Brazil project: Class HistoryFilter

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sunlabs.brazil.proxy Class HistoryFilter

java.lang.Object
  |
  +--sunlabs.brazil.proxy.HistoryFilter

All Implemented Interfaces:: Filter, Handler

public class HistoryFilter
extends Object
implements Filter

The HistoryFilter is both a Handler and a Filter that keeps a record of all pages visited by a given session.

The HistoryFilter can be used to make a user's session "mobile" as follows: A user's history is normally stored with the browser being used, on the user's machine. If the user runs a different browser or goes to a different machine, the user's history will not be there. Instead, the user can access the web via a proxy that keeps track of their history. No matter which browser the user chooses or machine the user is at, a server running with the HistoryFilter will automatically remember and be able to present the user's history.

The history is kept with respect to a Session ID.

This filter uses the following configuration properties:

prefix: This handler will only process URLs beginning with this string. The default value is "", which matches all URLs.
session: The name of the request property that holds the Session ID. The default value is "SessionID".
nosession: The Session ID to use if the Session ID was not specified. The default value is "common".
admin: URLs beginning with this prefix cause the HistoryFilter to store the history information for the current Session in the request properties
filter: If specified, then this is a Regexp pattern to match against the "Content-Type" of the result. Setting this also implies that the HistoryFilter will be invoked as a Filter and not a Handler. The default value is "", which indicates that the "Content-Type" is not examined and that this HistoryFilter will be invoked as a Handler.

Field Summary
`String`	`admin`
`Regexp`	`filter`
`String`	`nosession`
`String`	`session`
`String`	`urlPrefix`

Constructor Summary
`HistoryFilter()`

Method Summary
`byte[]`	`filter(Request request, MimeHeaders headers, byte[] content)` Returns the original content, since this filter does not change content.
`boolean`	`init(Server server, String prefix)` Initializes this filter by reading all its configuration properties.
`boolean`	`respond(Request request)` If the `admin` prefix is seen, store the history information associated with the session in the request properties.
`boolean`	`shouldFilter(Request request, MimeHeaders headers)` Called when invoked as a `Filter`.

Methods inherited from class java.lang.Object

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

Field Detail

urlPrefix

public String urlPrefix

session

public String session

nosession

public String nosession

admin

public String admin

filter

public Regexp filter

Constructor Detail

HistoryFilter

public HistoryFilter()

Method Detail

init

public boolean init(Server server,
                    String prefix)

Initializes this filter by reading all its configuration properties.

It is an error if the filter is specified but malformed.

Specified by:: init in interface Handler

Parameters:: server - The HTTP server.; prefix - The configuration property prefix.
Returns:: true if this filter initialized successfully, false otherwise.

respond

public boolean respond(Request request)

If the admin prefix is seen, store the history information associated with the session in the request properties.

If invoked as a Handler and the URL matches the prefix, records this page's address in the history.

Specified by:: respond in interface Handler

Parameters:: request - The Request object that represents the HTTP request.
Returns:: false, indicating that this respond method ran purely for its side effects.

shouldFilter

public boolean shouldFilter(Request request,
                            MimeHeaders headers)

Called when invoked as a Filter. If the URL matches the prefix and the returned "Content-Type" matches the filter, records this page's address in the history.

Specified by:: shouldFilter in interface Filter

Parameters:: request - The in-progress HTTP request.; headers - The MIME headers from the result.
Returns:: false indicating that this Filter does not want to modify the content.