Web Services Mark Sapossnek CS 594 Computer Science

Web Services Mark Sapossnek CS 594 Computer Science Department Metropolitan College Boston University A couple of additions And many deletions By Jim Fawcett CSE 681 – Software Modeling and Analysis Summer 2003

Agenda w w w Web Services Overview Underlying Technologies Developing a Web Service Consuming Web Services Miscellaneous. NET My Services

Web Services Overview Business Today w CEO challenges n n n Revamp customer service Overhaul supply chain Speed up the decision process w CIO challenges n n n Reorient IT architecture Connect with a limitless number of external constituents Extend processes to external constituents

Web Services Overview Internet Business Processes Span Companies

Web Services Overview Technology Fabric Must Span Companies Too

Web Services Overview Drivers w Companies, suppliers, partners, and customers must be able to work together n n n Faster than ever before Over the Internet Or risk “death by isolation” w Leverage Internet cost structure

Web Services Overview Distributed Computing w Client/server model n n Doesn‘t scale Not secure w Distributed object model n n n Components: packaging and interoperability Remoting: remote method invocation COM, CORBA, Java RMI and EJB l l l Not Internet-friendly Interoperability issues: poor/non-existent standards Tightly coupled: still doesn‘t scale

Web Services Overview Distributed Computing w 3 -tier Application Architecture n Great way to build scalable Web applications w But such applications are silos n n Integration is an afterthought They can be integrated behind the firewall l n Even that can be a problem They do not provide a way to integrate across the firewall (i. e. over the Internet)

Web Services Overview Portals Ads Mail Other Svcs Calendar Weather Finance News

Web Services Overview Portal Limitations w w w No standard way to expose functionality Integration is expensive and error-prone Hard to outsource Not designed to be used outside original scope The problem? n n n HTML is designed for presentation to people Can’t repurpose it in a general, reliable way Don’t even think about screen scraping

Web Services Overview What Is a Web Service? w The solution? Web Services! w A Web Service exposes functionality to a consumer n n n Over the Internet or intranet A programmable URL Functions you can call over the Internet w Based on Web standards n HTTP, XML, SOAP, WSDL, UDDI, with more to come w Can be implemented in any language on any platform w Black boxes n Component-like, reusable

Web Services Overview What Is a Web Service? w Web Services allow you to interconnect: n n Different companies Many/any devices Applications Different clients l Not just browsers w Distribution and integration of application logic w Enable the programmable Web n Not just the purely interactive Web w Web Services are loosely coupled

Web Services Overview What is a Web Service? w w w New paradigm for Internet development Deliver applications as services Richer, customer-driven experience Continuous delivery of value/bits Third-generation Internet

Web Services Overview Evolution of the Web HTML, XML Generation 1 Generation 2 Generation 3 Static HTML Web Applications Web Services

Web Services Overview Application Model Partner Web Service Other Web Services Internet + XML End Users Your. Company. com Application Business Logic Tier Data Access and Storage Tier Other Applications Partner Web Service

Web Services Overview Sample Web Services. NET Alerts . NET Inbox . NET Calendar . NET Application Settings . NET Contacts . NET Documents . NET Lists . NET Devices . NET Categories . NET Favorite. Websites . NET Location. NET Presence. NET Wallet . NET Profile

Web Services Overview Sample Web Services w E-commerce: order books, office supplies, other products w Track packages: UPS, Fed. Ex w Weather w Maps w Telephone redirection, customizable rules and messages

Agenda w w w Web Services Overview Underlying Technologies Developing a Web Service Consuming Web Services Miscellaneous. NET My Services

Underlying Technologies XML Is the Glue y IP / P C T og l o n h Tec Inn Connectivity ov ati FTP, on E-ma il, Go pher Connect the Web L M T H Presentation Web Pa ges Browse the Web XML Connecting Applications Web Se rvice s Program the Web

