[OAI-implementers] Flow Control chunk size

Chuck Koscher ckoscher at crossref.org
Fri Feb 2 08:34:18 EST 2007

We use a chunk size of 200 which produces a 40K response to a ListIdentifier
request and a 380K response to a ListRecords request. I think a primary
concern is to maintain acceptable response times when serving up the


-----Original Message-----
From: oai-implementers-bounces at openarchives.org
[mailto:oai-implementers-bounces at openarchives.org] On Behalf Of Ann Apps
Sent: Friday, February 02, 2007 7:01 AM
To: oai-implementers at openarchives.org
Subject: [OAI-implementers] Flow Control chunk size

Hi All,

The OAI-PMH spec section 3.5 Flow Control details how to respond to list
requests in installments with a resumptionToken. The reason for this
partitioning is that lists may be long from a large database. A couple of

1. Are there any guidelines on best practice for what to choose as a chunk
size? I guess this question is really asking what size of data package is it
reasonable to send over HTTP. 

I currently have a chunk size of 25, some records in a specific XML metadata
format being quite long. Someone recently asked me why we supply records 25
at a time, and I do not really have an answer.

2. Is it permissible to have a different chunk size for ListIdentifiers and
ListRecords? The former will be a much shorter response than the latter.
Also can one have a different chunk size for ListRecords in different
metadata formats?

>From the spec this looks to be OK - all the details are contained in the
resumptionToken and its XML attributes. But I don't want to implement
something that is invalid.

Thanks for any advice.
Best wishes,

Ann Apps. IT Specialist (Research & Development), MIMAS,
   The University of Manchester, Oxford Road, Manchester, M13 9PL, UK 
Tel: +44 (0) 161 275 6039  Fax: +44 (0) 161 275 6040
Email: ann.apps at manchester.ac.uk WWW: http://epub.mimas.ac.uk/ann.html

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