001 package edu.nrao.sss.util;
002
003 import java.io.StringReader;
004 import java.net.URL;
005 import java.util.List;
006 import java.util.ArrayList;
007 import java.rmi.RemoteException;
008 import javax.xml.bind.JAXBElement;
009 import javax.xml.namespace.QName;
010
011 import org.apache.log4j.Logger;
012 import org.apache.axis.client.Call;
013 import org.apache.axis.client.Service;
014
015 import edu.nrao.sss.astronomy.sesame.Resolver;
016 import edu.nrao.sss.astronomy.sesame.Sesame;
017 import edu.nrao.sss.astronomy.sesame.Target;
018
019 /**
020 * The SourceNameResolver encapsulates the networking and XML envolved in
021 * making a source name lookup at the CDS and provides quick javabeans methods
022 * for retreiving a particular bit of information about a source.
023 *
024 * @author btruitt
025 *
026 */
027 public class SourceNameResolver
028 {
029 private static final Logger log = Logger.getLogger(SourceNameResolver.class);
030
031 private Call call = null;
032 private Sesame data = null;
033
034 private static final String[] serviceUrls = {
035 "http://cdsws.u-strasbg.fr/axis/services/Sesame",
036 "http://vizier.hia.nrc.ca:8080/axis/services/Sesame",
037 "http://vizier.nao.ac.jp:8080/axis/services/Sesame",
038 };
039
040 private static int CURRENT_RESOURCE = 0;
041
042 public SourceNameResolver()
043 {
044 try
045 {
046 //Create a service to do the work.
047 Service service = new Service();
048
049 this.call = (Call)service.createCall();
050
051 //set the address, method, and parameters of the call. Also specify their types.
052 this.call.setTargetEndpointAddress(new URL(serviceUrls[CURRENT_RESOURCE]));
053
054 this.call.setOperationName(new QName("sesame"));
055
056 this.call.addParameter("name", org.apache.axis.Constants.XSD_STRING, javax.xml.rpc.ParameterMode.IN);
057 this.call.addParameter("resultType", org.apache.axis.Constants.XSD_STRING, javax.xml.rpc.ParameterMode.IN);
058 this.call.addParameter("all", org.apache.axis.Constants.XSD_STRING, javax.xml.rpc.ParameterMode.IN);
059 this.call.addParameter("service", org.apache.axis.Constants.XSD_STRING, javax.xml.rpc.ParameterMode.IN);
060
061 this.call.setReturnType(org.apache.axis.Constants.XSD_STRING);
062
063 //Shorten the timeout to something more reasonable.(in milliseconds)
064 this.call.setTimeout(new Integer(15000));
065 }
066
067 //Any other exception we'll just have to barf on and assume we can't
068 //get the source because something else is wrong.
069 catch (Exception e)
070 {
071 throw new IllegalStateException(e);
072 }
073 }
074
075 /**
076 * Does a name lookup at one of the sites in {@link #serviceUrls} and
077 * returns an object that has convenient java bean methods for accessing
078 * properties of a source. The urls in the serviceUrls array are tried in
079 * order (in the event that the service is down at the first site, the 2nd
080 * is tried, etc.).
081 *
082 * @throws SourceNotFoundException if <code>target</code> could not be found.
083 */
084 public SourceNameResolver(String target) throws SourceNotFoundException
085 {
086 this();
087 lookup(target);
088 }
089
090 /** Does a circular increment of CURRENT_RESOURCE */
091 private void incrementCurrentResourceCounter()
092 {
093 CURRENT_RESOURCE = ((CURRENT_RESOURCE + 1) < serviceUrls.length)? CURRENT_RESOURCE + 1 : 0;
094 }
095
096 /**
097 * @return a list of errors found trying to process our request.
