org.fcrepo.server.access.dissemination
Class DatastreamResolverServlet

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          org.fcrepo.server.SpringServlet
              org.fcrepo.server.access.dissemination.DatastreamResolverServlet

All Implemented Interfaces:

Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public class DatastreamResolverServlet
extends SpringServlet

This servlet acts as a proxy to resolve the physical location of datastreams.

It requires a single parameter named id that denotes the temporary id of the requested datastresm. This id is in the form of a DateTime stamp. The servlet will perform an in-memory hashtable lookup using the temporary id to obtain the actual physical location of the datastream and then return the contents of the datastream as a MIME-typed stream. This servlet is invoked primarily by external mechanisms needing to retrieve the contents of a datastream.

The servlet also requires that an external mechanism request a datastream within a finite time interval of the tempID's creation. This is to lessen the risk of unauthorized access. The time interval within which a mechanism must respond is set by the Fedora configuration parameter named datastreamMediationLimit and is specified in milliseconds. If this parameter is not supplied it defaults to 5000 milliseconds.

Author:

Ross Wayland

See Also:

Serialized Form

Field Summary

static String

ACTION_LABEL

Fields inherited from class org.fcrepo.server.SpringServlet

m_appContext, m_server, m_status

Constructor Summary

DatastreamResolverServlet()

Method Summary

void	destroy()
void	doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Processes the servlet request and resolves the physical location of the specified datastream.
void	init(javax.servlet.ServletConfig config) Initialize servlet.

Methods inherited from class org.fcrepo.server.SpringServlet

failStartup

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ACTION_LABEL

public static final String ACTION_LABEL

See Also:

Constant Field Values

Constructor Detail

DatastreamResolverServlet

public DatastreamResolverServlet()

Method Detail

init

public void init(javax.servlet.ServletConfig config)
          throws javax.servlet.ServletException

Initialize servlet.

Specified by:

init in interface javax.servlet.Servlet

Overrides:

init in class SpringServlet

Throws:

javax.servlet.ServletException - If the servlet cannot be initialized.

doGet

public void doGet(javax.servlet.http.HttpServletRequest request,
                  javax.servlet.http.HttpServletResponse response)
           throws javax.servlet.ServletException,
                  IOException

Processes the servlet request and resolves the physical location of the specified datastream.

Overrides:

doGet in class javax.servlet.http.HttpServlet

Parameters:

request - The servlet request.

response - servlet The servlet response.

Throws:

javax.servlet.ServletException - If an error occurs that effects the servlet's basic operation.

IOException - If an error occurrs with an input or output operation.

destroy

public void destroy()

Specified by:

destroy in interface javax.servlet.Servlet

Overrides:

destroy in class SpringServlet