In SEDA, there is a difference between the input side of a Queue, and the
input side of the Queue. They are called Source and Sink respectively.
There is futher a Queue interface that extends both.
In essence, what happens is that each Stage is connected by a full queue.
For instance, let us assume we have a Stage that puts events into a Sink.
That Sink is only part of the event queue, the other side of which is a
Source for another stage.
The question I have is one of preference. Is it worth it to separate the
input and output sides of the Queue?
I think it does simplify the the implementation of stages, as the
developer typically won't cast the Sink as a Queue to get at the other
side of the Queue. I also think that it is not preferable to mix these
concerns.
If this is the case, what are the preferred names for the Source and Sink
equivalent? It is a Source's responsibility to dequeue events, and the
Sink's responsibility to enqueue events.
The interfaces as part of SEDA mix concerns, so I intend to place a
simpler interface in Avalon. For instance, it is not the queue user's
responsibility to determine if the event should be placed in a lossy manner
or not. There are also methods for transactional queuing. It is unclear
whether this is appropriate or not. As an example:
Object key = null;
try
{
key = queue.enqueuePrepare( QueueElement[] elements );
queue.enqueueCommit( key );
}
catch ( SinkException se )
{
queue.enqueueAbort( key );
}
I think I may make that a specialization, and simply focus on the simplest
approach.
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deserve neither liberty nor safety."
- Benjamin Franklin
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