org.mmbase.servlet
Class MMBaseServlet

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          org.mmbase.servlet.MMBaseServlet

All Implemented Interfaces:

Serializable, Servlet, ServletConfig, MMBaseStarter

Direct Known Subclasses:

BridgeServlet, DoveServlet, JamesServlet, RMIHandlerServlet

public class MMBaseServlet
extends HttpServlet
implements MMBaseStarter

MMBaseServlet is a base class for other MMBase servlets (like ImageServlet). Its main goal is to store a MMBase instance for all its descendants, but it can also be used as a serlvet itself, to show MMBase version information.

Since:

MMBase-1.6

Version:

$Id: MMBaseServlet.java 40460 2010-01-11 15:11:37Z michiel $

Author:

Michiel Meeuwissen

See Also:

Serialized Form

Field Summary

protected MMBase	mmbase MMBase reference.
protected int	retryAfter If MMBase has not been started, a 503 is given, with this value for the 'Retry-After' header.

Constructor Summary

MMBaseServlet()

Method Summary

protected static void	associateMapping(String function, String servletMapping, Integer priority) Associate a given servletmapping with the given function.
protected boolean	checkInited(HttpServletResponse res) This methods can be (and is) called in the beginning of service.
protected void	decRefCount(HttpServletRequest req) Decrease the reference count of the servlet
void	destroy()
protected void	doGet(HttpServletRequest req, HttpServletResponse res) Serves MMBase version information.
protected Map<String,Integer>	getAssociations() On default, servlets are not associated with any function.
static String	getBasePath(String function)
MMBase	getMMBase() Returns the MMBase instance.
protected static String	getRequestURL(HttpServletRequest req) Return URI with QueryString appended
static String	getServletByAssociation(String function) Gets the name of the servlet that performs actions associated with the the given function.
static HttpServlet	getServletByMapping(String mapping) Gets the servlet that belongs to the given mapping
String	getServletInfo() Returns information about this servlet.
static List<String>	getServletMappings(String servletName) Gets all the mappings for a given servlet.
static List<String>	getServletMappingsByAssociation(String function) Gets all the mappings for a given association.
protected void	incRefCount(HttpServletRequest req) Increase the reference count of the servlet (for debugging) and send running servlets to log once every 32 requests
void	init() The init of an MMBaseServlet checks if MMBase is running.
void	service(HttpServletRequest req, HttpServletResponse res) The service method is extended with calls for the refCount functionality (for performance related debugging).
void	setInitException(ServletException e) Called by MMBaseStartThread, if something went wrong during initialization of MMBase.
void	setMMBase(MMBase mmb) Sets the mmbase member.

Methods inherited from class javax.servlet.http.HttpServlet

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

Methods inherited from class javax.servlet.GenericServlet

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

Methods inherited from class java.lang.Object

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

Field Detail

mmbase

protected MMBase mmbase

MMBase reference. While null, servlet does not accept request.

retryAfter

protected int retryAfter

If MMBase has not been started, a 503 is given, with this value for the 'Retry-After' header. See rfc 2616, section 10.5.4. Defaults to 60 seconds, can be configured in web.xml with the 'retry-after' propery on the servlets.

Since:

MMBase-1.7.2

Constructor Detail

MMBaseServlet

public MMBaseServlet()

Method Detail

getAssociations

protected Map<String,Integer> getAssociations()

On default, servlets are not associated with any function. This function is called in the init method.

Returns:

A map of Strings (function) -> Integer (priority). Never null.

getMMBase

public MMBase getMMBase()

Returns the MMBase instance.

Specified by:

getMMBase in interface MMBaseStarter

Returns:

the MMBase instance or null.

Since:

MMBase-1.7

setMMBase

public void setMMBase(MMBase mmb)

Sets the mmbase member. Can be overriden to implement extra initalization for the servlet which needs a running MMBase.

Specified by:

setMMBase in interface MMBaseStarter

Since:

MMBase-1.7

setInitException

public void setInitException(ServletException e)

Called by MMBaseStartThread, if something went wrong during initialization of MMBase. It will be thrown by checkInited then.

