LISTSERV mailing list manager LISTSERV 16.5

Help for CODE4LIB Archives


CODE4LIB Archives

CODE4LIB Archives


CODE4LIB@LISTS.CLIR.ORG


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

CODE4LIB Home

CODE4LIB Home

CODE4LIB  April 2011

CODE4LIB April 2011

Subject:

Re: MARC magic for file

From:

Jonathan Rochkind <[log in to unmask]>

Reply-To:

Code for Libraries <[log in to unmask]>

Date:

Wed, 6 Apr 2011 14:17:16 -0400

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (51 lines)

On 4/6/2011 2:02 PM, Kyle Banerjee wrote:
> I'd go so far as to question the value of validating redundant data that
> theoretically has meaning but which are never supposed to vary. The 4 and
> the 5 simply repeat what is already known about the structure of the MARC
> record. Choking on stuff like this is like having a web browser ask you want
> to do with a page because it lacks a document type declaration.

Well, the problem is when the original Marc4J author took the spec at 
it's word, and actually _acted upon_ the '4' and the '5', changing file 
semantics if they were different, and throwing an exception if it was a 
non-digit.

This actually happened, I'm not making this up!  Took me a while to debug.

So do you think he got it wrong?  How was he supposed to know he got it 
wrong, he wrote to the spec and took it at it's word. Are you SURE there 
aren't any Marc formats other than Marc21 out there that actually do use 
these bytes with their intended meaning, instead of fixing them? How was 
the Marc4J author supposed to be sure of that, or even guess it might be 
the case, and know he'd be serving users better by ignoring the spec 
here instead of following it?  What documents instead of the actual 
specifications should he have been looking at to determine that he ought 
not to be taking those bytes at their words, but just ignoring them?

To realize that we have so much non-conformant data out there that we're 
better off ignoring these bytes, is something you can really only learn 
through experience -- and something you can then later realize you're 
wrong on too:

Ie: I _thought_ I was writing only for Marc21, but then it turns out 
I've got to accept records from Outer Weirdistan that are a kind of 
legal Marc that actually uses those bytes for their intended meaning -- 
better go back and fix my entire software stack, involving various 
proprietary and open source products from multiple sources, each of 
which has undocumented behavior when it comes to these bytes, maybe they 
follow the spec or maybe the follow Kyle's advice, but they don't tell 
me.  This is a mess.

Maybe this scenario is impossible, maybe there ARE and NEVER HAVE BEEN 
any Marc variants that actually use leader bytes 20-22 in this way -- 
how can I determine that?  I've just got to guess and hope for the 
best.  The point of specifications in the first place is for 
inter-operability, so we know that if all software and data conforms to 
the spec, then all software and data will interact in expected ways.  
Once we start guessing at which parts of the spec we really ought to be 
ignoring....

Again, I realize in the actual environment we've got, this is not a 
luxury we have. But it's a fault, not a benefit, to have lots of 
software everywhere behaving in non-compliant ways and creating invalid 
(according to the spec!) data.

Top of Message | Previous Page | Permalink

Advanced Options


Options

Log In

Log In

Get Password

Get Password


Search Archives

Search Archives


Subscribe or Unsubscribe

Subscribe or Unsubscribe


Archives

August 2019
July 2019
June 2019
May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
July 2018
June 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
December 2006
November 2006
October 2006
September 2006
August 2006
July 2006
June 2006
May 2006
April 2006
March 2006
February 2006
January 2006
December 2005
November 2005
October 2005
September 2005
August 2005
July 2005
June 2005
May 2005
April 2005
March 2005
February 2005
January 2005
December 2004
November 2004
October 2004
September 2004
August 2004
July 2004
June 2004
May 2004
April 2004
March 2004
February 2004
January 2004
December 2003
November 2003

ATOM RSS1 RSS2



LISTS.CLIR.ORG

CataList Email List Search Powered by the LISTSERV Email List Manager