For connection-oriented services, the application and the SCCP task use connection IDs to reference the SAP (subsystem) and to reference the connection to which a particular message applies. The connection IDs reference both requests and responses from the application to the SCCP layer as well as indications and confirmations from the SCCP task to the application. The structure of a connection ID is as follows:
typedef struct connectID
{
S16 suId; /* service user ID */
S16 spId; /* service provider ID */
U32 suConnId; /* user's connection ref number */
U32 spConnId; /* SCCP's connection ref number */
} ConnectID;
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Field |
Description |
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suId |
The application reference number for the SAP that is used. This reference number is the same as the suId passed by the application in the bind request. The application that implements multiple SAPs can use this field on incoming messages to identify the associated SAP. |
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spId |
The SCCP SAP number to which the message belongs. The application sets this field on all messages from the application to the SCCP layer. |
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suConnId |
An arbitrary number that the application uses to identify the connection. The application sets this value on the first message associated with a connection - a connect request for outgoing connections or a connect response for incoming connections. The SCCP layer returns this value on all subsequent messages belonging to this connection. |
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spConnId |
SCCP number for identifying the connection. The application saves this value from the first message received associated with a connection - a connect confirm for outgoing connections or a connect indication for incoming connections - and passes it on all subsequent messages belonging to this connection. |
For connectionless functions, only suId and spId are used to enable the application and the SCCP layer, respectively, to identify the SAP associated with a connectionless request.