Sending to Remote (x_send)

Once we have the data we want to transfer we need to pass control over to Unix to allow it to handle the security aspects as well as determining the best method of 'talking' to the other machines. This is accomplished by a program called 'x_send', which has to :

1. Check the vet system for new work.
2. Copy it to an area of the disk that does not suffer from security restrictions.
3. Make sure that while this copy takes place no new work is added.
4. Work out where to send it.
5. As we may be transferring at peak phone rates we want it to compress the data down so it take less time.
6. Send it

The sending program will usually be run automatically for you. If you do need to run it manually there is an option on xmenu to start it.

Note: xmenu will be explained shortly in the next section.

Checking for work being present (x_check)

During the course of the day (or night) UUCP will be sending information into your machine. Work that UUCP transfers will be stored in a special area of the disk called a 'spool directory' until it is needed. The checking program will look in the spool directory and if there is work present, it will transfer it to the area of the disk used by Premvet 5.

The checking program (called x_check) has to:

1. Check to see if any information has been received from remote sites.
2. De-compress the data
3. Copy the received information to the area of the disk associated with Premvet 5, in a form the Veterinary software can handle.
4. If it is being run at the main site AND there are multiple branches then x_check will forward the information to the other sites.

In a similar manner to x_send, this checking program will be run automatically (usually every 30 minutes) but can be run manually via xmenu.

Both x_check and x_send are utilities run either from xmenu or from the Operating System prompt line. Having to remember to run these programs can be unreliable (someone forgets to type them in) and impractical (you want to update at 2am). Rather than get a user to run them we can get the computer to do it automatically. A utility called 'cron' can be given a list of jobs to carry out at specified times. Cron is running all the time in the 'background'; that is, it starts automatically and operates without user intervention and without tying up a screen.

So, we work out the times we want x_send and x_check to run, tell cron and then forget about it. Setting up cron is explained in the next section. But first, you need to think about the times you want to use. This is also affected by the cross-over of clients. If it is unlikely that clients will attend both sites on the same day it makes sense to transfer the information overnight to take advantage of cheap phone rates. Otherwise, you will have to schedule the transfers between surgery times.