inner workings of location-based services and devices. by
ability to know where a mobile device is physically located
at any given time is fast becoming an intrinsic feature of
any wireless application and service.
These type of services are a great benefit to field workers
who need access to enterprise applications and databases.
In addition, it also gives rise to a new class of location-based
applications and services, like Web mapping, street routing
and electronic Yellow Pages services through mobile devices.
Since location-based applications necessarily traverse large
geographical expanse and involve different operating platforms,
how can various operators deploy applications that can work
in an integrated fashionseamlessly?
A wireless gateway and built-in location technologies will
allow content providers to integrate location services with
business data, while delivering business information to wherever
they are needed. To manage spatial data directly, special
spatial database management systems will be required.
Examples of data collection applications are road navigation,
geographically-coded addressing and raster imaging. Geographically
sensitive services should become a mainstay consumer application.
I can imagine consumers being interested in local traffic
conditions, weather updates, location-based news and other
potential services. One limiting factor in the near term:
the lack of wireless bandwidth. Also, the paucity of power
and screen size in mobile devices will rein in the sophistication
of these applications.
A wireless location-based solution must be based on open platform
architecture. This will allow wireless carriers, Internet
portals, ASPs and enterprise information portals to deploy
location-based services that work with each other, and offer
content or mobile commerce services through common standard
In addition, the integration must be done using a standard
relational database concept to allow various service providers
to manage all the location information, such as billing, customer
relationship activities and enterprise management.
Key components in location-based applications include the
a) GPS triangulation. With Global Positioning System (GPS)-enabled
devices, the service or user location will probably be integrated
as part of the requested data. Without GPS, locations can
still be determined via longitude and latitude data obtained
from the transmitting telecommunication tower.
b) WAP gateway/converter. The main function of these is to
convert and transmit WML requests in accordance to the WAP
c) Transcoder. This will transform the WML request received
from the gateway into HTTP request to be forwarded to the
host server for processing.
d) Location query/database. This has to be a RDBMS (relational
database management system) database equipped with spatial
data content. The application must also cater to the deployment
of JDBC connectors as most transcoders are likely to be running
on Java based applications.
e) Personalization engine. A good feature to have, as the
system will automatically identify the request's owners preferences
based on previously configured preferences, and hence speed
up querying of databases and the displaying of results.
f) Additional service billing. Another good to have component
is an integrated billing system. Since all mobile subscribers
are customers of some telecommunication service provider,
it makes good sense to deploy services that can link up with
telcos' servers and their billing applications.
Most mobile users need to access two types of data content
from the mobile phones and PDAs, namely, static information
such as stock quotes, weather forecasts and news; and transactional
content that will induce the manipulation or creation of more
Static data can be multi-source and multi-format. Transactional
data are likely to be multi-service as well, in addition to
being multi-source and multi-format.
Across these multi-service or multi-domain networks, special
adapter applications will be needed, and deployed, as mobile
users move from one domain to another.
These adapters will convert content from its original format
to XML documents. Transcoders will then convert the XML documents
into WML format specific to the type of mobile devices that
are requesting the content.
Developers should bear in mind that for wireless content to
be useful, they must be kept simple and lightweight for snappy
delivery. This is due to the two main physical limitations
of mobile devices: their small screens and limited data entry
In particular, the lack of a keyboard and mouse as input devices
means that Web browsing and Web page navigation must follow
a very different paradigm on a mobile device as compared to
a desktop computer.
of a location-based service
1. John is new in town and would like to see a list of restaurants
that are in close proximity to his hotel. John can use his
WAP-enabled phone to perform a WAP query requesting for local
restaurants based on his physical location.
2. John's service provider receives his query and using a
WAP gateway and transcoder, converts the WAP query into a
HTTP request in order to extract the data from the host server.
Based on the concept of triangulation to determine John's
physical location (this information can also be purchased
from the telecommunication service providers), the system
appends John's co-ordinates to the query. John's position
can also be determined by using GPS.
The WAP gateway also adds metadata information about the mobile
device John is using such as the mobile device screen size
and supported font types. The transcoder converts the XML
content into WML as it stores the metadata of John's device
specification. It knows the markup language being used and
appropriate screen size. The bitmap is channeled back through
the service provider's gateway and to John's mobile device.
3. Once the HTTP request has been received by the host server,
the host server interprets the request and accesses the content
from the database using the appropriate database adapters
(eg JDBC connector), which passes the query to the database
via a connector.
As the database receives the JDBC call, the query is performed
to locate the nearest restaurants within John's area. The
resulting information is returned back to the server. In more
sophisticated installations, the host server may also be equipped
with a personalization engine, which captures John's restaurant
preferences and some of his pre-configured location marks.
Mah writes for Network Computing-Asian Edition