- Slides: 16
Web Services Primer Overview of Web Services Alphabet Soup (XML SOAP WSDL UDDI) Software Architecture Haven't we seen this before? ? Two views Are Web Services the Future? ? (Some of this material is lifted from Chris Ellsworth’s Intro. to Web Services podcast. )
Overview of Web Services Provide a means for distributed computing Based on Internet standards Platform and language independent A web service is a software unit which is exposed on the web through SOAP, described by a WSDL file, and registered in a UDDI directory.
Basic Web Service Architecture
Alphabet Soup XML – e. Xtended Markup Language WSDL – Web Service Description Language Written in XML Describes web services (location, methods, params, types, etc. ) SOAP – Simple Object Access Protocol Structured, hierarchical document spec: <mytag> </mytag> XML based message format for web service communications UDDI - Universal Description, Discovery and Integration Registries of published web services (MS, IBM)
Basic Web Service Architecture UDDI SOAP WSDL
We’ve seen program units before! Within a single application Procedures, objects, etc. NOT language, platform independent Cooperating and separate program units JNI (on same machine) Remote Procedure Call (RPC) Very low-level Client must know about server (methods, types, ports, etc. ) Other middlewares (CORBA, DCOM+, etc. )
Web Services Add. . . More decoupling between client and server units More independence, flexibility Standard communication method HTTP uses port 80 No special server configuration (firewalls, etc. ) Discovery (like Java's reflection) The WSDL file allows a client to learn about what services are available and how to use them.
A “Building Blocks” View Web Service Client http: // WSDL XML SOAP
A “Functional” View Web Server 1. HTTP request w/ SOAP payload 5. HTML reply w/ SOAP payload 4. SOAP reply Client HTML 3. Web Method Web Service 2. S O A P r eq
Web Services: The Future ? ? Customer – Retailer – Wholesaler – Producer “Value-added” products/hardware (think Dell)
Web Services: The Future ? ? Customer – Retailer – Wholesaler – Producer “Value-added” products/hardware (think Dell) Customer - Software Inc. - Service Provider “Value-added” information!!
Web Services: The Future ? ? Customer – Retailer – Wholesaler – Producer “Value-added” products/hardware (think Dell) Customer - Software Inc. - Service Provider “Value-added” information!! Google web service – search results Amazon web service – product details Map. Point web service – maps/directions
The “Not-So” Old Days Your sites/applications pushed custom parameters to other sites, then watched customers go there Consider a “Book. Broker” website/application A link to Map. Quest for a map to nearest bookstore A link to Amazon for book info A link to Google for search results of book clubs Customer leaves your site, goes there, hopefully comes back.
The “Not-So” Far Away Days Your Book. Broker site integrates the Map. Point, Google, and Amazon web services into your site. Customers never have to leave! Your site sends request to web service, gets back result data and integrates that data back into your site.
Web Services: Show Me the $$ ! Customer – Retailer – Wholesaler – Producer “Value-added” products/hardware (think Dell) Customer - Software Inc. - Service Provider “Value-added” information!!
Web Service Providers Make $$$ Microsoft Map Point Must purchase a license (free developer account!) (But, Free to qualified education institutions) Google Search Up to 1, 000 free queries per day (10/31/06) Amazon Web Services Some free, some have costs (Web. Search: $0. 30/1000)