Class LockMethod

java.lang.Object
org.apache.commons.httpclient.HttpMethodBase
All Implemented Interfaces:
org.apache.commons.httpclient.HttpMethod, DepthSupport

public class LockMethod extends XMLResponseMethodBase implements DepthSupport
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
  • Field Details

  • Constructor Details

    • LockMethod

      public LockMethod(String path, String owner, int timeout, boolean isTransaction)
      Creates a lock method that can start a transaction when server supports them in a MS like style. The transacion handle of the started transaction will be returned as the lock token. To let subsequent requests participate in the transaction add a Transaction header with the lock token as value. You will have to enclose it in '<' and '>' just like ordinary lock tokens.

      To either commit or abort the transaction use UnlockMethod.
      Parameters:
      path - any path inside Slide's scope
      owner - of this transaction
      timeout - timeout of this transaction
      isTransaction - true when this method is used to starte a transaction
    • LockMethod

      public LockMethod()
      Method constructor.
    • LockMethod

      public LockMethod(String path)
      Method constructor.
    • LockMethod

      public LockMethod(String path, String refreshOpaqueToken, int timeout)
      Method constructor.
    • LockMethod

      public LockMethod(String path, String owner, short scope, int timeout)
      Method constructor.
    • LockMethod

      public LockMethod(String path, String refreshOpaqueToken, long timeout)
      Deprecated.
      The timeout value MUST NOT be greater than 2^32-1.
      Method constructor.
    • LockMethod

      public LockMethod(String path, String owner, short scope, long timeout)
      Deprecated.
      The timeout value MUST NOT be greater than 2^32-1.
      Method constructor.
  • Method Details

    • setRequestHeader

      public void setRequestHeader(String headerName, String headerValue)
      Set a header value, redirecting the special cases of Depth and Time headers to setDepth(int) and setTimeout(int) as appropriate.
      Specified by:
      setRequestHeader in interface org.apache.commons.httpclient.HttpMethod
      Overrides:
      setRequestHeader in class org.apache.commons.httpclient.HttpMethodBase
      Parameters:
      headerName - Header name
      headerValue - Header value
    • isTypeTransaction

      public boolean isTypeTransaction()
    • setTypeTransaction

      public void setTypeTransaction(boolean typeTransaction)
    • setDepth

      public void setDepth(int depth)
      Depth setter.
      Specified by:
      setDepth in interface DepthSupport
      Parameters:
      depth - New depth value
    • getDepth

      public int getDepth()
      Depth getter.
      Specified by:
      getDepth in interface DepthSupport
      Returns:
      int depth value
    • getLockToken

      public String getLockToken()
    • isRefresh

      public boolean isRefresh()
    • getScope

      public short getScope()
    • setOwner

      public void setOwner(String owner)
      Sets the owner of the lock. This method provides only "basic" owner information. Thus, setOwner("Jezebel Lipshitz") will produce an owner element in the request document like this:
         <D:owner>Jezebel Lipshitz</D:owner>
       

      Examples in the Webdav specification suggest that one can use e-mail addresses, home page URLs, or other information; this implementation doesn't handle any of that.

    • getOwner

      public String getOwner()
      Return the owner of the lock as reported by the server.
    • setScope

      public void setScope(short scope)
    • getTimeout

      public int getTimeout()
      get the timeout value.
      Returns:
      timeout
    • setTimeout

      public void setTimeout(int timeout)
      Set the timeout value.
    • setTimeout

      public void setTimeout(long timeout)
      Deprecated.
      The timeout value MUST NOT be greater than 2^32-1.
      Set the timeout value.
    • getName

      public String getName()
      Specified by:
      getName in interface org.apache.commons.httpclient.HttpMethod
      Specified by:
      getName in class org.apache.commons.httpclient.HttpMethodBase
    • recycle

      public void recycle()
      Description copied from class: XMLResponseMethodBase
      Reset the State of the class to its initial state, so that it can be used again.
      Specified by:
      recycle in interface org.apache.commons.httpclient.HttpMethod
      Overrides:
      recycle in class XMLResponseMethodBase
    • addRequestHeaders

      public void addRequestHeaders(org.apache.commons.httpclient.HttpState state, org.apache.commons.httpclient.HttpConnection conn) throws IOException, org.apache.commons.httpclient.HttpException
      Generate additional headers needed by the request.
      Overrides:
      addRequestHeaders in class org.apache.commons.httpclient.HttpMethodBase
      Parameters:
      state - State token
      conn - The connection being used for the request.
      Throws:
      IOException
      org.apache.commons.httpclient.HttpException
    • generateRequestBody

      protected String generateRequestBody()
      DAV requests that contain a body must override this function to generate that body.

      The default behavior simply returns an empty body.

      Overrides:
      generateRequestBody in class XMLResponseMethodBase
    • parseResponse

      public void parseResponse(InputStream input, org.apache.commons.httpclient.HttpState state, org.apache.commons.httpclient.HttpConnection conn) throws IOException, org.apache.commons.httpclient.HttpException
      Parse response.
      Overrides:
      parseResponse in class XMLResponseMethodBase
      Parameters:
      input - Input stream
      Throws:
      IOException
      org.apache.commons.httpclient.HttpException