3649Re: [rest-discuss] Why do I care about visibility?
- May 1, 2003
>> I've been trying to get my mind around exactly what visibility meansWhy it's important? Hmm...
>> why its important to REST. I think I have a vague sense of what it
>> but I'm not sure I understand why its important. I took a look at
>> Fielding's thesis, but I didn't see much at all on visibility.
> What it said was pretty good though, even just this sentence;
> "Visibility in this case refers to the ability of a component to
> or mediate the interaction between two other components. "
There are several places where it comes into play:
o efficient intermediaries
- security across trust boundaries
Many networks don't trust each other, or at least don't trust what
is on the other side of a firewall. As a result, intermediaries are
installed to filter traffic. That is a hard problem for
application protocols, so we need to make it easier in order to make
filtering more efficient and gain the trust of firewall admins.
Visibility calls for more explicit descriptions within messages, as
opposed to relying on external IDLs or XDR-style typing by schema,
which in turn makes it easier to extend the functionality later.
When intermediaries can understand a request, they can more easily
perform or adjust it on behalf of the intended recipient, just as
WebTV or cell phone networks can adjust for their clients.
Visibility is necessary for cacheability.
It is simply easier to build complex systems if you can see and
understand the individual interactions.
People learn by emulation. That is described somewhat in the
There are probably others.
Roy T. Fielding, Chief Scientist, Day Software
2 Corporate Plaza, Suite 150
Newport Beach, CA 92660-7929 fax:+1.949.644.5064
Co-founder, The Apache Software Foundation
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