1 / 41

Client/Server Distributed Systems

Client/Server Distributed Systems. 240-322 Semester 1, 2005-2006. Objectives introduce the J2EE specification, and the J2EE SDK other approaches: Struts, Spring Web Services (XML-RPC). 14. J2EE and Web Services. Contents. 1. What is J2EE? 2. J2EE Overview 3. Some Services Explained

truda
Download Presentation

Client/Server Distributed Systems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Client/Server Distributed Systems 240-322 Semester 1, 2005-2006 • Objectives • introduce the J2EE specification, and the J2EE SDK • other approaches: Struts, Spring • Web Services (XML-RPC) 14. J2EE and Web Services

  2. Contents 1. What is J2EE? 2. J2EE Overview 3. Some Services Explained 4. Using Sun's J2EE SDK 5. More Information on J2EE 6. Struts 7. Spring 8. Web Services

  3. 1. What is J2EE? • J2EE is the Java 2 Enterprise Edition • J2EE helps with the construction of Web-based client/server applications • it supports simplified networking, concurrency, transactions, easy access to databases, etc. continued

  4. J2EE emphasies n-tier client/server design. • Application development uses objects, beans, and components. • J2EE is not language neutral • tightly connected to Java continued

  5. Sun initially released J2EE as a specification, which has been implemented by different vendors • e.g Tomcat from the Jakarta Project • http://jakarta.apache.org/tomcat/ • e.g. JRun from Macromedia (Allaire) • http://www.macromedia.com/software/jrun • The Sun implementation: • http://java.sun.com/j2ee/

  6. 2. J2EE Overview JDBC presentation logic JavaMail JSPs applet/ appl. Tag libraries servlets RMI app. deploymentdescription client Web container IIOP CORBA EJB container business logic JNDI Entity beans Session beans JMS server-side application network

  7. A server-side application usually has two parts: • presentation logic in the Web container • to create HTML pages (and other formats) • business logic in the EJB container • to handle server-side processing

  8. 3. Some Service Explained • Servlets • a servlet is a Java object on the server side that can repond to an HTTP message (GET, POST, etc) by calling a method • the results of the method is sent back to the client as a Web page continued

  9. JSP (Java Server Pages) • JSPs dynamically generate Web pages by using servlets • EJB (Enterprise Java Beans) • Java objects with predefined methods for simplifying network and inter-object communication continued

  10. Java IDL (Interface Definition Lang.) • a language which allows Java objects to interact with CORBA objects • RMI-IIOP • a bridge between Java’s RMI and the communication protocol used by CORBA over the Internet (IIOP) continued

  11. JTA (Java Transaction API) • JTA lets a Java object control transactions (e.g. bank account updates) • JMS (Java Message Service) • JMS lets a Java object asynchronously send messages to other objects continued

  12. JNDI (Java Naming & Directory Interface) • JNDI lets a Java object find other objects (over the network) by using their names continued

  13. The deployment description is a text file containing various information on how to configure/initialise the server-side application • the information is written in XML format

  14. 4. Using Sun's J2EE SDK • J2EE SDK is Sun's implementation of the J2EE specification. • The latest version: • Java 2 SDK, Enterprise Edition, v.1.4:http://java.sun.com/j2ee/1.4/ download.html • also obtain the tutorial for v.1.4 from the page continued

  15. This release is available for the following platforms: • Solaris, Windows 2000 Prof. Ed., Windows XP Prof. Ed., Linux Redhat • The API documentation is packaged with the download bundle. continued

  16. To download J2EE SDK v.1.4, you have to register as a member of the Java Developer Connection • membership is free • Easier to get it from Aj. Somchai's site: • http://java.coe.psu.ac.th/ RefImp.html#J2EE • 102 Mb for everything

  17. Sun's J2EE SDK as a Diagram

  18. Java Server Faces (JSF) • An API for building Web-based client-side user interfaces from components. • communication to the server side is built-in • the components are extensible • Simplifies the design and implementation of the presentation level of client/server applications. continued

  19. Coding is based on listening for events. • JSF 1.2 will be integrated into the next release of J2EE (version 1.5, renamed to 5.0)

  20. JSTL • The JavaServer Pages Standard Tag Library • structural tasks, such as iteration and conditionals • tags for manipulating XML documents • internationalization tags • SQL tags • a framework for integrating existing custom tags with JSTL

  21. Ant • The compilation of the examples in the J2EE tutorial use Ant, a Java-based make utility, found at: • http://jakarta.apache.org/ant/ • Ant v.1.6.2 (and before) are available here • http://java.coe.psu.ac.th/ OpenSource.html#Ant

