Internet Communications Using SIP : Delivering VoIP and Multimedia Services With Session Initiation Protocol {2Nd Ed.}

(Steven Felgate) #1

  1. Internet Standards—Specifications that have significant implementations
    and for which a successful operational experience has been obtained.
    For various reasons, not every specification is on the standards track, and
    such specifications have the maturity levels of “Experimental,” “Informational,”
    or “Historic.”
    Last, but not least, there are carefully designed procedures, called Standards
    Actions on how documents of the IETF are published, discussed, and
    processed. Standards Actions include (but are not limited to) advancements on
    the standards track, revisions, and retiring of standards.
    Internet standards may incorporate (by reference) other open standards,
    such as the American National Standards Institute (ANSI) standard for the
    ASCII character set.
    The IETF has very detailed rules on intellectual property rights so that the
    benefits to the Internet community are not in conflict with the legitimate rights
    of others. For this reason, contributions that are subject of confidentiality or
    have any other restrictions are not acceptable. Submissions that may be subject
    to copyright grant the Internet Society (ISOC) the license to the contribution,
    and must take into account quite complex other legal requirements that go
    beyond the scope of this book.


Protocols and Application Programming Interfaces


The reliance on protocols in Internet engineering is another significant differ-
ence from the practice in the software industry to use application program-
ming interfaces (APIs).
Internet protocols specify only how processes running on different computing
devices on the Internet communicate “across the wire” and do not impose any
restriction on how the applications and protocol machines are implemented
(this is best left to the creativity and competitiveness of the software developers).
By contrastAPIs are commonly used to program most applications by
developers. APIs are, however, most often owned and under the control of the
software vendor. In addition, they are often written for a specific operating
system only.
Users and developers of telecommunication equipment are informed of the
“open APIs” for the product so as to develop or customize services. Remem-
ber, however, that “open APIs” introduce a certain level of dependency on (1)
the software vendor and (2) the operating system vendor, because they both
have intellectual property rights and change control.
Protocols are preferred on the Internet for these reasons, since any Internet
standard or practice must be completely vendor- and computing-platform-
independent. Moreover, a core design principle for the Internet and the World


Architectural Principles of the Internet 49
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