Actions in black,action responses in blueandmeeting notesfrom in green andmeeting notes from in red
Control Task
This was not covered onand will be added to the agenda for
Nigel DavisDefinitions of task using Component-System principles (explaining the distinction) and show clear boundaries. Say what a task is and what not. Define recursion. Emphasize reuse.Place orchestration on a figure.
Component-System pattern as described in TR-512.A.4 (v1.5)
Various other considerations...
Use specialized term "ControlTask" to avoid terminology confusion
ControlTask: A definition of activity of a functional Component {hence it is opaque} that provides management-control capability.
By "activity" I mean externally visible behavior. Transfer function perhaps gives a better feel.
I am considering the Task as the definition here, but we may want to have an instance of running task and hence make it a thing with a definition.
Use "Transfer Functions"
Agreed that the following is sufficient for now
ControlTask: A functional Component that provides management-control capability where that capability is defined in terms of transfer functions.
As it is a Component, as described in TR-512.A.2, it:
has inputs and outputs
can be adjusted with policy and controls
In the case of the control task, these are all externally visible and provided via inputs.
has internal workflow
is described in terms of subordinate components
is... etc.
ControlTask capability (collection of transfer functions) is defined from the outside and hence its description does not vary due to internal hidden control
Other components expose capability that is defined from the inside.
To further clarify the component based definition for ControlTask...
It may take a set of inputs, process them, provide a set of outputs then complete/terminate.
The outputs may all be at the completion of the task or some may be at intermediate points
The outputs may directly update system state or may be streamed for use by other components
The inputs may all be available at the start of the task or they may be available at various points
The task will be initiated by the occurrence of some condition (trigger)
The inputs may be from monitored state or monitored stream
The task may pause to wait for an input, abandon if it does not have an input, skip the input etc.
It may run
as a single activity that terminates once complete
continuously with internal loops until requested to terminate via some state input
It may express its capability in terms of apparent control task flows that explain, in abstract, how the outputs are generated from the inputs
This is the definition of the transfer functions.
A structure of apparent encapsulated ControlTasks with some stated flow
A flow may have loops etc.
An apparent ControlTask may have its capability expressed
It may express its capability in terms of a transfer function or some other structure that is not of a task form
It may be realized by subordinate control task flows
A structure of real control tasks with stated flow
Flow is determined by trigger conditions that are caused by outputs from other tasks
Split is multiple tasks watching for the same trigger condition
Join of two requires two specific condition outputs (one from each) to cause the trigger condition
Alternative depends upon an output value
It may be realized by code (algorithms etc.)
There will be no deeper view of realization
There may be an expression of capability in terms of apparent encapsulated tasks with some stated flow
Multiple instances of a specific type of ControlTask may run at the same time
A ControlTask instance will be running in some specific instance of flow and will be related to instances in the same instance of flow (needs more work here)
Discussion STOPPED HERE
DISCUSSION CONTINUED
Nigel DavisHow the orchestrator interprets complex tasks with intermediate outputs with loops etc.
As above, the ControlTask is defined in terms of apparent ControlTasks
Clearly a ControlTask is designed and is potentially designed for both the provider ControlConstruct and client ControlConstruct (Orchestrator)
The Orchestrator may already be capable of dealing with the task in a hard coded way
Nigel DavisExample of a complex task description in terms of an abstract workflow with intermediate output and loops etc.
Nigel DavisWork a definition set for the "Task" space accounting for the fractal nature and the Component-System pattern aspect. Deal with "triggers" (events etc.), constraints etc.
See above
Nigel DavisSet out some meaningful examples an interaction of "Tasks" to achieve some relevant outcome (e.g., service creation, restoration...). Note that the action "Nigel DavisTo study the boundaries of Job/Task, ControlConstruct, PC, CASC (algorithmic). Consider path computation as an example.Action item from2020 OIMT Virtual Face to Face - Week of April 13" should be covered by this action.
See above
Note that the ControlTask:
may be run as a PC or within a PC with other Tasks where that PCmay be implemented with software running on one or more equipments as per model
may be initiated by a ControlConstruct or CASC which which is implemented as software running on one or more equipments
Nigel DavisProvide a mapping from "Task" terminology to other terminology sets (e.g., Use Case, Workflow...)
The following is partly extracted from earlier in the minutes...
ControlTask
A functional Component that provides management-control capability where that capability is defined in terms of a Transfer Functions.
