Web Services Index Overview SOAP WSDL UDDI Performance

Web Services Index - Overview - - SOAP WSDL UDDI - Performance - basado en UPC-DAC/FIB-AAD Jordi Torres; v 2. 0 -05/04 1

Web Services r What are web services? - - Web services are modular web applications that provide data and services to other applications over the web Web services apply web technologies such as HTTP and XML to the concepts of distributed computing technologies such as CORBA and DCOM Aplicaciones auto-contenidas, auto-escritas que pueden ser publicadas, localizadas e invocadas a través de la Web 2

Web Service Examples r A stock quote service. r A weather service, a map service, a web search service… - any composition of Web services. r e. g. Dollar Rent-A-Car - Create standard interfaces so business partners could tap into the company's car reservation system. r Google, Amazon, … http: //www. google. com/apis/ 3

What are Web Services? r Today’s web: Web designed for application to human interactions • Information sharing: a distributed content library. • Built on very few standards: http + html • Shallow interaction model: very few assumptions made about computing platforms. - Enabled B 2 C e-commerce. Non-automated B 2 B interactions. r “Web services” is an effort to build a distributed computing platform for the Web. - Services available via the Web. Meant mainly for application to application communication (as opposed to users directly) Enables Business-to-Business transactions. - E. g. , a web service is contacted on a URL using the SOAP protocol over HTTP. 4

Complete picture of distributed applications (using WS) 5

Core technologies used for WS r XML r SOAP - Simple Object Access Protocol - a framework for exchanging XML-based information in a network - the currently most hyped XML/Web service technology r WSDL - Web Service Description Language - an XML-based language for describing network services - WSDL descriptions of capabilities and locations of services - like an interface description language for Web services - communication using SOAP or direct HTTP r UDDI - Universal Description, Discovery, and Integration - provides a registry mechanism for clients and servers to find each other - uses SOAP for communication 6

Otra definición r Programas accesibles en Internet que exponen su funcionalidad recibiendo/enviando mensajes SOAP a través de HTTP(s) y describen su interfaz en WSDL 7

The Web Services Stack Service Publication/Discovery UDDI Service Description WSDL XML Messaging SOAP Transport Network HTTP, SMTP, MQSeries, etc. 8

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What is SOAP? r SOAP is a lightweight protocol for exchange of information in a decentralized, distributed environment using XML. 10

The Simple Object Access Protocol (SOAP) r XML-based protocol for messaging and RPC - Can works on top of existing transports • HTTP, SMTP, FTP, MQSeries r Use of XML schema for encoding typed values r Language independent - Generation of SOAP messages available in popular programming language • C, Java, Perl 11

SOAP: FORMATO GENERAL Envelope Header Key Body 12

SOAP: Formato general r SOAP especifica el formato de mensajes Envelope: datos globales (codificación, espacio de nombres, . . . ) contiene: header (opcional) + body (obligatorio) Body: contiene datos en formato XML Header: contiene meta-informaticón 13

Sample HTTP Interaction (C) Prof. Dr. Frank Leymann, IBM 14

HTTP POST: Invoking Code (C) Prof. Dr. Frank Leymann, IBM 15

A Simple SOAP RPC ( SOAP Message Embedded in HTTP Request) POST /Stock. Quote HTTP/1. 1 Host: www. stockquoteserver. com Content-Type: text/xml; charset="utf-8" Content-Length: nnnn SOAPAction: "Some-URI" Object Endpoint <SOAP-ENV: Envelope xmlns: SOAP-ENV="http: //schemas. xmlsoap. org/soap/envelope/" SOAP-ENV: encoding. Style="http: //schemas. xmlsoap. org/soap/encoding/"> <SOAP-ENV: Body> <m: Get. Last. Trade. Price xmlns: m="Some-URI"> Method name <symbol>DIS</symbol> Input parameter </m: Get. Last. Trade. Price> </SOAP-ENV: Body> </SOAP-ENV: Envelope> 16

