Rapid Prototyping for Service- Oriented Architectures

Transcription

1 Rapid Prototyping for Service- Oriented Architectures 2nd Workshop on Web Services Interoperability (WSI 2006) Julien Vayssière 1, Gorka Benguria 2, Brian Elvesæter 3, Klaus Fischer 4, Ingo Zinnikus 4 1 SAP Research, Brisbane, Australia, julien.vayssiere@sap.com 2 European Software Institute (ESI), Bizkaia, Spain, gorka.benguria@esi.es 3 SINTEF ICT, Oslo, Norway, brian.elvesater@sintef.no 4 DFKI GmbH, Saarbrücken, Germany, {klaus.fischer, ingo.zinnikus}@dfki.de

2 Outline Background and motivation Framework overview Model-driven development framework Web services enactment framework Agent-based execution platform Prototyping case study Conclusion 2

3 Background Service-Oriented Architecture architectural style gaining momentum mainstream in enterprise computing Four tenets of serviceorientation (Box 2004) explicit boundaries autonomy of services declarative interfaces and data formats policy-based service description Web services architecture technology most often used for implementing SOAs standards-based stack of specifications enable interoperable interactions between Webbased applications 3

4 Motivation Prototyping SOAs working implementation of an SOA that can be used for validating the initial design choices Different compared to traditional application development need to take into account existing services developed by organisations over which we have no control introduces constraints into the prototyping exercise Current state of the art tools assumes that we are starting with a blank page merely extends the approach of regular software prototyping to the scale of SOAs they make the implicit assumption that services will behave as expected This is why we designed an approach that from the start, takes into account the fact that parts of the SOA needs to be considered as a given; and should be treated with a healthy dose of caution. 4

5 Framework overview The ATHENA baseline methodology for SOA provides guidelines for developing platform independent models for SOA (PIM4SOA). Provides a set of modelling tools and services for mapping between PIM4SOA and platform specific models (Web services and BDI agents) PIM4SOA External for WSDL SOA Documents provides guidelines for autonomous agents platform allow SOAs to intermediary) developing and WSDL flexible platform Documentscommunication independent MDD Framework between BDI Teams Johnson and Lyndon provide enactment of all the roles found in an SOA (consumer, provider, intermediary) and flexible communication between Web services through an intuitive user interface The WSDL Analyzer tool detected syntactical mismatches between service descriptions and provides a basis for runtime mediation of Web service messages Modelling Johnson The and ATHENA Lyndon baseline provide methodology enactment of all the The Web service extensions to the JACK roles found in an SOA (consumer, provider, use agents for brokering, mediation and Web services models through for SOA an (PIM4SOA). intuitive user interface negotiation between WSDL Web Lyndon services The WSDL Provides Analyzer a set tool of modelling detected syntactical tools and BDI teams provide a flexible and composable mismatches services between for mapping service Johnson between descriptions and Jack alternative to traditional approaches «invoke» «invoke» to Web provides PIM4SOA a basis and for runtime platform mediation specific models of Web service composition service (Web messages services and BDI agents) Services Agents The Web service extensions to the JACK autonomous agents platform allow SOAs to use agents for brokering, mediation and negotiation between Web services BDI teams provide a flexible and composable alternative to traditional approaches to Web service composition 5

