Thanks @snovello. I have taken your suggestion of exposing the computed data via an action, and I believe I have it working. The code I have is made up of bits and pieces I've found in half a dozen other forum posts, so as a last check it would be appreciated if anyone can comment on whether the code is valid.
Back to my original description, I have a complicated service that builds interfaces to be used by multiple higher level services like Internet, L2VPN, etc. The high-level services were dependent on operational data in the interface service, but this failed when both were created in one transaction as the operational data didn't exist if the create function of the depended-on service was executed second.
So now I have added an action to the interface service, using the "Double" action in ncs.examples and various posts. The computed data is now exposed via action output and the action works fine when invoked via CLI.
But I want to invoke the action function from inside the create function of the high-level service, not CLI, and in the context of the interface service that is being created in the transaction.
So in the high-level service create function I have the following to call the action of the interface service.
A question about the code below:
- To reach the action, I am going back to the root and going into the interface service using its key which is known to the high-level service. Is there a better way?
def cb_create(self, tctx, root, service, proplist):
<snip>
# The action is called "summary" in container "action" in the interface service. Call it. It takes no input.
summary_action_function = root.services.interface[service["interface-svc-id"]].action.summary
action_input = summary_action_function.get_input()
action_output = summary_action_function.request(action_input)
# Store the returned data in this services operational data, so we can use it in the template.
service["important-stuff"] = action_output["important-stuff"]
<snip>
And in the low-level interface service, the action is implemented as follows. I have put the computation code in my_function() which is called by both the action when asked to by another service, and by its own create function so that it can use the computed data itself (eg in its own template or Python code).
Some questions about the code below:
- Is it valid? Or am I way off track?
- Is calling a common function from the action and create functions OK?
- What is the best way to access the service data to be used for computing the return data. Below I have two alternatives, one that access the service using the key name of the service that contains the action (I would pass it via input, just static for testing). The other uses the kp argument but has to go up one level with .. to get out of the "action" container. Both seem to work, but is either better?
def my_function(service):
result = {}
result["important-stuff"] = "insert complicated logic here"
return result
class SummaryAction(Action):
@Action.action
def cb_action(self, uinfo, name, kp, input, output, trans):
root = ncs.maagic.get_root(trans)
#service = root.services["interface"]["interface-1234"]
service = ncs.maagic.cd(root, str(kp)+"/..")
result = my_function(service)
output["important-stuff"] = result["important-stuff"]
class ServiceCallbacks(Service):
@Service.create
def cb_create(self, tctx, root, service, proplist):
<snip>
result = my_function(service)
self.log.info('result:', result["important-stuff"])
<snip>
Thanks,
Peter.