A simple soap response ( SOAP Message Embedded in HTTP Response) HTTP/1. 1 200 OK Content-Type: text/xml; charset="utf-8" Content-Length: nnnn <SOAP-ENV: Envelope xmlns: SOAP-ENV="http: //schemas. xmlsoap. org/soap/envelope/" SOAP-ENV: encoding. Style="http: //schemas. xmlsoap. org/soap/encoding/"/> <SOAP-ENV: Body> <m: Get. Last. Trade. Price. Response xmlns: m="Some-URI"> <Price>34. 5</Price> </m: Get. Last. Trade. Price. Response> </SOAP-ENV: Body> </SOAP-ENV: Envelope> 17

(three) standard aspects of SOAP r Overall message format A SOAP message is an envelope containing zero or more headers and exactly one body. r The SOAP encoding rules defines a serialization mechanism that can be used to exchange instances of application-defined datatypes. ( based on XSD) r The SOAP RPC representation defines a convention that can be used (optional) to represent remote procedure calls and responses (if not, message-oriented style) 18

Working example: A soap request POST /servlet/rpcrouter HTTP/1. 1 Host: www. messages. com Content-Type: text/xml; charset="utf-8" Content-Length: nnnn SOAPAction: "" <SOAP-ENV: Envelope xmlns: SOAP-ENV="http: //schemas. xmlsoap. org/soap/envelope/" <SOAP-ENV: Body> <ns 1: get. Message xmlns: ns 1="urn: Next. Message" SOAP-ENV: encoding. Style="http: //schemas. xmlsoap. org/soap/encoding/"> <User. ID xsi: type="xsd: string">JDoe</User. ID> <Password xsi: type="xsd: string">0 JDOE 0</Password> </ns 1: get. Message> </SOAP-ENV: Body> </SOAP-ENV: Envelope> 19

Working example: soap response HTTP/1. 1 200 OK Content-Type: text/xml; charset="utf-8" Content-Length: nnnn <SOAP-ENV: Envelope> xmlns: SOAP-ENV="http: //schemas. xmlsoap. org/soap/envelope/" <SOAP-ENV: Body> <ns 1: get. Message xmlns: ns 1="urn: Next. Message" SOAP-ENV: encoding. Style="http: //schemas. xmlsoap. org/soap/encoding/"> <return xsi: type="xsd: string">Call mom!</return> </ns 1: get. Message> </SOAP-ENV: Body> </SOAP-ENV: Envelope> 20

SOAP Endpoint Reference 85. 34. 235. 95 80 /servlet/rpcrouter/get. Message POST /servlet/rpcrouter HTTP/1. 1 Host: www. messages. com Content-Type: text/xml; charset="utf-8" Content-Length: nnnn SOAPAction: "" <SOAP-ENV: Envelope xmlns: SOAP-ENV="http: //schemas. xmlsoap. org/soap/envelope/" <SOAP-ENV: Body> <ns 1: get. Message xmlns: ns 1="urn: Next. Message" SOAP-ENV: encoding. Style="http: //schemas. xmlsoap. org/soap/encoding/"> <User. ID xsi: type="xsd: string">JDoe</User. ID> <Password xsi: type="xsd: string">0 JDOE 0</Password> </ns 1: get. Message> </SOAP-ENV: Body> </SOAP-ENV: Envelope> 21

SOAP client-server interaction 22

The Apache e. Xtensible Interaction System (AXIS) r A very flexible SOAP engine from Apache - Open and pluggable architecture - Design to cope with various deployment configuration • From very simplistic to highly sophisticated configurations r The Java Web Services facility (JWS) - Drop-in development • Simplest and quickest way to deploy a Java-base Web Service • Rename source file from xxx. java to xxx. jws • Drop xxx. jws into JWS directory 23

APIs de Java r SAAJ (SOAP with Attachment API for Java) tratar mensajes SOAP como objetos Java r JAX-RPC (Java API for XML based RPC) WSDL/XML <-> Java API para cliente: WSDL, Invocación, proxy dinámico r JWSDL acceso a descripciones WSDL r JAXR (Java API for XML registries) acceso a registros de servicios Web. . . 24

