SI and SL XML Files
Service Indication (SI) and Service Loading (SL) are two Wireless Application Protocol (WAP) push features used by Windows Mobile–based devices. SI and SL XML files can be used for sending provisioning updates, adding new services, downloading ring tones, and updating existing services.
An SI message notifies the user of new services, updates to existing services, and provisioning updates after the device has processed the message. For example, an SI can be used to notify the user of basketball scores and to provide a link for retrieving the most recent information from a Web site.
An SL message automatically downloads the new service, update, or provisioning file.
Note SL is ON by default. For an example of how to disable SL, see Security Policy Settings.
SI and SL messages are simple XML files that are sent to devices by the mobile operator or manufacturer (OEM). The messages are sent in connectionless unsecure WAP push operations from the Push Proxy Gateway, which encodes them by using WAP Binary XML (WBXML) tokens. Devices can process SI and SL messages that are encoded with the WBXML binary tokens as defined in the WAP Service Indication Specification Version 08-Nov-1999 and the WAP Service Loading Specification Version 08-Nov-1999. Windows Mobile supports Universal Transformation Format 8 (UTF-8) encoded XML documents.
Depending on the action level, which is specified in the action attribute of an SL message, the SL message is processed in different ways:
| Action level | Message processing |
|---|---|
| execute-high or execute-low | The downloaded service is run immediately without getting permission from the user. |
| cache | The downloaded service is cached and an e-mail message is sent to the Inbox. |
Although the information in the XML files could also be sent through Short Message Service (SMS) and e-mail messages, SI and SL messages provide richer features. Unlike Short Message Service (SMS) and e-mail messages, SI notifications (messages) give the sender control over user-intrusiveness levels and can have an expiration date. To control user-intrusiveness levels, set the action attribute to signal-low, signal-medium, or signal-high. To control notification expiration, set the expiration date and time in the expire attribute. For more information about the action attribute and expire attribute, see Creating an SI or an SL Message.
A user who notices the SL message in the Inbox can select the command, and the mobile Internet browser, Microsoft Internet Explorer Mobile, either displays the content or, if the command is an application, installs the content. For example, an SL message can be used to download the daily local forecast and then notify the user that it is available. When the user selects the command in the message, the new forecast appears. For more information about initiating automatic downloads with an SL message, see Creating an SI or an SL Message.
With a few exceptions that are discussed in this chapter, SI and SL messages are implemented on Smartphone and Pocket PC as they are described in the WAP Service Indication Specification Version 08-Nov-1999 and the WAP Service Loading Specification Version 08-Nov-1999. Both of the WAP specifications are available from the www.openmobilealliance.org/.
Although SI and SL functionality is on Smartphone and Pocket PC by default, support is an optional requirement for mobile operators. For information about disabling SI and SL, see Perimeter Security.
See Also
The User Experience with SL and SI Notifications | WBXML and Windows Mobile-Based Devices
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