Evgeny_CD (13.06.2018 22:38 - 13.06.2018 23:00, ссылка, ссылка, просмотров: 147)
[Книга] Formal Description Techniques IX -> Там статья [EPER]: Efficient Packed Encoding Rules for ASN.1 (стр. 179 по Acrobat) -->
Data elements in OSI (Open Systems Interconnection) upper layer protocols are defined and encoded using ASN.1 (Abstract Syntax Notation One). Recently, PER (Packed Encoding Rules) have been standardized to realize more efficient ASN.1 encoding/decoding than the widely used BER (Basic Encoding Rules), by means of minimizing the length of encoded data.
This paper proposes new encoding rules, EPER (Efficient Packed Encoding Rules), to further improve PER, in which the encoding time and decoding time are 1.3 to 4.2 and 1.3 to 5.4 times, respectively, faster than those in PER, and the length of encoded data is shortened to 41% to 96% of that in PER. EPER have the following features: (1) they encode bit-aligned data and octet-aligned data in separate consecutive fields, to avoid the increase of encoding/decoding time due to many bit-shift operations and the increase of data length due to padding for octet-alignment in PER, (2) they encode integer type frequently used, so as to further eliminate redundant length octets in PER, (3) they have single transfer syntax, unlike PER that have multiple transfer syntax selected depending on communication partners. Furthermore, EPER optionally provide extended encoding rules which enable more efficient encoding when a value of a particular type is constrained by an ASN.1 sub-type definition.
EPER are highly efficient encoding rules applicable to wide range of network speeds and applications with single transfer syntax