of any kind with          de quelque nature que ce
 *  respect to the software,             soit, concernant le logiciel,
 *  including without limitation         y compris sans restriction
 *  any warranty of merchantability      toute garantie de valeur
 *  or fitness for a particular          marchande ou de pertinence
 *  purpose. NRC shall not be            pour un usage particulier.
 *  liable in any event for any          Le CNRC ne pourra en aucun cas
 *  damages, whether direct or           être tenu responsable de tout
 *  indirect, special or general,        dommage, direct ou indirect,
 *  consequential or incidental,         particulier ou général,
 *  arising from the use of the          accessoire ou fortuit, résultant
 *  software.  Neither the name          de l'utilisation du logiciel. Ni
 *  of the National Research             le nom du Conseil National de
 *  Council of Canada nor the            Recherches du Canada ni les noms
 *  names of its contributors may        de ses  participants ne peuvent
 *  be used to endorse or promote        être utilisés pour approuver ou
 *  products derived from this           promouvoir les produits dérivés
 *  software without specific prior      de ce logiciel sans autorisation
 *  written permission.                  préalable et particulière
 *                                       par écrit.
 *
 *  This file is part of the             Ce fichier fait partie du projet
 *  OpenCADC project.                    OpenCADC.
 *
 *  OpenCADC is free software:           OpenCADC est un logiciel libre ;
 *  you can redistribute it and/or       vous pouvez le redistribuer ou le
 *  modify it under the terms of         modifier suivant les termes de
 *  the GNU Affero General Public        la “GNU Affero General Public
 *  License as published by the          License” telle que publiée
 *  Free Software Foundation,            par la Free Software Foundation
 *  either version 3 of the              : soit la version 3 de cette
 *  License, or (at your option)         licence, soit (à votre gré)
 *  any later version.                   toute version ultérieure.
 *
 *  OpenCADC is distributed in the       OpenCADC est distribué
 *  hope that it will be useful,         dans l’espoir qu’il vous
 *  but WITHOUT ANY WARRANTY;            sera utile, mais SANS AUCUNE
 *  without even the implied             GARANTIE : sans même la garantie
 *  warranty of MERCHANTABILITY          implicite de COMMERCIALISABILITÉ
 *  or FITNESS FOR A PARTICULAR          ni d’ADÉQUATION À UN OBJECTIF
 *  PURPOSE.  See the GNU Affero         PARTICULIER. Consultez la Licence
 *  General Public License for           Générale Publique GNU Affero
 *  more details.                        pour plus de détails.
 *
 *  You should have received             Vous devriez avoir reçu une
 *  a copy of the GNU Affero             copie de la Licence Générale
 *  General Public License along         Publique GNU Affero avec
 *  with OpenCADC.  If not, see          OpenCADC ; si ce n’est
 *  <http://www.gnu.org/licenses/>.      pas le cas, consultez :
 *                                       <http://www.gnu.org/licenses/>.
 *
 *  $Revision: 4 $
 *
 ************************************************************************
 */
package ca.nrc.cadc.ac.client;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.security.AccessControlContext;
import java.security.AccessControlException;
import java.security.AccessController;
import java.security.Principal;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLSocketFactory;
import javax.security.auth.Subject;

import org.apache.log4j.Logger;

import ca.nrc.cadc.ac.Group;
import ca.nrc.cadc.ac.GroupAlreadyExistsException;
import ca.nrc.cadc.ac.GroupNotFoundException;
import ca.nrc.cadc.ac.GroupReader;
import ca.nrc.cadc.ac.GroupWriter;
import ca.nrc.cadc.ac.GroupsReader;
import ca.nrc.cadc.ac.Role;
import ca.nrc.cadc.ac.UserNotFoundException;
import ca.nrc.cadc.auth.AuthenticationUtil;
import ca.nrc.cadc.auth.SSLUtil;
import ca.nrc.cadc.net.HttpDownload;
import ca.nrc.cadc.net.HttpPost;
import ca.nrc.cadc.net.HttpUpload;
import ca.nrc.cadc.net.NetUtil;

import com.csvreader.CsvReader;

