Fedora Repository Views
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But the angle one views the repository might also affect the number of entries seen. The above, recursive approach will always lead to one entry per data object. The remedy for this is to mark some classes as Entries for a certain view angle. This means that to compute the records for a given view angle, the view of all objects of a class that is an Entry should be computed. This is the view of the repository.
Fedora Implementation
This section describes how the above could be implemented in Fedora.
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void objectStateModified(String pid, Date date, String state) {
//Find the DomsObject rows that regard this object.
//There will be one per entry/viewAngle combination
List<DomsObject> results = OBJECTS.list(objectPid=pid);
//Find all Entries that include this object
for (DomsObject result : results) {
if (!result.getEntryPid().equals(pid)) {
//Mark them as updated
updateEntry(result.getEntryPid(),
state,
result.getViewAngle(),
date);
}
}
// Find view Info for this object
List<ViewInfo> viewInfoList = fedora.getViewInfo(pid, date);
for (ViewInfo viewInfo : viewInfoList) {
//If it is an entry object, set it in the ENTRIES table
if (viewInfo.isEntry()) {
updateEntry(pid, state, viewInfo.getViewAngle(), date);
updateDomsObjects(pid, pid, viewInfo.getViewAngle());
}
}
}
void updateEntry(String entryPid, String state, String viewAngle, Date date) {
//Find the Entry objects that fulfill these restrictions
List<Entry> results = ENTRIES.list(entrypid,state,viewangle)
//There might be no Entry, but if we are here, we know that an entry should exist, so create it.
if (results.size() == 0) {
ENTRIES.insert(new Entry(entryPid, viewAngle, state, date));
} else {
for (Entry result : results) {
//Or there might have been some results
//Is this entry older than the current change?
if (result.getDateForChange().getTime() < date.getTime()) {
result.setDateForChange(date);
result.setEntryPid(entryPid);
result.setState(state);
result.setViewAngle(viewAngle);
}
//Save the entry
ENTRIES.update(result);
}
}
}
void updateDomsObjects(String objectPid, String entryPid, String viewAngle) {
list<DomsObject> results = OBJECTS.list(objectPid,entryPid,viewAngle)
if (results.size() == 0) {
OBJECTS.insert(new DomsObject(objectPid, entryPid, viewAngle));
}
}
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Find all the EntryPids that refer to this object, by querying the OBJECTS table for rows objectPid.
Object Relations Changed
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void objectRelationsChanged(String pid, Date date) {
//This can change the structure of the views and we must therefore recaculate the views
//if a current entry object use this object, we will need to recalculate the view of that object
//This method will only be called on objects that already exist. Objects cannot change type once created.
//ObjectModified() creates an Entry row, if the object is an entry object. As such, there will always be
// the correct Entry entries when this method is called, and these should just be recalculated
List<DomsObject> results = OBJECTS.list(objectPid=pid);
//we now have a list of all the entries that include this object.
for (DomsObject result : results) {
//get the ViewBundle from fedora
ViewBundle bundle = fedora.calcViewBundle(result.getEntryPid(), result.getViewAngle(), date);
//First, remove all the objects in this bundle from the table
removeNotListedFromDomsObjects(bundle.getContained(), result.getEntryPid(), result.getViewAngle());
//Add all the objects from the bundle to the objects Table.
for (String objectPid : bundle.getContained()) {
updateDomsObjects(objectPid, bundle.getEntry(), bundle.getViewAngle());
}
updateEntry(bundle.getEntry(), STATE_INPROGRESS, bundle.getViewAngle(), date);
}
}
void removeNotListedFromDomsObjects(List<String> objectPid, String entryPid, String viewAngle) {
List<DomsObject> results = OBJECTS.list(entryPid,viewAngle);
for (DomsObject result : results) {
if (!objectPid.contains(result.getObjectPid())) {
OBJECTS.delete(result);
}
}
}
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There are several situations where the list will be used
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