4 Management Services Indications

For each indication, this chapter provides the following information:

Purpose of the indication, and the conditions in which SNAP-IX returns it to an application.
Description of the indication. For consistency, the term verb control block (VCB) is used to describe the indications, although this structure is not associated with a verb issued by the application. All the VCB structures are defined in the header file /usr/include/sna/ms_c.h.
For each parameter in the VCB structure, the following information is listed:
- Description
- Values that can be returned and their meanings
- Additional information where necessary

Many of the supplied and returned parameter values are numeric. To simplify coding, make the applications more portable, and make the program source easier to read, these values are represented by symbolic constants defined in the header file /usr/include/sna/ms_c.h. For example, the opcode (operation code) parameter for the FP_NOTIFICATION indication is the value represented by the symbolic constant AP_FP_NOTIFICATION.

Because different systems store these values differently in memory, it is important that you use the symbolic constant, and not the numeric value, when setting values for supplied parameters or when testing values of returned parameters. The value shown in the header file may not be in the format recognized by your system.

Note

Although the application allocates the VCBs for MS verbs, SNAP-IX allocates the VCBs for indications. Therefore, the application has access to the VCB information only from within the callback routine; the VCB pointer that SNAP-IX supplies to the callback routine is not valid outside the callback routine. The application must either complete all the required processing from within the callback routine, or it must make a copy of any VCB data that it needs to use outside this routine.

4.1 FP_NOTIFICATION

SNAP-IX sends this status indication to an MDS-level application that has requested information about the focal point for a particular MS category. The application requests this information by issuing REGISTER_MS_APPLICATION with the name of a particular MS category specified as part of the focal point data string. SNAP-IX sends FP_NOTIFICATION to inform the application of its current focal point for that category. Each time the focal point changes, SNAP-IX sends another FP_NOTIFICATION.

This indication is returned using the callback routine that the application supplied on the REGISTER_MS_APPLICATION verb. For more information about the requirements for this callback routine, see The Callback Routine Specified on the ms_async Entry Point.

4.1.1 VCB Structure

typedef struct fp_notification
{
   AP_UINT16       opcode;
   unsigned char   reserv2;             /* reserved                             */
   unsigned char   format;              /* reserved                             */
   AP_UINT16       primary_rc;          /* Primary return code                  */
   AP_UINT32       secondary_rc;        /* Secondary return code                */
   unsigned char   fp_routing;          /* routing to use with this focal point */
   unsigned char   reserv1;             /* reserved                             */
   AP_UINT16       fp_data_length;      /* Length of incoming focal point data  */
   unsigned char   *fp_data;            /* Focal point data                     */
} FP_NOTIFICATION;

4.1.2 Parameters

SNAP-IX includes the following parameters when it sends FP_NOTIFICATION to an MDS-level application:

opcode

AP_FP_NOTIFICATION

fp_routing

Specifies whether applications should use default or direct routing when sending MDS_MUs to this focal point. Possible values are:

AP_DEFAULT: MDS_MUs should be delivered to the focal point using default routing.
AP_DIRECT: MDS_MUs should be routed on a session directly to the focal point.

fp_data_length

Length of focal point data. This can be up to 78 bytes.

fp_data

Focal point data, which consists of the following:

Focal Point Notification (0xE1) subvector
Focal Point Identification (0x21) subvector, which contains an MS Category subfield. The MS Category subfield identifies the category for which the application requested focal point information and contains the following subfields:
- Focal point network identifier (NETID)
- Focal point network accessible unit (NAU) name
- Application ID

When sending an MDS_MU in the MS category associated with this focal point, the application should include the information from these subfields in the MDS_MU to ensure that it is routed to the appropriate focal point. For full details of the information contained in these subvectors, refer to the IBM manual System Network Architecture: Formats.