Giancarlo Tretola

Workflow fine-grained concurrency with automatic continuation

Workflow enactment systems are becoming an effective solution to ease programming, deployment and execution of distributed applications in several domains such as telecommunication, manufacturing, e-business, e-government and grid computing. In some of these fields, efficiency and traffic optimization represent key aspects for a wide diffusion of workflow engines and modeling tools. This paper focuses on a technique that enables fine-grained concurrency in compute and data-intensive workflows and reduces the traffic on the network by limiting the number of interactions to the ones strictly needed to bring the data where they are really necessary for continuing the flow of computations. We implemented this technique by using the concepts of wait by necessity and automatic continuation and we integrated it in a flexible, Java workflow engine that through the new mechanisms is able to navigate a workflow anticipating the enactment of sequential activities

Self-adaptive management of Web processes

Nowadays, we are assisting to a paradigmatic shift for the development of web applications due to the pervasive distribution of their components among a lot of servers, which are dynamically interconnected by web links. As a consequence, the application logic is often defined by exploiting workflow languages since they are more suitable to address the complexity of these new running environments. Moreover, in many business environments, the behaviour of a large-scale distributed web application is significantly influenced by context events, whose handling could require run-time adaptations of the application logic to properly react to the changing conditions of the execution context. This paper addresses the need for adaptation in large-scale web applications by proposing a programming paradigm based on “autonomic workflows”, i.e. workflows that are able to self-change their structure in order to allow for the continuation of the execution towards the termination, even if unexpected anomalies occur during the execution. The proposed approach exploits semantic languages for service description, autonomic managers driven by policies specified using a dedicated language, and a knowledge base containing information collected during processes execution. Autonomic actions are performed using Event Condition Action (ECA) rules for assessing system and process conditions, and a set of operations that allow for dynamic adaptation of the running processes. Furthermore, the correctness of workflow adaptation is checked before the modifications are performed, by using both syntactical and semantic constraints.

Extending Web Services Semantics to Support Asynchronous Invocations and Continuation

Asynchronous invocation and continuation are common patterns in some middleware infrastructures for object-based distributed computing. Their benefits are particularly significant in distributed environments characterized by high communication latencies and coarse-grained operations. Therefore, Web services could strongly benefit from the adoption of these patterns to (1) overlap communication with computation, (2) reduce the high number of interactions typically needed to handle stateless services by migrating the state of a service as parameters of service operations, (3) intercept at run-time data dependencies among consecutive services in a composition not visible from service descriptions. Unfortunately, current semantics of Web services do not directly support the patterns, but some specifications (i.e. WS-addressing) can simplify their implementation. In the paper we present the patterns, their benefits, and a module that implements a flexible schema useful to perform asynchronous invocations in several contexts. This way, modelling composed services can benefit from abstractions whilst more sophisticated low-level interactions among services are automatically handled at run-time.

Methodologies and Technologies for Networked Enterprises

The technological dimension and the organizational dimension are the two faces of Information Technology (IT) revolution shaping the life of large and small firms in last 50 years, from the first adoption of mainframe and reusable software to the recent integration of hardware and software technologies within Internet of Things. Over the last few decades, a number of scholars coming from computer science and from organization theory shared a deep confidence on the magic power of networks, especially of technological networks, more and more fast and reliable, and of organizational networks, more and more effective in balancing cooperation and competition among firms. Coherently with the aim of this volume, in this chapter we assume a more critical perspective deriving from the joint analysis of organizational challenges and of technological opportunities for networked enterprises aimed at developing new products/services. The management of innovation within networked enterprises requires a strategic approach to many dimensions. In this chapter we apply at open-closed trade-off the model developed by Pisano & Verganti in the paper Which kind of Collaboration is Right for You published by Harvard Business Review in December 2008. In the Chapter 4 we will focus the strategic models aimed at managing the new product development within the networked enterprise modelled as a design discourse. In the Chapter 5 authors will propose a third strategic perspective, proposing the application of a platform strategy in order to promote the a doption of advanced network infrastructures by Small and Medium Enterprises (SMEs).