Creación de un Servicio Web r Utilizar JWS - Con limitaciones (no package, . . . ) r WSDD (Web Service Deployment Descriptor) 25

Creación de un cliente 1. Acceder a WSDL http: . . Calculator. jws? wsdl -> almacenar Calculator. wsdl 2. Generar stubs java org. apache. axis. wsdl. WSDL 2 Java –p Calculator. wsdl 3. Clases generadas 4. Compilar ls Calculator/ *. javac Calculator/ *. java 5. Compilar cliente 6. Ejecutar cliente javac Cliente. Calculator. java Cliente. Calculator 26

What is WSDL? SOAP specifies the communication between a requester and a provider WSDL describes the services offered by the provider (an “endpoint”) and might be used as a recipe to generate the proper SOAP messages to access the services. • WSDL describes network services by using an XML grammar. • A WSDL document has a role similar to an IDL file in CORBA or the Remote Interface in a Java RMI implementation. 27

Complete picture of distributed applications (using WS) 28

WSDL service 1 -M port 1 -1 binding 1 -1 1 -M port types 1 -M operation message 1 -M types 29

Types: x. Schema definition of data Service Port Binding Port Types Operations Messages Types <types> <schema target. Namespace="http: //example. com/stockquote. xsd" xmlns="http: //www. w 3. org/2000/10/XMLSchema"> <element name="Trade. Price. Request"> <complex. Type> <element name="ticker. Symbol" type="string"/> </complex. Type> </element> <element name="Trade. Price"> <complex. Type> <element name="price" type="float"/> </complex. Type> </element> </schema> </types> 30

Messages: meaningful collections of Types Service Port Binding Port Types Operations Messages Types <message name="Get. Last. Trade. Price. Input"> <part name="body" element="xsd 1: Trade. Price. Request"/> </message> <message name="Get. Last. Trade. Price. Output"> <part name="body" element="xsd 1: Trade. Price"/> </message> 31

Operations: available Methods Service Port Binding Port Types Operations Messages Types <operation name="Get. Last. Trade. Price"> <soap: operation soap. Action="http: //example. com/Get. Last. Trade. Price"/> <input> <soap: body use="literal"/> </input> <output> <soap: body use="literal"/> </output> </operation> 32

Port Types: XML in/out for specific methods Service Maps Operations to Messages Port Binding Port Types Operations <port. Type name="Stock. Quote. Port. Type"> <operation name="Get. Last. Trade. Price"> <input message="tns: Get. Last. Trade. Price. Input"/> <output message="tns: Get. Last. Trade. Price. Output"/> </operation> </port. Type> Messages Types 33

Binding: Maps Protocols to Methods (Http, etc. ) Service Port Binding Port Types Operations Messages <binding name="Stock. Quote. Soap. Binding“ type="tns: Stock. Quote. Port. Type"> <soap: binding style="document“ transport="http: //schemas. xmlsoap. org/soap/http"/> <operation name="Get. Last. Trade. Price"> <soap: operation soap. Action="http: //example. com/Get. Last. Trade. Price"/> <input> <soap: body use="literal"/> </input> <output> <soap: body use="literal"/> </output> </operation> </binding> Types 34

Port: Maps URLs to Methods Service Port <port name="Stock. Quote. Port" binding="tns: Stock. Quote. Binding"> <soap: address location="http: //example. com/stockquote"/> </port> Binding Port Types Operations Messages Types 35

Service: Packages ports & bindings Service Port <service name="Stock. Quote. Service"> <documentation>My first service</documentation> <port name="Stock. Quote. Port" binding="tns: Stock. Quote. Binding"> <soap: address location="http: //example. com/stockquote"/> </port> </service> Binding Port Types Operations Messages Types 36

Document structure of WSDL r <definitions> element: the root of any WSDL - The name attribute specifies the name of the Web Service (usually it corresponds to the file name). - it contains a set of namespace definitions that are used throughout the document. name ='weatherservice‘ - <definitions. . . xmlns='http: //schemas. xmlsoap. org/wsdl/'> …… </definitions> 37

Document structure of WSDL r <definitions> contains other elements - - • types • messages • port. Type • bindings • services • . . . Each element within the document may contain a <documentation> element to provide some human readable explanation of the element that is specified. In addition, all the elements contain an attribute “name” serving as an identifier. 38

Document structure of WSDL r <types> - element Provide data types definitions All data type definitions relevant for sending and receiving the messages described The specification suggests using XML schema definitions. <types> <schema target. Namespace="http: //add. fib. upc. es/symbol. xsd" xmlns="http: //www. w 3. org/2000/10/XMLSchema"> <element name="example. Type">. . . </element>. . . </schema> </types> 39

Document structure of WSDL r <message> element - specifiy the data that will be communicated between a requester and a service - may appear multiple times and consists of a name and one or more <part> elements. - The parts specify the contents of the message. <message name='Weather. Get. Temperature'> <part name='zipcode' type='xsd: string'/> <part name='celsius' type='xsd: boolean'/> </message> <message name='Weather. Get. Temperature. Response'> <part name='Result' type='xsd: float'/> </message> 40

Document structure of WSDL r <operation> element - In order to tie the defined messages together as a request-response pair corresponding to a method call. - An operation specifies which message is the input and which message is the output. <operation name='Get. Temperature'> <input message='wsdlns: Weather. Get. Temperature' /> <output message='wsdlns: Weather. Get. Temperature. Response' /> </operation> 41

Document structure of WSDL r <port. Type> element - The collection of all operations (i. e. methods) exposed by your service <port. Type name='Weather. Soap. Port'> <operation name='Get. Temperature'> <input message='wsdlns: Weather. Get. Temperature' /> <output message='wsdlns: Weather. Get. Temperature. Response' /> </operation> <!-- other operations would go here --> </port. Type> 42

Document structure of WSDL r <binding> element - to bind the operation to the SOAP protocol. The elements presented so far described our operation in a generic way (Nothing has been said about a concrete implementation). - Next to a name attribute it contains a type attribute that references a port. Type and provides predefined binding for protocols such as SOAP, HTTP, and MIME. <binding name='Weather. Soap. Binding' type='wsdlns: Weather. Soap. Port' > …. </binding> 43

Document structure of WSDL r <binding> element (cont) - Binding to SOAP Inside the <binding> element you have a WSDL SOAP extension element called <soap: binding> which is used to specify the transport protocol you’re using (SOAP can be used over HTTP, SMTP, or possibly any other transport) and the style of request (rpc and document are the two styles). <soap: binding style='rpc' transport='http: //schemas. xmlsoap. org/soap/http' /> 44

Document structure of WSDL r <binding> element (cont) • Then for each operation that this service exposes, you specify the value of the SOAPAction that is used for the HTTP header of SOAP message <binding name='Weather. Soap. Binding' type='wsdlns: Weather. Soap. Port' > <soap: binding style='rpc' transport='http: //schemas. xmlsoap. org/soap/http' /> <operation name='Get. Temperature' > <soap: operation soap. Action='http: //tempuri. org/action/Weather. Get. Temperature' />. . </operation> </binding> 45

Document structure of WSDL r <binding> element (cont) • There has to be at least one binding for every port. Type. • In order to specify how the input and output messages of this operation are encoded, there is an operation element having three subelements: input, output, and fault. Each operation corresponds to an operation in the port. Type element. <binding name='Weather. Soap. Binding' type='wsdlns: Weather. Soap. Port' > <soap: binding style='rpc' transport='http: //schemas. xmlsoap. org/soap/http' /> <operation name='Get. Temperature' > <soap: operation soap. Action='http: //tempuri. org/action/Weather. Get. Temperature' /> <input> <soap: body use='encoded' namespace='http: //tempuri. org/message/' encoding. Style='http: //schemas. xmlsoap. org/soap/encoding/'/> </input> <output> <soap: body use='encoded' namespace='http: //tempuri. org/message/' encoding. Style='http: //schemas. xmlsoap. org/soap/encoding/'/> </output> </operation> 46

