Kai Jander

The Jadex Project: Programming Model

This chapter describes the priciples of the Jadex programming model. The programming model can be considered on two levels. The intra-agent level deals with programming concepts for single agents and the interagent level deals with interactions between agents. Regarding the first, the Jadex belief-desire-intention (BDI) model will be presented, which has been developed for agents based on XML and Java encompassing the full BDI reasoning cycle with goal deliberation and means-end reasoning. The success of the BDI model in general also led to the development goal based workflow descriptions, which are converted to traditional BDI agents and can thus be executed in the same infrastructure. Regarding the latter, the Jadex active components approach will be introduced. This programming model facilitates the interactions between agents with services and also provides a common back box view for agents that allows different agent types, being it BDI or simple reactive architectures, being used in the same application.

GOAL-ORIENTED PROCESSES WITH GPMN

Business process management is a challenging task that requires business processes being described, executed, monitored and continuously enhanced. This process management lifecycle requires business as well as IT people working together, whereby the view on business process is quite different on both sides. One important means for bridging the gap between both consists in having a modeling notation that can be easily understood but also has a precise semantics and can be used as a basis for workflow execution. Although existing approaches like BPMN and EPCs aim at being such as notation they are already very activity oriented and do not consider the underlying motivations of processes. Introducing the goal oriented process modeling notation (GPMN) a new language is presented that has the objective of bringing together both sides by establishing higher-level modeling concepts for workflows. This results in an increased intelligibility of workflow descriptions for business people and greater consideration for the way processes are described on the business side. The core idea of the approach consists in introducing different kinds of goals and goal relationships in addition to the established activity-centered behavior model. The applicability of the approach is further illustrated with an example workflow from Daimler AG.

Unifying Agent and Component Concepts

The construction of distributed applications is a challenging task due to inherent system properties like message passing and concurrency. Current technology trends further increase the necessity for novel software concepts that help dealing with these issues. An analysis of existing software paradigms has revealed that each of them has its specific strengths and weaknesses but none fits all the needs. On basis of this evaluation in this paper a new approach called active components is proposed. Active components are a consolidation of the agent paradigm, combining it with advantageous concepts of other types of software components. Active components, like agents, are autonomous with respect to their execution. Like software components, they are managed entities, which exhibit clear interfaces making their functionality explicit. The approach considerably broadens the scope of applications that can be built as heterogeneous component types, e.g. agents and workflows, can be used in the same application without interoperability problems and with a shared toolset at hand for development, runtime monitoring and debugging. The paper devises main characteristics of active components and highlights a system architecture and its implementation in the Jadex Active Component infrastructure. The usefulness of the approach is further explained with an example use case, which shows how a workflow management system can be built on top of the existing infrastructure.

A Middleware for Managing Non-Functional Requirements in Cloud PaaS

A key aspect of distributed applications in platform-as-a-service clouds revolves around the definition of requirements for quality of service and the most efficient use of the available resources to achieve them. Matching both the requirements and resources represents a unique challenge: While requirements are generally defined in relatively abstract form and defined as system-wide parameters, the resources are concrete, low-level entities that, by themselves, are only of marginal influence on the requirements. In order to establish a relationship between these two requires both the agglomeration of properties into more abstract ones as well as refining requirements in more detailed, concrete ones, both of which can often only be done to a certain degree. This paper presents a vision how both aspects can be brought to the same level and introduces an approach enhancing component-based cloud applications with non-functional properties in the context of an integrated programming model. This allows developers of such applications to formally declare properties that may influence the application during runtime and document the expectations regarding non-functional aspects of the overall system. This can be used to ensure the health of the application and, in case requirements are violated, actions like the deployment of additional resources can be performed in order to alleviate any degradation of its non-functional state, either by evaluating, choosing and performing pre-defined actions automatically or by manual administrative intervention.

Go4Flex: Goal-Oriented Process Modelling

Many companies consider business process management strategies a fundamental source for successful business operation. Despite this importance of business processes a conceptual and operational gap still exists between the business and the IT view of processes. In this paper we argue that an important reason for this gap is the strong focus of IT on the behaviour and execution perspective of workflows while more abstract and higher-level process properties are often neglected. This is especially apparent in the way processes are modelled and described on the IT-side using state of the art modelling approaches like BPMN. The presented Go4Flex research project, which is conducted in cooperation with Daimler AG, has the objective of bringing together both sides by establishing higher-level modelling concepts for workflows, which results both in increased intelligibility of workflow descriptions for business people and greater consideration for the way processes are described on the business side. The core idea of the approach is to strengthen the context perspective of a workflow by introducing different kinds of goals and goal relationships in addition to the established activity-centred behaviour model. The applicability of the approach is further illustrated with an example workflow from Daimler AG.

