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Widget instances and widget invocations

From: Robin Berjon <robin@berjon.com>
Date: Thu, 30 Apr 2009 16:45:59 +0200
Message-Id: <D1EB3064-6DC5-4200-B7FE-80BE5822D8E0@berjon.com>
To: public-webapps WG <public-webapps@w3.org>
Hi,

here's my quick stab at a definition:

  - multiple instances of a widget are the same widget (one  
installation) being run multiple times in parallel, e.g. a weather  
widget that you run once for the weather in Paris and once for the  
weather in Sydney;
  - multiple invocations of a widget are the same widget being run  
multiple times serially in time, which is to say that the n+1  
invocation happens after invocation n has been stopped.

The above part is for the definitions, what follows is discussion of  
some implications.

Now consider this:

  - I invoke a widget once
  - I change some preferences or effect storage somehow
  - I kill it
  - I go eat some ice-cream
  - I come back, and invoke the same widget again

In this case, I want the second invocation to have access to the same  
storage  otherwise my work is lost.

Now here's with multiple instances:

  - I invoke a widget once
  - I change some preferences or effect storage somehow
  - I invoke the same widget a second time, getting a second instance
  - I kill widget 1
  - I change some preferences or effect storage somehow in widget 2
  - I kill widget 2
  - I go eat more ice-cream
  - I come back, and invoke the widget again

What information do I get back if I look inside the storage? There are  
multiple options:

  a) the UA has somehow allowed me to pick which instance I run, I get  
back what I put for the right instance
  b) the UA has become confused, I get both values, or something  
broken, or nothing
  c) the UA has a single origin mapped to my widget, I get the last  
write

The ideal option here may be (a) but I'm unsure that it's realistic.  
Basically it would mean that the UA would have a mechanism to run an  
extra instance and to allow me to identify it (e.g. run widget as new  
profile). Would a newly created instance inherit the storage from one  
of the previous ones or a clean slate? This is getting uncomfortably  
close to a UI spec for me.

I think we agree we don't want (b).

I'm going to propose that we go with (c)  this is just like multiple  
tabs open to the same page. If a UA wants to offer a way to make a  
given instance separate (i.e. provide it with a different origin) that  
is of course fine, but IMHO it is the same problem as allowing a user  
to have different cookies in different tabs in a browser: useful, but  
not defined per spec.

-- 
Robin Berjon - http://berjon.com/
     Feel like hiring me? Go to http://robineko.com/
Received on Thursday, 30 April 2009 14:46:36 GMT

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