[Developers] impending changes to mwLastWriteTime cookie

[Michael Masouras]

We are about to change the format of the mwLastWriteTime cookie.

For reference, this cookie is used as a cache control mechanism, as  
described here:
http://blog.freebase.com/2008/01/22/caching-dynamic-content/

You should never be parsing the value of the mwLastWriteTime cookie.   
It's intended to be an opaque token.  Unfortunately, there are a few  
systems that have to inspect these.  If you're one of those, please  
pay attention to the following.


The current cookie format contains a time value and a guid, separated  
by a pipe character:

mwLastWriteTime=1225749629|9202a8c04000641f8000000009b1d1b0

We are adding the database instance that generated that guid at the  
end as an additional value, so the new cookie will look like this:

mwLastWriteTime=1225749629|9202a8c04000641f8000000009b1d1b0|sandbox

If your application always talks to the same freebase service (e.g. www.freebase.com/api/mqlwrite) 
, you can ignore the value of this last parameter and continue using  
the other two values as before.

The intent is to allow us to issue this cookie at a lower level domain  
(such as .freebase.com) but still be able to correctly identify which  
cookie value is meant for which graph instance in the case where  
multiple mwLastWriteTime cookies exist.

These changes are coming in the following days, so please let us know  
if you will need more time to accommodate them.

Thanks,
Michael Masouras

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