Presentation on theme: "Web Services Development in WebSphere v5"— Presentation transcript:
1 Web Services Development in WebSphere v5 byTapas BanerjeeCEO, Web Age Solutions Inc.
2 What are Web Services?Applications that can be published, located and invoked programmatically over the Web.XML-based (XML-in, XML-out).Self-contained functions that can be used individually to provide services.Good applications:Business Information.Business IntegrationBusiness Process Externalization.
3 Service Oriented Architecture A service-oriented architecture is created by services communicating with each otherThe SOA architecture allowsDifferent systems and programming languages to talk to each otherDescribes the service interface clearlyAllows search for needed servicesIt’s made up of - service provider, service broker and service requestorWeb Services implement this architecture
4 Web Services Supporting Architecture Standards Web Services rely on:XML (eXtensible Markup Language).UDDI (Universal Description Discovery and Integration).Publish and discover.SOAP (Simple Object Access Protocol).Query UDDI, binding and use of services.WSDL (Web Services Description Language).Describe the interfaces of Web Services.Web Services rely on four essential elements:Web Services need a language/platform-neutral and structured way to represent business information and interaction. XML provides a framework for describing what a service can do, how it can be invoked, discovering the available service, passing request/parameters for invoking the service, and receiving responses.UDDI defines the way for businesses to publish and/or discover information about Web Services they provide and/or look for. Service providers register the services to a global UDDI registry by using a WSDL descriptor. The descriptor describes the services, their interfaces, and specifies how to bind to the services to execute them. Customers/clients can search for services in the UDDI registry.SOAP is an XML-based standard for messaging over HTTP. It is a lightweight protocol using the exchange of information in a decentralized, distributed environment. It is used to query the UDDI registry for Web Services and it enables the binding and usage of the Web Services by defining a message path for routing message.WSDL is an XML-based open description that describes the interfaces to the Web Services. In order to make a Web Service available, service providers publish a WSDL for a service to a UDDI registry.
5 The Functions and Information Flow Service BrokerUDDI Registry2. Assign a unique ID andpopulate the registryThis slide shows the flow from registration, to discovery, to use of the service.A service provider hosts the Web Services. The service provider creates, tests and deploys the service, makes the service available, and describes (using WSDL) and publishes the service to a UDDI registry.A service broker provides a UDDI registry. The UDDI registry registers and categorizes services, and provides a search service.Server consumers/requesters use the service broker to discover (through use of the UDDI API) the service they are looking for. The broker will hand out the binding information for the service to the consumer. The binding information tells the consumer how to invoke the service and what to expect in response/return.The client binds the information and uses the service.Service ProviderService Consumer1. Publish3. DiscoverWeb ServiceClient4. Request/Response via SOAP
6 Web Services Programming Model RPC-based:Service-specific.Synchronous model.Similar to RMI and DCOM.Message-based:Document-driven.Asynchronous model.The programming model dictates how to implement, assemble, deploy and invoke Web Services. There are two types of Web Services: Remote Procedure Call (RPC) -based and message-based.The interaction between a client and an RPC-based Web Service centers around a service-specific interface. RPC-based Web Services are synchronous. That is, when a client sends a request, it then waits for a response before doing anything else.Message-based Web Services are document-driven rather than being associated with a service-specific interface. When a client invokes a message-style Web Service, the client typically sends it an entire document, such as a shipping order, rather than a discrete set of parameters as in an RPC-based model. Message-based Web Services are asynchronous. A client that invokes the Web Service does not then wait for a response before it does anything else.
7 Web Services Programming APIs APIs for RPC-based Web Services:Sun’s JAX-RPC (Java API for XML-RPC) in WSDP.Apache’s SOAP-RPC (Apache SOAP 2.3 ships with WAS5)APIs for Message-based Web Services:Sun’s JAXM (Java API for XML Messaging) in WSDP.Apache’s SOAP-Message.APIs for publishing and discovering Web Services:Sun’s JAXR(Java API for XML Registry) in WSDP.IBM’s UDDI4J.Web Service APIs are interfaces that consume XML messages. Vendors have implemented APIs based on specifications such as SOAP, WSDL and UDDI. Developers can use these APIs to develop Web Service clients for accessing UDDI registries (for publishing and discovering) and using or binding the Web Services. Some use GUI tools for accessing a UDDI registry. We will give an overview of the APIs here. More details regarding programming Web Services and UDDI clients will be discussed in greater detail later. We will concentrate on Sun’s APIs available in WSDP.
