[OAI-implementers] OAI identifier resolver

Lonnie D. Harvel ldh@ece.gatech.edu
Mon, 20 Oct 2003 20:01:59 -0400 

--------------040207050508060601080505
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit


I am in favor of just the URL:[collection name] approach.  Why make it 
more complicated than necessary? URL's are unique. Is there a particular 
reason why it needs to be shorter?

Adam Farquhar wrote:

> Xiaoming,
>
> Selecting an approach that will be certain to fail, but unpredictably, 
> is not a good 'engineering' approach, especially when there are other 
> approaches that do not fail.  For example, taking a base64 encoding of 
> the base URL or just using the base URL itself will both provide a 
> unique identifier.
>
> Adam.
>
>>>Hash algorithms such as MD5 or CRC32 cannot be used to generate unique
>>>identifiers.  These algorithms will occasionally produce the same output for
>>>different input strings (this is why hash tables require a mechanism for dealing
>>>with collisions).  Common approaches to generating unique identifiers use some
>>>sort of a registration mechanism to appropriately partition the space of possible
>>>values.  Successful ones will leverage an existing registration mechanism, such
>>>as DNS.
>>>    
>>>
>>
>>I agree hash algorithm is not a "perfect" way to generate unique
>>identifier for a repository, but it may be acceptable in engineering
>>perspect, the collision possibility will be pretty low in current scale of oai data
>>providers (<500?).
>>
>>I think the basic problem is how to render OAI baseURL to a shorter,
>>readable string in non-collision way. The algorithm should be repeatable
>>-- Anyone can use same algorithm to generate same output given a baseURL.
>>I will be glad to see other approaches.
>>
>>  
>>
> _______________________________________________ OAI-implementers 
> mailing list List information, archives, preferences and to 
> unsubscribe: 
> http://oaisrv.nsdl.cornell.edu/mailman/listinfo/oai-implementers 



--------------040207050508060601080505
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit

<html>
<head>
</head>
<body>
<br>
I am in favor of just the URL:[collection name] approach. &nbsp;Why make it more
complicated than necessary? URL's are unique. Is there a particular reason
why it needs to be shorter?<br>
<br>
Adam Farquhar wrote:<br>
<blockquote type="cite" cite="mid:3F945C01.1000708@alumni.utexas.net">
  <title></title>
       Xiaoming,<br>
  <br>
 Selecting an approach that will be certain to fail, but unpredictably, is
not a good 'engineering' approach, especially when there are other approaches
that do not fail.&nbsp; For example, taking a base64 encoding of the base URL
or just using the base URL itself will both provide a unique identifier.<br>
  <br>
 Adam.<br>
  <br>
  <blockquote type="cite" cite="midPine.GSO.4.56.0310201319460.12404@dilbert.cs.odu.edu">
    <blockquote type="cite">
      <pre wrap="">Hash algorithms such as MD5 or CRC32 cannot be used to generate unique<br>identifiers.  These algorithms will occasionally produce the same output for<br>different input strings (this is why hash tables require a mechanism for dealing<br>with collisions).  Common approaches to generating unique identifiers use some<br>sort of a registration mechanism to appropriately partition the space of possible<br>values.  Successful ones will leverage an existing registration mechanism, such<br>as DNS.<br>    </pre>
      </blockquote>
      <pre wrap=""><!----><br>I agree hash algorithm is not a "perfect" way to generate unique<br>identifier for a repository, but it may be acceptable in engineering<br>perspect, the collision possibility will be pretty low in current scale of oai data<br>providers (&lt;500?).<br><br>I think the basic problem is how to render OAI baseURL to a shorter,<br>readable string in non-collision way. The algorithm should be repeatable<br>-- Anyone can use same algorithm to generate same output given a baseURL.<br>I will be glad to see other approaches.<br><br>  </pre>
      </blockquote>
 _______________________________________________ OAI-implementers mailing
list List information, archives, preferences and to unsubscribe: <a class="moz-txt-link-freetext" href="http://oaisrv.nsdl.cornell.edu/mailman/listinfo/oai-implementers">http://oaisrv.nsdl.cornell.edu/mailman/listinfo/oai-implementers</a> 
 </blockquote>
      <br>
      </body>
      </html>

--------------040207050508060601080505--