service dependency examples?

From: Wayne Marshall <wcm_at_b0llix.net>
Date: Mon, 3 Nov 2014 08:15:02 -0800

Hi,

Would someone kindly provide a real-world example of a service
dependency? That is, some service "foo" that critically depends on
another service "bar", and that satisfies either or both of the
following conditions:

 c1: service "foo" MUST NOT be started, or be attempted to be started,
 until service "bar" is running, lest something undesirable happens.

 c2: service "foo" MUST be terminated whenever service "bar" stops
 running, lest something undesirable happens.

To elaborate a little, the following scenarios are of *no* interest to
this inquiry:

 s1: service "foo" fails immediately on startup if service "bar" is not
 available.

 s2: service "foo" terminates itself whenever service "bar" is not
 available.

 s3: service "foo" successfully starts and runs even if service "bar"
 is not running, and waits or queues or times-out or retries with
 diagnostics while "bar" is unavailable, but otherwise does nothing
 undesirable in the absence of "bar".

Many thanks,

Wayne
Received on Mon Nov 03 2014 - 16:15:02 UTC