2.2.2 Message Headers

All Content Indexing Services Protocol messages have a 16-byte header.

The following diagram shows the Content Indexing Services Protocol message header format.

0	1	2	3	4	5	6	7	8	9	1 0	1	2	3	4	5	6	7	8	9	2 0	1	2	3	4	5	6	7	8	9	3 0	1
_msg
_status
_ulChecksum
_ulReserved2

_msg (4 bytes): A 32-bit integer that identifies the type of message following the header. The following table lists the Content Indexing Services Protocol messages and the integer values specified for each message. As shown in the table, some values identify two messages in the table. In those instances, the message following the header can be identified by the direction of the message flow. If the direction is client to server, the message with "In" appended to the message name is indicated. If the direction is server to client, the message with "Out" appended to the message name is indicated.

Value	Meaning
0x000000C8	CPMConnectIn or CPMConnectOut
0x000000C9	CPMDisconnect
0x000000CA	CPMCreateQueryIn or CPMCreateQueryOut
0x000000CB	CPMFreeCursorIn or CPMFreeCursorOut
0x000000CC	CPMGetRowsIn or CPMGetRowsOut
0x000000CD	CPMRatioFinishedIn or CPMRatioFinishedOut
0x000000CE	CPMCompareBmkIn or CPMCompareBmkOut
0x000000CF	CPMGetApproximatePositionIn or CPMGetApproximatePositionOut
0x000000D0	CPMSetBindingsIn
0x000000D1	CPMGetNotify
0x000000D2	CPMSendNotifyOut
0x000000D7	CPMGetQueryStatusIn or CPMGetQueryStatusOut
0x000000D9	CPMCiStateInOut
0x000000E1	CPMForceMergeIn
0x000000E4	CPMFetchValueIn or CPMFetchValueOut
0x000000E6	CPMUpdateDocumentsIn
0x000000E7	CPMGetQueryStatusExIn or CPMGetQueryStatusExOut
0x000000E8	CPMRestartPositionIn
0x000000E9	CPMStopAsynchIn
0x000000EC	CPMSetCatStateIn or CPMSetCatStateOut

_status (4 bytes): An HRESULT value, indicating the status of the requested operation. When sent by the client, can be set to any arbitrary value and MUST be ignored on receipt.<5>

_ulChecksum (4 bytes): The _ulChecksum MUST be calculated as specified in section 3.2.4 for the following messages:

• CPMConnectIn

• CPMCreateQueryIn

• CPMSetBindingsIn

• CPMGetRowsIn

• CPMFetchValueIn

Note For all other messages from the client, _ulChecksum MUST be set to 0x00000000. A client MUST ignore the _ulChecksum field.

_ulReserved2 (4 bytes): If 32-bit offsets are being used, MUST be set to 0x00000000 and MUST be ignored by the receiver. _ulReserved2 can be used in 64-bit scenarios, as specified in section 2.2.3.16.