ISBN1013 API Followup

A couple questions about my API to convert 10 digit ISBNs to 13 digits pointed out somethings I failed to mention earlier.
First, the API actually works both ways. That is, it identifies and validates both 10 and 13 digit ISBNs on input, and returns both versions in the output. Example: 0811822842 and 978081182284-8.
And, as yet, [...]

Converting Between ISBN-10 and ISBN-13

David Kane asked the web4libbers:
Can anyone tell me what the conversion between ISBN-10 and ISBN-13 is, please. I need to write a little conversion program. Anything in PHP, for example.
Answers:
“There is already an online converter: http://www.isbn.org/converterpub.asp;” some pointing at Wikipedia on ISBNs, Bookland, and EANs; John Blyberg’s PHP port of the PERL ISBN-10/13 [...]

OPAC Web Services Should Be Like Amazon Web Services

No, I’m not talking about the interface our users see in the web browser — there’s enough argument about that — I’m talking about web services, the technologies that form much of the infrastructure for Web 2.0.
Once upon a time, the technology that displayed a set of data, let’s say catalog records, was inextricably [...]