S60 Location Technologies
The S60 platform provides various interfaces for accessing location information to provide appealing mobile, location-based applications and services.
Landmarks
Landmarks represent geographical places. Landmarks, or points-of-interest (POIs), are to places what bookmarks are to Web pages or books – they help users find the same spot again. A landmark records the name, street address, coordinates, category (e.g., café, theater, gas station), contact information (e.g., phone, e-mail, Web), and many other attributes about a place.
People can download landmarks from the Web, receive them from friends over multimedia messaging service (MMS) or Bluetooth (BT), or create them by themselves using any compatible mobile device. Landmarks allow users to explore and reach out to the world in a new and exciting way, directly from their S60 device.
S60 3rd Edition includes a dedicated application for the centralized management of user landmarks. Thus, it is not necessary for application developers to put their effort into constructing such a system. Instead, they are free to concentrate on how they would like to use landmarks in their own applications. Users can access landmarks either directly or hierarchically via categories, using the Landmarks API, the Landmarks Search API, and the Landmarks Database Management API. Note that the Location API for Java™ ME (JSR-179) can also be used to access landmarks from Java MIDlets.
See also the Landmarks Exchange Format Specification for details about how landmarks can be represented in XML format and as such exchanged between mobile devices (through local connectivity) or between content providers and their mobile users (for example, through Web sites).
If a developer's application creates new landmarks, it is likely that the application will need to prompt the end user for some additional information about the landmark, for example, how the user would like to name or categorize the landmark. There is a ready-made UI component, Landmarks UI Add/Edit API, just for this purpose. The component also does the coordinate acquisition via the Location Acquisition API. Developers can use the component in view-only mode if they wish to show the details of a certain landmark to the end user and want to avoid the possibility of the end user modifying the landmark in any way.
Many times a developer's application will need the end user to indicate one or more landmarks, for example if the user requires the application to show the indicated landmark(s) on a map or provide navigation guidance to them. To help developers with that, S60 3rd Edition includes a ready-made UI component, Landmarks UI Selector API, that can be used to prompt the end user for one or more landmarks or for one or more landmark categories. Simply launch the UI component and you will get the landmarks or categories selected by the end user as return values. The UI component takes care of all the required end-user interaction.
For more details on Landmarks APIs, please see the API documentation and the source code of the related example applications in the S60 SDK.
Making an application location-aware
Access to a mobile device's location information is a key issue for any developer creating mobile-location-based services. The Location Acquisition API (supported from S60 2nd Edition, Feature Pack 2 onwards) provides easy access for Symbian native applications to determine a user's current location, independent of the positioning technology being used. Applications can thus use all available positioning technologies, such as Bluetooth Global Positioning System (GPS) accessories and network-based positioning, via a single API.
For more information on how to make a mobile application location-aware, see the Location Acquisition API and the source code of the related example applications.
GPS satellite view
Every decent location-aware application has a GPS satellite view, right? Now wouldn't it be excessive if every developer needed to make his or her own satellite view? And wouldn't it be a pain for end users to try to cope with different-looking views that are supposed to depict the same thing, the availability of the GPS satellites?
To address these concerns, S60 3rd Edition offers developers a ready-made UI component that applications can use to display GPS satellite availability in a clear, coherent way. To learn how easy it is to embed the satellite view into an application, see the Satellite Info API and the source code of the related example application.
Network-based positioning mechanisms
Starting from S60 2nd Edition, Feature Pack 1, MT-LR Privacy messages from network-resident LBS applications are supported. MT-LR is an acronym for Mobile Terminated Location Request, also known as LCS Location Notification. These messages let the device owner decide if a network-resident LBS application, such as a weather service, may use the device’s location to provide the service requested by the device owner. For more information on the role of LCS Location Notification in Location Services, please refer to 3GPP TS 23.271 (or 03.71). For signalling protocol level information about LCS-Location Notification, please refer to 3GPP TS 24.030 (or 04.30).
A cellular network and a mobile device can exchange location information extracted from cellular communication measurements to boost GPS’s time-to-first-fix, or to compensate for a weak signal while indoors or in urban canyon areas. This is called Assisted GPS (A-GPS), or network-based positioning if the GPS signal loss is total. These are based on an industry standard called Secure User Plane (SUPL), which is used for exchanging location information between a mobile device and a cellular network over User Plane protocols such as GPRS, WLAN, or CS-Data. SUPL is an operator-friendly solution because unlike competing solutions it does not require expensive, time-consuming cellular network infrastructure updates. SUPL is supported from S60 3rd Edition, FP2 onwards.
Testing made easy
Developing location-aware software can be tedious if it involves transferring an application to a mobile device and walking or driving around to test the effects of the latest changes. To overcome this problem, the S60 platform allows developers to create a text file from which the positioning system will fetch coordinates, thus simulating the device moving along the given path.
There are two tools that need to be installed; one providing the positioning simulation and the other providing the configuration UI to choose the desired simulation data file.
Make sure that the Simulation positioning method is the selected positioning method when testing. Developers can check and alter this setting using the Location Settings application, or in S60 3rd Edition FP1 and onwards using the Positioning folder of the Settings application.
The positioning simulation tools are available in the S60 SDKs (you can also find the latest, S60 3rd Edition FP2 compatible versions here). For more information on the usage of the tools, please see the Simulation PSY Configurator User Guide and the Simulation PSY User Guide in the S60 3rd Edition, MR SDK or S60 3rd Edition SDK supporting Feature Pack 1.