Jadexcloud - an infrastructure for enterprise cloud applications

Cloud computing allows business users to scale up or down resource needs according to current demands (utility computing). Infrastructures for cloud computing can be distinguished with respect to the layer they operate on. In case of platform as a service (PAAS) frameworks are provided in order to simplify the construction of cloud applications relying on common base abstractions and tool sets. The focus of current PAAS frameworks is quite narrow and directed towards support for web applications and also visual tools for non-programmers. We envision that cloud computing can also substantially push forward typical enterprise applications if these applications are made to exploit cloud capabilities. In this paper we present an infrastructure for developing, deploying and managing distributed applications with the vision of distribution transparency in mind. The infrastructure is meant to be on PAAS layer but addresses developers instead of end users. It is founded on the active component paradigm for distributed applications, which allows applications being composed of agent-like autonomous entities interacting via services. The model facilitates building scalable and robust enterprise applications due to the high modularity and independently acting modules that can be replaced or restarted if unexpected errors occur. In addition to the infrastructure, a real world scenario of a distributed workflow management systems will be explained.

Validation of agile workflows using simulation

Increasing automation of business processes and industrial demand for complex workflow features have led to the development of more flexible and agile workflow concepts. One of those concepts is the use of goal-oriented workflows, which rely on ideas derived from agent technology like describing the workflows based on a goal hierarchy.While this reduces the gap between business view and IT view and allows for easy implementation of contengencies, the concepts have greater conceptual abstraction obscuring the control flow and reducing the ability of workflow engineers to identify specification flaws in the workflow. This paper shows an approach to address this problem by presenting a system for testing and validating workflows within a specified parameter space. The system allows the definition of test cases (scenarios), each of which contains parameter states applied during workflow execution. The workflow engineer can define a set of scenarios for a workflow testing specific situation that are likely to occur during operation or are otherwise interesting corner cases, allowing automated tests and correction of faults before deployment of the workflow in production environments.

Jadex WfMS: Distributed Workflow Management for Private Clouds

Structuring an organization around its business processes has many benefits for both the processes themselves as well as the workflow and business process management within an organization in general. However, there are many challenges that make such a transition from a classical hierarchic to a state-of-the-art process organization difficult. In particular, traditional departments often resist loss of autonomy within their organization and, thus, may prevent successful implementation of business process management techniques such as process-oriented workflow management systems. Therefore, this paper proposes a flexible workflow management system architecture consisting of multiple parts that can be replicated and distributed within an organizations private cloud network. Based on distributed components of a workflow management system, it supports both organizations with legacy organizational structures as well as those which require increased autonomy of their respective organizational units. As a result, this system allows, on the one hand side, to manage some organizational units independently and to regulate them in a distributed, process-driven way while, on the other, still allowing the overall organization to exploit many advantages of a centralized workflow management system. The resulting system is based on experiences of a DFG funded technology transfer project aiming at applying previous research results in autonomous business process management to practical needs and requirements of a real production system application.

Compact and Efficient Agent Messaging

Messages are considered to be a primary means of communication between agents in multi-agent systems. Since multi-agent systems are used for a wide variety of applications, it also includes applications like simulation and calculation of computer generated graphics which need to employ a large number of messages or very large messages. In addition, another set of applications target hardware which is resource constrained in either bandwidth or processing capacity. As a result, these applications have different requirements regarding their messages than other agent message formats. This paper proposes useful properties of agent messages and evaluates them with regard to different types of applications. Based on this evaluation a message format for Jadex called Jadex Binary is proposed which emphasizes properties which are not traditionally the focus of agent message formats and compare it to well-known formats based on those properties.

Distributed monitoring and workflow management for goal-oriented workflows

Business process management has often focused on business processes with a production or administrative focus, resulting in a task‐centric approach for modeling and execution of workflow based on the processes. However, the area of collaborative business processes exists, which includes important processes like research and development which have not been adequately addressed by the techniques offered for production workflows. For this, goal‐oriented processes have been proven useful to allow for a more flexible approach in modeling and executing workflow. In addition, distributed workflow management allows for a more flexible approach regarding organizational structures. However, the actual recording of action taken in a process is still relevant for workflow analysis and re‐engineering. As a result, this paper presents a distributed approach for generating, gathering, distributing, and storing events resulting from the execution of goal‐oriented workflows in a distributed workflow environment while allowing the real‐time association of occuring actions with business goals in the process using drill‐down analysis. Copyright