/**
 * Client class for performing group searching and group actions
 * with the access control web service.
 */
public class GMSClient
{
    private static final Logger log = Logger.getLogger(GMSClient.class);
    
    // socket factory to use when connecting
    public SSLSocketFactory sslSocketFactory;
    
    private String baseURL;

    /**
     * Constructor.
     * 
     * @param baseURL The URL of the supporting access control web service
     * obtained from the registry.
     */
    public GMSClient(String baseURL)
        throws IllegalArgumentException
    {
        if (baseURL == null)
        {
            throw new IllegalArgumentException("baseURL is required");
        }
        try
        {
            URL testURL = new URL(baseURL);
//            if (!testURL.getProtocol().equals("https"))
//            {
//                throw new IllegalArgumentException(
//                        "URL must have HTTPS protocol");
//            }
        }
        catch (MalformedURLException e)
        {
            throw new IllegalArgumentException("URL is malformed: " + 
                                               e.getMessage());
        }

        if (baseURL.endsWith("/"))
        {
            this.baseURL = baseURL.substring(0, baseURL.length() - 1);
        }
        else
        {
            this.baseURL = baseURL;
        }
    }

    /**
     * Get a list of groups.
     *
     * @return The list of groups.
     */
    public List<Group> getGroups()
    {
        throw new UnsupportedOperationException("Not yet implemented");
    }

    /**
     * Create a new group.
     *
     * @param group The group to create
     * @return The newly created group will all the information.
     * @throws GroupAlreadyExistsException If a group with the same name already
     *                                     exists.
     * @throws AccessControlException If unauthorized to perform this operation.
     * @throws UserNotFoundException
     * @throws IOException
     */
    public Group createGroup(Group group)
        throws GroupAlreadyExistsException, AccessControlException, 
               UserNotFoundException, IOException
    {
        URL createGroupURL = new URL(this.baseURL + "/groups");
        log.debug("createGroupURL request to " + createGroupURL.toString());
        
        // reset the state of the cache
        clearCache();

        StringBuilder groupXML = new StringBuilder();
        GroupWriter.write(group, groupXML);
        log.debug("createGroup: " + groupXML);

        byte[] bytes = groupXML.toString().getBytes("UTF-8");
        ByteArrayInputStream in = new ByteArrayInputStream(bytes);

        HttpUpload transfer = new HttpUpload(in, createGroupURL);
        transfer.setSSLSocketFactory(getSSLSocketFactory());

        transfer.run();

        Throwable error = transfer.getThrowable();
        if (error != null)
        {
            log.debug("createGroup throwable", error);
            // transfer returns a -1 code for anonymous uploads.
            if ((transfer.getResponseCode() == -1) || 
                (transfer.getResponseCode() == 401) || 
                (transfer.getResponseCode() == 403))
            {
                throw new AccessControlException(error.getMessage());
            }
            if (transfer.getResponseCode() == 400)
            {
                throw new IllegalArgumentException(error.getMessage());
            }
            if (transfer.getResponseCode() == 409)
            {
                throw new GroupAlreadyExistsException(error.getMessage());
            }
            if (transfer.getResponseCode() == 404)
            {
                throw new UserNotFoundException(error.getMessage());
            }
            throw new IOException(error);
        }

        String retXML = transfer.getResponseBody();
        try
        {
            log.debug("createGroup returned: " + groupXML);
            return GroupReader.read(retXML);
        }
        catch (Exception bug)
        {
            log.error("Unexpected exception", bug);
            throw new RuntimeException(bug);
        }
    }

