org.mmbase.servlet
Class BridgeServlet

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

All Implemented Interfaces:

Serializable, Servlet, ServletConfig, MMBaseStarter

Direct Known Subclasses:

Performance

public abstract class BridgeServlet
extends MMBaseServlet

BridgeServlet is an MMBaseServlet with a bridge Cloud in it. Extending from this makes it easy to implement servlet implemented with the MMBase bridge interfaces. An advantage of this is that security is used, which means that you cannot unintentionly serve content to the whole world which should actually be protected by the security mechanism. Another advantage is that implementation using the bridge is easier/clearer. The query of a bridge servlet can possible start with session= in which case the cloud is taken from that session attribute with that name. Otherewise 'cloud_mmbase' is supposed. All this is only done if there was a session active at all. If not, or the session variable was not found, that an anonymous cloud is used. Object can only be accessed by alias if a mapping on query string is used (so not e.g. /images/*, but /img.db). Normally this is no problem, because the alias is resolved by the image-tag. But if for some reason you need aliases to be working on the URL, you must map to URL's with a question mark.

Since:

MMBase-1.6

Version:

$Id: BridgeServlet.java 45359 2011-02-23 08:33:03Z michiel $

Author:

Michiel Meeuwissen

See Also:

Serialized Form

Nested Class Summary

static class

BridgeServlet.QueryParts Keeps track of determined information, to avoid redetermining it.

Field Summary

static Pattern	FILE_PATTERN Pattern used for the 'filename' part of the request.
static String	MESSAGE_ATTRIBUTE

Fields inherited from class org.mmbase.servlet.MMBaseServlet

mmbase, retryAfter

Constructor Summary

BridgeServlet()

Method Summary

protected Node	desperatelyGetNode(Cloud cloud, String nodeIdentifier) Extensions can override this, to produce a node, even if cloud.hasNode failed.
protected Cloud	findCloud(Cloud c, String nodeNumber, BridgeServlet.QueryParts query) Tries to find a Cloud which can read the given node.
protected Cloud	getAnonymousCloud() Obtains an 'anonymous' cloud.
protected Cloud	getClassCloud() Obtains a cloud using 'class' security.
protected Cloud	getCloud(BridgeServlet.QueryParts qp) Obtains a cloud object, using a QueryParts object.
protected String	getCloudName() The name of the mmbase cloud which must be used.
protected long	getLastModified(HttpServletRequest req) The idea is that a 'bridge servlet' on default serves 'nodes', and that there could be defined a 'last modified' time for nodes.
protected Node	getNode(BridgeServlet.QueryParts query) Servlets would often need a node.
protected Node	getServedNode(BridgeServlet.QueryParts qp, Node node) If the node associated with the resonse is another node then the node associated with the request.\ (E.g.
void	init() Inits lastmodifiedField.
protected BridgeServlet.QueryParts	readQuery(HttpServletRequest req, HttpServletResponse res) Creates a QueryParts object which wraps request and response and the parse result of them.
static BridgeServlet.QueryParts	readQuery(String query)
protected BridgeServlet.QueryParts	readQueryFromRequestURI(HttpServletRequest req, HttpServletResponse res)
static BridgeServlet.QueryParts	readServletPath(String servletPath)

Methods inherited from class org.mmbase.servlet.MMBaseServlet

associateMapping, checkInited, decRefCount, destroy, doGet, getAssociations, getBasePath, getMMBase, getRequestURL, getServletByAssociation, getServletByMapping, getServletInfo, getServletMappings, getServletMappingsByAssociation, incRefCount, service, setInitException, setMMBase

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPost, doPut, doTrace, 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

MESSAGE_ATTRIBUTE

public static final String MESSAGE_ATTRIBUTE

See Also:

Constant Field Values

FILE_PATTERN

public static final Pattern FILE_PATTERN

Pattern used for the 'filename' part of the request. The a node-identifying string may be present in it, and it the one capturing group. It is a digit optionially followed by +.* (used in ImageServlet for url-triggered icache production)

Constructor Detail

BridgeServlet

public BridgeServlet()

Method Detail

getCloudName

protected String getCloudName()

The name of the mmbase cloud which must be used. At the moment this is not supported (every mmbase cloud is called 'mmbase').

readQuery

protected BridgeServlet.QueryParts readQuery(HttpServletRequest req,
                                             HttpServletResponse res)
                                      throws IOException

Creates a QueryParts object which wraps request and response and the parse result of them.

Returns:

A QueryParts or null if something went wrong (in that case an error was sent, using the response).

Throws:

IOException

readQueryFromRequestURI

protected BridgeServlet.QueryParts readQueryFromRequestURI(HttpServletRequest req,
                                                           HttpServletResponse res)
                                                    throws IOException

Throws:

IOException

readServletPath

public static BridgeServlet.QueryParts readServletPath(String servletPath)

Since:

MMBase-1.7.4

readQuery

public static BridgeServlet.QueryParts readQuery(String query)

Since:

MMBase-1.7.4

getCloud

protected final Cloud getCloud(BridgeServlet.QueryParts qp)

Obtains a cloud object, using a QueryParts object.

Returns:

A Cloud or null if unsuccessful (this may not be fatal).

getAnonymousCloud

protected final Cloud getAnonymousCloud()

Obtains an 'anonymous' cloud.

getClassCloud

protected Cloud getClassCloud()

Obtains a cloud using 'class' security. If e.g. you authorize org.mmbase.servlet.ImageServlet by class-security for read all rights, it will be used.

Since:

MMBase-1.8

findCloud

protected Cloud findCloud(Cloud c,
                          String nodeNumber,
                          BridgeServlet.QueryParts query)
                   throws IOException

Tries to find a Cloud which can read the given node.

Throws:

IOException

Since:

MMBase-1.8

getNode

protected final Node getNode(BridgeServlet.QueryParts query)
                      throws IOException

Servlets would often need a node. This function provides it.

Parameters:

query - A QueryParts object, which you must have obtained by readQuery(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

Throws:

IOException

desperatelyGetNode

protected Node desperatelyGetNode(Cloud cloud,
                                  String nodeIdentifier)

Extensions can override this, to produce a node, even if cloud.hasNode failed. ('title aliases' e.g.).

Since:

MMBase-1.7.5

getServedNode

protected Node getServedNode(BridgeServlet.QueryParts qp,
                             Node node)
                      throws IOException

If the node associated with the resonse is another node then the node associated with the request.\ (E.g. a icache based on a url with an image node).

Parameters:

qp - A QueryParts object, which you must have obtained by readQuery(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

node - The node which is specified on the URL (obtained by getNode(org.mmbase.servlet.BridgeServlet.QueryParts)

Throws:

IOException

Since:

MMBase-1.7.4

getLastModified

protected long getLastModified(HttpServletRequest req)

The idea is that a 'bridge servlet' on default serves 'nodes', and that there could be defined a 'last modified' time for nodes. This can't be determined right now, so 'now' is returned. This function is defined in HttpServlet

Overrides:

getLastModified in class HttpServlet

init

public void init()
          throws ServletException

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

Overrides:

init in class MMBaseServlet

Throws:

ServletException