[cap-talk] OO interoperation via OCap, presentation level issues

[John Carlson]

On May 19, 2008, at 11:31 PM, John Carlson wrote:

>
>>
>>
>>> Is there no way to describe the essential and core
>>> capability concept and to provide for communication
>>> of capabilities between different systems (language
>>> or OS) without getting drawn into issues such as the
>>> synchrony of the communication and the presentation
>>> of the data parameters?

> I hate to continue this topic, but...
> You may have been referring to natural language, with it's notable  
> lack of types.  Another thing you could do is something visual.  Is  
> there a capability icon that would be useful?  Perhaps an icon with  
> a key?

I am thinking more about presentation, so if you don't want to get  
drawn into this issue, delete this message.  You can skip down to the  
last paragraph for the whole problem with presentation.

Thinking more on this, addresses and indexes could be pointers to a  
list of boxes.  There could be other icons for read, write, take,  
give, find, start and stop.  You could show an arrow flowing into the  
"box" with the data going into an operation, and an arrow flowing out  
of a box showing data coming out.  The order of the objects flowing  
into and out of the box would show the marshalling and unmarshalling,  
if required.

I saw an old math primer with this sort of thing...basically treating  
a function as a black box, and just showing the inputs and outputs and  
a box.


I believe your difficulty may be showing this within the context of  
the granovetter diagram.  If alice wanted to introduce bob to carol  
through the method call write, like status = bob.write(carol),  it  
might be something like:
+-------------------------------------+
| Alice					     |
| /-------\     +---------------+          |
| | carol|     | bob              |          |
| |          | ----> write icon---+      |
| \--++--/     |.more icons |   |      |
|     |  |         +---------------+   |     |
|     > |                                    |     |
|     > |            status<--------+     |
|     > |                                          |
|     \  |                                          |
+-------------------------------------+

(Alice drags the carol key over the write icon inside of bob, method  
is called, then result is dragged to status).  Another thing you could  
show with multiple parameters is clicking on each of the parameters in  
order and dragging the whole selection into bob's write icon.  The  
write method would check the types of the parameters and throw an  
error if there was an error.  There would be different outlines (key,  
seal, etc) for each design pattern in cap-lore.

The problem with visualizing this is that the GUI needs to be  
introduced to at least a facet of alice, bob and carol.  What if you  
don't want your GUI to have access?  My guess is that such a GUI might  
only be used for presentation purposes.  Is there a good tool for  
generating animations like this?

John
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