DL_CONNECT_IND Primitive

Communications Technical Reference, Volume 1

DL_CONNECT_IND Primitive

Purpose

Informs the local data link service (DLS) user that a remote (calling) DLS user is attempting to establish a data link connection.

Structure

The primitive consists of one M_PROTO message block, which contains the following structure.

typedef struct 
{
   ulong dl_primitive;
   ulong dl_correlation;
   ulong dl_called_addr_length;
   ulong dl_called_addr_offset;
   ulong dl_calling_addr_length;
   ulong dl_calling_addr_offset;
   ulong dl_qos_length;
   ulong dl_qos_offset;
   ulong dl_growth;
} dl_connect_req_t;

Description

The DL_CONNECT_IND primitive informs the local DLS user that a remote (calling) DLS user is attempting to establish a data link connection. The primitive contains the data link service access point (DLSAP) addresses of the calling and called DLS user.

The DL_CONNECT_IND primitive also contains a number that allows the DLS user to correlate the primitive with a subsequent DL_CONNECT_RES, DL_DISCONNECT_REQ, or DL_DISCONNECT_IND primitive.

The number of outstanding DL_CONNECT_IND primitives issued by the DLS provider must not exceed the value of the dl_max_conind parameter specified by the DL_BIND_ACK primitive. If this limit is reached and an additional connect request arrives, the DLS provider does not pass the corresponding connect indication to the DLS user until a response is received for an outstanding request.

Note: This primitive applies to connection mode.

Parameters

dl_primitive	Specifies the DL_CONNECT_IND primitive.
dl_correlation	Specifies the correlation number to be used by the DLS user to associate this message with the DL_CONNECT_RES, DL_DISCONNECT_REQ, or DL_DISCONNECT_IND primitive that is to follow. This value enables the DLS user to multithread connect indications and responses. All outstanding connect indications must have a distinct, nonzero correlation value set by the DLS provider.
dl_called_addr_length	Specifies the length of the address of the DLSAP for which this DL_CONNECT_IND primitive is intended. This address is the full DLSAP address specified by the calling DLS user and is typically the value returned on the DL_BIND_ACK associated with the given stream.
dl_called_addr_offset	Specifies where the called DLSAP address begins. The value of this parameter is the offset from the beginning of the M_PROTO message block.
dl_calling_addr_length	Specifies the length of the address of the DLSAP from which the DL_CONNECT_REQ primitive was sent.
dl_calling_addr_offset	Specifies where the calling DLSAP address begins. The value of this parameter is the offset from the beginning of the M_PROTO message block.
dl_qos_length	The DLS provider does not support QOS parameters. This length field is set to 0.
dl_qos_offset	The DLS provider does not support QOS parameters. This length field is set to 0.
dl_growth	Defines a growth field for future enhancements to this primitive. Its value must be set to 0.

States

Valid	The primitive is valid in the DL_IDLE state. It is also valid in the DL_INCON_PENDING state when the maximum number of outstanding DL_CONNECT_IND primitives has not been reached on this stream.
New	The resulting state is DL_INCON_PENDING, regardless of the current state.

Acknowledgments

The DLS user must send either the DL_CONNECT_RES primitive to accept the connect request or the DL_DISCONNECT_REQ primitive to reject the connect request. In either case, the responding message must convey the correlation number received from the DL_CONNECT_IND primitive. The DLS provider uses the correlation number to identify the connect request to which the DLS user is responding.

Implementation Specifics

This primitive is part of Base Operating System (BOS) Runtime.

Related Information

The DL_BIND_ACK primitive, DL_CONNECT_RES primitive, DL_DISCONNECT_IND primitive, DL_DISCONNECT_REQ primitive.