The whole defined transfer function is available and active
Note that the ControlTask defines a specific purposeful transfer functionality where the underlying componentry may be far more capable.
Perhaps need to adjust to one of the following (to emphasize that this is NOT the underlying/implementation component
"An Abstract Functional Component..." (recognizing that all functional components are abstract)
"An Apparent Functional Component..."
Achieves outcomes/goals etc.
<other notes from above to be added>
Covers all success and failure behaviors
Architected behavior...
Related Terms
Task
Job
Runnable Task (Kestra)
Activity
Use Case
Function
Action
TransferFunction (perhaps this should be specialized to ControlTaskTransferFunction?)
A statement of the capability of the ControlTask in necessary detail to enable a client to fully understand the externally visible characteristics of the ControlTask (i.e., how the outputs are generated from the inputs, or from any other relevant internal behavior)
It may be expressed in terms of an apparent ControlTaskFlow that explain, in abstract, how the outputs are generated from the inputs
This is the definition of the transfer functions.
It may express its capability in terms of a logic function, arithmetic function or some other structure that is not in a ControlTaskFlow form
Related Terms
??
ControlTaskFlow
A structure of interconnected apparent/abstract ControlTasks where the structure expresses all possible flows (including cycles/loops) from exposed inputs to exposed outputs (which are the inputs and outputs of the ControlTask the ControlTaskFlow defines)
Each apparent ControlTask will have a defined Transfer Function
Related Terms
Workflow
Flow (Kestra)
Use Case sequence
Process
Procedure
Action Steps
Component
Uses the term Workflow
From earlier in the minutes:
It may be realized by subordinate control task flows
A structure of real control tasks with stated flow
Flow is determined by trigger conditions that are caused by outputs from other tasks
Split is multiple tasks watching for the same trigger condition
Join of two requires two specific condition outputs (one from each) to cause the trigger condition
Alternative depends upon an output value
Capability: The (description of the) opportunity for a thing (e.g., Component) to carry out activities
ControlTask capability (stated as a transfer function) is defined from the outside and hence its description does not vary due to internal hidden control
Other components expose capability that is defined from the inside.
DISCUSSION: Due to lack of time, just briefly highlight the new blue text below. Will go through that in
Spec model review and agreement
Nigel DavisTake the spec model, prune out the stuff that are not relevant to simple layer hierarchy, look at how to apply the general principles (slide 32) notation to the stack of layers & rules, write it in the context of the original spec structure. Note that the action "Nigel Davis To prune out the unneeded stuff from the current Spec document so that to show the Yang "when" and "must" of the Occurrence pattern. Action item from2021 Sep 07-10 : OIMT Virtual Face-to-Face" is covered by this action.
Proposal: Additional TR on simplified use of spec that takes the spec model, prunes classes and associations that are not necessary for a basic usage then shows examples of usage,
During TAPI discussions on NEP/CEP model several multi-layer compact forms of CEP have been proposed. The internal structures are relatively complex including multiplexing reversal. These structures emphasize then need for a spec representations (it is necessary to enable the orchestrator to interpret the data of the structure). Some predefined patterns may be suitable as there are only a few cases of complexity. The apparent constraints are summarized below:
Complex order tends to go with fixed internal connectivity and simple 1:1 adapter flow
Connection flexibility options are limited to the patterns of the MTNM mapping mode property (although their may be some additional directional variety)
The adapter is complex in some cases
There are multiple LP occurrences in a single spec
The inter-LP flow is relatively simple not requiring full fledged LpPortSpecs
For TAPI, it is expected that an equipment spec occurrence complex would have a related structure of NEP/CEP occurrences which where each CEP would reference a CEP spec (built following the simplified spec definition). The CEP spec structure would be defined to cover the extent of the cases anticipated so far with extension opportunities for more sophisticated cases. It is unlikely that the full capability of the spec model will be required for TAPI in the near future. Nevertheless, it is still important to enable the opportunity for full expansion.
Some examples are shown below:
Nigel DavisConstruct simple spec example using layer hierarchy modelfor the OTN payload structure, try longhand form, correct number of occurrence set, based on some specific ports. Code it in JSON form of YANG. Note that the action "Nigel DavisLay out the spec model with sufficient occurrence pattern of equipment in it. Relate UML to Yang. Action item from2021 Sep 07-10 : OIMT Virtual Face-to-Face" is superseded by this action.
Nigel DavisCover combinatorial rule for layer protocol options. "And" & "Or" in spec language.