6 Internal Infrastructure Services Business Process/Agent Active (Business) Model Web/Server Component Middleware Process/Agent Middleware Component Service Wrappers (Enterprise X) Process Execution Adaptive Distributed Server-side Component Platform (.NET, J2EE) Service Wrappers (Enterprise Y) Service Wrappers (Enterprise A) Evaluation & Negotiation of Available Functionality Goal-oriented Adaptive Execution Platform (Agents) Intraorg. Message- Oriented Platform (MQSeries) Active Model Platform (AKMii) Composed WebService Enhanced Service Interconnection Bus Existing Enterprise Applications annotated with Enterprise Model UML Profile for POP* Process Organisation Product Reference Ontology annotated with Business Requirements Analysis Service-Oriented Architecture Model Model to Model Transformation Model to Model Transformation Architecture Specification Model Transformation UML Profile for SOA Information Service Process QoS annotated with UML Profile for Web Services UML Profile for Agents Web Service Specification Model Agent Specification Model BPEL Specification Model P2P Specification Model UML Profile for BPEL UML Profile for P2P Model to Text Transformation Model Transformation OWL Ontology Semantic Space annotated with Web Service Execution Artefacts ATHENA Integrated Execution Infrastructure Agent Execution Artefacts Legend Registry Repository Platform (BPEL) Resource Mgt Platform (P2P) BPEL Execution Artefacts Public Infrastructure Services Platform (WebServices) Crossorg. P2P Execution Artefacts Deployment ATHENA baseline methodology for SOA (overview) 6

7 Model-driven development framework PIM4SOA Model 1..* 1 Information View Service View Process View QoS View Model to Model Transformation UML Profile for PIM4SOA Information Service Process QoS UML Profile for XSD Platform Specific Model 1 1 XML Schema WSDL Description BDI Teams BPEL Process Model to Text Transformation UML Profile for WSDL UML Profile for BDI Agents UML Profile for BPEL Execution Artefacts XSD Document WSDL Document JACK BDI Teams BPEL Document Integrated Execution Infrastructure for Web Services and BDI Agents Follows the OMG Model Driven Architecture (MDA) Defines a Platform Independent Model (PIM) for SOA (PIM4SOA) Platform Specific Models (PSMs) for describing Web services (XML Schemas and WSDL), Jack BDI agents and BPEL (Business Process Execution Language) PIM4SOA is a visual PIM which specifies services in a technology independent manner Integrated view of the SOA in which different components can be deployed on different execution platforms. The PIM4SOA model helps us to align relevant aspects of enterprise and technical IT models Allows us to raise the abstraction level at which we can talk about and reason on the architecture we design. 7

8 PIM4SOA platform specific models PIM4SOA Metamodel Symbols PIM Metamodel Concept Relationship Correspondence PSMs Web Services Metamodel Agent Metamodel (AgentMM) P2P Metamodel Grid Metamodel 8

9 PIM4SOA addresses four system aspects Metamodel for (software) services Services are an abstraction and an encapsulation of the functionality provided by an autonomous entity. Service architectures are composed of functions provided by a system or a set of systems to achieve a shared goal. Web Services Architecture as proposed by W3C (W3C 2004) UML Profile for Enterprise Distributed Object Computing (OMG 2002) Metamodel for information Metamodel for (automated software) processes Processes describe sequencing of work in terms of actions, control flows, information flows, interactions, protocols, etc. Business Process Definition Metamodel (BPDM) (IBM et al. 2004) UML Profile for Enterprise Distributed Object Computing (OMG 2002) Metamodel for quality of service (QoS) Information is related to the messages or structures exchanged, processed and stored by software systems or software components. Structural constructs for class modelling in UML 2.0 (OMG 2003) UML Profile for Enterprise Distributed Object Computing (OMG 2002) Extra-functional qualities that can be applied to services, information and processes. UML Profile for Modeling Quality of Service and Fault Tolerance Characteristics and Mechanisms (OMG 2004) 9

10 Web services architecture metamodel <<Metamodel>> Coordination + WS-Coordination. <<Metamodel>> Reliability + WS-ReliableMessaging. <<Metamodel>> Eventing + WS-BaseNotification. + WS-BrokeredNotification. + WS-Eventing. + WS-Topics. <<Metamodel>> Resource Access and Management + WS-Enumeration. + WS-Resource. + WS-ResourceLifetime. + WS-ResourceProperty. + WS-Transfer. <<Metamodel>> Registry + UDDI. <<Metamodel>> Endpoint Description + WS-MetadataExchange. + WS-Policy. + WS-PolicyAttachement. <<Metamodel>> Messaging + SOAP. + WS-Addressing. <<Metamodel>> Transport + HTTP. <<Metamodel>> Service Interface Description + WSDL WSDL 2.0. <<Metamodel>> Security + WS-Security. <<Metamodel>> XML + XML Core / XSD. + XML Encryption. + XML Signature. + XPATH. <<Metamodel>> Composition + ACE-GIS Composition Extensions. + WS-BPEL. + WS-CDL. <<Metamodel>> econtract + ATHENA econtract Extensions. 10