    /**
     * Get the group object.
     *
     * @param groupName Identifies the group to get.
     * @return The group.
     * @throws GroupNotFoundException If the group was not found.
     * @throws AccessControlException If unauthorized to perform this operation.
     * @throws java.io.IOException
     */
    public Group getGroup(String groupName)
        throws GroupNotFoundException, AccessControlException, IOException
    {
        URL getGroupURL = new URL(this.baseURL + "/groups/" + groupName);
        log.debug("getGroup request to " + getGroupURL.toString());
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        HttpDownload transfer = new HttpDownload(getGroupURL, out);

        transfer.setSSLSocketFactory(getSSLSocketFactory());
        transfer.run();

        Throwable error = transfer.getThrowable();
        if (error != null)
        {
            log.debug("getGroup throwable", error);
            // transfer returns a -1 code for anonymous access.
            if ((transfer.getResponseCode() == -1) || 
                (transfer.getResponseCode() == 401) || 
                (transfer.getResponseCode() == 403))
            {
                throw new AccessControlException(error.getMessage());
            }
            if (transfer.getResponseCode() == 400)
            {
                throw new IllegalArgumentException(error.getMessage());
            }
            if (transfer.getResponseCode() == 404)
            {
                throw new GroupNotFoundException(error.getMessage());
            }
            throw new IOException(error);
        }

        try
        {
            String groupXML = new String(out.toByteArray(), "UTF-8");
            log.debug("getGroup returned: " + groupXML);
            return GroupReader.read(groupXML);
        }
        catch (Exception bug)
        {
            log.error("Unexpected exception", bug);
            throw new RuntimeException(bug);
        }
    }
    
    /**
     * Get the all group names.
     *
     * @return The list of names.
     * @throws AccessControlException If unauthorized to perform this operation.
     * @throws java.io.IOException
     */
    public List<String> getGroupNames()
        throws AccessControlException, IOException
    {
        URL getGroupNamesURL = new URL(this.baseURL + "/groups");
        log.debug("getGroupNames request to " + getGroupNamesURL.toString());
        
        HttpURLConnection conn = 
                (HttpURLConnection) getGroupNamesURL.openConnection();
        conn.setRequestMethod("GET");

        SSLSocketFactory sf = getSSLSocketFactory();
        if ((sf != null) && ((conn instanceof HttpsURLConnection)))
        {
            ((HttpsURLConnection) conn)
                    .setSSLSocketFactory(sf);
        }
        int responseCode = -1;
        try
        {
            responseCode = conn.getResponseCode();
        }
        catch(Exception e)
        {
            throw new AccessControlException(e.getMessage());
        }
        
        if (responseCode != 200)
        {
            String errMessage = NetUtil.getErrorBody(conn);
            log.debug("deleteGroup response " + responseCode + ": " + 
                      errMessage);

            if ((responseCode == 401) || (responseCode == 403) || 
                    (responseCode == -1))
            {
                throw new AccessControlException(errMessage);
            }
            if (responseCode == 400)
            {
                throw new IllegalArgumentException(errMessage);
            }
            throw new IOException("HttpResponse (" + responseCode + ") - " + errMessage);
        }

        try
        {
            List<String> groupNames = new ArrayList<String>();
            Reader ioReader = new InputStreamReader(conn.getInputStream());
            BufferedReader br = new BufferedReader(ioReader);
            CsvReader reader = new CsvReader(br);
            
            for (int i=0; i<reader.getColumnCount(); i++)
            {
                groupNames.add(reader.get(i));
            }
            
            return groupNames;
        }
        catch (Exception bug)
        {
            log.error("Unexpected exception", bug);
            throw new RuntimeException(bug);
        }
    }

    /**
     * Update a group.
     *
     * @param group The update group object.
     * @return The group after update.
     * @throws IllegalArgumentException If cyclical membership is detected.
     * @throws GroupNotFoundException If the group was not found.
     * @throws GroupNotFoundException If a member was not found.
     * @throws AccessControlException If unauthorized to perform this operation.
     * @throws java.io.IOException
     */
    public Group updateGroup(Group group)
        throws IllegalArgumentException, GroupNotFoundException, UserNotFoundException,
               AccessControlException, IOException
    {
        URL updateGroupURL = new URL(this.baseURL + "/groups/" + group.getID());
        log.debug("updateGroup request to " + updateGroupURL.toString());
        
