This part of ISO 17575 defines how to convey all or parts of the data element structure defined in other
parts of ISO 17575 over any communication stack and media suitable for this application. It is applicable
only to mobile communication links (although wired links, i.e. back office connections, can use the same
methodology).
To establish a link to a sequence of service calls initializing the communication channel, addressing the
reception of the message and forwarding the payload are required. The definition provided in this part
of ISO 17575 includes the required communication medium independent services, represented by an
abstract application programming interface (API).
The communication interface is implemented as an API in the programming environment of choice for
the Front End (FE) system. The specification of the Back End (BE) API is outside the scope of this part
of ISO 17575.
The definition of this API in concrete terms is outside of the scope of this part of ISO 17575. This part
of ISO 17575 specifies an abstract API that defines the semantics of the concrete API and its protocol implementation conformance statement (PICS) proforma. Where no distinction is made between the abstract
and concrete communications APIs, the term “communications API” or just “API” can be used.
This part of ISO 17575 also provides a detailed specification for the structure of associated API
statements, an example on how to implement it and its role in a complex toll cluster such as the EETS.
Media selection policies, certificate handling and encryption mechanisms are outside of the scope of
this part of ISO 17575.