Marc in JSON can be a nice middle-ground, faster/smaller than MarcXML 
(although still probably not as binary), based on a standard low-level 
data format so easier to work with using existing tools (and developers 
eyes) than binary, no maximum record length. 

There have been a couple competing attempts to define a 
marc-expressed-in-json 'standard', none have really caught on yet. I 
like Ross's latest attempt:  
http://dilettantes.code4lib.org/blog/2010/09/a-proposal-to-serialize-marc-in-json/

Patrick Hochstenbach wrote:
> Dear Nate,
>
> There is a trade-off: do you want very fast processing of data -> go for binary data. do you want to share your data globally easily in many (not per se library related) environments -> go for XML/RDF. 
> Open your data and do both :-)
>
> Pat
>
> Sent from my iPhone
>
> On 25 Oct 2010, at 20:39, "Nate Vack" <[log in to unmask]> wrote:
>
>   
>> Hi all,
>>
>> I've just spent the last couple of weeks delving into and decoding a
>> binary file format. This, in turn, got me thinking about MARCXML.
>>
>> In a nutshell, it looks like it's supposed to contain the exact same
>> data as a normal MARC record, except in XML form. As in, it should be
>> round-trippable.
>>
>> What's the advantage to this? I can see using a human-readable format
>> for poorly-documented file formats -- they're relatively easy to read
>> and understand. But MARC is well, well-documented, with more than one
>> free implementation in cursory searching. And once you know a binary
>> file's format, it's no harder to parse than XML, and the data's
>> smaller and processing faster.
>>
>> So... why the XML?
>>
>> Curious,
>> -Nate
>>     
>
>