How Direct Push Works

Direct push traffic looks like small HTTP requests to an Internet Web site that takes a long time to respond.  The direct push process, however, is actually a series of requests from the device and responses from the server.  A direct push session continues until it expires according to a set direct push timeout.  (See Recommendations for Direct Push Settings below.)  The following steps outline the direct push process:

 

STEP 1: Initiating Device Request.  The NotifyLink device client issues an HTTP(S) message or heartbeat request to the NotifyLink server, asking that the server report any changes that occur in the user’s mailbox within a specified time limit.

STEP 2: Server Response.  When NotifyLink server receives the heartbeat request, it monitors the mailbox specified until one of the following occurs:

Occurrence	NotifyLink Server Response
A change occurs in the mailbox.	Issues an HTTP 200 OK response indicating that changes have occurred.
No changes occur in the mailbox.	Issues an HTTP 200 OK response indicating that no changes have occurred.
The time limit expires.	Issues an HTTP 200 OK response indicating that no changes have occurred.  NOTE: The time limit is determined by the shortest time out in the network path.  It is recommended that all time outs in the network path match or exceed the direct push time-out.  (See Recommendations for Direct Push Settings.)

 

STEP 3: Device Reaction to Server Response.  The NotifyLink device client reacts to the response from the NotifyLink server in one of the following ways:

Response From the Server	Device Reaction
An HTTP 200 OK response indicating that changes have occurred.	Issues a synchronization request to the mailbox and then a heartbeat request once the synchronization is completed.
An HTTP 200 OK response indicating that NO changes have occurred.	Re-issues the heartbeat request.
No response from the server within the specified time.	Re-issues the heartbeat request.

 

Steps 2 and 3 are repeated until the direct push interval expires – a time limit settable on the device by the user or through device policies accessed by an IT administrator on the server.

The device reconnects 60 seconds after the interval expires, establishing another direct push session.