TODO: Merge with Adapters
An Outlet is a special kind of entity
TODO: Connections, Attachments, Subscribtions, Adapters, Remote rendez-vous
The Orchestra API provides a flexible method for dynamically interfacing external software
components (i.e. adapters and analytics) to entities. The outlet construct serves this purpose.
Orchestra outlets use a unique distributed rendezvous mechanism for synchronizing access. An
outlet is an entity interface point that allows an adapter application to intercept and process
the method invocations and attribute inquisitions requested of an entity. Outlets also provide
a means for event subscribers to asynchronously receive entity event publication notices.
Internally, these two capabilities are provided using rendezvous and queuing type mechanisms.
Adapters are software processes that provide entities with their method and attribute
behaviors. Specifically, adapters respond to the set of methods/attributes that may be
invoked/inquired of an entity. To perform this role, adapters must communicate with entities
through interface points so that when any of an entity’s methods are invoked or its attributes
inquired, the requests are forwarded to the correct adapters to fulfill. Adapters perform these
operations via communication with an outlet. In concert with the CONNECT/ DISCONNECT and
ATTACH/DETACH operations described above, outlets provide the necessary interfacing points.
After an entity is created, it must first be “activated” in order to receive any attachments or
connections. Entity activation is necessary in order to ensure that the appropriate
rendezvous/queueing resources have been allocated.
When an entity method is invoked or an attribute is inquired, the request is forwarded to the
appropriate outlet as determined by the entity’s connection/attachment list and the specified
precedence level. Adapters are notified of such invocation/inquisition requests via these
outlets. Specifically, when a method invocation/attribute invocation request is received at an
outlet, the adapter communicating with the outlet is notified of the request via the respective
rendezvous on a first-in-first-out basis. The current state of this rendezvous can be obtained via
the RENDEZVOUS operation. However, as a result of a concurrent application, the actual state
of the rendezvous could dynamically change.
Adapters are notified using the callback parameter specified when they communicate with the
outlet. It is this overall entity/outlet interfacing structure that contributes to Orchestra’s ability
to operate in a highly distributed plug-in fashion, alleviating the need for any centralized
components, and enabling its scalability.
Find code sample here:
https://training.ledr.io/_modules/module/utils/outlet_connections.html#outlet_connections
sources: