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20 Maart 2006ISS - Internet Applications Part 21 Internet Applications part 2 René de Vries Based on slides by M.L. Liu and Marko van Eekelen.

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Presentation on theme: "20 Maart 2006ISS - Internet Applications Part 21 Internet Applications part 2 René de Vries Based on slides by M.L. Liu and Marko van Eekelen."— Presentation transcript:

1 20 Maart 2006ISS - Internet Applications Part 21 Internet Applications part 2 René de Vries Based on slides by M.L. Liu and Marko van Eekelen

2 20 Maart 2006ISS - Internet Applications Part 22 Overview 1.Applets 2.Servlets 3.Web Services 4.SOAP References, Exercises

3 20 Maart 2006ISS - Internet Applications Part Applets

4 20 Maart 2006ISS - Internet Applications Part 24 Introduction Three kinds of Java programs: –An application is a standalone program that can be invoked from the command line. –An applet is a program that runs in the context of a browser session. –A servlet is a program that is invoked on demand on a server program and that runs in the context of a web server process.

5 20 Maart 2006ISS - Internet Applications Part 25 Applets, web page, client, server Applets are programs stored on a web server, similar to web pages. When an applet is referred to in a web page that has been fetched and processed by a browser, the browser generates a request to fetch (or download) the applet program, then executes the program in the browser’s execution context, on the client host.

6 20 Maart 2006ISS - Internet Applications Part 26 Java Applet Execution - 1 An applet program is written as a subclass of the java.Applet class or the javax.swing.Japplet class. There is no main method: you must override the start method. Applet objects uses AWT for graphics. JApplet uses SWING. An applet is a Graphics object that runs in a Thread object, so every applet can perform graphics, and runs in parallel to the browser process.

7 20 Maart 2006ISS - Internet Applications Part 27 Java Applet Execution - 2 When the applet is loaded, these methods are automatically invoked in order: –The init( ) method is invoked by the Java Virtual Machine. –The start( ) method –The paint( ) method. The applet is now running and rendered on the web page. You program the start( ) method and the paint( ) method for your application, and invoke a repaint call to re-render the graphics, if necessary. At the end of the execution, the stop( ) method is invoked, followed by the destroy( ) method to deallocate the applet’s resources.

8 20 Maart 2006ISS - Internet Applications Part 28 Applet Security For security reasons, applets that are loaded over the network have several restrictions. –an applet cannot ordinarily read or write files on the computer that it's executing on –an applet cannot make network connections except to the host that it came from

9 20 Maart 2006ISS - Internet Applications Part 29 Advanced Applets You can use threads in an applet. You can make socket calls in an applet, subject to the security constraints.

10 20 Maart 2006ISS - Internet Applications Part 210 Proxy server A proxy server can be used to circumvent the security constraints.

11 20 Maart 2006ISS - Internet Applications Part 211 HTML tags for applets - 1

12 20 Maart 2006ISS - Internet Applications Part 212 HTML tags for applets - 2 end of this parameter specifies the end of the HTML applet code

13 20 Maart 2006ISS - Internet Applications Part 213 The HelloWorld Applet // applet to display a message in a window import java.awt.*; import java.applet.*; public class hello extends Applet{ public void init( ){ setBackground(Color.yellow); } public void paint(Graphics g){ final int FONT_SIZE = 42; Font font = new Font("Serif", Font.BOLD, FONT_SIZE); // set font, and color and display message on // the screen at position 250,150 g.setFont(font); g.setColor(Color.blue); // The message in the next line is the one you will see g.drawString("Hello, world!",250,150); }

14 20 Maart 2006ISS - Internet Applications Part 214 Applets Summary An applet is a Java class Its code is downloaded from a web server It is run in the browser’s environment on the client host It is invoked by the browser when it scans a web page and encounters a class specified with the APPLET tag For security reasons, the execution of an applet is normally subject to restrictions: –applets cannot access files in the file system on the client host –applets cannot make network connection except to the server host from which it originated

15 20 Maart 2006ISS - Internet Applications Part Servlets

16 20 Maart 2006ISS - Internet Applications Part 216 Introduction Servlets are modules that extend request/response-oriented servers, such as Java-enabled web servers. Servlets can be embedded in many different servers because the servlet API, which you use to write servlets, assumes nothing about the server's environment or protocol. Servlets are portable.

