UUID가 “8-4-4-4-12″(숫자) 형식으로 표시되는 이유는 무엇입니까? 이유를 둘러 보았지만 필요한 결정을 찾을 수 없습니다.
16 진 문자열로 형식화 된 UUID의 예 : 58D5E212-165B-4CA0-909B-C86B9CEE0111
답변
time, version, clock_seq_hi, clock_seq_lo, node다음 rfc에 표시된대로로 구분됩니다 .
로부터 IETF RFC4122 :
4.1.2. Layout and Byte Order
To minimize confusion about bit assignments within octets, the UUID
record definition is defined only in terms of fields that are
integral numbers of octets. The fields are presented with the most
significant one first.
Field Data Type Octet Note
#
time_low unsigned 32 0-3 The low field of the
bit integer timestamp
time_mid unsigned 16 4-5 The middle field of the
bit integer timestamp
time_hi_and_version unsigned 16 6-7 The high field of the
bit integer timestamp multiplexed
with the version number
clock_seq_hi_and_rese unsigned 8 8 The high field of the
rved bit integer clock sequence
multiplexed with the
variant
clock_seq_low unsigned 8 9 The low field of the
bit integer clock sequence
node unsigned 48 10-15 The spatially unique
bit integer node identifier
In the absence of explicit application or presentation protocol
specification to the contrary, a UUID is encoded as a 128-bit object,
as follows:
The fields are encoded as 16 octets, with the sizes and order of the
fields defined above, and with each field encoded with the Most
Significant Byte first (known as network byte order). Note that the
field names, particularly for multiplexed fields, follow historical
practice.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| time_low |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| time_mid | time_hi_and_version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|clk_seq_hi_res | clk_seq_low | node (0-1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| node (2-5) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
답변
형식은 섹션 3의 IETF RFC4122 에 정의되어 있습니다 . 출력 형식은 “UUID = …”라고 표시된 곳에 정의됩니다.
3.- 네임 스페이스 등록 템플릿
네임 스페이스 ID : UUID 등록 정보 : 등록 날짜 : 2003-10-01
네임 스페이스 등록자 선언 : JTC 1 / SC6 (ASN.1 Rapporteur Group)
구문 구조의 선언 : UUID는 모든 UUID의 공간과 관련하여 공간과 시간 모두에서 고유 한 식별자입니다. UUID는 고정 된 크기이고 시간 필드를 포함하므로 값이 롤오버 될 수 있습니다 (사용 된 특정 알고리즘에 따라 AD 3400 주변). UUID는 수명이 매우 짧은 개체에 태그를 지정하는 것부터 네트워크에서 매우 지속적인 개체를 안정적으로 식별하는 것까지 다양한 용도로 사용할 수 있습니다.
The internal representation of a UUID is a specific sequence of bits in memory, as described in Section 4. To accurately represent a UUID as a URN, it is necessary to convert the bit sequence to a string representation. Each field is treated as an integer and has its value printed as a zero-filled hexadecimal digit string with the most significant digit first. The hexadecimal values "a" through "f" are output as lower case characters and are case insensitive on input. The formal definition of the UUID string representation is provided by the following ABNF [7]: UUID = time-low "-" time-mid "-" time-high-and-version "-" clock-seq-and-reserved clock-seq-low "-" node time-low = 4hexOctet time-mid = 2hexOctet time-high-and-version = 2hexOctet clock-seq-and-reserved = hexOctet clock-seq-low = hexOctet node = 6hexOctet hexOctet = hexDigit hexDigit hexDigit = "0" / "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" / "9" / "a" / "b" / "c" / "d" / "e" / "f" / "A" / "B" / "C" / "D" / "E" / "F"