098 */
099 public List<String> getErrors()
100 {
101 List<String> errs = new ArrayList<String>();
102
103 List<Target> targets = this.data.getTarget();
104 if (targets != null)
105 {
106 for (Target t : targets)
107 {
108 List<String> err = t.getERROR();
109 if (err != null)
110 errs.addAll(err);
111
112 List<String> info = t.getINFO();
113 if (info != null)
114 for (String i : info)
115 if (i.startsWith("!***") || i.startsWith("***"))
116 errs.add(i);
117 }
118 }
119
120 return errs;
121 }
122
123 //XXX temporary!
124 public Sesame getData()
125 {
126 return this.data;
127 }
128
129 //TODO Method comments
130 public Sesame lookup(String target) throws SourceNotFoundException
131 {
132 //Try all addresses if we have to, but then give up.
133 for (int tries = 0; tries < serviceUrls.length; tries++)
134 {
135 try
136 {
137 //make the call, passing in the arguments as an array of objects. Note
138 //that this cast is safe because I explicitly set the return type
139 //to string.
140 //Note on arguments: first arg is the target name, the second tells
141 //Sesame to return xml, the 3rd to return all aliases of the target,
142 //and the 4th tells it to query Simbad, and then, if not found in
143 //Simbad, query NED.
144 String xml = (String)call.invoke(new Object[] {target, "x", true, "SN"});
145
146 log.debug("Returned XML:\n" + xml);
147
148 //Create a Sesame object from the xml
149 JaxbUtility xmlUtil = new JaxbUtility();
150 xmlUtil.setFailIfDefaultSchemaNotFound(false);
151 xmlUtil.setLookForDefaultSchema(false);
152 this.data = xmlUtil.readObjectAsXmlFrom(new StringReader(xml), Sesame.class, null);
153
154 List<String> errs = getErrors();
155
156 //if this worked and we haven't thrown an exception, we can break
157 //out of the loop.
158 if (errs == null || errs.isEmpty())
159 break;
160
161 else
162 {
163 StringBuilder errors = new StringBuilder("Errors found while attempting to resolve '");
164 errors.append(target);
165 errors.append("' @ ");
166 errors.append(serviceUrls[CURRENT_RESOURCE]);
167 errors.append(":\n\t");
168
169 for (String err : errs)
170 {
171 errors.append(err);
172 errors.append("\n\t");
173 }
174
175 log.warn(errors.toString());
176 incrementCurrentResourceCounter();
177 }
178 }
179
180 //Service is broken, try a different one.
181 catch (RemoteException re)
182 {
183 log.warn("Axis service is down @ " + serviceUrls[CURRENT_RESOURCE], re);
184
185 //increment our place in our round robin attempts to find a working service.
186 incrementCurrentResourceCounter();
187
188 log.warn("Trying next service @ " + serviceUrls[CURRENT_RESOURCE]);
189 }
190
191 //Any other exception we'll just have to barf on and assume we can't
192 //get the source because something else is wrong.
193 catch (Exception e)
194 {
195 throw new SourceNotFoundException(e);
196 }
197 }
198
199
200 // Only pay attention to the first target as I don't think we can return
201 // more than one target with the way we're using the call.
202 if (this.data != null)
203 {
204 List<Target> targets = this.data.getTarget();
205 if (targets != null && !targets.isEmpty())
206 {
207 List<Resolver> resolvers = targets.get(0).getResolver();
208 if (resolvers != null)
209 {
210 for (Resolver r : resolvers)
211 {
212 // If there's a position, then return our data, we found it!
213 if (hasPosition(r))
214 return this.data;
215 }
216 }
217 }
218 }
219
220 //If we didn't get any position information back, there was an error
221 //so we throw a SourceNotFoundException.
222 throw new SourceNotFoundException("Could not find source: " + target);
223 }
224
225 private boolean hasPosition(Resolver r)
226 {
227 if (r != null)
228 {
229 List<JAXBElement<?>> info = r.getINFOOrERROROrOtype();
230
231 if (info != null)
232 {
233 for (JAXBElement<?> e : info)
234 {
235 String name = e.getName().getLocalPart();
236 if ("jradeg".equalsIgnoreCase(name))
237 return true;
238 }
239 }
240 }
241
242 return false;
243 }
244 }