17 20 Maart 2006ISS - Internet Applications Part 217 Java Servlet Basics A servlet is an object of the javax.servlet class, which is not part of the JDK. A servlet runs inside a Java Virtual Machine (JVM) on a server host. A servlet is an object. It is loaded and runs in an object called a servlet engine, or a servlet container.

18 20 Maart 2006ISS - Internet Applications Part 218 Uses for Servlets Providing the functionalities of CGI scripts with a better API and enhanced capabilities. Allowing collaboration between people. A servlet can handle multiple requests concurrently, and can synchronize requests. This allows servlets to support systems such as on-line conferencing. Forwarding requests. Servlets can forward requests to other servers and servlets. Thus servlets can be used to balance load among several servers that mirror the same content, and to partition a single logical service over several servers, according to task type or organizational boundaries.

19 20 Maart 2006ISS - Internet Applications Part 219 The Servlet class The Servlet class is not part of the Java Development Kit (JDK). There are many packages that support servlets, including –The JSWDK (Java Server Web Development Kit) – the API documentation can also be downloaded from the same site – freeware provided by Sun for demonstration of the technology, downloadable from om/products/servlet/download.html om/products/servlet/download.html –The Tomcat : a free, open-source implementation of Java Servlet and JavaServer Pages technologies developed under the Jakarta project at the Apache Software Foundation. –Application servers such as WebLogic, iPlanet, WebSphere.

20 20 Maart 2006ISS - Internet Applications Part 220 The architecture for servlet support

21 20 Maart 2006ISS - Internet Applications Part 221 The Life Cycle of an HTTP Servlet The web server loads a servlet when it is called for in a web page. The web server invokes the init( ) method of the servlet. The servlet handles client responses. The server destroys the servlet (at the request of the system administrator). A servlet is normally not destroyed once it is loaded.

22 20 Maart 2006ISS - Internet Applications Part 222 The Servlet Life Cycle

23 20 Maart 2006ISS - Internet Applications Part 223 A simplified sequence diagram

24 20 Maart 2006ISS - Internet Applications Part 224 The Servlet Interface

25 20 Maart 2006ISS - Internet Applications Part 225 Generic Servlets and HTTP Servlets Java Servlet Programming, O’Reilley Press Every servlet must implement the javax.servlet.Servlet interface Most servlets implement the interface by extending one of these classes –javax.servlet.GenericServlet: most general –javax.servlet.http.HttpServlet: an extension of HTTP servers. A generic servlet should override the service( ) method to process requests and generate appropriate responses. An HTTP servlet overrides the doPost( ) and/or doGet( ) method.

26 20 Maart 2006ISS - Internet Applications Part 226 Generic and HTTP Servlets

27 20 Maart 2006ISS - Internet Applications Part 227 A simple Servlet, from public class SimpleServlet extends HttpServlet { /** * Handle the HTTP GET method by building a simple web page. */ public void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { PrintWriter out; String title = "Simple Servlet Output"; // set content type and other response header fields first response.setContentType("text/html"); // then write the data of the response out = response.getWriter(); out.println(" "); out.println(title); out.println(" "); out.println(" " + title + " "); out.println(" This is output from SimpleServlet."); out.println(" "); out.close(); } //end method } // end class

28 20 Maart 2006ISS - Internet Applications Part 228 Using HTTP Servlet to process web forms Requests and Responses Methods in the HttpServlet class that handle client requests take two arguments: –An HttpServletRequest object, which encapsulates the data from the client –An HttpServletResponse object, which encapsulates the response to the client The methods for handling HTTP requests and responses are: –public void doGet (HttpServletRequest request, HttpServletResponse response) for requests sent using the GET method. –public void doPost(HttpServletRequest request, HttpServletResponse response) for requests sent using the POST method.

29 20 Maart 2006ISS - Internet Applications Part 229 HttpServletRequest Objects An HttpServletRequest object –provides access to HTTP header data, such as any cookies found in the request and the HTTP method with which the request was made. –allows you to obtain the arguments that the client sent as part of the request. To access client data sent with an HTTP request: The getQueryString method returns the query string. The getParameter method returns the value of a named parameter. The getParameterValues method returns an array of values for the named parameter.