        // reset the state of the cache
        clearCache();

        StringBuilder groupXML = new StringBuilder();
        GroupWriter.write(group, groupXML);
        log.debug("updateGroup: " + groupXML);

        HttpPost transfer = new HttpPost(updateGroupURL, groupXML.toString(), 
                                         "application/xml", true);

        transfer.setSSLSocketFactory(getSSLSocketFactory());
        transfer.run();

        Throwable error = transfer.getThrowable();
        if (error != null)
        {
            log.debug("updateGroup throwable", error);
            if (transfer.getResponseCode() == 302)
            {
                return getGroup(group.getID());
            }
            // transfer returns a -1 code for anonymous access.
            if ((transfer.getResponseCode() == -1) || 
                (transfer.getResponseCode() == 401) || 
                (transfer.getResponseCode() == 403))
            {
                throw new AccessControlException(error.getMessage());
            }
            if (transfer.getResponseCode() == 400)
            {
                throw new IllegalArgumentException(error.getMessage());
            }
            if (transfer.getResponseCode() == 404)
            {
                if (error.getMessage() != null && error.getMessage().toLowerCase().contains("user"))
                    throw new UserNotFoundException(error.getMessage());
                else
                    throw new GroupNotFoundException(error.getMessage());
            }
            throw new IOException(error);
        }

        String retXML = transfer.getResponseBody();
        try
        {
            log.debug("updateGroup returned: " + groupXML);
            return GroupReader.read(retXML);
        }
        catch (Exception bug)
        {
            log.error("Unexpected exception", bug);
            throw new RuntimeException(bug);
        }
    }

    /**
     * Delete the group.
     *
     * @param groupName Identifies the group to delete.
     * @throws GroupNotFoundException If the group was not found.
     * @throws AccessControlException If unauthorized to perform this operation.
     * @throws java.io.IOException
     */
    public void deleteGroup(String groupName)
        throws GroupNotFoundException, AccessControlException, IOException
    {
        URL deleteGroupURL = new URL(this.baseURL + "/groups/" + groupName);
        log.debug("deleteGroup request to " + deleteGroupURL.toString());
        
        // reset the state of the cache
        clearCache();
        
        HttpURLConnection conn = 
                (HttpURLConnection) deleteGroupURL.openConnection();
        conn.setRequestMethod("DELETE");

        SSLSocketFactory sf = getSSLSocketFactory();
        if ((sf != null) && ((conn instanceof HttpsURLConnection)))
        {
            ((HttpsURLConnection) conn)
                    .setSSLSocketFactory(sf);
        }
        int responseCode = -1;
        try
        {
            responseCode = conn.getResponseCode();
        }
        catch(Exception e)
        {
            throw new AccessControlException(e.getMessage());
        }
        
        if (responseCode != 200)
        {
            String errMessage = NetUtil.getErrorBody(conn);
            log.debug("deleteGroup response " + responseCode + ": " + 
                      errMessage);

            if ((responseCode == 401) || (responseCode == 403) || 
                    (responseCode == -1))
            {
                throw new AccessControlException(errMessage);
            }
            if (responseCode == 400)
            {
                throw new IllegalArgumentException(errMessage);
            }
            if (responseCode == 404)
            {
                throw new GroupNotFoundException(errMessage);
            }
            throw new IOException("HttpResponse (" + responseCode + ") - " + errMessage);
        }
    }