Underlying Technologies Web Services Stack Directory: Publish & Find Services: UDDI Inspection: Find Services on server: DISCO Description: Formal Service Descriptions: WSDL Wire Format: Service Interactions: SOAP Universal Data Format: XML Ubiquitous Communications: Internet Simple, Open, Broad Industry Support

Underlying Technologies Web Services Stack w Discovery n Directory allows potential clients to locate relevant Web Services l n Inspection allows you to locate documents about Web Services located on at a given URL l n UDDI DISCO A Description language defines the format of methods provided by a Web Service l WSDL

Underlying Technologies Web Services Stack UDDI Inspection http: //www. ibuyspy. com/ibuyspy. disco Request Discovery Document DISCO Return Discovery Document (XML) Description WSDL http: //www. ibuyspy. com/ibuyspycs/Instant. Order. asmx? wsdl Request Service Description Return Service Description (XML) Wire Format Request Service Return Service Response (XML) SOAP Web Service Client Link to Discovery Document (XML) UDDI or other directory service Directory http: //www. uddi. org Locate a Service

Underlying Technologies Web Service Wire Format w The Web Service Wire Format specifies how specific messages are exchanged n n n HTTP-GET HTTP-POST SOAP w HTTP-GET and HTTP-POST use a minimal HTTP interface to invoke Web Services n Limited support for data types w SOAP provides a robust HTTP/XML interface n Extensive support for data types

XML Overview XML Schemas w XML schemas describe the structure of an XML document n XML schemas describe the tag and attribute specifications l n n Simple and compound data types XML schemas also describe constraints on the contained text XML schemas and the DTD are mutually exclusive

SOAP Overview w A lightweight protocol for exchanging information in a distributed, heterogeneous environment n It enables cross-platform interoperability w Interoperable n n n OS, object model, programming language neutral Hardware independent Protocol independent w Works over existing Internet infrastructure

SOAP Overview w Guiding principle: “Invent no new technology” w Builds on key Internet standards n n SOAP ≈ HTTP + XML Submitted to W 3 C w The SOAP specification defines: n n The SOAP message format How to send messages How to receive responses Data encoding

SOAP Is Not… w Objects-by-reference n n Distributed garbage collection Bi-directional HTTP w Activation w Complicated n n Doesn’t try to solve every problem in distributed computing Can be easily implemented

SOAP The HTTP Aspect w SOAP requests are HTTP POST requests POST /Web. Calculator/Calculator. asmx HTTP/1. 1 Content-Type: text/xml SOAPAction: “http: //tempuri. org/Add” Content-Length: 386 <? xml version=“ 1. 0”? > <soap: Envelope. . . >. . . </soap: Envelope>

SOAP Message Structure SOAP Message The complete SOAP message Headers Protocol binding headers SOAP Envelope <Envelope> encloses payload SOAP Headers SOAP Body Message Name & Data <Header> encloses headers Individual headers <Body> contains SOAP message name XML-encoded SOAP message name & data

SOAP Message Format w An XML document using the SOAP schema: <? xml version=“ 1. 0”? > <soap: Envelope. . . > <soap: Header. . . >. . . </soap: Header> <soap: Body> <Add xmlns=“http: //tempuri. org/”> <n 1>12</n 1> <n 2>10</n 2> </Add> </soap: Body> </soap: Envelope>

SOAP Server Responses w Server replies with a “result” message: HTTP/1. 1 200 OK. . . Content-Type: text/xml Content-Length: 391 <? xml version=“ 1. 0”? > <soap: Envelope. . . > <soap: Body> <Add. Result xmlns=“http: //tempuri. org/”> <result>28. 6</result> </Add. Result> </soap: Body> </soap: Envelope>

SOAP Encoding Complex Data w Data structures are serialized as XML: <soap: Envelope. . . > <soap: Body> <Get. Stock. Data. Result xmlns=“http: //tempuri. org/”> <result> <Description>Plastic Novelties Ltd</Description> <Price>129</Price> <Ticker>PLAS</Ticker> </result> </Get. Stock. Data. Rseult> </soap: Body> </soap: Envelope>