30 20 Maart 2006ISS - Internet Applications Part 230 HttpServletRequest Interface public String ServletRequest.getQueryString( ); returns the query string of the request. public String GetParameter(String name): given the name of a parameter in the query string of the request, this method returns the value. public String[ ] GetParameterValues(String name): returns multiple values for the named parameter – use for parameters which may have multiple values, such as from checkboxes. public Enumeration getParameterNames( ): returns an enumeration object with a list of all of the parameter names in the query string of the request.

31 20 Maart 2006ISS - Internet Applications Part 231 HttpServletResponse Objects An HttpServletResponse object provides two ways of returning data to the user: –The getWriter method returns a Writer –The getOutputStream method returns a ServletOutputStream Use the getWriter method to return text data to the user, and the getOutputStream method for binary data. Closing the Writer or ServletOutputStream after you send the response allows the server to know when the response is complete.

32 20 Maart 2006ISS - Internet Applications Part 232 HttpServletResponse Interface public interface HttpServletResponse extends ServletResponse: “The servlet engine provides an object that implements this interface and passes it into the servlet through the service method” – “Java Server Programming” public void setContentType(String type) : this method must be called to generate the first line of the HTTP response: public PrintWriter getWriter( ) throws IOException: returns an object which can be used for writing the responses, one line at a time using out.println().

33 20 Maart 2006ISS - Internet Applications Part 233 Servlets are Concurrent HTTP servlets are typically capable of serving multiple clients concurrently: the servlet engine uses a separate thread to invoke each method. Hence servlet methods should be thread-safe: If the methods in your servlet do work for clients by accessing a shared resource, then you must either: –Synchronize access to that resource, or –Ensure that the servlet can handle only one client request at a time (by using semaphores or locks).

34 20 Maart 2006ISS - Internet Applications Part 234 Handling GET requests methods.html public class BookDetailServlet extends HttpServlet { public void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {... // set content-type header before accessing the Writer response.setContentType("text/html"); PrintWriter out = response.getWriter(); // then write the response out.println(" " + " Book Description " +... ); //Get the identifier of the book to display String bookId = request.getParameter("bookId"); if (bookId != null) { // fetch the information about the book and print it... } out.println(" "); out.close(); }... }

35 20 Maart 2006ISS - Internet Applications Part 235 Handling POST Requests methods.html public class ReceiptServlet extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {... // set content type header before accessing the Writer response.setContentType("text/html"); PrintWriter out = response.getWriter( ); // then write the response out.println(" " + " Receipt " +...); out.println("Thank you for purchasing your books from us " + request.getParameter("cardname") +...); out.close(); }... }

36 20 Maart 2006ISS - Internet Applications Part 236 Servlet Examples See Servlet\simple folder in code sample: HelloWorld.java: a simple servlet Counter.java: illustrates that a servlet is persistent Counter2.java: illustrates the use of synchronized method with a servlet GetForm.html, GetForm.java: illustrates the processing of data sent with an HTTP request via the GET method PostForm.html, PostForm.java: illustrates the processing of data sent with an HTTP request via the POST method

37 20 Maart 2006ISS - Internet Applications Part 237 Session State Information The mechanisms for state information maintenance with CGI can also be used for servlets: hidden-tag, URL suffix, file/database, cookies. In addition, a session tracking mechanism is provided, using an HttpSession object.

38 20 Maart 2006ISS - Internet Applications Part 238 Cookies in Java A cookie has a name, a single value, and optional attributes such as a comment, path and domain qualifiers, a maximum age, and a version number. Some Web browsers have bugs in how they handle the optional attributes, so use them sparingly to improve the interoperability of your servlets. The servlet sends cookies to the browser by using the HttpServletResponse.addCookie(javax.servelet.http.Cookie) method, which adds fields to HTTP response headers to send cookies to the browser, one at a time. The browser is expected to support 20 cookies for each Web server, 300 cookies total, and may limit cookie size to 4 KB each. The browser returns cookies to the servlet by adding fields to HTTP request headers. Cookies can be retrieved from a request by using the HttpServletRequest.getCookies( ) method. Several cookies might have the same name but different path attributes.

