2.2.1 Shared Message Header (SHARED_MSG_HEADER)

Every Remote Desktop Protocol: XPS Print Virtual Channel Extension packet contains a common header.

InterfaceId (4 bytes): A 32-bit unsigned integer that represents the common identifier for the interface. The default value is 0x00000000, and if the message uses this default interface ID, it is interpreted as the main interface for which this channel has been instantiated. All other values MUST be retrieved either from an Interface Query message response (QI_RSP) or from responses that contain interface IDs. For example, in section 2.2.4.3.1.1 the Callback parameter describes an interface, and it represents an ID suitable for use as an interface ID in another set of request/reply sequences.

This ID is valid until an IFACE_RELEASE message is sent/received with that ID. After an IFACE_RELEASE message, this ID is considered invalid. A packet with an invalid InterfaceId causes channel termination from the packet parser on the receiving end.

MessageId (4 bytes): A 32-bit unsigned integer that represents a unique ID for the request and response pair. Requests and responses are matched, in part, based on this ID.

FunctionId (4 bytes): A 32-bit unsigned integer. This field MUST be present only in request packets. Its value is either used in interface manipulation messages or defined for a specific interface. The following values are categorized by the interface for which they are defined.

Common IDs for all interfaces are as follows.

Value	Meaning
RIMCALL_RELEASE 0x00000001	Release the given interface ID
RIMCALL_QUERYINTERFACE 0x00000002	Query for a new interface

Printer Ticket FunctionIds are as follows.

Value	Meaning
GET_SUPPORTED_VERSIONS_REQ 0x00000100	Server Get Supported Versions request
BIND_PRINTER_REQ 0x00000101	Server Bind Printer request
QUERY_DEV_NS_REQ 0x00000102	Server Query Device Namespace request
PRINT_TKT_TO_DEVMODE_REQ 0x00000103	Server Print Ticket to Devmode request
DEVMODE_TO_PRINT_TKT_REQ 0x00000104	Server Devmode to Print Ticket request
PRINT_CAPS_REQ 0x00000105	Server Print Caps request
PRINT_CAPS_FROM_PRINT_TKT_REQ 0x00000106	Server Print Caps From Print Ticket request
VALIDATE_PRINT_TKT_REQ 0x00000107	Server Validate Print Ticket request

Printer Driver FunctionIds are as follows.

Value	Meaning
INIT_PRINTER_REQ 0x00000100	Server Initialize Printer request
GET_ALL_DEV_CAPS_REQ 0x00000101	Server Get All Dev Caps request
CONVERT_DEVMODE_REQ 0x00000102	Server Convert Devmode request
GET_DEVICE_CAP_REQ 0x00000104	Server Get Device Capability request
DOC_PROPERTIES_REQ 0x00000105	Server Document Properties request
ASYNC_PRINTER_PROPS_REQ 0x00000107	Server Async Printer Properties request
CANCEL_ASYNC_PRINTER_PROPS_REQ 0x0000010A	Server Cancel Async Printer Properties request
ASYNC_DOC_PROPS_REQ 0x00000106	Server Async Document Properties request
CANCEL_ASYNC_DOC_PROPS_REQ 0x00000109	Server Cancel Async Document Properties request
MOVE_DOC_PROPERTIES_REQ 0x0000010B	Server Move Document Properties Window request
MXDC_GETPDEV_ADJUSTMENT_REQ 0x0000010C	Server Get Device Adjustments request

Printer Properties Callback FunctionIds are as follows.

Value	Meaning
PRINTER_PROPS_CALLBACK_REQ 0x00000100	Client Printer Properties Callback request

Document Properties Callback FunctionIds are as follows.

Value	Meaning
DOC_PROPS_CALLBACK_REQ 0x00000100	Client Document Properties Callback request

MessagePayload (variable): An array of unsigned 8-bit integers. The remainder of the message is interpreted based on the interface for which the packet is sent. This field is optional based on the packet length.