    /**
     * Add a group as a member of another group.
     *
     * @param targetGroupName The group in which to add the group member.
     * @param groupMemberName The group member to add.
     * @throws IllegalArgumentException If cyclical membership is detected.
     * @throws GroupNotFoundException If the group was not found.
     * @throws AccessControlException If unauthorized to perform this operation.
     * @throws java.io.IOException
     */
    public void addGroupMember(String targetGroupName, String groupMemberName)
        throws IllegalArgumentException, GroupNotFoundException,
               AccessControlException, IOException
    {
        URL addGroupMemberURL = new URL(this.baseURL + "/groups/" + 
                                        targetGroupName + "/groupMembers/" + 
                                        groupMemberName);
        log.debug("addGroupMember request to " + addGroupMemberURL.toString());
        
        // reset the state of the cache
        clearCache();

        HttpURLConnection conn = 
                (HttpURLConnection) addGroupMemberURL.openConnection();
        conn.setRequestMethod("PUT");

        SSLSocketFactory sf = getSSLSocketFactory();
        if ((sf != null) && ((conn instanceof HttpsURLConnection)))
        {
            ((HttpsURLConnection) conn)
                    .setSSLSocketFactory(getSSLSocketFactory());
        }
        
        // Try to handle anonymous access and throw AccessControlException 
        int responseCode = -1;
        try
        {
            responseCode = conn.getResponseCode();
        }
        catch (Exception ignore) {}
    
        if ((responseCode != 200) && (responseCode != 201))
        {
            String errMessage = NetUtil.getErrorBody(conn);
            log.debug("addGroupMember response " + responseCode + ": " + 
                      errMessage);

            if ((responseCode == -1) || 
                (responseCode == 401) || 
                (responseCode == 403))
            {
                throw new AccessControlException(errMessage);
            }
            if (responseCode == 400)
            {
                throw new IllegalArgumentException(errMessage);
            }
            if (responseCode == 404)
            {
                throw new GroupNotFoundException(errMessage);
            }
            throw new IOException(errMessage);
        }
    }

    /**
     * Add a user as a member of a group.
     *
     * @param targetGroupName The group in which to add the group member.
     * @param userID The user to add.
     * @throws GroupNotFoundException If the group was not found.
     * @throws GroupNotFoundException If the member was not found.
     * @throws java.io.IOException
     * @throws AccessControlException If unauthorized to perform this operation.
     */
    public void addUserMember(String targetGroupName, Principal userID)
        throws GroupNotFoundException, UserNotFoundException, AccessControlException, IOException
    {
        String userIDType = AuthenticationUtil.getPrincipalType(userID);
        String encodedUserID = URLEncoder.encode(userID.getName(), "UTF-8");
        URL addUserMemberURL = new URL(this.baseURL + "/groups/" + 
                                       targetGroupName + "/userMembers/" + 
                                       encodedUserID + "?idType=" + userIDType);

        log.debug("addUserMember request to " + addUserMemberURL.toString());
        
        // reset the state of the cache
        clearCache();

        HttpURLConnection conn = 
                (HttpURLConnection) addUserMemberURL.openConnection();
        conn.setRequestMethod("PUT");

        SSLSocketFactory sf = getSSLSocketFactory();
        if ((sf != null) && ((conn instanceof HttpsURLConnection)))
        {
            ((HttpsURLConnection) conn)
                    .setSSLSocketFactory(getSSLSocketFactory());
        }
        
        // Try to handle anonymous access and throw AccessControlException 
        int responseCode = -1;
        try
        {
            responseCode = conn.getResponseCode();
        }
        catch (Exception ignore) {}

        if ((responseCode != 200) && (responseCode != 201))
        {
            String errMessage = NetUtil.getErrorBody(conn);
            log.debug("addUserMember response " + responseCode + ": " + 
                      errMessage);

            if ((responseCode == -1) || 
                (responseCode == 401) || 
                (responseCode == 403))
            {
                throw new AccessControlException(errMessage);
            }
            if (responseCode == 400)
            {
                throw new IllegalArgumentException(errMessage);
            }
            if (responseCode == 404)
            {
                if (errMessage != null && errMessage.toLowerCase().contains("user"))
                    throw new UserNotFoundException(errMessage);
                else
                    throw new GroupNotFoundException(errMessage);
            }
            throw new IOException(errMessage);
        }
    }

