[MS-ASCMD]: ActiveSync Command Reference Protocol Specification

Order Client action Server action
6 If the meeting was not declined, the client sends
a Sync command for the calendar collection,
specifying the GetChanges element.
The server responds with any changes to the
Calendar folder caused by the last
synchronization and the new calendar item
for the accepted meeting.
3.1.5.6 Handling Status Errors
The client MUST handle errors that occur during synchronization sessions. Errors fall into two
categories: HTTP errors and ActiveSync protocol errors. HTTP errors are standard error codes, such
as "401 Logon failed", and they are returned from the server in response to an HTTP POST.
ActiveSync protocol errors result from a problem on the server, in an attempt to perform the task
requested by the command request message. ActiveSync protocol errors are indicated by codes that
are returned in the Status element (section 2.2.3.152) of a command response. For more details
about the status codes, see section 2.2.4.
The client MUST implement error handling and a user interface (UI). Some errors are handled by a
recovery procedure. Other errors require that an error message be displayed, along with a prompt
for the user to respond. The client determines whether to run a recovery procedure or prompt for
user input.
In addition to the ActiveSync protocol errors that the server sends, incomplete communication
between server and client can result in the failure of a synchronization session. The server has an
error recovery feature that enables a client to respond to errors by repeating the most recent
synchronization session. The client MUST handle synchronization failures by retrying the
synchronization. The server tracks synchronization requests to be able to respond appropriately in
both of the following cases:
•The client failed in communicating a full request to the server for synchronization.
•In this case, the client sends a request but the server does not receive the request. The server
does not act on the request, and no server-side changes occur. Therefore, no response is sent
to the client. The client MUST resend a synchronization request if there is no immediate server
response and neither the airsync:Wait element (section 2.2.3.171) nor the
airsync:HeartbeatInterval element (section 2.2.3.75.2) was sent in the Sync request
(section 2.2.2.19.1), or if the airsync:Wait element value or airsync:HeartbeatInterval
element value was specified in the Sync request and the time has elapsed.
•The server failed in communicating a response to the client for updates.
•In this case, the server response is not received by the client. The client knows it has not
received a response if neither the airsync:Wait element nor airsync:HeartbeatInterval
element was sent in the Sync request and the server response is not received immediately, or
if the airsync:Wait element value or the airsync:HeartbeatInterval element value was
specified in the Sync request and that time has elapsed. The data on the server changed. The
client MUST resend the request. The server recognizes the duplicate request. Because the
server changes have already occurred, the server resends the response to the client to keep
the server and client synchronized.
3.1.6 Timer Events
None.
[MS-ASCMD] — v20110315
ActiveSync Command Reference Protocol Specification
Copyright © 2011 Microsoft Corporation.
Release: Tuesday, March 15, 2011
271 / 369