[wsf-dev] 160 bit message id

[Asa Hardcastle]

Unfortunately, java can't get to the MAC address.

According to wikipedia (which I realize can't be trusted) on random  
128 bit UUIDs:

"The number of theoretically possible UUIDs is therefore 2(128) = 256 
(16) or about 3.4 × 10(38).  This means that 1 trillion UUIDs have to  
be created every nanosecond for 10 billion years to exhaust the  
number of UUIDs."

My understanding from the specification:

* must ensure a negligible risk of collision (as Conor has said)
* if pseudorandom, must use at least 160 random bits
* according to WSAv1,  wsa:MessageId must be an IRI - like "http:// 
example.com/someuniquestring"

Which leaves me with: "http://someurl.com/160bitsofrandomfun" - which  
should be extremely unlikely to collide - seems like the  "http:// 
someurl.com/" is somewhat unnecessary - and potentially a privacy  
concern.

asa






--
Asa Hardcastle, Technical Lead, openLiberty
Tel: +1.413.429.1044 Skype: subsystem7


On Apr 30, 2007, at 4:51 PM, Cahill, Conor P wrote:

> There's an interesting history in the discussion of the message ID  
> value.
>
> The current requirement (lines 557-559 of the SOAP Bindings  
> specification) is:
> Any party that assigns a value to a <wsa:MessageID> header block  
> MUST ensure that there is negligible probability that that party or  
> any other party will accidentally assign the same identifier to any  
> other message
>
> This is not a 160 or 128 bit requirement.
>
> I would presume that a 128 bit UUID that included the 48 bits of  
> mac address of the issuing host would meet that requirement.
>
> Conor
>
> From: wsf-dev-bounces at openliberty.org [mailto:wsf-dev- 
> bounces at openliberty.org] On Behalf Of Asa Hardcastle
> Sent: Monday, April 30, 2007 4:36 PM
> To: wsf-dev at openliberty.org
> Subject: [wsf-dev] 160 bit message id
>
> Hi All,
>
> Does anyone know the origin of the 160 bit message id requirement  
> in the <wsa:MessageID> header?  Before I read that line I was  
> thinking of using a 128 bit UUID.
>
> thanks,
>
> asa
>
>
>
>
> --
> Asa Hardcastle, Technical Lead, openLiberty
> Tel: +1.413.429.1044 Skype: subsystem7
>
>

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