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RE: Pessimistic Locking

From: Marvin D. Toll <MarvinToll_at_gtcGroup.com>
Date: 2006-07-01 18:10:19 CEST

Thanks Erik - inline comments below ...

-----Original Message-----
From: Erik Huelsmann [mailto:ehuels@gmail.com]
Sent: Saturday, July 01, 2006 11:40 AM
Subject: Re: Pessimistic Locking

> Context: I'm a J2EE consultant currently working at a Fortune 300 company
> using ClearCase (with pessimistic locking) for Java development artifacts.

> Question: Can Subversion be configured to (reliably) "force" pessimistic
> locks? (Hook Scripts?)

Well, that's not enough context: what's a pessimistic lock?

[MDT] See http://www.agiledata.org/essays/concurrencyControl.html for a
definition within a database context. Traditionally, mainframe version
control systems and more recent (last 10 years or so) vendor supported
client/server tools like ClearCase and PVCS default to pessimistic locking
of artifacts "checked-out" for modification.

Subversion supports locking through its 'svn lock'/'svn unlock' commands.

[MDT] The *key* word of my inquiry was "force". I understand the default
implementation of Subversion (for example as implemented by SourceForge) to
support "optional" locking - however, my world is not one in which such
options are bestowed to commodity developers - onshore or offshore.

See for more info:
http://svnbook.red-bean.com/nightly/en/svn.advanced.locking.html

[MDT] The "Harry" example leaves it to the individual developer to make a
decision often made corporate-wide at large companies. Excerpt:

"An example is in order, to demonstrate. Let's say that Harry has decided to
change a JPEG image. To prevent other people from committing changes to the
file, he locks the file in the repository using the svn lock command ..."

HTH,
Erik.

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Received on Sat Jul 1 18:11:00 2006

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