[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Handle-info] indirect handles actually implemented?

Eric and all,

Getting back to this....

To confirm your understanding of HS_ALIAS - yes, it redirects handle clients to a completely different handle, and ignores any other type/ value pairs in the first handle. It is rarely used, to my knowledge, and can be thought of as a last resort method for managing ownership/ admin changes when none of the usual methods will work, for whatever reason.

Regarding the 'indirect' handle notion - there are a number of situations in which the value for a handle/type/value triple is, routinely, another handle. Linking a handle prefix to the right handle service is one example - some handle services are responsible for multiple handle prefixes, so instead of associating the specifics of a handle service, e.g., IP address(es), with the prefix, another level of indirection is used - the HS_SERV type whose value is a handle. That handle resolves to information about the relevant handle service. So, if HandleServiceA is responsible for 100 prefixes, and you have to add or change an IP address, you can change a single service handle instead of 100 prefix handles. There are other cases of handle types which take handles as values.

The point is that, although it may have seemed like a simple idea in the early days, there is no general approach to substituting another handle for a given value - it will depend on the type that holds the value and, importantly, on the type or types in the handle to which you are being redirected. Clients have to have some notion of what they are looking for at the other end.

The case that I believe is behind your question, which is how to manage multiple URLs associated with a single handle where the URLs are probably controlled by different organizations, is one of a number of similar use cases which are coming to the fore right now. There has been some internal discussion at CNRI on this which will likely result in a new type, which addresses multiple URLs for a single handle, at a somewhat higher level and which will be understood by the proxy server that we make available.

Regards,

Larry

On Mar 26, 2008, at 12:05 PM, Eric Auer wrote: 
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1


Hi, to follow-up myself: I notice that the
HS_ALIAS *is* processed by both the browser
plugins and the hdl.handle.net web proxy:

Having a HS_ALIAS field with any arbitrary
index for a handle makes the system return
the data of the handle listed in the data
of the HS_ALIAS (eg "42/111")... In short,
the HS_ALIAS "blocks" access to any other
field/index of the "original" handle, and
lets you see contents  from the referred-
to handle for all your queries.

That is quite useful and somehow similar to
the indirect handles described in 1995, but
the "URL indirection" suggested in my other
mail is still useful in other scenarios. It
would be nice if the web proxy could do it.

Regards, Eric

... 
I am told that the Handle System supports a
thing called "indirect handles", as seen in:
www.cnri.reston.va.us/home/cstr/handle-overview.html
(The Handle System A Technical Overview, June 1995)
...

... 
For now, I did some experiments with putting a
hdl:... value into URL records of handles. This
also creates an indirection, but for example the
hdl.handle.net web proxy does not follow that,
it just returns the hdl:... URL/URI. If you have
a browser with Handle System plugin (tested and
works w/ MSIE) then it should still be possible
to follow the recursion without having to install
special client or server side software. Of course
the described "URL field indirection" only works
for the URL field, not for other data stored on
a handle server for a given handle. That is okay
for now, but redirecting an entire handle can be
interesting / useful, too.
...

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.5 (GNU/Linux)
Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org

iD8DBQFH6nQw99dkROyhRRsRAt16AJ9xa/ywoKp2IG/T8xqLpWXzivI/0wCfTENj
fVx0gCwQJ+bQUnGhzq7Yitc=
=ffeu
-----END PGP SIGNATURE-----


_______________________________________________
Handle-Info mailing list
Handle-Info@cnri.reston.va.us
http://www.handle.net/mailman/listinfo/handle-info



_______________________________________________
Handle-Info mailing list
Handle-Info@cnri.reston.va.us
http://www.handle.net/mailman/listinfo/handle-info