  22. 5. More Information on J2EE • J2EE main site: • http://java.sun.com/j2ee/ • it has links to pages dedicated to parts of J2EE (e.g. EJB, JSP, servlets, XML) • Aj. Somchai's J2EE books section: • http://java.coe.psu.ac.th/ ForMember/Books.html#J2EE

  23. notifies controller 6. Struts model view updates • An open source framework • intended to be a simpler replacement for J2EE • many components of J2EE can be used • http://struts.apache.org/ • Utilises the Model-View-Controller(MVC) design style for applications. continued

  24. Model tools: • JDBC, EJB, Hibernate • View tools: • JSP, XML/XSLT, JSF • Controller tools: • servlets, tag libraries, specific to Struts • Available from: • http://struts.apache.org/

  25. 7. Spring • Another open source framework • intended to be a simpler replacement for J2EE • many components of J2EE can be used • http://www.springframework.org/ • Utilises the Inversion of Control (IoC)design pattern • the framework does more (manages more) , the programmer codes less continued

  26. The core of Spring's design is the org.springframework.beans package, designed for working with Java Beans • objects utilise standard get/set methods to simplify communication • A Spring bean factory enables objects to be retrieved by name, and manages relationships between objects. continued

  27. Configuration details are specified using XML and method prototypes. • Unit testing is simpler. • Primary use is to replace or simplify EJB applications.

  28. 8. Web Services • A collection of XML-based APIs for allowing Web-based (J2EE) applications to: • exchanging messages • describing their services/capabilities • publish their Web service description(s) • find other Web service descriptions

  29. 8.1. Web Service Architecture

  30. 8.2. Some Web Services APIs • Simple Object Access Protocol (SOAP) • XML-based messaging protocol • Web Services Description Language (WSDL) • XML language for describing Web services and their capabilities • Java API for XML Registries (JAXR) • language for building XML directories of information about Web services continued

  31. Java API for XML-based RPC (JAX-RPC) • language for converting remote procedure call data into XML • Java API for XML Messaging (JAXM)

  32. 8.3. Focus on XML-RPC • An implementation of RPC which uses HTTP and XML to support remote method calls • there are implementations for Java, C++, PHP, etc. • http://www.xmlrpc.com

  33. The most popular Java implementation of XML-RPC is Apache XML-RPC • http://xml.apache.org/xmlrpc • part of the larger Apache XML project

  34. XML-RPC Approach 1. send inputs as XML in a POST message XML-RPCserver :int x = sqS.square(14) : 2. send result as aHTTP response page XML-RPC client sqS handler at foobar.com

  35. Example XML-RPC Request POST /XMLRPC HTTP/1.0Host: foobar.comConnection: CloseContent-Type: text/xmlContent-Length: 151User-Agent: OSE/XML-RPC<?xml version="1.0"?><methodCall> <methodName>sqS.square</methodName> <params> <param> <value> <int>14</int> </value> </param> </params></methodCall>

  36. XML-RPC Response HTTP/1.0 200 OKDate: Wed, 11 May 2005 22:08:09 GMTServer: Apache/1.3.26 (Unix)Content-Length: 157Connection: closeContent-Type: text/xml<?xml version="1.0"?><methodResponse> <params> <param> <value> <int>196</int> </value> </param> </params></methodResponse>

  37. Sample Client Code // create client link to serverXmlRpcClient client = new XmlRpcClient( "http://foobar.com/XMLRPC");// create a parameters vector for the requestVector params = new Vector();params.addElement( new Integer(14) );// send the request and get the responseObject resultObj = client.execute( "sqS.square", params);int result ((Integer) resultObj).intValue(); // result will be 196

  38. Sample Server Code public class SquareServer{ public SquareServer() {} public Integer square(int x) { return new Integer( x*x ); } : continued

  39. public static void main(String[] args) { try { // invoke XML-RPC server WebServer server = new WebServer(); // add handler for the service server.addHandler("sqS", new SquareServer()); } catch (Exception ex) {} }} // end of SquareServer class

  40. 8.4. Web Services Resources • The Java Web Services Developer Pack (Java WSDP), version 1.5 • http://java.sun.com/webservices/ or • http://java.coe.psu.ac.th/ RefImp.html#WebServices continued

  41. In the CoE library: • Java Web Services for Experienced ProgrammersDeitel et al, Prentice Hall, 2003 • very detailed, but a little bit out of date

More Related