Overview of java web services
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This document provides an overview of web services and compares SOAP and RESTful web services. It defines web services as application components that provide useful functionality via standard Internet protocols. SOAP is a protocol for sending messages in an XML format, while REST is an architectural style using resources identified by URLs and HTTP methods. The document explains how web services work and key concepts for both SOAP and REST like WSDL, UDDI, requests, and responses.
Overview of java web services
- 1. Java Training Overview Web Services
- 2. Introduction • Who am I? – Worked for TSB for 13+ years as FNA – October 2012 moved to ITSO – TSB and ITSO was kind enough to send me to San Antonio with Sean, Vicky and Tony
- 3. What we will be covering • • • • Web services architecture Web services definitions and terms How Web Services work Overview and examples of SOAP and RESTful Web Services
- 4. What we won’t be covering • Java programming • How to functional test Web Services
- 5. What are Web Services? “A piece of software that provides some useful functionality by a programmatic interface that is available via the standard protocols of the Internet.”
- 6. What are Web Services? • • • • Application components Use open protocols Self-contained and self-describing Can be discovered using Universal Description Discovery and Integration (UDDI) • Can be used by other applications • Allows data exchange between different applications and different platforms
- 7. Web Services Platform • • • • • • Lots of confusion 2 general types of Web Services – SOAP and REST SOAP is a protocol, REST is an architecture style Can have many overlaps Usually over HTTP Usually uses XML (or JSON)
- 8. How do Web Services work? CGI Web Application Browser HTML Web Service Client (Phone App) Web Service Web Service Web Service Provider Database
- 9. SOAP
- 10. SOAP… • • • • • • • • • Stands for Simple Object Access Protocol Is a communication protocol Is a format for sending messages Is designed to communicate via the Internet Is platform and language independent Is based on XML Is simple and extensible Allows you to get around firewalls Is a W3C standard
- 11. SOAP building blocks A SOAP message is an ordinary XML document containing the following elements: • An Envelope element that identifies the XML document as a SOAP message • A Header element that contains header information • A Body element that contains call and response information • A Fault element containing errors and status information
- 12. SOAP syntax rules • A SOAP message MUST be encoded using XML • A SOAP message MUST use the SOAP Envelope namespace • A SOAP message MUST use the SOAP Encoding namespace • A SOAP message must NOT contain a DTD reference • A SOAP message must NOT contain XML Processing Instructions • SOAP request could be an HTTP POST or HTTP GET
- 13. Example: A SOAP Request POST /InStock HTTP/1.1 Host: www.example.org Content-Type: application/soap+xml; charset=utf-8 Content-Length: nnn <?xml version="1.0"?> <soap:Envelope xmlns:soap="http://www.w3.org/2001/12/soap-envelope" soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding"> <soap:Body xmlns:m="http://www.example.org/stock"> <m:GetStockPrice> <m:StockName>IBM</m:StockName> </m:GetStockPrice> </soap:Body> </soap:Envelope>
- 14. Example: A SOAP Response HTTP/1.1 200 OK Content-Type: application/soap+xml; charset=utf-8 Content-Length: nnn <?xml version="1.0"?> <soap:Envelope xmlns:soap="http://www.w3.org/2001/12/soap-envelope" soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding"> <soap:Body xmlns:m="http://www.example.org/stock"> <m:GetStockPriceResponse> <m:Price>34.5</m:Price> </m:GetStockPriceResponse> </soap:Body> </soap:Envelope>
- 15. WSDL WSDL is an XML-based language for locating and describing Web services. • WSDL stands for Web Services Description Language • WSDL is based on XML • WSDL is used to describe Web services • WSDL is used to locate Web services • WSDL is a W3C standard
- 16. WSDL document structure The main structure of a WSDL document looks like this: <definitions> <types> data type definitions........ </types> <message> definition of the data being communicated.... </message> <portType> set of operations...... </portType> <binding> protocol and data format specification.... </binding> </definitions> A WSDL document can also contain other elements, like extension elements, and a service element that makes it possible to group together the definitions of several web services in one single WSDL document.
