Policy support for call control

Abstract

The need for policies to control calls is justified by the changing face of communications. It is argued that call control requires distinctive capabilities in a policy system. A specialised policy language called APPEL (ACCENT Project Policy Environment/Language) has therefore been developed for this purpose. However the policy language is cleanly separated into a core plus specialisations for various application domains. The paper describes both the foundation and the call control ontologies. Sample policy examples are provided to illustrate use for call control. The paper also presents the policy system architecture in which the policy language is interpreted. The components of the policy system are described, particularly the policy server and the policy wizard.

Towards a Task-Oriented, Policy-Driven Business Requirements Specification for Web Services

“…Policy description languages [13] have been used to express quality of service constraints or access control, that is to describe very low level properties of systems. The Appel policy language [20,23] has been defined to express end-user rules in telecommunications systems and we are extending this in our ongoing work to interact with the task maps discussed in this paper.…”

“…Our further work includes refinement of the ideas presented on policies, as briefly described in section 3.4. A possible implementation of these may be the APPEL policy language [23], which was developed with respect to telephony systems.…”

StPowla: SOA, Policies and Workflows

“…A policy rule is a variant of an ECA (event-condition-action) rule, consisting of an optional trigger, an optional condition, and an action. To help the user, a wizard has been presented to formulate policies [21]. The applicability of a rule depends on whether its trigger has occurred and whether its conditions are satisfied.…”

“…So, the second ingredient is a policy language: here we use Appel [19,21]. Though developed in the context of telecommunications, Appel is a general language for expressing policies in a variety of application domains.…”

Dynamically Evolvable Dependable Software: From Oxymoron to Reality

“…Here, we can be satisfied with the simplest combinators: sequence, choice, and fork/join, as they are available, for instance in UML activity diagrams. Currently, we use Appel [40,42], a general language for expressing policies in a variety of application domains, which was designed to support a clear separation between the core language and its specialization for concrete domains. This fosters its use in different business domains.…”