Emerging Web Services Technology (eBook)

Contents 6
Preface 8
Organization 9
Introduction 11
Ontoprise: Semantic Web Technologies at Business 13
BPEL-Mora: Lightweight Embeddable Extensible BPEL Engine 15
1. Introduction 15
2. Background 17
2.1. BPEL4WS 17
2.2. Apache Axis2 17
3. Related Work 18
4. Motivation and Our Approach 19
4.1. Design principles 20
4.2. High level architecture 21
5. Information Model 21
6. Process Model 23
6.1. Handling Links 24
7. Kernel 25
7.1. Scheduling BPEL activities 25
7.2. Process instance life cycle 27
8. Interfacing with web service engine 28
8.1. Providing web service operations 29
8.2. Invoking web service operations 29
9. Evaluation 29
10. Conclusion and future work 30
References 31
Acknowledgment 32
A Cross-Layer Approach to Performance Monitoring of Web Services 33
1. Introduction 33
2. Quality-of-Service and Performance of Web Services 35
2.1. Quality-of-Service with regard to Web Services 35
2.2. Performance of Web Services 36
3. A Cross-layer Approach to Performance Monitoring and Anomaly Detection 37
3.1. Protocol Parameters for Performance Monitoring 37
3.2. Metrics and Heuristics for Performance Anomaly Detection 38
3.3. Exemplary Evaluation of Our Approach 39
3.4. Identi.cation of Required Architectural Components 40
4. Related Work 41
5. Conclusion and Future Work 42
References 43
Acknowledgements 44
Employing Intelligent Agents to Automate SLA Creation 45
1. Introduction 45
2. Service Level Agreements 46
3. Service Level Objectives 47
4. Intelligent Agents 49
5. Negotiations 50
6. Implementation 52
6.1. System dependencies 53
6.2. Negotiation Manager Model 54
6.3. Negotiation Mechanism 55
6.4. Service Process Explained 56
7. Conclusion 57
References 58
A Flexible Approach to Service Management-Related Service Description in SOAs 59
1. Introduction 59
2. Requirements for Service Description 61
2.1. Requirements Overview 61
2.2. Information Relevant for Service Lifecycle Management 61
2.3. QoS Guarantees 62
3. Related Work 62
3.1. Standards for Service Description 62
3.2. QoS-Speci.c Standards – UML Pro.le for QoS 64
3.3. Approaches to Semantic Service Description, Discovery, and Selection 64
4. Extension of OWL-S 65
4.1. Extension for Service Lifecycle Management 66
4.2. Extension for QoS with UML Pro.le for QoS Description 67
5. Service Management Prototype 69
5.1. Overview – Architecture and Functionality 69
5.2. Functions and Methodology of the Prototype 71
5.2.1. Taxonomy/Ontology Definition. 71
5.2.2. Service Description and Semantic Annotation. 71
5.2.3. Service Registration. 72
5.2.4. Service Discovery and Review. 72
5.2.5. User Access Control. 72
6. Importance for Matching, SLA Negotiation and Enforcement 73
7. Conclusion and Outlook 73
References 74
Model Centric Approach of Web Services Composition 77
1. Introduction 77
2. Conceptual Modeling of Services 78
2.1. Service Modeling 79
3. Structural Concerns 81
3.1. Service Aggregation 81
3.2. Properties Specification 81
3.3. Additional Semantic Constraints 83
3.4. Service Aggregation Examples 83
4. Behavioral Concerns 86
4.1. The BestStoreService Case Study 86
4.2. Web Service Dynamic Selection 88
5. Code Generation 89
5.1. Metamodels Definition 89
5.2. Model to Model Transformations 90
5.3. Model to Code Transformations 90
6. Conclusions and Further work 91
References 92
Model Driven Design of Web Service Operations using Web Engineering Practices 94
1. Introduction 94
2. An overview of the Web service design process 95
2.1. Web Service Design Process 95
2.1.1. Requirements Elicitation. 96
2.1.2. The OO-Method. 96
2.1.3. OOWS. 97
2.2. Sequencing of Activities 97
3. The Web service design activity 98
3.1. Identifying operations from Analysts’ WorkProduct 99
3.2. Identifying operations from OOWS modelers’ WorkProduct 101
3.2.1. User Model. 101
3.2.2. Navigational Model. 103
3.2.3. Presentation Model. 106
3.3. Tool support 108
4. Conclusions and Further Work 109
References 110
A Logic-based Approach for Service Discovery with Composition Support 112
1. Introduction 112
2. Discovery Approach 113
2.1. Modeling services 113
2.2. Matching Web services and requests 116
2.2.1. Matching based on capabilities. 116
2.2.2. Matching for Web service composition. 119
3. A Prototype System for Service Discovery 119
3.1. System overview 120
3.2. Application to use case scenario 121
3.2.1. Matching based on capabilities. 123
3.2.2. Matching forWeb service composition. 124
4. Related Work 125
5. Conclusions and Future Work 126
Acknowledgements 126
References 126
Mobile and Dynamic Web Services 128
1. Introduction 128
2. Related Work 129
2.1. Web Services Standards 129
2.2. Scenarios of using Web services in mobile phones 130
2.2.1. WS-aware mobile device. 130
2.2.2. WS-agnostic mobile device. 130
2.3. Specifications 131
2.4. Discussion 131
3. Client Applications with J2ME 132
4. Mobile Web Services Framework 134
4.1. Service Providers and Service Clients 135
4.2. Service Managers 135
4.3. UDDI Registry 135
4.4. Interactions 135
4.5. Conceptual Model of Service Manager 136
5. Development and Results 138
5.1. Performance 139
5.1.1. Test Description. 140
5.1.2. Results. 140
5.2. Discussion 141
6. Conclusions and Future Work 142
References 143
Software Metrics for the Effcient Execution of Mobile Services 145
1. Introduction 145
2. Related Work 146
3. Analysis of the Problem Domain 147
4. Theoretical Evaluation 149
4.1. Distance Framework 150
4.2. Coupling Metrics 151
4.3. Size Metrics 152
5. Empirical Evaluation 153
5.1. De.nition 153
5.2. Planning 153
5.3. Operation 154
5.4. Analysis and Interpretation of the Results 154
5.4.1. Correlation Analysis. 154
5.4.2. Univariate Regression Analysis. 155
5.4.3. Validity. 155
6. Practical Applicability 156
7. Concluding Remarks 158
Appendix 160
References 160
Acknowledgment 162
Dynamically Adapting Clients to Web Services Changing 163
1. Introduction 163
2. Aspect Oriented Programming (AOP) 164
3. Adapting BPEL processes 165
3.1. Extended BPEL generator 166
3.2. The extended interaction protocol 167
4. Generating dynamic clients 169
4.1. The dynamic client interpreter 169
4.2. Formalisation steps 170
4.3. Execution Scenario 171
5. Related work 172
6. Conclusion 173
References 173
Web Service Standards: Do we need them? 176
1. Introduction 176
1.1. Web Service De.nition 177
1.2. Standards De.nition 177
2. Too Many Overlapping Standards 178
2.1. Standards Organizations 178
2.2. Repercussions of Overlapping Standards 179
2.3. Examples of Overlapping Standards 180
2.3.1. Orchestration. 180
2.3.2. Business Transactions. 180
2.3.3. Reliable Messaging. 181
2.3.4. Registries. 181
3. Standards are not Constraining Enough 182
4. Standards Are Too Proprietary 185
5. Solution 187
6. Conclusion 189
References 190
Author Index 192

