Examples of org.apache.webdav.lib.methods.LockMethod

org.apache.webdav.lib.methods.LockMethod
Web resources can be locked to ensure that only one user is updating the resource at a time. Locking helps to prevent the "lost update" problem. There are two types of lock currently defined by the WebDAV specification: exclusive locks and shared locks.
Per the specification, a lock indicates that someone is updating the resource, (hence the lock is a "write lock"), although the specification notes that the the syntax is extensible, and permits the eventual creation of locking for other access types.
Shared and Exclusive Locks

The most basic form of lock is an exclusive lock. This is a lock where the access right in question is only granted to a single client. The need for this arbitration results from a desire to avoid having to merge results. However, there are times when the goal of a lock is not to exclude others from exercising an access right but rather to provide a mechanism for principals to indicate that they intend to exercise their access rights. Shared locks are provided for this case. A shared lock allows multiple clients to receive a lock. Hence any user with appropriate access can get the lock.
With shared locks there are two trust sets that affect a resource. The first trust set is created by access permissions. Principals who are trusted, for example, may have permission to write to the resource. Among those who have access permission to write to the resource, the set of principals who have taken out a shared lock also must trust each other, creating a (typically) smaller trust set within the access permission write set.
Lock Compatibility

The following table indicates what happens if a new lock request is sent to a resource that is already locked:

Lock Request

Current Lock Exclusive Lock Shared Lock

None Success Sucess

Shared Failure Sucess

Exclusive Failure Failure

@author Remy Maucherat @author B.C. Holmes

	Lock Request
Current Lock	Exclusive Lock	Shared Lock
None	Success	Sucess
Shared	Failure	Sucess
Exclusive	Failure	Failure

        throws HttpException, IOException {


        setClient();
        // default lock type setting
        short lockType = LockMethod.SCOPE_EXCLUSIVE;
        LockMethod method = new LockMethod(URIUtil.encodePath(path), owner,
                                           lockType, timeout);
        generateIfHeader(method);
        int statusCode = client.executeMethod(method);
        String lock = method.getLockToken();
        WebdavState state = (WebdavState) client.getState();
        if (state != null) {
            state.addLock(path, lock);
        }
        this.owner = method.getOwner();


        // Possbile LOCK Status Codes => SC_OK
        // WebdavStatus.SC_SC_PRECONDITION_FAILED, SC_LOCKED
        setStatusCode(statusCode, lock);

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   public static String lockResource(HttpClient client, HttpURL url, 
                                     String ownerInfo, int depth, int timeout)
      throws IOException, HttpException
   {
      LockMethod lock = new LockMethod(url.getURI());
      lock.setDepth(depth);
      lock.setTimeout(timeout);
      lock.setOwner(ownerInfo);
      //lock.setDebug(1);
      lock.setFollowRedirects(true);
      int status = client.executeMethod(lock);
      if (status == WebdavStatus.SC_OK) {
         Header header = lock.getResponseHeader("Lock-Token");
         if (header != null) {
            String l = header.getValue();
            return l.substring(1, l.length()-1);
         } else {
            String l = lock.getLockToken();
            if (l != null) {
               return l;
            }
            throw new WebdavException("LOCK does not provide a lock token.");
         }
      } else if (status == WebdavStatus.SC_MULTI_STATUS) {
         throw Utils.makeBuildException("Can't lock", lock.getResponses());
      } else {
         throw Utils.makeBuildException("Can't lock", status, lock.getStatusText());
      }
   }

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        throws HttpException, IOException {


        setClient();
        // default lock type setting
        short lockType = LockMethod.SCOPE_EXCLUSIVE;
        LockMethod method = new LockMethod(URIUtil.encodePath(path), owner,
                                           lockType, timeout);
        generateIfHeader(method);
        int statusCode = client.executeMethod(method);
        String lock = method.getLockToken();
        WebdavState state = (WebdavState) client.getState();
        if (state != null) {
            state.addLock(path, lock);
        }
        this.owner = method.getOwner();


        // Possbile LOCK Status Codes => SC_OK
        // WebdavStatus.SC_SC_PRECONDITION_FAILED, SC_LOCKED
        setStatusCode(statusCode, lock);

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Examples of org.apache.webdav.lib.methods.LockMethod

Shared and Exclusive Locks

Lock Compatibility

Related Classes of org.apache.webdav.lib.methods.LockMethod