SOAP Security and Features w Builds on HTTP Security n n HTTPS X. 509 certificates w Developers / IT choose which methods to expose explicitly w Does not pass application code w Firewall-friendly w Type safe

SOAP Industry Support w w w w Develop. Mentor Inc. Digital Creations IONA Technologies PLC Jetform Object. Space Inc. Rockwell Software Inc. SAP Compaq w w w w w Microsoft Rogue Wave Software Inc. Scriptics Corp. Secret Labs AB User. Land Software Inc. Zveno Pty. Ltd. IBM Hewlett Packard Intel

SOAP Example of a SOAP Request POST /Stock. Quote HTTP/1. 1 Host: www. stockquoteserver. com Content-Type: text/xml; charset="utf-8" Content-Length: nnnn SOAPAction: "Some-URI“ <SOAP-ENV: Envelope xmlns: SOAPENV="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"> <symbol>DIS</symbol> </m: Get. Last. Trade. Price> </SOAP-ENV: Body> </SOAP-ENV: Envelope>

SOAP Example of a 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: 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>

SOAP Example of a SOAP Error HTTP/1. 1 500 Internal Server Error 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> <SOAP-ENV: Fault> <faultcode> SOAP-ENV: Must. Understand </faultcode> <faultstring>SOAP Must Understand Error </faultstring> </SOAP-ENV: Fault> </SOAP-ENV: Body> </SOAP-ENV: Envelope>

WSDL Web Services Description Language w XML schema for describing Web Services 1. Service interface definition – 2. Abstract semantics for Web Service implementation definition – Concrete end points and network addresses where Web Service can be invoked w Clear delineation between abstract and concrete messages

WSDL Schema Interface Implementation <definitions> <import> <types> <service> <message> <port. Type> <binding> <port>

WSDL Schema Interface <definitions> <import> <types> <message> • <definitions> are root node of WSDL • <import> allows other entities for inclusion • <types> are data definitions xsd • <message> defines parameters of a Web Service function <port. Type> • <port. Type> defines input and output operations <binding> • <binding> specifies how each message is sent over the wire

WSDL Schema Implementation • <service> specifies details about the implementation • <port> contains the address itself <definitions> <import> <service> <port>

Inspection DISCO w Inspection lets you find Web Services on a given site n n n A Web site publishes DISCO documents, which returns the URLs of WSDL descriptions DISCO documents can contain references to other sites and DISCO documents Dynamic discovery enables trees of directories to be searched

UDDI Overview w UDDI = Universal Description, Discovery, and Integration w Industry Initiative to address discovery n A registration database for Web Services w Specifications n n Schema for service providers and descriptions API for publishing and searching Developed on industry standards (XML, HTTP, TCP/IP, SOAP) Applies to both XML and non-XML services w Implementation n Public and private instances of specification

UDDI The Vision Advanced Discovery via Portals and Marketplaces Marketplace UDDI Registries and Protocol Marketplace Search Portal Business Users Technical Users

UDDI Information Model Provider: Information about the entity who offers a service t. Model: Descriptions of specifications for services. 1…n 0…n Service: Descriptive information about a particular family of technical offerings 0…n Binding: Technical information about a service entry point and construction specs Bindings contain references to t. Models. These references designate the interface specifications for a service.