11 PIM4SOA platform specific models PIM4SOA source metamodel Mapping model Web services target metamodels 11

12 Model transformations EMF RSM PIM4SOA Plugin eproc Model (.ecore) PIM4SOA Metamodel (.ecore) UML 2.0 Metamodel (.ecore) eproc Model (.emx) <<applied>> UML Profile for PIM4SOA (.epx) BPEL Metamodel (.ecore) EMF EMF a) BPEL Document (.bpel) b) MTF WSDL Metamodel (.ecore) c) WSDL Document (.wsdl) WID eproc Model (.ecore) Eclipse WST EMF: Eclipse Modeling Framework RSM: Rational Software Modeler UML modelling tool PIM4SOA Plugin: RSM plugin UML Profile for PIM4SOA MTF: Model Transformation Framework Eclipse WST: WSDL graphical editor WID: WebSphere Integration Developer 12

13 Rapid prototyping framework for SOA The ATHENA baseline methodology for SOA provides guidelines for developing platform independent models for SOA (PIM4SOA). Provides a set of modelling tools and services for mapping between PIM4SOA and platform specific models (Web services and BDI agents) Modelling External WSDL Documents WSDL Documents PIM4SOA MDD Framework BDI Teams WSDL Analyzer Lyndon «invoke» Johnson «invoke» Jack Johnson and Lyndon provide enactment of all the roles found in an SOA (consumer, provider, intermediary) and flexible communication between Web services through an intuitive user interface The WSDL Analyzer tool detected syntactical mismatches between service descriptions and provides a basis for runtime mediation of Web service messages Services Agents The Web service extensions to the JACK autonomous agents platform allow SOAs to use agents for brokering, mediation and negotiation between Web services BDI teams provide a flexible and composable alternative to traditional approaches to Web service composition 13

14 WSDL Analyzer The WSDL Analyzer is a tool for detecting similarities between Web service descriptions. The tool can be used to find a list of similar services and produces a mapping between messages, thereby enabling brokering and mediation of services. The idea of the tree-edit distance is that a similarity between two XML structures can be measured by stepwise transforming a tree representation of the first structure into the other. A possible scenario for using the WSDL Analyzer is that the user already knows a service which provides the correct format. The WSDL of this service can be used as requirement for a similarity search. The WSDL Analyzer allows browsing the original WSDL and the candidate files. 14

15 Web services enactment framework (1) User Interface Incoming messages Inbound Endpoints Inbound processing chains INBOX OUTBOX Folders for storing messages Outbound processing chains Outbound Endpoints Outgoing messages Johnson is a runtime enactment tool It enables users to enact most of the roles typically found in an SOA. It allows sending real SOAP messages between Web services without having to write a single line of code. It features a Web-based user interface designed to closely resemble Web-based applications SOAP messages and Web Services endpoints are used in place of messages and addresses The user can see incoming SOAP messages in the Inbox and create outgoing SOAP messages in the Outbox that will be sent to external Web services. A powerful user-interface generator relieves the user from having to deal with XML documents by generating forms for displaying and editing any XML-based data type. 15

16 Web services enactment framework (2) User Interface Incoming messages Inbound Endpoints Inbound processing chains INBOX OUTBOX Folders for storing messages Outbound processing chains Outbound Endpoints Outgoing messages Lyndon is the design-time counterpart of the Johnson tool It analyses WSDL files and automatically configures Johnson for playing either the role of consumer or provider of the service described. Lyndon parses a WSDL file and determines which endpoints need to be created, and which processing chains need to be assigned to them. Determining which processing modules to include in the processing chain takes into account information extracted from the WSDL file as well as options set by the user. The user may, for example, specify whether Johnson should be configured as a service consumer or a service provider, or whether messages sent to or from the service should be logged Some configuration information can be extracted from the WSDL file, such as the need for implementing the WS-Addressing specification, which is specified as part of the description of the bindings of a Web service. 16

