2.2.4.1.3.3 AgentSpecific
The AgentSpecific packet is transmitted from a TAPI client to a TAPI server in a remote procedure call. Sending this packet allows the application to access proprietary handler-specific functions of the agent handler that is associated with the address.
The meaning of the extensions are specific to the agent handler. Each set of agent-related extensions is identified by a universally unique 128-bit extension ID that MUST be obtained, along with the specification for the extension, from the promulgator of that extension (usually the author of the agent handler software on the telephony server).
The list of extensions that are supported by the agent handler is obtained from the LINEAGENTCAPS packet that is returned by the GetAgentCaps packet.
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Req_Func |
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Reserved1 |
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dwRequestID |
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lpContext |
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hLine |
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dwAddressID |
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dwAgentExtensionIDIndex |
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lpParamsContext |
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lpParams |
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dwSize |
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Reserved2 |
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Reserved3 |
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Reserved4 |
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Reserved5 |
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Reserved6 |
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VarData (variable) |
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Req_Func (4 bytes): An unsigned 32-bit integer. The identifier of the function that will be invoked on the remote server. This value MUST be set to 6.
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Return Values
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On completion of ClientRequest, this field contains the result of the encapsulated telephony request. A nonzero request ID value indicates that the request is in progress and will complete asynchronously, and a LINEERR_Constants value indicates synchronous failure.
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Returns a positive request identifier if the function will be completed asynchronously or a negative error number if an error occurs. If the client specified a nonzero value in the dwRequestID field of the packet, the same MUST be used as the value for the returned positive request identifier.
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Common return values are as follows:
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Name
Value
LINEERR_INVALADDRESSID
0x80000011
LINEERR_INVALAGENTID
0x80000057
LINEERR_INVALLINEHANDLE
0x8000002B
LINEERR_INVALPARAM
0x80000032
LINEERR_INVALPOINTER
0x80000035
LINEERR_NOMEM
0x80000044
LINEERR_OPERATIONFAILED
0x80000048
LINEERR_OPERATIONUNAVAIL
0x80000049
LINEERR_RESOURCEUNAVAIL
0x8000004B
LINEERR_STRUCTURETOOSMALL
0x8000004D
LINEERR_UNINITIALIZED
0x80000050
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Additional return values are specific to the agent handler.
Reserved1 (4 bytes): An unsigned 32-bit integer. MUST be set to zero when sent and MUST be ignored on receipt.
dwRequestID (4 bytes): An unsigned 32-bit integer. The identifier of the asynchronous request.
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Value
Meaning
0x00000000
The server MUST generate a unique positive request ID to return as the Ack_ReturnValue.
0x00000001 — 0x7FFFFFFF
The server MUST use this value instead of generating a unique positive request ID.
lpContext (4 bytes): An unsigned 32-bit integer. The opaque, client-specified value that is used by the client upon request completion; MUST be returned by the server in the request completion packet.
hLine (4 bytes): An HLINE. The handle to the open line device. This field MUST have been obtained by sending the Open packet.
dwAddressID (4 bytes): An unsigned 32-bit integer. The address on the open line device. An address identifier is permanently associated with an address; the identifier remains constant across operating system upgrades. A valid value of dwAddressID is in the range 0 to dwNumAddresses –1. The client obtains dwNumAddresses from the LINEDEVCAPS obtained by sending a GetDevCaps packet to the remote server.
dwAgentExtensionIDIndex (4 bytes): An unsigned 32-bit integer. The position in the ExtensionIDList packet in LINEAGENTCAPS of the agent handler extension being invoked. A valid value of dwAgentExtensionIDIndex is in the range 0 to dwNumAgentExtensionIDs – 1. The client obtains dwNumAgentExtensionIDs from the LINEAGENTCAPS obtained by sending a GetAgentCaps packet to the remote server.
lpParamsContext (4 bytes): An unsigned 32-bit integer. The opaque, client-specified value that is used by the client upon request completion; MUST be returned by the server in the request completion packet.
lpParams (4 bytes): An unsigned 32-bit integer. The offset, in bytes, in the VarData field of a parameter block. The format of this parameter block is device specific and its contents are passed by TAPI to and from the agent handler application on the telephony server. This parameter block MUST specify the function to invoke and include sufficient room for data to be returned.
dwSize (4 bytes): An unsigned 32-bit integer. The size, in bytes, of the parameter block that is indicated in the lpParams field.
Reserved2 (4 bytes): An unsigned 32-bit integer. This field is used for padding and MUST be ignored on receipt. It can be any value.
Reserved3 (4 bytes): An unsigned 32-bit integer. This field is used for padding and MUST be ignored on receipt. It can be any value.
Reserved4 (4 bytes): An unsigned 32-bit integer. This field is used for padding and MUST be ignored on receipt. It can be any value.
Reserved5 (4 bytes): An unsigned 32-bit integer. This field is used for padding and MUST be ignored on receipt. It can be any value.
Reserved6 (4 bytes): An unsigned 32-bit integer. This field is used for padding and MUST be ignored on receipt. It can be any value.
VarData (variable): Contains a parameter block that corresponds to the proprietary handler-specific functions of the agent handler. This data is opaque to the protocol.