sunlabs.brazil.handler

Class PollHandler

public class PollHandler extends Thread implements Handler

Handler for periodically polling another web site, whose results are (optionally) added to the server's properties. This also includes the ability to request URL's on a cron-like schedule.

The result of fetching the url is expected to be a text document in java Properties format.

Properties:

url
URL to fetch periodically. any ${...} constructs are evaluated at each poll, with the values in the server properties object. If the URL starts with "/", then the current server is used.
post
The "post" data, if any. ${...} are evaluates as per url above.
headers
A list of white space delimited tokens that refer to additional HTTP headers that are added onto the polled request. For each token the server properties [token].name and [token].value define a new http header.
interval
The interval (in seconds) to fetch the url. Defaults to 10 seconds. If match is specified, this is the interval used to check for a time/date match. At each "interval", the current time format is computed, based on "format", below. If the computed format has not changed since the previous poll, then no poll is done. The interval is recalculated after each poll.
fast
If set, don't wait "interval" before 1st poll.
prepend
The string to prepend to the properties. If not supplied no properties are loaded.
namespace
The namespace to use to store the properties to. If the sessionTable (see below)parameter is identical to the sessionTable parameter of the SetTemplate, then this specifies the namespace parameter that may be used with the SetTemplate "namespace" parameter to obtain the extracted data. Defaults to the "prepend" parameter.
match
If specified, a regular expression that must match the current time for this URL to run. The format to match is specified by the "format" parameter, below. "EEE-dd-HH-mm" (eg: Thu-Dec, 14, 14:12 pm).
format
a {@link java.text.SimpleDateFormat date format specifier} to use for matching "match" patterns. Defaults to "EE-MM-dd-HH-mm".
proxy
If specified, connect through a proxy. This should be in the form host:port, or host it the desired port is 80.
sessionTable
The name of the SessionManager table to use for storing values. By default, properties are stored in server.props. The value should match the sessionTable used by the {@link sunlabs.brazil.template.SetTemplate} to allow values obtained by this handler to be accessable from within templates.

If the sessionTable is set, the namespace value is used to name the table (e.g. the namespace specified by {@link sunlabs.brazil.template.SetTemplate}. If no namespace parameter is given, then prepend is used as the namespace parameter.

If prepend is specified, the following additional properties are created, and added to the properties with the specified prefix.

count.attempts
The total number of polls attemped.
count.errors
The total number of poll failures.
error.at
The poll attempt # for the last failure.
error.msg
The message describing the last failure.
error.time
The timestamp of the last failure.
timestamp
The timestamp for the last successful poll.

Version: %V% PollHandler.java 2.5

Author: Stephen Uhler

Field Summary
intinterval
Stringpost
Stringurl
Method Summary
voidfillProps(Properties props, HttpRequest target)
Fill the properties from the input stream
booleaninit(Server server, String prefix)
Set up the initial configuration, and kick off a thread to periodically fetch the url.
booleanrespond(Request request)
This might allow control over the polling via requests at a later date.
voidrun()
Periodically poll the url, and copy the results into the server properties.

Field Detail

interval

public int interval

post

public String post

url

public String url

Method Detail

fillProps

public void fillProps(Properties props, HttpRequest target)
Fill the properties from the input stream

init

public boolean init(Server server, String prefix)
Set up the initial configuration, and kick off a thread to periodically fetch the url.

respond

public boolean respond(Request request)
This might allow control over the polling via requests at a later date. For now, it always returns false.

run

public void run()
Periodically poll the url, and copy the results into the server properties.