I still needed to show how you can send an Service Indication (SI) document like:
< ?xml version="1.0"?>
< !DOCTYPE si PUBLIC "-//WAPFORUM//DTD SI 1.0//EN"
si-expires="2009-03-04T16:25:00Z">Check out Mobile Tidings!</indication>
This document, a Service Indication, tells the WAP client to store the following:
- A link to http://mobiletidings.com/
- With text “Check out Mobile Tidings!“
- This typically shows up in a “WAP Push Inbox” or sometimes in the “SMS Inbox”
- The link will show when it was created
- It should automatically be removed after the expiry time mentioned
Well here is the AT command to send this particular SI document:
As I started to explain in the last post, a WAP push consists of an XML document sent to the device over SMS. This is true but somewhat simplified.
The truth is that we send:
- an WBXML encoded XML
- over WSP (Wireless Session Protocol)
- over WDP (Wireless Datagram Protocol)
- over SMS
This is called an unconfirmed push.
As you may understand, the data you can send via SMS is limited. It is limited because:
- A single message can only hold 160 GSM-7 encoded characters
- Even though messages can be combined in to bigger ones, the total size is still limited in several ways:
- A message can have at most 256 parts
- The receiving device as a (much lower) limit on how many parts it can reassemble into a bigger message
- And if the technical limits aren’t prohibitive, the cost might be
So how do you send more and richer information to a device? There are 2 possibilities:
Today I’ll focus on WAP push.