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[bluetooth-dev] some issues regarding SDP



Re. (1):  This is the primary attribute upon which service searching is
expected to be done.  Typically an SDP client will search on service class
("is there a printing service?"  "is there a DUN service?"  etc.).  Only
UUID values are searchable, and ServiceClass is a UUID.

Re. (2) and (3):  These are described in the SDP specification, excerpted
below.  Basically the "aliases" are just "short UUIDs" pre-defined by the
Bluetooth SIG and specified in the Assigned Numbers portion of the
Bluetooth core specification.  The "short UUIDs" are just for convenience
and compactness.  Methods for matching UUIDs are also described in the
specification, excerpted below.

---------------------

2.7.1 UUID
A UUID is a universally unique identifier that is guaranteed to be unique
across
all space and all time. UUIDs can be independently created in a distributed
fashion. No central registry of assigned UUIDs is required. A UUID is a
128-bit
value.
To reduce the burden of storing and transferring 128-bit UUID values, a
range
of UUID values has been pre-allocated for assignment to often-used,
regis-tered
purposes. The first UUID in this pre-allocated range is known as the
Bluetooth Base UUID and has the value 00000000-0000-1000-7007-
00805F9B34FB, from the Bluetooth Assigned Numbers document. UUID val-ues
in the pre-allocated range have aliases that are represented as 16-bit or
32-bit values. These aliases are often called 16-bit and 32-bit UUIDs, but
it is
important to note that each actually represents a 128-bit UUID value.
The full 128-bit value of a 16-bit or 32-bit UUID may be computed by a
simple
arithmetic operation.
128_bit_value = 16_bit_value * 2 96 + Bluetooth_Base_UUID
128_bit_value = 32_bit_value * 2 96 + Bluetooth_Base_UUID
A 16-bit UUID may be converted to 32-bit UUID format by zero-extending the
16-bit value to 32-bits. An equivalent method is to add the 16-bit UUID
value to
a zero-valued 32-bit UUID.
Note that two 16-bit UUIDs may be compared directly, as may two 32-bit
UUIDs or two 128-bit UUIDs. If two UUIDs of differing sizes are to be
com-pared,
the shorter UUID must be converted to the longer UUID format before
comparison.

Regards,
Brent
B. A. Miller RTP, NC
(919) 543-6959 TIE 441
FAX (919) 254-6430 TIE 444
Internet: bamiller@xxxxxxx.com
---------------------- Forwarded by Brent Miller/Raleigh/IBM on 03/02/2001
09:01 AM ---------------------------

"Rakesh Gupta" <rakesh.gupta@xxxxxxx.com on 03/02/2001
07:36:47 AM

Please respond to "Rakesh" <rakesh.gupta@xxxxxxx.com>

Sent by:  owner-bluetooth-dev@xxxxxxx.com


To:   <bluetooth-dev@xxxxxxx.com>
cc:
Subject:  [bluetooth-dev] some issues regarding SDP







hello everyone,

   The following are the unresolved  issues regarding SDP and they need to
be clarified before implementation. I  would be thankful if any of u can
give more clarification about them. they are  following:

1) The concept of Service ID and its use for the  purpose of Searching.
2) What is the format of the aliases provided for  service and service
class IDs and who provides the same and where.
3) Matching of UUIDs sent in a search pattern to  the attribute value of
the ServiceClassIDList Attribute.

regards,
Rakesh


                                                                            
                                                                            
                                                                            




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