    /**
     * Remove a group as a member of another group.
     *
     * @param targetGroupName The group from which to remove the group member.
     * @param groupMemberName The group member to remove.
     * @throws GroupNotFoundException If the group was not found.
     * @throws java.io.IOException
     * @throws AccessControlException If unauthorized to perform this operation.
     */
    public void removeGroupMember(String targetGroupName, 
                                  String groupMemberName)
        throws GroupNotFoundException, AccessControlException, IOException
    {
        URL removeGroupMemberURL = new URL(this.baseURL + "/groups/" + 
                                           targetGroupName + "/groupMembers/" + 
                                           groupMemberName);
        log.debug("removeGroupMember request to " + 
                  removeGroupMemberURL.toString());
        
        // reset the state of the cache
        clearCache();

        HttpURLConnection conn = 
                (HttpURLConnection) removeGroupMemberURL.openConnection();
        conn.setRequestMethod("DELETE");

        SSLSocketFactory sf = getSSLSocketFactory();
        if ((sf != null) && ((conn instanceof HttpsURLConnection)))
        {
            ((HttpsURLConnection) conn)
                    .setSSLSocketFactory(getSSLSocketFactory());
        }
        
        // Try to handle anonymous access and throw AccessControlException 
        int responseCode = -1;
        try
        {
            responseCode = conn.getResponseCode();
        }
        catch (Exception ignore) {}
        
        if (responseCode != 200)
        {
            String errMessage = NetUtil.getErrorBody(conn);
            log.debug("removeGroupMember response " + responseCode + ": " + 
                      errMessage);

            if ((responseCode == -1) || 
                (responseCode == 401) || 
                (responseCode == 403))
            {
                throw new AccessControlException(errMessage);
            }
            if (responseCode == 400)
            {
                throw new IllegalArgumentException(errMessage);
            }
            if (responseCode == 404)
            {
                throw new GroupNotFoundException(errMessage);
            }
            throw new IOException(errMessage);
        }
    }

    /**
     * Remove a user as a member of a group.
     *
     * @param targetGroupName The group from which to remove the group member.
     * @param userID The user to remove.
     * @throws GroupNotFoundException If the group was not found.
     * @throws UserNotFoundException If the member was not found.
     * @throws java.io.IOException
     * @throws AccessControlException If unauthorized to perform this operation.
     */
    public void removeUserMember(String targetGroupName, Principal userID)
        throws GroupNotFoundException, UserNotFoundException, AccessControlException, IOException
    {
        String userIDType = AuthenticationUtil.getPrincipalType(userID);
        String encodedUserID = URLEncoder.encode(userID.toString(), "UTF-8");
        URL removeUserMemberURL = new URL(this.baseURL + "/groups/" + 
                                          targetGroupName + "/userMembers/" + 
                                          encodedUserID + "?idType=" + 
                                          userIDType);

        log.debug("removeUserMember request to " + 
                  removeUserMemberURL.toString());
        
        // reset the state of the cache
        clearCache();

        HttpURLConnection conn = 
                (HttpURLConnection) removeUserMemberURL.openConnection();
        conn.setRequestMethod("DELETE");

        SSLSocketFactory sf = getSSLSocketFactory();
        if ((sf != null) && ((conn instanceof HttpsURLConnection)))
        {
            ((HttpsURLConnection) conn)
                    .setSSLSocketFactory(getSSLSocketFactory());
        }
        
