Web Signals is a service that provides
organizations with the ability to push a URL for a target web page and
two icons (a read icon and an unread icon) to a BlackBerry device. This
is similar to the way Browser Channels work, but a limited version. With Browser Channels, developers have control over many of the options
for the channel, but Web Signals can only push a URL and two icons to
the destination device—nothing more. Where an application uses HTTP
headers to deliver a Browser Channel parameters to a device, with Web
Signals, it’s done through parameters included in the push URL.
In practical use, a developer is likely not going to
change the URL being pushed to a subscriber. If the Web Signal is
architected correctly, the information that the backend system needs to
render the correct information for the subscriber should be built into
the URL. Rather than sending a custom URL with every push, craft the
URL carefully (with all the information needed to generate custom
content for the subscriber), and then just generate the content as
needed on the backend, leaving the URL static. In this case, subsequent
push requests merely notify the user that there is new data available
for the Web Signal. The Web Signal can send different icons
periodically, but it would likely not push a different URL every time.
Some examples of how this technology could be used are
Weather:
An organization providing weather forecasts could build a Web Signal
and periodically push a weather icon to subscribers. The signal’s icon
would show graphically what the current weather conditions are for the
registered location.
Stocks:
A financial management service could create a Web Signal that allowed a
subscriber to register for the stocks they were interested in
monitoring. It would deliver an icon that indicated by color or some
other mechanism (such as a plus/minus or up/down arrow), indicating the
current value of the stock being monitored.
News:
A news aggregator service could offer a Web Signal that allowed
subscribers to define search terms they were interested in. The Web
Signal would push an alert when any related items were published
online. The icon for the Web Signal could be just the icon for the news
service or could indicate visually for example the priority of the
items in the current update (high, medium, or low, based on source or
date).
To see a listing of the available Web Signals, go to RIM’s Web Signals website at http://na.blackberry.com/eng/services/websignals/. Figure 1 shows the site.
1. How Web Signals Work
This section uses one of the public Web Signals to
demonstrate how a Web Signal works from the end user’s perspective.
Subsequent sections discuss how each step would be performed by a push
application.
The first Web Signal announced by RIM was a free weather service provided by AccuWeather (www.accuweather.com).
Subscribers register for the Web Signal and identify the location for
which they are interested in receiving weather reports. Figure 2 shows the AccuWeather Web Signals page.
To register for the Web Signal, the subscriber must access the signal’s registration page at www.accuweather.com/blackberry/push/signup.asp
from a BlackBerry device. Because Web Signals push data using the BIS
service rather than the BES, the Internet browser must be used to access the registration site.
On the site, the first thing the subscriber sees is a page describing
the service and a link for them to use to subscribe to the service, as
shown in Figure 3.
The
subscriber is presented with information about the service and might
need to agree to the terms and conditions for the service before he can
continue. After the user indicates that he wants to use the service, he
is directed to the RIM’s website, where he must agree to RIM’s terms,
as shown in Figure 4.
After the subscriber accepts RIM’s agreement, he is
directed to a page where he can configure the location for which he
will receive weather alerts, as shown in Figure 5.
Some time after you complete the registration process, the first weather Web Signal is delivered to the device, as shown in Figure 6.
The AccuWeather icon is highlighted in the figure.
The icon indicates that snow flurries are currently falling and the
title of the Web Signal (shown at the bottom of the screen) indicates
that the projected high temperature is 23 degrees and the projected low
is 10 degrees.
When the Web Signal is opened, the browser opens and displays the weather report for the specified location, as shown in Figure 7.
Having the weather pushed to a device
periodically is useful. The subscriber can tell at a glance what the
weather is without ever opening the application.
