“Orchestration is the study and practice of arranging music for an orchestra or musical ensemble. In practical terms it consists of deciding which instruments should play which notes in a piece of music.” [Wiki] In musical terms, the orchestra would be made up of Web services, BPEL would be the sheet music and the business process manager (BPM) would be the composer that selects the necessary Web services and decides how they should interact with each other. Organizations use Web services in two broad categories, Enterprise Application Integration (EAI) and Business-to-Business (B2B) e-commerce as well as less complex scenarios such as technical functions and information services (common services). This thesis provides an insight on how the Web service standards resolve the limitations of conventional middleware and extend the benefits of process management to a wider scope of business problems. Web service standards like SOAP, XML, WSDL, and BPEL enable customers to solve integration problems easily by providing interoperability within a company or across multiple companies and improve B2B eCommerce and supply chain management by shifting to a service-oriented paradigm in application development. Web service orchestration provides an open, standards-base approach to create high-level business processes, such as workflows. This thesis will focus on BPEL for describing the business logic, although competing standards are still in use. The steps for the workflow implementation will be explained on the basis of a sample procurement scenario.
Table of Contents
1 Preface.
1.1. Chapter Overview
2 Process Management and Web Services
2.1. Enterprise Application Integration
2.1.1. Message-broker-based EAI
2.2. Workflow Management Systems
2.3. From EAI and WfMS to Web Services
3 Introduction to XML-Technologies
3.1. Extensible Markup Language
3.1.1. Well-formed vs. valid
3.1.2. XML Namespaces
3.2. Document Type Definition
3.3. XML Schema Definition
3.4. The Extensible Stylesheet Language
3.5. XML Path Language
3.6. XML Query Language
4 Introduction to Web Services
4.1. Service Oriented Architecture
4.2. Web Service
4.3. Basic Web Service Technologies
4.3.1. SOAP
4.3.2. Web Service Description Language
4.3.3. Universal Description, Discovery, and Integration
4.3.3.1. Public and Private Registries
4.3.3.2. Representing Information within UDDI
4.3.3.3. Representing Businesses and Providers
4.3.3.4. Representing Services
4.3.3.5. Representing Web Services
4.3.3.6. Technical Models
5 Web Services in a Business World
5.1. Web Service Orchestration
5.1.1. Orchestration Requirements
5.1.2. Orchestration Standards
5.2. Business Process Executing Language for Web Services
5.2.1. Document Structure
5.2.2. Variables Variables in BPEL
5.2.3. Service Selection
5.2.4. Activities
5.2.4.1. Implementing Structured Activities
5.2.5. Exceptions and Transactions
5.2.6. Instance Routing
6 Realization
6.1. Scenario Overview
6.2. System Environment
6.2.1. J2EE for Web Service Implementation
6.2.1.1. JAX-WS
6.2.2. The Oracle BPEL Process Manager for WS Orchestration
6.3. Implementation
6.3.1. Database Structure
6.3.1.1. Connecting to the MySQL Database
6.3.3. Building a JAX-WS Web service
6.3.3. Developing the BPEL Process
6.3.3.1. Dynamic Binding with WS-Addressing
6.3.3.2. Dynamic Procurement Process Steps
7 Conclusion and Future of Work
7.1. Conclusion
7.2. Future of Work
Objectives & Core Topics
This thesis aims to demonstrate how Web service standards can be utilized to automate business processes. The primary research question examines how Web service orchestration, specifically using the Business Process Execution Language (BPEL), can resolve the limitations of traditional middleware to create flexible, service-oriented workflows in a procurement scenario.
