Creating & Consuming Web Services MIS 424 MIS 424 Professor Sandvig Professor Sandvig

Overview – Web Services What are Web Services? Benefits Who is using them Using in.NET –How to create –How to consume

What are Web Services? Web services allow applications to communicate with each other via Internet Islands of data Huge databases –Every large organization –Can’t communicate, share Between organizations Within organizations

What are Web Services? Underlying Technologies –XML Defines data content –SOAP Simple object access protocol –Protocol  rules Advantage –HTTP: name-value pairs –SOAP: data relationships Data types Both are W3.org standards –Supported by all major vendors

Why Now? Historically –Physical distance –Small data pipelines Now –Internet, fiber optics, … –Distance not a problem Recent: mid-1990’s Limitation –Need common language & protocols Solution –Web Services: XML & Soap

Who is using? Amazon –Retrieve shipping info –Expose product database UPS –Shipping status, pricing information, etc. Google –Expose database –Tap creativity of programmers Ideas for free Ideas for free Others?? –Difficult to tell, background process Overstock.com web site

Using Web Services in.NET Web Service Namespaces –Implements XML & SOAP technologies –Dozens of classes High level Handle messy details –MSDN Documentation Documentation Heavily promoted functionality of.NET

Using Web Services Two roles: –Create Expose your data/application to other –Consume Utilize web services offered by others

Creating Web Services Visual Studio: –Add new item: Web Service.asmx file

Creating Web Service Default.asmx file:

Creating Web Services Example:Testing –Via HTTP Request.asmx file –CreateWebService.asmx, (source.doc) CreateWebService.asmxsourceCreateWebService.asmxsource

Consuming Web Service Create proxy –Visual Studio 1. Add service reference… 2. Paste in web service description language (wsdl) –VS creates classes that utilize service 3. Use like any other classes

Consuming Web Service Visual Studio Paste web service URL

Consuming Web Service WSDL returns service description: –Give descriptive name and click OK

Consuming Web Service Visual Studio creates class (proxy) representing web service Adds info to web.config

Consuming Web Services Service now represented by class Service methods visible via Intellisense

Consuming Web Service Example: –ConsumeWebService.aspx ConsumeWebService.aspx –.asmx files can handle AJAX calls See assignment 4 –ObjectDataSource control: Use VS wizard to select web service class

Summary – Web Services Allow applications to communicate –Connect islands of data Based upon W3 standards.NET support –Very easy to publish & consume