Document structure of WSDL r <service> and <port> element - A service is a set of related ports. - The binding is specified within the port element. - In order to bind to the SOAP protocol a <soap: address> is defined. • It contains a name and a location that defines an address of the same type as the transport specified in the soap: binding element. That means that we have to define a HTTP address. See the Web Service Example 47

WSDL Structure Overview r port. Type - Abstract definition of a service (set of operations) Service Port Binding (e. g. http: //host/svc) r Multiple bindings per (e. g. SOAP) port. Type: - How to access it r Ports - Where to access it port. Type operation(s) in. Mesage out. Message Abstract interface 48

WSDL Example: float Weather: : Get. Temperature(String zip. Code, bool celsius) { if (celsius) return 21. 7; else return 71. 06; } 49

WSDL Example: Defining Services r You can think of the class as the Web service and the Get. Temperature method as an operation on that service. To describe this service, you use the WSDL <service> element. <definitions name ='weatherservice‘ xmlns='http: //schemas. xmlsoap. org/wsdl/'> <service name='Weather. Service' > …… </service> </definitions> 50

WSDL Example: Defining Services (cont. ) r Each service is defined using a service element. Inside the service element, you specify the different ports on which this service is accessible. r The port definition would be like this: <port name='Weather. Soap. Port' binding='wsdlns: Weather. Soap. Binding' > <soap: address location='http: //localhost/demos/wsdl/devxpert/weatherservice. asp' /> </port> 51

WSDL Example: Defining Services (cont. ) r A Web service does not have to be exposed using SOAP. For example, if your Web service is exposed via HTTP GET, the port element would contain an <http: address/> element similar to this: <http: address location="http: //localhost/demos/wsdl/devxpert/weather. GET. asp"/> r A Web service may be accessible on many ports. For example, you might make your service available via SOAP and HTTP GET and possibly even via SMTP. For this Web service, you would have three ports each one with a different name. 52

WSDL Example: What’s Your Message? (cont. ) r To use Web services in a remote procedure call (RPC) model, there are two messages you must describe. r To describe the message structures, you use the WSDL <message> element. Each <message> contains zero or more <part> elements. A <part> corresponds to a parameter or a return value in the RPC call. <message name='Weather. Get. Temperature'> <part name='zipcode' type='xsd: string'/> <part name='celsius' type='xsd: boolean'/> </message> <message name='Weather. Get. Temperature. Response'> <part name='Result' type='xsd: float'/> </message> 53

WSDL Example: Port Types and Operations r An operation specifies which message is the input and which message is the output like this: <operation name='Get. Temperature'> <input message='wsdlns: Weather. Get. Temperature' /> <output message='wsdlns: Weather. Get. Temperature. Response' /> </operation> 54

WSDL Example: Port Types and Operations (cont. ) r The collection of all operations (i. e. methods) exposed by your service is called a port. Type and is defined using the WSDL <port. Type> element like this: <port. Type name='Weather. Soap. Port'> <operation name='Get. Temperature'> <input message='wsdlns: Weather. Get. Temperature' /> <output message='wsdlns: Weather. Get. Temperature. Response' /> </operation> <!-- other operations would go here --> </port. Type> 55

WSDL Example: Binding It All Together r We are now making a transition from abstract data types, messages, and operations to concrete physical representation of messages on the wire. To define the concrete aspects of operations, you use the WSDL <binding> element: <binding name='Weather. Soap. Binding' type='wsdlns: Weather. Soap. Port' > …. </binding> 56