- Web Service Orchestration and the role of BPEL
- XML-based technologies (XML Schema, XSLT, XPath, XQuery)
- Service Oriented Architecture (SOA) and the Web service stack (SOAP, WSDL, UDDI)
- Dynamic service binding using WS-Addressing
- Realization of an automated procurement process using J2EE and Oracle BPEL
Excerpt from the book
5.1. Web Service Orchestration
“Processes being built today need the business agility to quickly adapt to customer needs and market conditions.” [WSO1] Web service orchestration provides an open, standards-based approach to create high-level business processes by managing the automatic execution of business services to fulfill an enterprise-wide or inter-enterprise business process. Thereby the services are the instruments being orchestrated into a whole. [BOS] Web service orchestration can be seen as the creation of an executable process model that implements a new first class business service in a SOA world. The process model describes a flow from the perspective and under control of a single endpoint (commonly: workflow) by harmonizing pre-existing business services and managing their tempo.
Just like workflows, orchestrations are self-propelled. The orchestration engine invokes business processes from applications, organizations, and people, not the other way around. This allows processes to run independently of the implementation of the underlying services, as long as the business services expose accessible interfaces by creating Metadata about them and populating standards' registries. Metadata standards such as XML, SOAP, and WSDL deliver key orchestration connectivity. Web services are published first, before they are orchestrated. A Web service has to be made available through a supported interface/protocol. The details of the service interface have to be defined using a WSDL contract. The published Web service receives an XML request message and generates a set of XML response messages, whereas the transport and the exchange of the messages are implemented using protocols such as e.g. HTTP, JMS or SMTP.
Summary of Chapters
Preface: Introduces the concept of orchestration in a musical context and outlines the thesis focus on BPEL for workflow implementation within a procurement scenario.
Process Management and Web Services: Provides insight into EAI and WfMS, highlighting their limitations in Wide Area Networks and explaining how Web services offer a solution.
Introduction to XML-Technologies: Covers essential XML basics, including validation, namespaces, DTDs, Schemas, XSLT, XPath, and XQuery, as these are foundational for Web services.
Introduction to Web Services: Details the SOA framework, defines Web services, and explains the fundamental technologies like SOAP, WSDL, and UDDI.
Web Services in a Business World: Explores orchestration, requirements for business-level interactions, and standard languages like BPEL, WSCI, and BPML.
Realization: Describes the practical implementation of a procurement scenario, including the system environment, database setup, JAX-WS web services, and the BPEL orchestration process.
Conclusion and Future of Work: Summarizes the benefits of Web service orchestration for standardizing business processes and suggests future extensions like dynamic branching with FlowN.
Keywords
Web Services, Orchestration, BPEL, SOA, XML, WSDL, SOAP, UDDI, Enterprise Application Integration, EAI, Workflow Management, J2EE, JAX-WS, Procurement, Dynamic Binding
Frequently Asked Questions
What is the core focus of this thesis?
The work focuses on the role of metadata and standardized Web service technologies in orchestrating complex, automated business processes across different systems.
What are the central thematic fields?
The core topics include XML technologies, Service Oriented Architecture (SOA), Web service standards like SOAP and WSDL, and the implementation of business workflows using BPEL.
What is the primary goal of this research?
The goal is to demonstrate how organizations can transition from static, inflexible middleware to an open, service-oriented paradigm for high-level business process integration.
Which scientific methods are employed?
The research combines a theoretical review of existing standards with a practical implementation approach, using a procurement scenario to illustrate the development and deployment of an automated BPEL process.
What is covered in the main section of the document?
The main sections provide a comprehensive guide to Web service standards, a deep dive into BPEL document structure, and a detailed step-by-step realization of a procurement process using Oracle BPEL and J2EE.
Which keywords best characterize this work?
Key terms include Web Service Orchestration, BPEL, SOA, XML, WSDL, UDDI, EAI, and dynamic binding.
How does dynamic binding work in the context of this thesis?
Dynamic binding is implemented using WS-Addressing, allowing the BPEL process to manage and redefine service locations at runtime, rather than being restricted to static endpoints defined at design time.
Why is the procurement scenario used as a sample case?
It serves as a practical example to demonstrate common business challenges—such as multi-supplier interaction, price comparison, and inventory checking—that can be resolved by orchestrating individual Web services.
- Quote paper
- Marlen Krebs (Author), 2006, The Role of Metadata in the Orchestration of Web Services, Munich, GRIN Verlag, https://www.grin.com/document/57469