39 20 Maart 2006ISS - Internet Applications Part 239 Processing Cookies with Java Java Server Programming – Wrox press A cookie is an object of the javax.servlet.http.cookie class. Methods to use with a cookie object: public Cookie(String name, String value): creates a cookie with the name-value pair in the arguments. import javax.servlet.http.* Cookie oreo = new Cookie(“id”,”12345”); public string getName( ) : returns the name of the cookie public string getValue( ) : returns the value of the cookie public void setValue(String _val) : sets the value of the cookie public void setMaxAge(int expiry) : sets the maximum age of the cookie in seconds.

40 20 Maart 2006ISS - Internet Applications Part 240 Processing Cookies with Java – 2 Java Server Programming – Wrox press public void setPath(java.lang.String uri) : Specifies a path for the cookie to which the client should return the cookie. The cookie is visible to all the pages in the directory you specify, and all the pages in that directory's subdirectories. A cookie's path must include the servlet that set the cookie, for example, /catalog, which makes the cookie visible to all directories on the server under /catalog. public java.lang.String getPath() : Returns the path on the server to which the browser returns this cookie. The cookie is visible to all subpaths on the server. public String getDomain( ) : returns the domain of the cookie. if orea.getDomain.equals(“.foo.com”) … // do something related to golf public void setDomain(String _domain): sets the cookie’s domain.

41 20 Maart 2006ISS - Internet Applications Part 241 doGet/doPost Method using cookies Public void doGet(HttpServletResponse req, HttpServletResponse res) throws ServletException, IOExceiption{ res.setContentType(“text/html”); PrintWriter out = res.getWriter( ); out.println (“ Contents of your shopping cart: ”); Cookie cookies[ ]; cookies = req.getCookies( ); if (cookies != null) { for ( int i = 0; i < cookies.length; i++ ) { if (cookies[i].getName( ).startWith(“Item”)) out.println( cookies[i].getName( ) + “: “ + cookies[i].getValue( )); out.close( ); }

42 20 Maart 2006ISS - Internet Applications Part 242 Servlet & Cookies Example See Servlet\cookies folder in code sample: Cart.html: web page to allow selection of items Cart.java: Servlet invoked by Cart.html; it instantiates a cookie object for each items selected. Cart2.html: web page to allow viewing of items currently in cart Cart2.java: Servlet to scan cookies received with the HTTP request and display the contents of each cookie.

43 20 Maart 2006ISS - Internet Applications Part 243 HTTP Session Objects The javax.servlet.http package provides a public interface HttpSession: Provides a way to identify a user across more than one page request or visit to a Web site and to store information about that user. The servlet container uses this interface to create a session between an HTTP client and an HTTP server. The session persists for a specified time period, across more than one connection or page request from the user. A session usually corresponds to one user, who may visit a site many times.

44 20 Maart 2006ISS - Internet Applications Part 244 HTTP Session Object - 2 This interface allows servlets to –View and manipulate information about a session, such as the session identifier, creation time, and last accessed time –Bind objects to sessions, allowing user information to persist across multiple user connections Session object allows session state information to be maintained without depending on the use of cookies (which can be disabled by a browser user.) Session information is scoped only to the current web application ( ServletContext ), so information stored in one context will not be directly visible in another.

45 20 Maart 2006ISS - Internet Applications Part 245 The Session object

46 20 Maart 2006ISS - Internet Applications Part 246 Obtaining an HTTPSession Object A session object is obtained using the getSession( ) method of the HttpServletRequest object (from doPost or doGet) public HTTPSession getSession(boolean create): Returns the current HttpSession associated with this request or, if if there is no current session and create is true, returns a new session. If create is false and the request has no valid HttpSession, this method returns null. To make sure the session is properly maintained, you must call this method before the response is committed. public class ShoppingCart extends HttpServlet { public void doPost(HttpServletRequest req, HttpServletRespnse res) throws ServletException, IOException … // get session object HttpSession session = req.getSession(true) if (session != null) { … } …

47 20 Maart 2006ISS - Internet Applications Part 247 The HTTPSession Object public java.lang.String getId( ) : r eturns a string containing the unique identifier assigned to this session. The identifier is assigned by the servlet container and is implementation dependent. public java.lang.Object getAttribute(java.lang.String name) : returns the object bound with the specified name in this session, or null if no object is bound under the name. public java.util.Enumeration getAttributeNames( ) : returns an Enumeration of String objects containing the names of all the objects bound to this session. public void removeAttribute(java.lang.String name) : removes the object bound with the specified name from this session. If the session does not have an object bound with the specified name, this method does nothing.

