[Embedlets-developer] Avalon inspired interface hunting

[Ted K. <tk...@ya...>]

I spent a significant amount of time on the Avalon site yesterday and the
container design ideas there are absolutely fabulous!   So far I am aware of
the following 4 containers that we might be able to gain some insight from for
designing an Embedlet container: The EJB container, the Servlet container, the
BeanContext container and now the Avalon container.  Of these 4 I think that
the BeanContext container and the Avalon framework container appear to have the
most to offer us.

One theme that came across very clearly in the Avalon framework documentation
was the need for well-thought-out interfaces between the components in the
container and between the components and the container itself.   I could see
how the Avalon interfaces were evolved to meet the needs of a server side
component framework and then I started wondering if the interfaces for an
embedded systems container would be similar or different than these interfaces?

So, I decided to do some embedded system container interface hunting by putting
together a visual mockup of what I thought a couple of Embedlet container based
applications might look like and then search these applications for interfaces.

This is what I came up with:

http://embedlets.sourceforge.net/devdocs/diagrams/embedlet_pictures1.png


The interfaces immediately wanted to sort themselves into digital-oriented
interfaces like:

BitProducer and BitConsumer


and analog signal oriented interfaces like:

SignalStreamProducer and SignalStreamConsumer


The Embedlets themselves seemed to want to divide themselves into standard
Embedlets that lived in the middle of the container and Device & Service proxy
Embedlets that encapsulated connections to devices and services outside of the
container.  These proxy Embedlets appeared to work best attached to the inside
walls of the container to indicate that they had some kind of connection to the
outside world.

As I came up with generalized device proxy Embedlets to solve my programming
problems they started to look like what James describes as 'Abstract
Peripherals' and it occurred to me that perhaps if people did similar mockups
of the Embedlet container implementations they are interested in that more of
these 'Abstract Peripherals' would be discovered.

A final observation was that if an Embedlet container could be implemented
anywhere then why not allow it to be embedded inside of another Embedlet
container?  As an alternative to programming some of the Embedlets in Java
source code, it seemed that there should be no problem with programming the
internal logic of an Embedlet using another Embedlet container.


I only pulled out some of the 'low hanging fruit' interfaces from these mockups
because they were easy to see.  I wonder what some of the other interfaces are?


Ted


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