        // Try to handle anonymous access and throw AccessControlException 
        int responseCode = -1;
        try
        {
            responseCode = conn.getResponseCode();
        }
        catch (Exception ignore) {}

        if (responseCode != 200)
        {
            String errMessage = NetUtil.getErrorBody(conn);
            log.debug("removeUserMember response " + responseCode + ": " + 
                      errMessage);

            if ((responseCode == -1) || 
                (responseCode == 401) || 
                (responseCode == 403))
            {
                throw new AccessControlException(errMessage);
            }
            if (responseCode == 400)
            {
                throw new IllegalArgumentException(errMessage);
            }
            if (responseCode == 404)
            {
                if (errMessage != null && errMessage.toLowerCase().contains("user"))
                    throw new UserNotFoundException(errMessage);
                else
                    throw new GroupNotFoundException(errMessage);
            }
            throw new IOException(errMessage);
        }
    }

    /**
     * Get all the memberships of the user of a certain role.
     * 
     * @param userID Identifies the user.
     * @param role The role to look up.
     * @return A list of groups for which the user has the role.
     * @throws UserNotFoundException If the user does not exist.
     * @throws AccessControlException If not allowed to peform the search.
     * @throws IllegalArgumentException If a parameter is null.
     * @throws IOException If an unknown error occured.
     */
    public List<Group> getMemberships(Principal userID, Role role)
        throws UserNotFoundException, AccessControlException, IOException
    {
        if (userID == null || role == null)
        {
            throw new IllegalArgumentException("userID and role are required.");
        }
        
        List<Group> cachedGroups = getCachedGroups(userID, role);
        if (cachedGroups != null)
        {
            return cachedGroups;
        }
        
        String idType = AuthenticationUtil.getPrincipalType(userID);
        String id = userID.getName();
        String roleString = role.getValue();
        
        StringBuilder searchGroupURL = new StringBuilder(this.baseURL);
        searchGroupURL.append("/search?");
        
        searchGroupURL.append("ID=" + URLEncoder.encode(id, "UTF-8"));
        searchGroupURL.append("&IDTYPE=" + URLEncoder.encode(idType, "UTF-8"));
        searchGroupURL.append("&ROLE=" + URLEncoder.encode(roleString, "UTF-8"));
        
        log.debug("getMemberships request to " + searchGroupURL.toString());
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        URL url = new URL(searchGroupURL.toString());
        HttpDownload transfer = new HttpDownload(url, out);

        transfer.setSSLSocketFactory(getSSLSocketFactory());
        transfer.run();

        Throwable error = transfer.getThrowable();
        if (error != null)
        {
            log.debug("getMemberships throwable", error);
            // transfer returns a -1 code for anonymous access.
            if ((transfer.getResponseCode() == -1) || 
                (transfer.getResponseCode() == 401) || 
                (transfer.getResponseCode() == 403))
            {
                throw new AccessControlException(error.getMessage());
            }
            if (transfer.getResponseCode() == 404)
            {
                throw new UserNotFoundException(error.getMessage());
            }
            if (transfer.getResponseCode() == 400)
            {
                throw new IllegalArgumentException(error.getMessage());
            }
            throw new IOException(error);
        }

        try
        {
            String groupsXML = new String(out.toByteArray(), "UTF-8");
            log.debug("getMemberships returned: " + groupsXML);
            List<Group> groups = GroupsReader.read(groupsXML);
            setCachedGroups(userID, groups, role);
            return groups;
        }
        catch (Exception bug)
        {
            log.error("Unexpected exception", bug);
            throw new RuntimeException(bug);
        }
    }
    
    /**
     * Return the group, specified by paramter groupName, if the user,
     * identified by userID, is a member of that group.  Return null
     * otherwise.
     * 
     * This call is identical to getMemberShip(userID, groupName, Role.MEMBER)
     *  
     * @param userID Identifies the user.
     * @param groupName Identifies the group.
     * @return The group or null of the user is not a member.
     * @throws UserNotFoundException If the user does not exist.
     * @throws AccessControlException If not allowed to peform the search.
     * @throws IllegalArgumentException If a parameter is null.
     * @throws IOException If an unknown error occured.
     */
    public Group getMembership(Principal userID, String groupName)
        throws UserNotFoundException, AccessControlException, IOException
    {
        return getMembership(userID, groupName, Role.MEMBER);
    }
    
