View Source Skitter.Invocation (Skitter v0.5.3)
Metadata of data being processed.
It is often necessary to store metadata that belongs to a (set of) tokens. This data is stored in the invocation. Strategies have the ability to create new invocations or to add data to an invocation.
This module defines the invocation type and the operations that can be performed on it.
Link to this section Summary
Link to this section Types
Specs
t() :: %{_id: reference()} | :external | :meta
Invocation definition.
An invocation is either a map which stores metadata belonging to a set of tokens or an atom which defines that the data associated with this invocation does not store metadata. This can occur in two situations:
The data is external. This occurs when a source component receives a message that is not sent through Skitter. In this case, the invocation is marked as
:external
. The strategy handling the message is responsible for creating a proper invocation.The message is a "meta-message". This occurs when strategies wish to propagate information through the workflow that is not data to be processed. When this is the case, the message is marked as
:meta
.
Regular invocation contain an :_id
field, which contains a unique identifer. This can be used
to differentiate between invocations created at different points in time.