Model Centric Approach of Web Services Composition (p. 65-66)

Ricardo Quintero, Victoria Torres and Vicente Pelechano Abstract. The development of composite Web Services is being specified in a more declarative way than imperative programming. In this context, conceptual modeling has been the most accepted solution. Conceptual modeling of Web services has been done using behavioral models (like activity diagrams) considering mainly the dynamic view. We believe that, besides the dynamic aspects, the models should capture structural requirements between web service operations. In this way, behavioral models could be complemented with a structural model. In this paper we introduce a Web service composition modeling solution, following the MDA approach, considering both -structural and dynamic properties- enriched with semantic constraints in order to automatically generate composite Web services implemented in BPEL. Keywords. Web Services, Composition, Conceptual Modeling, Web Engineering, MDA.

1. Introduction

Current e-business processes have, as an important requirement, the integration (the composition) of diverse application functionalities. The main strategy that has been followed by the industry is the use of Web Services to export the functionality and the use of programming languages to define service composition [11].

Because the majority of them were not designed with this goal in mind, they do not have abstractions for this objective, so usually the composition definitions are cumbersome. In contrast, conceptual modeling offers abstractions and models in order to define this composition at a high level of abstraction [12,13,14]. The main focus of these approaches is on dynamic concerns (as in UML Activity diagrams) forgetting the structural concerns. Although there are some model-driven solutions that generate in a semi-automatic way Web services and WS-BPEL [15], the problem with these modeling approaches is some lack of semantics that makes it difficult to capture the composition requirements in a precise way. This drawback does make it unfeasible to build modeling tools that validate models and generate complete and fully operative implementations. We consider that structural and dynamic models are needed in order to capture these issues, especially static and dynamic binding properties between the Web services that are being composed (the main focus of this work). Moreover it could be used as a way to export the functionality of the application: by means of methodological guidelines it is possible to detect functional groups from the business layer (specified by a structural model) and export them as a set of Web services. These Web services could be consumed by other applications to enable collaboration with other third parties. In this work we introduce, as a main contribution, two models (the Service Model and the Dynamic Model for Service Composition) which allow us specifying the structural and dynamic requirements of Web services compositions by using aggregation/ association relationships with a precise semantics, defined in the context of a multidimensional framework [3]. In order to obtain the equivalent software artifacts of these models we follow a Model driven approach where the application of a set of transformation rules generates the corresponding WS-BPEL specification.

This solution extends ourWeb engineering method Object-OrientedWeb Solutions (OOWS) [1] in order to capture the collaborative requirements that are necessary to produce (in an automatic way) complete collaborative Web applications. The remainder of the paper is structured as follows: section 2 explains our proposal to conceptual modeling of Services, section 3 shows the introduced models from the point of view of their structural properties, section 4 explains the dynamic properties and the transformation of the models to a specific Web service composition technology (in this case we choose WS-BPEL [4], although it can be another -like BPML [5]), section 5 explains our code generation strategy and finally, section 6 presents conclusions and further work.