Specified by:

setInitException in interface MMBaseStarter

Since:

MMBase-1.7

init

public void init()
          throws ServletException

The init of an MMBaseServlet checks if MMBase is running. It not then it is started.

Overrides:

init in class GenericServlet

Throws:

ServletException

getServletByMapping

public static HttpServlet getServletByMapping(String mapping)

Gets the servlet that belongs to the given mapping

Parameters:

mapping - the mapping used to access the servlet

Returns:

the Servlet that handles the mapping

getServletMappings

public static List<String> getServletMappings(String servletName)

Gets all the mappings for a given servlet. So, this is a method to obtain info from web.xml.

Parameters:

servletName - the name of the servlet

Returns:

an unmodifiable list of servlet mappings for this servlet

getServletMappingsByAssociation

public static List<String> getServletMappingsByAssociation(String function)

Gets all the mappings for a given association. Use this to find out how to call a servlet to handle a certain type of operation or data (i.e 'images', 'attachments').

Parameters:

function - the function that identifies the type of association

Returns:

an unmodifiable list of servlet mappings associated with the function

getServletByAssociation

public static String getServletByAssociation(String function)

Gets the name of the servlet that performs actions associated with the the given function. Use this to find a servlet to handle a certain type of operation or data (i.e 'imageservlet', 'myimageservlet', 'images');

Parameters:

function - the function that identifies the type of association

Returns:

the name of the servlet associated with the function, or null if there is none

getBasePath

public static String getBasePath(String function)

Since:

MMBase-1.8.5

associateMapping

protected static void associateMapping(String function,
                                       String servletMapping,
                                       Integer priority)

Associate a given servletmapping with the given function. Use this to set a servletmapping to call for a certain type of operation or data (i.e 'image-processing'); For now, only one servletmapping can be registered.

Parameters:

function - the function that identifies the type of association

servletMapping - mapping of the servlet to associate with the function

priority - priority of this association, the association only occurs if no servlet or servletmapping with higher priority for the same function is present already

doGet

protected void doGet(HttpServletRequest req,
                     HttpServletResponse res)
              throws ServletException,
                     IOException

Serves MMBase version information. This doesn't do much useful yet, but one could image lots of cool stuff here. Any other MMBase servlet will probably override this method.

Overrides:

doGet in class HttpServlet

Throws:

ServletException

IOException

checkInited

protected boolean checkInited(HttpServletResponse res)
                       throws ServletException,
                              IOException

This methods can be (and is) called in the beginning of service. It sends an UNAVAILABLE error if MMBase has not bee started, or throws an exeption if that was unsuccessful.

Returns:

A boolean. If false, then service must return immediately (because mmbase has not been inited yet).

Throws:

ServletException

IOException

Since:

MMBase-1.7.2

service

public void service(HttpServletRequest req,
                    HttpServletResponse res)
             throws ServletException,
                    IOException

The service method is extended with calls for the refCount functionality (for performance related debugging). So you can simply override doGet in extension classes, and this stays working, without having to think about it.

Overrides:

service in class HttpServlet

Throws:

ServletException

IOException

getServletInfo

public String getServletInfo()

Returns information about this servlet. Don't forget to override it.

Specified by:

getServletInfo in interface Servlet

Overrides:

getServletInfo in class GenericServlet

getRequestURL

protected static String getRequestURL(HttpServletRequest req)

Return URI with QueryString appended

Parameters:

req - The HttpServletRequest.

decRefCount

protected void decRefCount(HttpServletRequest req)

Decrease the reference count of the servlet

Parameters:

req - The HttpServletRequest.

incRefCount

protected void incRefCount(HttpServletRequest req)

Increase the reference count of the servlet (for debugging) and send running servlets to log once every 32 requests

Parameters:

req - The HttpServletRequest.

Bad-constant:

31 should be configurable.

destroy

public void destroy()

Specified by:

destroy in interface Servlet

Overrides:

destroy in class GenericServlet