8 JAXR – Java API for XML Registry Enables Java programs to access XML registries.JAXR provider:Accesses XML registry.A façade to a registry provider.JAXR client:A client program that accesses an XML registry using JAXR API.Perform queries and update UDDI registries.Sun’s registry browserIncluded in WSDP download.Is a JAXR client with GUI.Allows to publish and search XML registries.The client must create a connection with the JAXR provider in order to use a registry. Once connected to the UDDI registry, the client can interact with the UDDI via XML messages or RPC calls.We will discuss the JAXR API and the Registry Browser in more detail in the UDDI chapter later in this course.
9 Other Web Services Concepts Several other important Web Services concepts:Web Services Invocation FrameworkWeb Services Inspection Language (WS- Inspection)WorkflowsWeb Services GatewayWeb Services Security
10 Web Services Invocation Framework Web Services Invocation Framework (WSIF)A framework for the simple invocation of Web Services over a Java API.Allows for maximum flexibility and late (even runtime) binding for clients
11 Web Services Inspection Language (WS Inspection) A complementary technology to UDDIA service discovery mechanismXML-based model for building a list of references to existing Web Service descriptors
12 Workflow and Web Services A Workflow description allows a process to be described as a sequence of discrete events (e.g. service calls)A workflow engine can then parse the workflow description and execute the sequence automaticallyDefines a business process
13 Workflow Languages There are three web services workflow languages: Web Services Flow Language (WSFL)XML-basedFlow Definition Markup Language (FDML)Similar to WSFL, but with extensionsBusiness Process Execution Language For Web Services (BPEL4WS)A meeting of IBM's WSFL and Microsoft's XLANG
14 Web Services Gateway (WSGW) The WSGW acts as an additional layer between a web service client, and a web service providerServer sideAllows for better control over web service communication
15 The Gateway Administrative Console Open a web browser to The hostname is of the server to which you installed the gateway. The port number is the HTTP transport port for that server.
16 Security NeedsSince web services are inherently network based (and typically Internet-based), security is crucialAdditionally, web service communication can be compromised at many levelsAt this time, Web Service security still has no formal standards. Much of the material discussed in these sections is based on informal approaches and proposed drafts.
17 SOAP HTTP Request Example POST /SampleWebServiceWeb/servlet/rpcrouter HTTP/1.0Host: localhost:9080Content-Type: text/xml; charset=utf-8Content-Length: 526SOAPAction: ""<?xml version='1.0' encoding='UTF-8'?><SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><SOAP-ENV:Body><ns1:findDepartmentByName xmlns:ns1="http://tempuri.org/webservice.ejb.EmployeeDirectory" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><departmentName xsi:type="xsd:string">Sales</departmentName></ns1:findDepartmentByName></SOAP-ENV:Body></SOAP-ENV:Envelope>The payload is in XML – a single <SOAP-ENV:Envelope> element. All the attributes of the <SOAP-ENV:Envelope> are required as shown in the example above. The <SOAP-ENV:Envelope> must contain a single <SOAP-ENV:Body> element, which contains a single element which is the procedure call. The name of the procedure is the name of this element. Note that the procedure name must be a valid XML element name.The elements contained within the procedure call are the parameters to the procedure. The names of the parameters is significant, the order of the parameters is not. Parameter type is indicated by the xsi:type attribute.For example, the procedure name could be the name of a file containing a script that executes on an incoming request. It could be the name of a cell in a database table. Or it could be a path to a file contained within a hierarchy of folders and files.A procedure call may take no parameters. If it takes no parameters, the procedure element must not contain sub-elements.
