Direct Push

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Direct Push

The Direct Push feature, originally introduced in Microsoft Exchange Server 2003 Service Pack 2, provides timely message delivery to mobile devices. Direct Push uses the following steps:

  • The mobile device issues a long-standing HTTPS request to the server. This request is known as a PING.
  • The server waits for a specified length of time to elapse or for a new item to arrive. If there are no new or changed items in the specified folders during the lifetime of the PING request, the server sends an empty response to the device. If new or changed items exist, the server sends a response to the device that includes the folders that contain the new or changed items.
  • If the mobile device receives an empty response, it issues a new PING request. If the response is not empty, the mobile device issues a synchronization request. After the mobile device synchronizes with the server, the mobile device sends a new PING request.

The follwing figure illustrates the direct push sequence.

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Figure: Direct Push sequence