48 20 Maart 2006ISS - Internet Applications Part 248 Session Object example based on an example in “Java Server Programming”, Wrox Press // Get item count from session object Integer itemCount = (Integer)session.getAttribute(“itemCount); // if this is the first call during the session, no attribute exists if (itemCount == null) { itemCount = new Integer(0); // process form data String[ ] itemSelected; String itemName; itemSelected = req.getParameterValues(“item”); // if user has selected items on form, add them to the session object if (itemSelected != null) { for ( int i=0; i < itemSelected.length; i ++) { itemName = itemSelected[I]; itemCount = new Integer(itemCount.intValue( ) +1); session.setAttribue(“Item” + itemCount, itemName); }// end for session.setAttribtue(“itemCount”, itemCount); } // end if

49 20 Maart 2006ISS - Internet Applications Part 249 Session object example - continued PrintWriter out = res.getWriter( ); res.setContentType(“text/html”); // … output HTML for web page heading // Output current contents of the shopping cart out.println(“ Current Shopping Cart Contents ”); for (int i = 1; i <= ItemCount.intValue( ); i++) ( // retrieve objects from the session object String item = (String) session.getAttribute(“”Item” + i); out.println(“item ”); } // … output HTML for web page footing out.close( );

50 20 Maart 2006ISS - Internet Applications Part 250 Session Object example See Servlet\Session folder in code sample: Cart.html: web page to allow selection of items Cart.java: Servlet invoked by Cart.html; it instantiates a session object which contains descriptions of items selected. Cart2.html: web page to allow viewing of items currently in cart Cart2.java: Servlet to display items in the shopping cart, as recorded by the use a session object in the Cart servlet

51 20 Maart 2006ISS - Internet Applications Part 251 Servlets Summary - 1 A servlet is a Java class. Its code is loaded to a servlet container on the server host. It is initiated by the server in response to a client ’ s request. Once loaded, a servlet is persistent.

52 20 Maart 2006ISS - Internet Applications Part 252 Servlets Summary - 2 For state information maintenance: –hidden form fields –cookies –the servlet’s instance variables may hold global data –a session object can be used to hold session data

53 20 Maart 2006ISS - Internet Applications Part Web Services

54 20 Maart 2006ISS - Internet Applications Part 254 Introduction Web Services Network services provided over HTTP – “wired services” It is promoted as a new way to build network applications from distributed components that are language- and platform-independent The technologies are still evolving We are more interested in the concept and principles, but we will look into one API (Apache SOAP).

55 20 Maart 2006ISS - Internet Applications Part 255 Web Services

56 20 Maart 2006ISS - Internet Applications Part 256 Web Service Software Components A web service is a message-based network service. Messages are sent via a remote procedure call mechanism using SOAP for the parameter format.

57 20 Maart 2006ISS - Internet Applications Part 257 Just-in-time integration Network services can be integrated dynamically, on an as-needed basis. SunMicro’s jini is a framework that supports the idea. Network services are registered with a service registry; a service consumer/client looks up the registry to fulfill its needs. The binding of a client to the service can occur at runtime.

58 20 Maart 2006ISS - Internet Applications Part 258 Web service protocol stack

59 20 Maart 2006ISS - Internet Applications Part 259 Web service protocols

60 20 Maart 2006ISS - Internet Applications Part 260 Webservices Summary A web service is a message-based network service. Web services can be integrated dynamically, on an as-needed basis. Network services are registered with a service registry. Webservices use a remote procedure protocol over HTTP using SOAP messages.