18 SOAP HTTP Response Example HTTP/ OKServer: WebSphere Application Server/5.0Set-Cookie: JSESSIONID=000050K5KBO5DKK1CC4A2J2VKIY:-1;Path=/Cache-Control: no-cache="set-cookie,set-cookie2"Expires: Thu, 01 Dec :00:00 GMTContent-Type: text/xml; charset=utf-8Content-Length: 659Content-Language: en-USConnection: close<?xml version='1.0' encoding='UTF-8'?><SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><SOAP-ENV:Body><ns1:findDepartmentByNameResponse xmlns:ns1="http://tempuri.org/webservice.ejb.EmployeeDirectory" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><return xmlns:ns2="http://bean.webservice/" xsi:type="ns2:Department"><location xsi:type="xsd:string">Toronto</location><name xsi:type="xsd:string">Sales</name></return></ns1:findDepartmentByNameResponse></SOAP-ENV:Body></SOAP-ENV:Envelope>Unless there's an error, return 200 OK.The content-type is text/xml. Content-length may be specified. If it is specified, it must be correct.The body of the response is in XML, a single <SOAP-ENV:Envelope> element.The <SOAP-ENV:Envelope> must contain a single <SOAP-ENV:Body> element, which contains a single element which is the returned value of the procedure.The single element contained in the <SOAP-ENV:Body> has an arbitrary name which must match the name of the procedure that was called, with the word "Response" tacked on to the end of its name. Let's call this element the wrapper for the response. Even this is not the actual value of the response, which is contained in the single optional sub-element of the wrapper and must be a valid parameter.The namespace of the wrapper element should match the namespace in the request.If the wrapper has no sub-elements, then the procedure did not return a value.
19 Different SOAP Implementations SOAP4J - A Java reference implementation of the SOAP 1.1 specification. It now became the basis of the Apache SOAP 3.x project, also called Axis.Apache SOAP 2.3Ships with WebSphere V5Important elements areRpcrouter and messagerouter servletsThe deployment descriptorType mapping registryRpcrouter and messagerouter servlets intercept requests sent from web services clients who use HTTP.
20 What is WSDL?WSDL is an XML-based language for defining available Web Services and describing how to access the services, including URL endpoint, message format, encoding and required protocol.Similar to IDL (Interface Definition Language) for CORBA, describing the services and how to use the servicesWSDL 1.1 is the current standard.Tools available to generate WSDL files.In the WSDL document, the following information is defined:What are services.What are the ports(network endpoints/address) in each service?What is the protocol binding for each port?What is the portType (operation/method) in each binding?What is the operation type(one way, request-response, solicit-response, or notification)?What are the messages (parameters) for the operation?What is the data type of the parameter?
21 UDDI Data Structure Five data structure types: businessEntity businessServicebindingTemplat epublisherAsserti ontModel<publisherAssertion>Namedescription<businessEntity>name, contact, identificationdescription, category<businessEntity>name, contact, identificationdescription, category<businessService>(1..n)namedescriptionThe information model of UDDI registries is defined in XML schema. The XML format is used to describe services in UDDI compliant registries because XML allows cross-platform and language-independent service discovery.There are five XML data structure types defined for a registration, including business information, service information, binding information, business relationship, and information about specification for services. Each of these XML structures contains a number of data attributes that serve either a business or technical descriptive purpose.The businessEntity structure contains 1 to n unique businessService structures. Individual businessService structures contain specific instances of bindingTemplate data, which in turn contains information that includes pointers to specific instances of tModel structures.publisherAssertion allows large companies to represent several businessEntities (such as subsidiaries) that are associated. The relation is published by using the UDDI xxx_publisherAssertion messages to be discussed later in this chapter.<businessService>(1..n)namedescriptionreference<bindingTemplate><bindingTemplate><tModel>NameDescriptionURL pointerto specification
22 UDDI4J IBM’s UDDI4J is a Java-based UDDI client API. It provides package/classes for accessing UDDI registry (publishing and discovering).UDDIProxy object is the client side proxy of the registry.Program the UDDIProxy for publishing/discovering services.
23 Developing Web Services Generate deployable web service fromJava BeanDADX (XML/DB2 mapping documents)Enterprise Java BeanURLGenerate skeleton Java Bean and sample application from WSDL documentWeb Services Client wizard also createsWeb Service Proxy as Java BeanSample JSP-based client application
24 Overall Workflow Typical development path Create a Web Project Create/Import a resource from which to create a web service (Java Bean, EJB, DADX document, …)Create a Web Service using Web Service WizardPublish a Business Entity, if requiredPublish the Web ServiceAs with any web project, you use the Server tools to manage server instances and configurations. When the server is running, most changes to project resources are picked up without restarting the server.The web project and any other J2EE projects will belong to a WSAD Enterprise Application Project. When you create a web service, it also becomes part of the Enterprise Application Project and can be deployed as easily as deploying any Enterprise Application. In a typical deployment, only the web service end point needs to be configured differently than in the test environment.