    /**
     * Return the group, specified by paramter groupName, if the user,
     * identified by userID, is a member (of type role) of that group.
     * Return null otherwise.
     * 
     * @param userID Identifies the user.
     * @param groupName Identifies the group.
     * @param role The membership role to search.
     * @return The group or null of the user is not a member.
     * @throws UserNotFoundException If the user does not exist.
     * @throws AccessControlException If not allowed to peform the search.
     * @throws IllegalArgumentException If a parameter is null.
     * @throws IOException If an unknown error occured.
     */
    public Group getMembership(Principal userID, String groupName, Role role)
        throws UserNotFoundException, AccessControlException, IOException
    {
        if (userID == null || groupName == null || role == null)
        {
            throw new IllegalArgumentException("userID and role are required.");
        }
        
        List<Group> cachedGroups = getCachedGroups(userID, role);
        if (cachedGroups != null)
        {
            int index = cachedGroups.indexOf(groupName);
            if (index != -1)
            {
                return cachedGroups.get(index);
            }
            else
            {
                return null;
            }
        }
        
        String idType = AuthenticationUtil.getPrincipalType(userID);
        String id = userID.getName();
        String roleString = role.getValue();
        
        StringBuilder searchGroupURL = new StringBuilder(this.baseURL);
        searchGroupURL.append("/search?");
        
        searchGroupURL.append("ID=" + URLEncoder.encode(id, "UTF-8"));
        searchGroupURL.append("&IDTYPE=" + URLEncoder.encode(idType, "UTF-8"));
        searchGroupURL.append("&ROLE=" + URLEncoder.encode(roleString, "UTF-8"));
        searchGroupURL.append("&GROUPID=" + URLEncoder.encode(groupName, "UTF-8"));
        
        log.debug("getMembership request to " + searchGroupURL.toString());
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        URL url = new URL(searchGroupURL.toString());
        HttpDownload transfer = new HttpDownload(url, out);

        transfer.setSSLSocketFactory(getSSLSocketFactory());
        transfer.run();

        Throwable error = transfer.getThrowable();
        if (error != null)
        {
            log.debug("getMembership throwable", error);
            // transfer returns a -1 code for anonymous access.
            if ((transfer.getResponseCode() == -1) || 
                (transfer.getResponseCode() == 401) || 
                (transfer.getResponseCode() == 403))
            {
                throw new AccessControlException(error.getMessage());
            }
            if (transfer.getResponseCode() == 404)
            {
                throw new UserNotFoundException(error.getMessage());
            }
            if (transfer.getResponseCode() == 400)
            {
                throw new IllegalArgumentException(error.getMessage());
            }
            throw new IOException(error);
        }

        try
        {
            String groupsXML = new String(out.toByteArray(), "UTF-8");
            log.debug("getMembership returned: " + groupsXML);
            List<Group> groups = GroupsReader.read(groupsXML);
            if (groups.size() == 0)
            {
                return null;
            }
            if (groups.size() == 1)
            {
                // don't cache these results as it is not a complete
                // list of memberships--it only applies to one group.
                return groups.get(0);
            }
            throw new IllegalStateException(
                    "Duplicate membership for " + id + " in group " + groupName);
        }
        catch (Exception bug)
        {
            log.error("Unexpected exception", bug);
            throw new RuntimeException(bug);
        }
    }
    
    /**
     * Check if userID is a member of groupName.
     * 
     * This is equivalent to isMember(userID, groupName, Role.MEMBER)
     * 
     * @param userID Identifies the user.
     * @param groupName Identifies the group.
     * @return True if the user is a member of the group
     * @throws UserNotFoundException If the user does not exist.
     * @throws AccessControlException If not allowed to peform the search.
     * @throws IllegalArgumentException If a parameter is null.
     * @throws IOException If an unknown error occured.
     */
    public boolean isMember(Principal userID, String groupName)
        throws UserNotFoundException, AccessControlException, IOException
    {