WSDL Example: Binding It All Together (cont. ) r Inside the <binding> element you have a WSDL SOAP extension element called <soap: binding> which is used to specify the transport protocol you’re using (SOAP can be used over HTTP, SMTP, or possibly any other transport) and the style of request (rpc and document are the two styles). For example: <soap: binding style='rpc' transport='http: //schemas. xmlsoap. org/soap/http' /> 57

WSDL Example: Binding It All Together (cont. ) r Then for each operation that this service exposes, we specify the value of the SOAPAction HTTP header : <binding name='Weather. Soap. Binding' type='wsdlns: Weather. Soap. Port' > <soap: binding style='rpc' transport='http: //schemas. xmlsoap. org/soap/http' /> <operation name='Get. Temperature' > <soap: operation soap. Action='http: //tempuri. org/action/Weather. Get. Temperature' />. . </operation> </binding> 58

SOAP client-server interaction (rep) 59

WSDL Example: Binding It All Together (cont. ) r Finally, we must specify how the input and output messages of this operation are encoded, the complete binding looks like this: <binding name='Weather. Soap. Binding' type='wsdlns: Weather. Soap. Port' > <soap: binding style='rpc' transport='http: //schemas. xmlsoap. org/soap/http' /> <operation name='Get. Temperature' > <soap: operation soap. Action='http: //tempuri. org/action/Weather. Get. Temperature' /> <input> <soap: body use='encoded' namespace='http: //tempuri. org/message/' encoding. Style='http: //schemas. xmlsoap. org/soap/encoding/'/> </input> <output> <soap: body use='encoded' namespace='http: //tempuri. org/message/' encoding. Style='http: //schemas. xmlsoap. org/soap/encoding/'/> </output> </operation> </binding> 60

What is UDDI? r Universal Description, Discovery, and Integration (UDDI) is a standard designed to provide a searchable directory of businesses and their Web Services. r Thus, it represents the service broker that enables service requesters to find a suitable service provider. 61

Complete picture of distributed applications (using WS) 62

What is UDDI? r To get access to the UDDI services, the UDDI directory exposes a set of APIs in the form of a SOAP -based Web Service. r UDDI APIs - Publication API - Authenticated set of operations that allow organizations to publish businesses, service type specifications - Inquiry API - Non authenticated public set of operations that allows users to extract information out of the UDDI registry. 63

What is UDDI? r UDDI classifies businesses and services according to standard taxonomies r Why Classification ? - Searches based on keywords alone, could return a large set of hits for a particular search Classification of services and businesses allows to perform better searches r Registry Data • • White Pages Yellow Pages Green Pages Service. Type Registrations 64

What is UDDI? (In many ways UDDI is designed like a phone book) White Pages r White - r contains business name, text description, contact info and other related info. Yellow Pages - contains classification information about the business entity and types of the services the entity offers. Searches can be performed to locate businesses which service a particular industry or product category, or that are located within a specific geographic region. Green Pages r Green - contains information about how to invoke the offered services. • If a business entity were to offer its catalog online, its Green pages entry would have a reference to its catalog URL 65

Web Service Deployment Service. Provider Write Application Deploy Application As Service WSDL File Generation and Registration 1 WSDL SOAP Request Remote UDDI Web Service Registry Start Listener 66

Dynamic Service Invocation Service Requestor Automated Web Service Lookup Automatic Service Selection 2 3 SOAP Request WSDL(s) Remote UDDI Web Service (Registry) (SOAP Response) 1 Dynamic Client Code Generation Web Service Invocation Remote Web service 4 SOAP Request 5 SOAP Response Publish Web Service 67

r Business registry nodes - http: //uddi. microsoft. com - http: //uddi. ibm. com - http: //uddi. <companyname>. com -. . . 68

Web Services Performance r New technologies are often marketed with grand promises to solve business problems, but. . . PERFORMANCE? r Performance criteria - simultaneous requests, - latency in responding to requests, - levels of operational degradation due to increases in transaction loads. -. . . 69

Web Services Performance r Web service component stack 70

Web Services Performance r Impact of parsing and marshalling (source: http: //www-106. ibm. com/developerworks/library/ws-best 9) 71