The Wireless FAQ

4.18 What is PUSHing and how does it work?

PUSH was added to WAP 1.2, and is only available in WAP 1.2 environments. In short PUSH provides another way of sending data from a content or application server to a mobile user agent. The "traditional" way, PULLing is for the user agent to request the information, and then receive it. PUSH means that the server can send the data to the user agent without it having to ask for it.

The content or application server cannot send the data to the user agent directly, but will have to use a so called Push Proxy Gateway. This PPG sits between the internet based Push Initiator (the content or application server) and the mobile user agent. On the internet side, the Push Access Protocol is used, and on the mobile internet side, the Push Over-the-Air Protocol is used.

Note that the user agent does not automatically accept data from any content provider - only those that it has listed as trusted.

Currently the only WAP 1.2 development platform to support PUSH is the Nokia Toolkit 2.0. Remember to register first. Note that the Nokia Toolkit 2.0 only support PUSHing internally. Meaning, you can push messages to from the toolkit interface to the emulator phone. If you try to point the toolkit to an external Push Proxy Gateway, the toolkit crashes. But as it says in the readme file that comes with the toolkit, PUSHing has not been fully tested.

As soon as a publicly available PUSH capable development environment (that also supports actual Push Proxy Gateways) has been confirmed, the topic will be covered in detail in this FAQ. Until then, read the PUSH, Push Access Protocol and Push-OTA Protocol specifications available here.

Related information

Chapter 16 in "Professional WAP" from Wrox

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