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java.lang.Object | +--sunlabs.brazil.handler.DynamicConfigHandler
The DynamicConfigHandler allows the user to change the
 configuration of the server and its handlers on the fly.  This handler
 can therefore be used to swap in and out functionality, for example,
 by dynamically adding a new AuthHandler to add a new
 form of authentication to a running server.
 
This handler uses a special set of URLs to allow a new set of configuration properties to be uploaded. The new configuration replaces the old configuration.
 The name of another Handler is supplied when this
 DynamicConfigHandler is initialized.  This Handler
 is the helper or sub-handler for the DynamicConfigHandler.
 When the DynamicConfigHandler receives a regular HTTP
 request (that matches the URL prefix described below), it redirects
 that request to the respond method of the sub-handler.  
 
 The uploaded configuration properties are kept in a separate properties
 object from the server's properties.  The server's properties
 are in fact not accessible from the sub-handler; the sub-handler can
 only access and/or change the properties owned by the
 DynamicConfigHandler.
 
This handler uses the following configuration properties:
DynamicConfigHandler will use to process requests.  When
	new properties are uploaded, the sub-handler will be replaced with
	whatever is specified in the newly uploaded handler
	property.
 DynamicConfigHandler and is not changed when
	new properties are uploaded.  The default is "/".
 DynamicConfigHandler and is not
	changed when new properties are uploaded.  The default
	is "/config/".
      Properties may be uploaded by sending them as "name=value" pairs in the body of a POST or in the "?" query parameters. The URL for uploading properties is "config/set".
The current set of properties may be retrieved from this handler by sending the URL "config/get"
handler=sunlabs.brazil.server.ChainHandler port=8081 log=5 handlers=dyn cgi dyn.class=sunlabs.brazil.server.DynamicConfigHandler dyn.prefix=/sparky/ dyn.config=/config-sparky/ dyn.handler=chain chain.class=sunlabs.brazil.server.ChainHandler chain.handlers=foo baz garply foo.class=sunlabs.brazil.handler.HomeDirHandler foo.home=/home/users/ baz.class=sunlabs.brazil.handler.FileHandler garply.class=sunlabs.brazil.handler.NotFoundHandler garply.root="/errors/" garply.fileName="nofile.html" cgi.class = sunlabs.brazil.handler.CgiHandler . . .These parameters set up a normal
Server on port 8081,
 running a ChainHandler which dispatches to a
 DynamicConfigHandler and a CgiHandler.
 
 The DynamicConfigHandler will listen for HTTP requests
 beginning with "/sparky/" and dispatch to its dynamically generated
 list of handlers, and listen for requests beginning with "/config-sparky/"
 to dynamically change that set of handlers.
 
 To give this DynamicConfigHandler something to do, an initial
 set of handlers is provided with the same prefix ("dyn") as the
 DynamicConfigHandler itself.  The prefix is stripped off
 those properties and the revised set of properties is passed to the
 DynamicConfigHandler to initialize its dynamically
 configurable world.
| Constructor Summary | |
| DynamicConfigHandler() | |
| Method Summary | |
|  boolean | init(Server server,
     String prefix)Initializes this DynamicConfigHandlerby loading the
 initial handler. | 
|  boolean | respond(Request request)Responds to an HTTP request by examining the "Host:" request header and dispatching to the main handler of the server that handles that virtual host. | 
| Methods inherited from class java.lang.Object | 
| equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait | 
| Constructor Detail | 
public DynamicConfigHandler()
| Method Detail | 
public boolean init(Server server,
                    String prefix)
DynamicConfigHandler by loading the
 initial handler.  An initial handler does not need to be defined,
 however, since the handler configuration can be downloaded later.
init in interface Handlerserver - The HTTP server that created this handler.prefix - A prefix to prepend to all of the keys that this
		handler uses to extract configuration information.
false if the initial handler was specified but
		could not be initialized, true otherwise.
public boolean respond(Request request)
                throws IOException
init
 from the list of virtual hosts, this method returns without
 handling the request.
respond in interface Handlerrequest - The HTTP request to be forwarded to one of the sub-servers.
true if the sub-server handled the message,
		false if it did not.  false is
		also returned if the "Host:" was unspecified or unknown.
IOException - if there was an I/O error while sending the response to
		the client.  Typically, in that case, the Server
		will (try to) send an error message to the client and then
		close the client's connection.
		
		The IOException should not be used to silently
		ignore problems such as being unable to access some
		server-side resource (for example getting a
		FileNotFoundException due to not being able
		to open a file).  In that case, the Handler's
		duty is to turn that IOException into a
		HTTP response indicating, in this case, that a file could
		not be found.
| 
 | Version 2.1, Generated 12/30/04 Copyright (c) 2001-2004, Sun Microsystems. | ||||||||
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