usually specified through the primitives such as class (sub-class), property (attribute, relationship), and axiom. Standard taxonomy and process templates are also often included in the process ontologies.
3.3
Goal Modeling
Goal is considered as an important concept to represent business strategy and support decision making. Goal models are used to represent business objectives for stakeholders and also to drive the elaboration of business requirements for business analysis and executions. The research on goal-driven methodologies brought out some goal modeling approaches and languages. From the literature, goal modeling is mostly designed as a requirements engineering method, such as KAOS [21], i*/GRL [55], GBRAM [56]. With the development of Web services, goal modeling is associated with Web services modeling for goal-driven services discovery, such as WSMO [210].
3.3.1 KAOS (Knowledge Acquisition in autOmated Specification)
KAOS [21] is a goal-driven methodology which is based on a rich framework for re- quirements elicitation, analysis and management. Goal modeling in KAOS is based on a goal-oriented process. The process starts with goals which are easy to understand and communicate. They describe the problems instead of the solutions, and can be refined to different levels of abstraction for incremental analysis process. With KAOS, functional and non-functional requirements are formally modeled in terms of goals, con- straints, objects, operations, agents, etc. Goals are from available sources and asking why and how questions; objects, relationships and attributes are derived from the goal specifications; agents are identified and are assigned alternative responsibility based on goals; operations and domain pre-/postconditions are also identified from the goal specifications [192].
3.3.2 i*/GRL (Goal-oriented Requirement Language)
GRL is an extended version of i*, a language for supporting actor/role oriented model- ing, goal-oriented modeling and reasoning of requirements, especifally for dealing with non-functional requirements [40]. Main concepts associated with goals are represented by intentional elements, intentional relationships and actors. The intentional elements in GRL are goal, task, softgoal, belief and resource. The intentional relationships in- clude means-ends, decompositions, contribution, correlation and dependency. An actor is an active entity that carries out actions to achieve goals. Goals and requirements are analyzed through modeling strategic actor relationships. The relationships are modeled through Strategic Dependency (SD) models and Strategic Rational (SR) models. In a SD model, one actor (the depender) depends on another actor (the dependee) for a dependum. According to different types of dependum, several types of dependencies are distinguished in the Strategic Dependency model, namely goal dependency, task dependency, resource dependency, and softgoal dependency. The SR model provides a more detailed level of modeling by looking "inside" actors to model internal intentional
50 CHAPTER 3. STATE OF THE ART relationships. Intentional elements appear in SR models not only as external depen- dencies, but also as internal elements arranged into (mostly hierarchical) structures of means-ends, task-decompositions and contribution relationships [212]. The means-ends links provide understanding about why an actor would engage in some tasks, pursue a goal, need a resource, or want a soft goal; the task-decomposition links provide a hi- erarchical description of intentional elements that make up a routine; the contribution links provide elaboration of the effects from intentional elements to softgoals.
3.3.3 GBRAM (Goal-Based Requirements Analysis Method)
GBRAM [56] addresses the critical nature of the discovery process in goal analysis. GBRAM can be used in goal analysis and goal refinement/evolution. It defines a top-down analysis method refining goals and attributing them to agents starting from inputs such as corporate mission statements, policy statements, interview transcripts etc. Therefore operationalization process is provided for defining a goal with enough de- tail so that its subgoals have an operational definition. GBRAM distinguishes between achievement goals and maintenance goals. Achievement goals are objectives of func- tional processes. Maintenance goals are those goals that are satisfied while their target condition remains true. They tend to be operationalized as actions or constraints that prevent certain states from being reached. Achievement goals usually map to actions that occur in a system, while maintenance goals map to nonfunctional requirements.
In GBRAM, agents are the entities or processes that seek to achieve goals within an organization or system based on the implicit responsibility that must assume for the achievement of certain goals; constraints place conditions on the achievement of a goal; goal obstacles are behaviors or other goals that prevent or block the achievement of a given goal. GBRAM supports goal decomposition to subdividing a set of goals into a logical subgrouping.
3.3.4 Goal modeling in EEML
Goals in an EEML model can be decomposed into sub-goals and goal connectors such as "and", "or", or "xor". Those connectors can be used to specify logical relationships between the goal and its sub-goals. Besides, EEML provides more connecting relation types to associate goals with the elements in an EEML process model. The connecting relationships in the EEML goal modeling are listed in Table 3.3.
3.3.5 Goal specification in WSMO
Goal models in WSMO [210] are descriptions of Web services that would potentially satisfy the user desires. They provide the user view in the Web service usage process. Goal is represented through the capability of the Web services the user would like to have, and the interface of the Web service the user would like to have and interact with. A set of properties strictly belonging to a goal are defined as non-functional properties of a WSMO goal. A goal may be defined by reusing one or several already-existing goals by using goal mediators.