Client-Side Implementation of Dynamic Asynchronous Invocations for Web Services

Web Services are becoming more and more fundamental building blocks of Web-based distributed applications and a core technology for grid systems. Due to their flexibility, Web Services easily combine, in a common and coherent framework, ubiquitous computing with heterogeneous applications composed of different kinds of resources and, typically distributed in many organizations. We expect that this technology will follow the same evolution paths that have characterized other technologies so far, with some specificity due to the openness and size of the application context. In this connection, optimizations tied to invocations and workflows are assuming a primary role in Web Services research. The synchronous request/reply nature of the most diffused underling protocol (HTTP) introduces several restrictions in many application scenarios. On the other hand, asynchronous interactions are allowed by using message oriented middleware platforms, like JMS, which are typically harder to handle than object- and process-oriented middleware. In this paper, we propose a first implementation of a module that allows for dynamic Web Services invocations, which, on the basis of metadata added to WSDL, is able to select the most appropriate invocation technique for calling a Web Services operation.

Activity pre-scheduling for run-time optimization of grid workflows

The capability to support resource sharing between different organizations and high-level performance are noteworthy features of grid computing. Applications require significant design effort and complex coordination of resources to define, deploy and execute components on heterogeneous and often unknown resources. A common trend today aims at diffusing workflow management techniques to reduce the complexity of grid systems through model-driven approaches that significantly simplify application design through the composition of distributed services often belonging to different organizations. With this approach, the adoption of efficient workflow enactors becomes a key aspect to improve efficiency through run-time optimizations, so reducing the burden for the developer, who is only responsible of defining the functional aspects of complex applications since he/she has only to identify the activities that characterize the application and the causal relationships among them. This paper focuses on performance improvements of grid workflows by presenting a new pattern for workflow design that ensures activity pre-scheduling at run-time through a technique that generates fine-grained concurrency with a couple of concepts: asynchronous invocation of services and continuation of execution. The technique is implemented in a workflow enactment service that dynamically optimizes process execution with a very limited effort for application developer.

Structure Matching for Enhancing UDDI Queries Results

To enhance UDDI query capability, typically based on taxonomic classification, semantic matching is assuming a key role. Even if we recognize the great importance of semantics in the discovery process, structure-based matching can be very useful in many situations where semantic annotations are not provided at publish time or ontologies are not yet well defined. Moreover, structure matching has a potential application in dynamic binding and invocation to perform correct parameter passing based on syntactic elements obtained from the mapping returned by the structure matching algorithm. The paper discusses the problem of similarity structure matching and proposes and compares different implementations of the algorithm introduced by Wang-Stroulia with the aim of obtaining better performance. We integrated the algorithm in a matchmaking framework based on multiple cascade filters that are able to combine several matchmaking techniques in order to improve precision and recall in a flexible and effective way.

Activity Pre-Scheduling in Grid Workflows

Grid computing is becoming a prominent field of interest for distributed systems. The capability to support resource sharing between different organizations and the high level of performance are noteworthy features. However, to define, deploy and execute grid applications require significant design effort and complex resource coordination, which can be alleviated by using workflow management systems. This technology is more and more adopted in distributed systems and grids since it ensures easiness and flexibility at design-time and performance and dynamicity at run-time. This paper gives a contribution to performance improvements of workflow by presenting a technique to exploit fine-grained concurrency at run-time. The technique is implemented in a workflow enactment service that dynamically optimizes process execution limiting the design effort of application developers

Putting It All Together: Using the ArtDeco Approach in the Wine Business Domain

This chapter summarises the results achieved by the ArtDeco project and presents the overall approach for developing the models that the large-scale middleware infrastructure designed during the project uses to drive the behaviours of the information systems of a sample networked enterprise operating in the domain of wine production. This domain is sufficiently wide to cover many business aspects that highlight the ability of the proposed infrastructure to adapt its behavior to the evolving execution context by reacting to unexpected events with a very limited human intervention.

Autonomic Workflow and Business Process Modelling for Networked Enterprises

As markets become more and more competitive and dynamic, companies need to increase control over their business processes to quickly adapt them to the changing conditions of the operational environment. Workflow management technology is a means to automate and control business processes, but they need more sophisticated capabilities to cope with highly dynamic execution contexts.