Thursday, September 24, 2009

RAMADDA, take two: browsing the tree

Assume you have a Ramadda server with some groups created and some data uploaded, something that look like:



Want to access it programmatically and browse it? Here is the code to do so, shown in an example that traverses the repository tree and prints out all of the entries.


The main dump method:


/**
* Dumps the tree of the repository.
*
* @throws Exception
*/
public void dumpTree() throws Exception {
List postEntries = new ArrayList();
postEntries.add(HttpFormEntry.hidden(ARG_SESSIONID, repositoryClient.getSessionId()));
postEntries.add(HttpFormEntry.hidden(ARG_OUTPUT, "xml.xml"));
String[] result = repositoryClient.doPost(repositoryClient.URL_ENTRY_SHOW, postEntries);
if (result[0] != null) {
System.err.println("Error:" + result[0]);
}
outputStream.println(result[1]);
Element response = XmlUtil.getRoot(result[1]);

// the root id
String entryId = response.getAttribute("id");
ClientEntry rootEntry = repositoryClient.getEntry(entryId);
outputStream.println(entryToString(rootEntry));

dumpRecursive(rootEntry, TAB);
}



The recursive method and the toString method:


/**
* Recursively traverses the entries and dumps its childs and subchilds.
*
* @param entry the start entry.
* @param tab the tabulator characters to use.
* @throws Exception
*/
private void dumpRecursive( ClientEntry entry, String tab ) throws Exception {
List childEntries = getChildEntries(entry.getId());
for( int i = 0; i < childEntries.size(); i++ ) {
ClientEntry childEntry = childEntries.get(i);
outputStream.println(tab + entryToString(childEntry));
dumpRecursive(childEntry, tab + tab);
}
}

/**
* Extract some base information from the {@link ClientEntry entry}.
*
* @param entry the entry.
* @return the string representation.
*/
public String entryToString( ClientEntry entry ) {
String name = entry.getName();
String id = entry.getId();
Resource resource = entry.getResource();
String type = resource.getType();
return name + " ( id=" + id + ", type=" + type + ")";
}



And here the most important method, that gets childs from entries:


/**
* Creates a {@link List} of {@link ClientEntry}s for a particular entry.
*
* @param parentId the id of the parent entry.
* @return the lsit of child entries.
* @throws Exception
*/
public List getChildEntries( String parentId ) throws Exception {
String[] args = new String[]{ARG_ENTRYID, parentId, ARG_OUTPUT, "xml.xml", ARG_SESSIONID,
repositoryClient.getSessionId()};
String url = HtmlUtil.url(repositoryClient.URL_ENTRY_SHOW.getFullUrl(), args);
String xml = IOUtil.readContents(url, getClass());
Element root = XmlUtil.getRoot(xml);

List childEntries = new ArrayList();
List children = XmlUtil.getElements(root, "entry");
for( int i = 0; i < children.size(); i++ ) {
Object object = children.get(i);
String id = XmlUtil.getAttribute((Node) object, "id");
ClientEntry entry = repositoryClient.getEntry(id);
childEntries.add(entry);
}
return childEntries;
}



The result launch on the above repository is:


morpheo ( id=02c47d07-6f7d-473b-b104-b922348f7d51, type=unknown)
documents ( id=660cb2ce-99f5-4d4b-9682-2f408c2b105e, type=unknown)
client code ( id=9977cbc1-2589-49c8-b7e0-9b944970d169, type=storedfile)
call_4_papers.odt ( id=33a026f4-87f3-4c78-8c1d-d14da597aa06, type=storedfile)
rasterlite-how-to ( id=0a138888-b5ee-42bf-be3e-f78c8c3a5232, type=storedfile)
hydrologis logo ( id=209c182d-e22c-48b2-933a-8d03ab4b72d9, type=storedfile)
netcdf ( id=91b9a338-d68e-4411-bdd3-b3e5a3f111c6, type=unknown)
cami_0000.nc ( id=3a74f349-a4bf-4f9d-916d-83f4511e0877, type=localfile)
water.nc ( id=400a17cc-f33c-40f4-a896-b2bffbed2f84, type=storedfile)
water_surf.nc ( id=6b69040b-7a96-46dc-95b2-0d6ae044f948, type=storedfile)
water_surf.nc ( id=eded7693-8b6e-4941-87f5-2fc9bb2a6bb7, type=storedfile)
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