25 Creating a Web Service from a Java Bean Typical steps:Create/Import Java Bean into Web ProjectGenerate binding WSDL document using Web Service WizardDeploy Web Service to a Web ServerGenerate client proxyGenerate sample client applicationThen publish, discover and use web serviceThe client proxy that WSAD’s Web Services Wizard generates provides access to the web services as RPCs (remote procedure calls). Object marshalling and unmarshalling is doing via XML instead of the standard Java serialization mechanism; therefore parameters do not need to be Serializable.The generated sample client application is a simple JSP-based test client that looks similar to the Universal Test Client. You can select a method, enter input parameters and see a text representation of the result.
26 … from an EJB Typical steps: … then it’s “business as usual” Create a Web ProjectCreate/Import EJBs into an EJB Project belonging to the same Enterprise Application Project as the Web ProjectUpdate project dependencies… then it’s “business as usual”WSAD only generates a Web Service from a Stateless Session EJB… but that session bean can always use entity beans!Starting with WSAD v4.0.3, class loading within an Enterprise Application has changed and there is no need to explicitly specify the dependency that a Web Project has on the various EJB Projects contained in the same Enterprise Application Project. For WSAD/WAS v4.0, however, you must add the appropriate project references and place the EJB projects in the Web project’s Java Build Path.
27 Web Service Development Phases BuildMay start from Java code, then we generate WSDL from thatOr start from WSDL and build/morph Java code to matchDeploymentWe can publish usingUDDI, WSIL or ing customersRunManagementBuild – Represents the development phase of the web service. Includes requirement gathering, analysis, design, implementation and test.Deployment – Includes (a) publishing to the UDDI, (b) publishing the WSDL file and (c) deployment in the application server environmentRun – Client finding the web service and invoking itManagement – Day to day overseeing of the web service
28 Different web service creation paths From an existing application – bottom-upMost common. We like to expose existing back-end systems for enterprise integration (EAI) purposes.From WSDL, generate a completely new application – top-downThis may be due to a new spec imposed by a governing bodyThe wizards can create skeleton code from WSDL, we then fill up the detailsCombine independent web services to provide new functionality. This route is similar to the façade design pattern.
29 Different WebSphere products – how do they fare? There are three products in the WebSphere family that can be usedWSADWSAD IEWebSphere SDK for web services (WSDK) familyAll three can do bottom-up and top-down from JavaBeansWSAD IE and WSDK can do bottom-up and top- down from EJB’sRegular WSAD cannot do top-down for EJB’s I.e. cannot create EJB’s from WSDL.
30 … from XML schema Generate Java Bean from XML schema Create any project that works with Java source code (Java, EJB, Web, …)Create/Import XML schema in the projectStart Web Services WizardSelect Java beans for XML Schema.Follow instructions to generate Java BeansNow generate the Web Service from the new Java Bean
31 WSDK 5.0 WebSphere SDK for Web Services Entry level developer kit, free for developmentBut not for production or deploymentRuns on Windows 2000/XP and LinuxBased on Axis (Apache SOAP engine)Has embedded application server (mini WebSphere 5.0) and a private UDDI registrySupports SOAP 1.1, WSDL 1.1, UDDI 2.0, JAX_RPC 1.0, WSDL4J, UDDI4J and WS-SecurityThe UUDI server runs as an EAR file inside the application server.
32 ETTK (previously called WSTK) IBM Emerging Technologies Toolkit (previously called Web Services toolkit)An IBM alphaworks technology, showcases technologies to comeExposes the AXIS programming modelWSTK version includesWS-C/WS-Tx for transaction flows between componentsWeb Services matchmaking engine – Businesses submit advertisements. When a customers search matches an advertisement, a response is triggeredWSXL – For better handshaking of web services with portal applications
33 Web Services Deployment in WebSphere If you are using WSAD 5, it is same as deploying an EAR fileIf you are using WSAD 4Export the Web Service as a WARUse AAT to create an EARUse soapearenabler.bat to add SOAP services
34 Summary We discussed What are Web Services. Web Services programming model.How does a SOAP message look.Developing Web Services.Web Service Development Phases.