/**
* Constructor. Initialises the servlet, reading the ontology model from static files and creating
* a cleaner thread that removes obsolete sessions.
*/
public LiberServletImpl() {
System.out.println("Starting up");
try {
ontology = new OntologyReader(); // reads PolicyGrid ontologies
// ontology = new GeographyOntologyReader(); //reads geography ontology
clean =
new TimerTask() {
public void run() { // Removes obsolete sessions from the map, running every 10 min.
long time = new GregorianCalendar().getTimeInMillis();
synchronized (userMap) {
Iterator it = userMap.keySet().iterator();
List<String> obsolete = new ArrayList<String>();
while (it.hasNext()) {
String key = (String) it.next();
long timeDif = time - userMap.get(key).getLastUpdated();
if ((timeDif < 0)
|| (timeDif > 3600000)) // if an hour has lapsed, or the next day has started
obsolete.add(key); // (let's just hope no-one starts using the tool at midnight)
}
for (int i = 0; i < obsolete.size(); i++) // then remove that session
userMap.remove(obsolete.get(i));
}
}
};
Timer timer = new Timer();
timer.schedule(clean, 0, 600000);
Runtime r = Runtime.getRuntime();
r.gc(); // FORCES GARBAGE COLLECTION
r.runFinalization();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* Returns an NL-expression of the given date.
*
* @param user User ID
* @param input QueryDateValue containing restriction on date
* @return String with nl-expression for date restriction (e.g. 'before 2007'), empty String if
* session expired or null if error occurred
*/
public String getDateExpression(String user, QueryDateValue input) {
if (!userMap.containsKey(user)) return "";
try {
return new SGDateNode(input.getDates()).getQueryNLExpression(input.getComparator());
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* Creates a new session for the editing tool.
*
* @param user user id
* @param project Project ID
* @param resource Resource ID
* @return String[] with user id and name
*/
public String[] newSession(String user, String project, String resource) {
try {
LiberSession session = new LiberSession(ontology, user, project, resource, LiberSession.EDIT);
userMap.put(user, session);
Runtime r = Runtime.getRuntime();
r.gc(); // FORCES GARBAGE COLLECTION
r.runFinalization();
return session.getUserDetails();
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* Returns the values of resourceID for the properties specified in formInformation.
*
* @param user User ID
* @param resourceID Resource ID
* @param formInformation FormInfo[] specifying properties
* @return String[] with values, null if session expired or error occurred
*/
public String[] getDescriptionValues(String user, String resourceID, FormInfo[] formInformation) {
try {
if (!userMap.containsKey(user)) return null;
LiberSession session = userMap.get(user);
synchronized (session) {
session.setLastUpdated();
return session.getDescriptionValues(resourceID, formInformation);
}
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* Returns a tag cloud for the given property.
*
* @param user User ID
* @param property Property name
* @return TagCloud, null if session expired or error occurred
*/
public TagCloud getTagCloud(String user, String property) {
try {
if (!userMap.containsKey(user)) return null;
LiberSession session = userMap.get(user);
synchronized (session) {
session.setLastUpdated();
TagCloud tc =
new Folksonomy(user)
.getTagCloud(session.getReader(), session.getReader().getProperty(property));
return tc;
}
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* Initialises a new editing session.
*
* @param user user id
* @param data Data provided about resource
* @return AnchorInfo[] containing the feedback text.
*/
public AnchorInfo[] initSession(String user, InstanceData data) {
try {
LiberSession session = userMap.get(user);
Runtime r = Runtime.getRuntime();
r.gc(); // FORCES GARBAGE COLLECTION
r.runFinalization();
synchronized (session) {
session.setLastUpdated();
return session.init(data); // initialise the session and return the text
}
} catch (Exception e) {
e.printStackTrace();
return new AnchorInfo[0];
}
}
/**
* Returns an aggregated tag cloud for a set of properties.
*
* @param user User ID
* @param properties String[] with property names
* @return TagCloud, null if session expired or error occurred
*/
public TagCloud getTagCloud(String user, String[] properties) {
try {
if (!userMap.containsKey(user)) return null;
LiberSession session = userMap.get(user);
synchronized (session) {
session.setLastUpdated();
List<OntProperty> list = new ArrayList<OntProperty>();
for (int i = 0; i < properties.length; i++)
list.add(session.getReader().getProperty(properties[i]));
TagCloud tc = new Folksonomy(user).getTagCloud(session.getReader(), list);
return tc;
}
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* Retrieves the values already added for this property and anchor
*
* @param user User ID
* @param property Property name
* @param anchor Unique ID of Anchor
* @param key browsing session id (null if session type is EDIT)
* @return String[] with values already added for this property and anchor, first element
* --EXPIRED-- if session expired, null if error occurred
*/
public String[] getAddedValues(
String user, String property, String anchor, int type, String key) {
if (!userMap.containsKey(user)) {
String[] result = new String[1];
result[0] = "---EXPIRED---";
return result;
}
try {
LiberSession session = userMap.get(user);
synchronized (session) {
session.setLastUpdated();
return session.getAddedValues(property, anchor, type, key);
}
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* Initialises a new query session, and returns the class hierarchy. This hierarchy is special
* because it includes the number of instances of each type.
*
* @param user user id
* @param roots root classes of the hierarchy (null to get complete hierarchy)
* @return Hierarchy[] containing class hierarchy
*/
public Hierarchy[] initSessionAndGetClassHierarchy(String user, String[] roots) {
try {
if (userMap.containsKey(user)) userMap.get(user).setLastUpdated();
else userMap.put(user, new LiberSession(ontology, user, null, null, LiberSession.QUERY));
LiberSession session = userMap.get(user);
Runtime r = Runtime.getRuntime();
r.gc(); // FORCES GARBAGE COLLECTION
r.runFinalization();
synchronized (session) {
return session.getCountedClassHierarchy(roots);
}
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* Retrieves existing instances that qualify to be a target of this property, and instances that
* already are a target of the property and anchor! Returns an array with first the range class
* name, then those objects already in the range, then a 'null', and then all eligible objects.
*
* @param user user id
* @param name property name
* @param anchor Unique ID of Anchor
* @param type session type
* @param key browsing session id (null if session type is EDIT)
* @return ExistingInstances, holds all necessary information about object that already are or
* could be in the range, empty if session expired, or null if error occurred.
*/
public ExistingInstances getInstances(
String user, String name, String anchor, int type, String key) {
try {
if (!userMap.containsKey(user)) {
ExistingInstances result = new ExistingInstances();
result.setRange(null, null);
return result;
}
LiberSession session = userMap.get(user);
synchronized (session) {
session.setLastUpdated();
ExistingInstances e = session.getRangeInstances(name, anchor, type, key);
return e;
}
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* Initialises a new browsing session, creating a new session for this user.
*
* @param user user id
* @param resource Resource id
* @param type Type of session (edit, query, browse)
* @return AnchorInfo[] containing the feedback text.
*/
public AnchorInfo[] initSession(String user, String resource, int type) {
try {
if (type == LiberSession.BROWSE) // make a new user session if this is the browse tab
userMap.put(
user, new LiberSession(ontology, user, null, resource.replaceAll("\"", ""), type));
else if (!userMap.containsKey(user)) return null;
LiberSession session = userMap.get(user);
Runtime r = Runtime.getRuntime();
r.gc(); // FORCES GARBAGE COLLECTION
r.runFinalization();
synchronized (session) {
session.setLastUpdated();
return session.init(
resource.replaceAll("\"", "")); // initialise the session and return the text
}
} catch (Exception e) {
e.printStackTrace();
return new AnchorInfo[0];
}
}