UDDI Schema Interface Implementation <business. Entity> <business. Service> <t. Model> <binding. Template>

UDDI How UDDI Works: t. Model w t. Model = Technology Model w Generic meta-data structure to uniquely represent any concept or construct w Also includes interface protocol definitions w Powerful abstraction modeling system w Examples: WSDL files, XML schema, namespaces, categorization schemes

UDDI <t. Model> w <t. Model> represents meta-data and interfaces <t. Model xmlns="urn: uddi-org: api" t. Model. Key="UUID: AAAA-AAAAAAAA"> <name>microsoft-com: creditcheck</name> <description xml: lang="en">Check credit limits</description> <overview. Doc> <overview. URL>http: //schema. com/creditcheck. wsdl </overview. URL> </overview. Doc> <category. Bag> <keyed. Reference t. Model. Key="UUID: CD 153257 -086 A-4237 -B 336 -6 BDCBDCC 6634" key. Name="Consumer credit gathering or reporting services" key. Value="84. 16. 01. 00"/> <keyed. Reference t. Model. Key="UUID: C 1 ACF 26 D-9672 -4404 -9 D 70 -39 B 756 E 62 AB 4" key. Name="types" key. Value="wsdl. Spec"/> </category. Bag> </t. Model>

UDDI Providers, Services And Bindings w Providers n n n Examples: Accounting Department, Corporate Application Server Name, Description, Contact Information Categorization and Identification Information w Services n n n Examples: Purchase Order services, Payroll services Name, Description(s) Categorization Information w Bindings n n Description(s), access points, parameters Examples: Access Point (http: //. . . ) for Web Service

UDDI <binding. Template> w <binding. Template> represents data and implementation details <binding. Template service. Key="33 c 3 d 124 -e 967 -4 ab 1 -8 f 51 d 93 d 95 fac 91 a" binding. Key="48 f 2 bc 6 b-a 6 de-4 be 8 -9 f 2 b 2342 aeafaaac"> <access. Point URLType="http"> http: //localhost/Hello. World/Service 1. asmx </access. Point> <t. Model. Instance. Details> <t. Model. Instance. Info t. Model. Key="uuid: 64 c 756 d 1 -33744 e 00 -ae 83 -ee 12 e 38 fae 63“/> </t. Model. Instance. Details> </binding. Template>

UDDI Important UDDI Features w Neutral in terms of protocols – as a registry, it can contain pointers to anything w Can search by business, service, Web Service (t. Model), binding w Usage of Globally Unique Identifiers (GUIDs) w Specification allows public and private nodes w Delineation between interface and implementation

GXA Global XML Web Services Architecture Inter Application Protocols Reliable Messaging Eventing Discovery Building Block Modules Directory Inspection Description Transactions Referral Security … Routing License … SOAP The Internet TCP/IP XML HTTP/SMTP

GXA New Web Services Specifications w WS-Inspection n Inspection w WS-Routing n Route messages over protocols w WS-Referral n Dynamic configuration of message routing w WS-Security n Credentials, integrity, confidentiality w WS-License n Signed user credentials

Agenda w w w Web Services Overview Underlying Technologies Developing a Web Service Consuming Web Services Miscellaneous. NET My Services

Developing a Web Service Basics w Web Service n n Implemented in ASP. NET Similar to Web Forms, but l l n n n have a. asmx file extension contains code, w/o UI Lives in a virtual directory Can have a code-behind ASP. NET provides simple test harness ASP. NET automagically generates WSDL Can use. NET Framework classes and custom assemblies and classes

Developing a Web Service Code and Syntax w Codebehind <%@ Web. Service Language="c#" Codebehind="My. Web. Service. cs" Class="First. Web. Service. Math. Service" %> w Inline (in C#) <%@ Web. Service Language=“C#“ Class=“Math. Service“ %> using System. Web. Services; public class Math. Service : Web. Services { [Web. Method] public int Add(int num 1, int num 2) { return num 1 + num 2; } }

Agenda w w w Web Services Overview Underlying Technologies Developing a Web Service Consuming Web Services Miscellaneous. NET My Services

Consuming Web Services Overview w Locate the desired Web Service n n UDDI DISCO w Get detailed description of Web Service n WSDL w Create a proxy that represents the Web Service n Proxy has the same methods/arguments/return values as the Web Service w Application instantiates and uses the proxy as if it were a local object

