Use case: start the DAS

Purpose: to prepare the UltraDAS server and controller programs for use.

Actors: any user.

Outline: the user logs into the DAS computer and starts all the attached cameras. The user then manipulates the CIA to get access to the cameras of choice.

Associated use-cases:

Access the DAS computer

Typical course of events:

	User action	System response
1.	Begins with the DAS shut down.
2.	Runs use-case access DAS.	As per subordinate use-case.
3.	Gives the startobssys command.	Determines which cameras are in the "unclaimed" state. Moves those cameras to the "on-line" state. Reports to the user the state of all the cameras.
4.	Checks the state of the cameras needed for the work.	Shows the relevant cameras as "on-line".
5.	Runs use-case start CIA and ICS.	Finds the relevant cameras and puts them in the "idle" state.

Variations:

This use-case can begin with the DAS partly running. That is some cameras are in the "idle" state already and are reflected as such at step 4. It is a bad idea to do this use case when the cameras are "busy".
The needed cameras may show up in some other state than "on-line". The appropriate user actions are as follows.

Disconnected state:

call the DE to get the camera connected.

Lab-mode state:

find the member of technical staff using the lab software and negotiate for access to the camera.

Idle state or busy state:

check whether another person is using the system remotely. If so, negotiate for access. Otherwise, the camera is available and no further action is needed.

A camera of choice may not be listed at all. This means the profiles for the camera have not been introduced to the system. This can only be fixed by a member of the CCD group.

Notes:

Step 3 implies that the system can work out a number of lists:

which cameras have profiles;

which interfaces to cameras are present on the computer;

of the interfaces, which are in use;

of the interfaces in use, which are used by server programmes and which by lab. programmes;

of the interfaces not in use, the detector IDs of the attached cameras.