For the services that take a long time to start or to stop, a mechanism is provided to feed back or hint to the process that started or stopped them. This mechanism allows the process to determine dynamically how long to wait for the service to (1) complete the startup or stop and (2) provide the estimated time to the user, if determined by the application. The service can set the text field svci2_text as part of its status information.

The services and programs that start or stop the services can use this mechanism to communicate during the start and stop operations. The control completion pending (CCP) code values are used when a service expects to take a long time to start or stop. Any service that has a nontrivial initialization or shutdown task can use this method.

If a service is not using CCP codes, the svcs_code field in the data structure should be set to 0 while the service status is INSTALL_PENDING or UNINSTALL_PENDING.

If a service is using CCP codes, then the svcs_code field is mapped as follows:

33322222 222221111 111111
21098765 432109876 54321098 76543210
 
xxxxxxxx xxxxxxxxH TTTTTTTT CCCCCCCC
 
 
x = not used (must be 0)
H = hint is given            SERVICE_CCP_QUERY_HINT
T = time to wait             SERVICE_CCP_WAIT_TIME
C = checkpoint number        SERVICE_CCP_CHKPT_NUM
 

Bits that are not used must be set to 0.

The time to wait is the expected time to complete the current operation (start or stop), in tenths of a second.

The checkpoint number is a number that should be incremented, or at least changed to a higher value, each time the service calls the NetServiceStatus API. A service should call the NetServiceStatus API fairly often to keep updating this number, remembering that it is an 8-bit quantity.

A controlling application assumes the service is still active if this checkpoint value constantly changes. For that reason, the code that calls the NetServiceStatus API to update the CCP code should be in the main code path, rather than in some time-triggered thread that might continue even while the current operation has halted as the result of an error.

The "hint" bit informs the application controlling the service that the other (time and count) information is valid. If this bit is set, the field svc2_text can contain an ASCIIZ string that, when displayed to a user, provides some information about the current state of the service. The service can continue to use a null string if it does not need to provide text. It is up to the controlling application to make use of the text field, but it can assume that the text is suitable for display to the user.