The ACSE supports two modes of communication: connection-mode and connectionless-mode. The ACSE service
definition (see ITU-T Rec. X.217 bis | ISO/IEC 15953) includes both modes of communication. This Recommendation |
International Standard only includes the connection mode of communication. This Recommendation | International
Standard for the connectionless mode of communication is contained in ITU-T Rec. X.237 bis | ISO/IEC 15955.
This Recommendation | International Standard defines procedures that are applicable to instances of communication
between systems which wish to interconnect in an open systems interconnection environment in a connection mode. This
Recommendation | International Standard includes the Kernel functional unit that is used to establish and release
ASO-associations. The Authentication functional unit provides additional facilities for exchanging information in
support of authentication during association establishment without adding new services. The ACSE authentication
facilities can be used to support a limited class of authentication methods. The ASO-context negotiation functional unit
provides the additional facility for the recipient to select the ASO-context from a list offered by the initiator during
association establishment. The optional Higher Level Association functional unit provides for the facility to identify
ASO-associations and transparently pass data to child ASOs and allows the ASO-context or the presentation context on
an ASO-association to be modified during the lifetime of the association.
This Recommendation | International Standard specifies:
a) procedures for the transfer of information for ASO-association control and the authentication of ASOs
and application-entities; and
b) the abstract syntax for the representation of the ACSE APDUs.
The ACSE procedures are defined in terms of:
a) the interactions among peer ACSE protocol machines through the use of Presentation services or
supporting ACSE services; and
b) the interaction between an ACSE protocol machine and its service-user.
This Recommendation | International Standard also specifies conformance requirements for systems implementing these
procedures. It does not contain tests which can be used to demonstrate conformance.