- 17. Example: WSDL document <message name="getTermRequest"> <part name="term" type="xs:string"/> </message> <message name="getTermResponse"> <part name="value" type="xs:string"/> </message> <portType name="glossaryTerms"> <operation name="getTerm"> <input message="getTermRequest"/> <output message="getTermResponse"/> </operation> </portType>
- 18. UDDI UDDI is a directory service where companies can register and search for Web services. • UDDI stands for Universal Description, Discovery and Integration • UDDI is a directory for storing information about web services • UDDI is a directory of web service interfaces described by WSDL • UDDI communicates via SOAP • UDDI is built into the Microsoft .NET platform
- 19. REST
- 20. REST • • • • • • • • XML HTTP URIs Soap has a single front door, REST has URIs Resource based, each with it's own URI Requests are GETs and responses are XML No request body, no SOAP envelope SOAP only does GET and POST, REST does GET, POST, PUT, DELETE (and others)
- 21. Key component of a REST architecture • Resources, which are identified by logical URLs. Both state and functionality are represented using resources. – The logical URLs imply that the resources are universally addressable by other parts of the system. – Resources are the key element of a true RESTful design, as opposed to "methods" or "services" used in RPC and SOAP Web Services, respectively. You do not issue a "getProductName" and then a "getProductPrice" RPC calls in REST; rather, you view the product data as a resource -and this resource should contain all the required information (or links to it).
- 22. Key component of a REST architecture • A web of resources, meaning that a single resource should not be overwhelmingly large and contain too fine-grained details. Whenever relevant, a resource should contain links to additional information -- just as in web pages. • The system has a client-server, but of course one component's server can be another component's client. • There is no connection state; interaction is stateless (although the servers and resources can of course be stateful). Each new request should carry all the information required to complete it, and must not rely on previous interactions with the same client.
- 23. Key component of a REST architecture • Resources should be cachable whenever possible (with an expiration date/time). The protocol must allow the server to explicitly specify which resources may be cached, and for how long. – Since HTTP is universally used as the REST protocol, the HTTP cache-control headers are used for this purpose. – Clients must respect the server's cache specification for each resource. • Proxy servers can be used as part of the architecture, to improve performance and scalability. Any standard HTTP proxy can be used.
- 24. REST: Request Example • REST Request is often just a URL http://www.acme.com/phonebook/UserDetails?firstName=John&lastName=Doe or http://www.acme.com/phonebook/UserDetails/firstName/John/lastName/Doe • While REST services might use XML in their responses (as one way of organizing structured data), REST requests rarely use XML.
- 25. REST: Response Example • Response is usually XML or JSON <person> <firstName>John</firstName> <lastName>Doe</lastName> <age>25</age> <address> <streetAddress>21 2nd Street</streetAddress> <city>New York</city> <state>NY</state> <postalCode>10021</postalCode> </address> <phoneNumbers> <phoneNumber type="home">212 555-1234</phoneNumber> <phoneNumber type="fax">646 555-4567</phoneNumber> </phoneNumbers> </person>
- 26. That, in a nutshell, is it
- 27. What we covered • • • • Web services architecture Web services definitions and terms How Web Services work Overview and examples of SOAP and RESTful Web Services
- 28. Questions?
Editor's Notes
- #17: A WSDL document describes a web service using these major elements:ElementDescription<types>A container for data type definitions used by the web service<message>A typed definition of the data being communicated<portType>A set of operations supported by one or more endpoints<binding>A protocol and data format specification for a particular port type
- #18: In this example the <portType> element defines "glossaryTerms" as the name of a port, and "getTerm" as the name of an operation.The "getTerm" operation has an input message called "getTermRequest" and an output messagecalled "getTermResponse".The <message> elements define the parts of each message and the associated data types.Compared to traditional programming, glossaryTerms is a function library, "getTerm" is a function with "getTermRequest" as the input parameter, and getTermResponse as the return parameter.