Consuming Web Services Overview Web Service Developer Create with WSDL. exe Web Application Developer Web Server S. asmx Service App Web Server C Proxy. cs Web Form. aspx Service Application

Consuming Web Services Overview w Web Services are URL addressable n HTTP request/response w Can request WSDL via URL w Can invoke via: n n n HTTP-GET HTTP-POST HTTP-SOAP

Consuming Web Services Invoking via HTTP-GET w HTTP-GET http: //localhost//Math. Service. asmx/Multiply? a=11&b=11 n Result is an XML document <? xml version="1. 0" encoding="utf-8" ? > <int xmlns="http: //www. microsoft. com/Math. Service/">121</int>

Consuming Web Services Invoking via HTTP-POST w HTTP-POST /Math. Service. asmx/Multiply HTTP/1. 1 Host: localhost Content-Type: application/x-www-form-urlencoded Content-Length: length a=11&b=11 n Result is an XML document <? xml version="1. 0" encoding="utf-8" ? > <int xmlns="http: //www. microsoft. com/Math. Service/">121</int>

Consuming Web Services Invoking: HTTP-SOAP w XML grammar for n Web. Method, Method parameter, results w Supports all standard. NET datatypes and value classes n Additionally: classes, structs, datasets w Class and struct marshalling n Serialization in XML format

Consuming Web Services Type Marshalling w Using HTTP-GET or HTTP-POST n Primitive types l n n n E. g. int, string, float, double, byte, … Enum types Arrays of primitives and enums By-value only

Consuming Web Services Type Marshalling w Using SOAP n n n n Primitive types Enum types Classes and structs Data. Set Xml. Node Arrays of all of the above By-value and by-reference are supported

Consuming Web Services Trying It Out w Request without method name or parameters n ASP. NET returns a page listing all methods http: //localhost/Math. Service. asmx w Click one of the methods and you can test it out http: //localhost/Math. Service. asmx? op=Multiply n Specify parameters and Invoke l n Only for primitive data types Sample requests/responses

Consuming Web Services Trying It Out w Request with parameter “WSDL” n n n Formal WSDL description of Web Service XML-based grammar Can be used as input for wsdl. exe http: //localhost/Math. Service. asmx? WSDL

Consuming Web Services Creating a Proxy w Use wsdl. exe to generate a proxy wsdl http: //localhost/Math. Service. asmx? WSDL n n Creates Math. Service. cs Contains Math. Service class, derived from Soap. Http. Client. Protocol in the System. Web. Services. Protocols namespace l l n Or Http. Get. Client. Protocol or Http. Post. Client. Protocol You can instantiate these classes dynamically Proxy embeds URL to the Web Service in the constructor

Consuming Web Services Using Visual Studio. NET w Use Add Web Reference to search UDDI or to discover Web Services given a URL w This builds a proxy, and you can start using the Web Service immediately n Visual Studio. NET essentially calls disco. exe and wsdl. exe for you

Agenda w w w Web Services Overview Underlying Technologies Developing a Web Service Consuming Web Services Miscellaneous. NET My Services

Miscellaneous State Management w Web Services are stateless w Use ASP. NET session state mechanism n What is a session? l l n Functionality l l n Restricted to a logical application Context in which a user communicates to a server Request identification and classification Store data across multiple requests Session events Release of session data . NET State Server Process

Miscellaneous Security Model w Reasons for security n n Prevent access to areas of your Web server Record and store secure relevant user data w Security configuration w Authentication, Authorization, Impersonation Web Client IIS ASP. NET App w Code Access Security n Are you the code you told me you are? . NET OS

Miscellaneous HTTP and Firewalls Client U DCOM Service Port 80 Web Service U RMI Service Firewall

Miscellaneous Secure Sockets Layer Raw HTTP Client <soap: Body> <Add. Result xmlns=. . . > <result>28. 6</result> </Add. Result> </soap: Body> Client SSL <soap: Body> <Add. Result xmlns=. . . > <result>28. 6</result> </Add. Result> </soap: Body> Web Service

Miscellaneous Security Model w Similar to securing a Web site n Clients are computers and businesses w Possible options with IIS n n n n IPSec Basic over SSL Digest Integrated Client certificates Passport?