17 Rapid prototyping framework for SOA The ATHENA baseline methodology for SOA provides guidelines for developing platform independent models for SOA (PIM4SOA). Provides a set of modelling tools and services for mapping between PIM4SOA and platform specific models (Web services and BDI agents) Modelling External WSDL Documents WSDL Documents PIM4SOA MDD Framework BDI Teams WSDL Analyzer Lyndon «invoke» Johnson «invoke» Jack Johnson and Lyndon provide enactment of all the roles found in an SOA (consumer, provider, intermediary) and flexible communication between Web services through an intuitive user interface The WSDL Analyzer tool detected syntactical mismatches between service descriptions and provides a basis for runtime mediation of Web service messages Services Agents The Web service extensions to the JACK autonomous agents platform allow SOAs to use agents for brokering, mediation and negotiation between Web services BDI teams provide a flexible and composable alternative to traditional approaches to Web service composition 17

18 Agent-based execution platform Teams/Agents Incoming request trigger send Events handle use Plans Web Service Supplier 1 WS calls User Supplier 2 Web Service Interface Beliefs modify Web Service At its core the JACK agent framework with plan library and knowledge base. Following the MDA approach, a modeller specifies at design time a set of plans (PSM level) that constitute the workflow library of the agents. Web service calls are integrated as steps into plans. Workflows are modelled graphically and most of the common workflow patterns are supported. 18

19 Prototyping case study External WSDL Documents e-procurement PIM4SOA WSDL Documents MDD Framework 1 BDI Teams Services Enactment WSDL Analyzer 2 Lyndon 3 «invoke» Johnson 4 «invoke» 5 Jack The following approach was followed for the validation of the rapid prototyping framework Used the MDD framework (1) to derive the WSDL files and BDI models from the e- procurement PIM4SOA model. Enact the services identified for the e-procurement scenario using the WSDL Analyser (2) and the Lyndon (3) tools. Used the WSDL Analyser to locate existing services similar to those required in the e- procurement scenario. Used the Lyndon tool to configure the Johnson platform to simulate required, new services. Configure Johnson (4) to act as a service proxy This allowed us to change the final service endpoints without affecting the process execution. Finally the PSM model for Jack (5) was implemented and tested with the enacted services. 19

20 M1. Request for Quotation M2. Quotation M3. Order M4. Order Confirmation MANUFACTURER Retailer-Manufacturer 1. RFQ 2. Quote 3. Order Manufacturer-Supplier 1. RFQ 2. Quote 3. Order 4. Order Confirmation R1. Request for Quotation R2. Quotation R4. Order Confirmation Interior Decoration Project R3. Order PROVIDER Retailer-Manufacturer 4. Order Confirmation RETAILER

21 PIM4SOA: Order process 21

22 PIM4SOA: Furniture procurement collaboration Three roles Retailer, Manufacturer Supplier Two usage of collaboration Goods Supply Materials Supply Relationships between role and collaboration use RoleBinding 22

23 PIM4SOA: Goods supply collaboration 23

24 PIM4SOA: Services interfaces 24

25 PIM4SOA: Order document 25

26 Conclusion This paper presented a rapid prototyping framework for SOAs built around a model-driven development (MDD) methodology which is used for transforming high-level specifications of an SOA into executable artefacts Web Services autonomous agents The framework can handle a mix of new and existing services; and provides facilities for simulating, logging, analysing and debugging The framework was validated in an industrial electronic procurement scenario from the furniture manufacturing industry input from business expert had been collected creating the high-level PIM4SOA model deriving the Web service description and incorporating existing Web services took less than a day for a person already familiar with all the tools involved The model-based approach helps us in keeping all the pieces of the SOA aligned with high-level business objectives throughout rounds of prototyping 26