Miscellaneous Transactions w Like ASP. NET Web Forms w COM+ services n n COM+ automatic transactions atomic, consistent, isolated, durable (ACID) SQL Server Application Web Service COM+ transaction context MSMQ Server

Miscellaneous Transactions w [Web. Method(Transaction= Transaction. Required)] w Transaction modes n n Supported Not. Supported Requires. New

Miscellaneous Execution Model w Synchronous n Like any other call to class methods w Asynchronous n Split the method into two code blocks l l n Begin. Method. Name End. Method. Name CLR determines if operation has finished

Miscellaneous SOAP Toolkit w An SDK for building Web Services using Visual Studio 6. 0 n n n Components allowing an ASP page to act as a facade for a COM object Wizard for generating WSDL descriptions from COM servers Client-side engine for dynamically creating an Automation proxy from WSDL

Agenda w w w Web Services Overview Underlying Technologies Developing a Web Service Consuming Web Services Miscellaneous. NET My Services

. NET My. Services What If You Could… w Access the entire Internet with one password w Buy anything instantly w Be alerted of the things you care about w Change your address in one place w Use a single calendar across your work and family

. NET My. Services How Would That Change Your Business? w w w Reach new customers Provide better service Create revolutionary new applications Gain competitive advantage Differentiate your company . NET My Services creates the opportunity to do things that couldn’t be done before

. NET My. Services Motivation ? ? w Users have multiple technology islands w Inconsistent, impersonal, user not in control w Islands don’t work well together

. NET My. Services User-Centric Web Services. NET Alerts . NET Inbox . NET Calendar . NET Application Settings . NET Contacts . NET Documents . NET Lists . NET Devices . NET Categories . NET Favorite. Websites . NET Location . NET Passport . NET Presence. NET Wallet . NET Profile

. NET My. Services . NET Alerts Available Now w Alerts are a better way to touch customers so they can act on new info quickly n n n Product shipment Outbid at an auction … w User in control n n Routed based on user preferences Users opt-in and cannot be spammed w You can reach a huge customer base today n n MSN Messenger has more than 40 million users Many other end-points: Windows XP, cell phones… Alerts SDK here now; test cloud coming later this year On the road to. NET My Services

Conclusion w w w Web Services Overview Underlying Technologies Developing a Web Service Consuming Web Services Miscellaneous. NET My Services

Resources w Web Services Essentials http: //msdn. microsoft. com/library/default. asp? URL= /library/techart/webservicesessentials. htm w SOAP http: //msdn. microsoft. com/soap w SOAP Specification http: //www. w 3. org/TR/SOAP/ w Don Box on SOAP http: //msdn. microsoft. com/msdnmag/issues/0300/soap. asp w Introduction to SOAP http: //www. w 3. org/2000/xp/Group/Admin/minutes-oct 1100 /soap-xp-wg_files/frame. htm

Resources w WSDL Specification http: //www. w 3. org/TR/wsdl w A Quick Introduction to WSDL http: //msdn. microsoft. com/library/default. asp? url=/library /enus/soap/htm/soap_overview_72 b 0. asp? frame=true w UDDI http: //www. uddi. org http: //uddi. microsoft. com w Hail. Storm http: //www. microsoft. com/net/hailstorm. asp w Building Web Services with SOAP and ASP. NET http: //msdn. microsoft. com/msdnmag/issues/01/02/Web. Comp /webcomp. asp

Resources w GXA Web Services Specifications http: //msdn. microsoft. com/library/default. asp? url=/library/enus/dnsrvspec/html/wsspecsover. asp? frame=true