61 20 Maart 2006ISS - Internet Applications Part SOAP

62 20 Maart 2006ISS - Internet Applications Part 262 SOAP SOAP is a protocol which applies XML for message exchange in support of remote method calls over the Internet. Compared to remote method invocation or CORBA-based facilities: –SOAP is web-based or “wired” and hence is not subject to firewall restrictions –Language-independent –Can provide just-in-time service integration

63 20 Maart 2006ISS - Internet Applications Part 263 Introduction “SOAP is a Remote Procedure Calling protocol that works over HTTP (and TCP/SMTP etc.). The body of the request is in XML. A procedure executes on the server and the value it returns is also formatted in XML. Procedure parameters and returned values can be scalars, numbers, strings, dates, etc.; and can also be complex record and list structures.” (- A Busy Developer’s Guide To Soap1.1)

64 20 Maart 2006ISS - Internet Applications Part 264 Remote Procedure Call using HTTP

65 20 Maart 2006ISS - Internet Applications Part 265 SOAP Messages

66 20 Maart 2006ISS - Internet Applications Part 266 An XML-encoded SOAP RPC

67 20 Maart 2006ISS - Internet Applications Part 267 Example of a SOAP message (xml)

68 20 Maart 2006ISS - Internet Applications Part 268 A SOAP Message that contains a remote procedure call source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1 41

69 20 Maart 2006ISS - Internet Applications Part 269 An Example SOAP Request source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

70 20 Maart 2006ISS - Internet Applications Part 270 Response example source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

71 20 Maart 2006ISS - Internet Applications Part 271 Example of a SOAP message for an error RPC response source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

72 20 Maart 2006ISS - Internet Applications Part 272 HTTP and SOAP RPC Request source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1 A SOAP message can be used to transport a SOAP remote procedure request/response, as follows: POST /examples HTTP/1.1 User-Agent: Radio UserLand/7.0 (WinNT) Host: localhost:81 Content-Type: text/xml; charset=utf-8 Content-length: 474 SOAPAction: "/examples"

73 20 Maart 2006ISS - Internet Applications Part 273 An HTTP request that carries a SOAP RPC request source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1 POST /examples HTTP/1.1 User-Agent: Radio UserLand/7.0 (WinNT) Host: localhost:81 Content-Type: text/xml; charset=utf-8 Content-length: 474 SOAPAction: "/examples" 41

74 20 Maart 2006ISS - Internet Applications Part 274 An HTTP request that carries a SOAP RPC response source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1 HTTP/ OK Connection: close Content-Length: 499 Content-Type: text/xml; charset=utf-8 Date: Wed, 28 Mar :05:04 GMT Server: UserLand Frontier/7.0-WinNT South Dakota

75 20 Maart 2006ISS - Internet Applications Part 275 Error Example source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1 HTTP/ Server Error Connection: close Content-Length: 511 Content-Type: text/xml; charset=utf-8 Date: Wed, 28 Mar :06:32 GMT Server: UserLand Frontier/7.0-WinNT SOAP-ENV:Client Can't call getStateName because there are too many parameters.

76 20 Maart 2006ISS - Internet Applications Part 276 SOAP Packages source: Apache SOAP for Java Apache Axis for Java Idoox WASP for C++ Microsoft SOAP Toolkit (part of the.net framework) SOAP::Lite for Perl

77 20 Maart 2006ISS - Internet Applications Part 277 Apache SOAP Allows clients and services to be written in Java Part of the Apache-XML project (http://xml.apache.org/)http://xml.apache.org/ SOAP package downloadable: Installation instruction: pache.html

78 20 Maart 2006ISS - Internet Applications Part 278 Apache SOAP installation

79 20 Maart 2006ISS - Internet Applications Part 279 Classpath setting set CLASSPATH= C:\soap\soap-2_2\lib\xerces.jar; C:\jdk1.3\bin; C:\jdk1.3\lib\tools.jar; C:\soap\soap-2_2\lib\mail.jar; C:\soap\soap-2_2\lib\soap.jar; C:\soap\soap-2_2\lib\activation.jar; C:\tomcat\lib\servlet.jar;.;

80 20 Maart 2006ISS - Internet Applications Part 280 Writing a Client Application using Apache SOAP source: Classpath Your CLASSPATH environment variable should have both the "soap.jar" and "xerces.jar" JAR files included. Importing packages For basic SOAP method invocation, you should import the following at minimum: // Required due to use of URL class, required by Call class import java.net.*; // Required due to use of Vector class import java.util.*; // Apache SOAP classes used by client import org.apache.soap.util.xml.*; import org.apache.soap.*; import org.apache.soap.rpc.*;

81 20 Maart 2006ISS - Internet Applications Part 281 Ready-made SOAP Services A number of SOAP ready-made services are available at XMethods Service Weather Temperature ID8 Service Owner:xmethods.netxmethods.net Contact Service Description:Current temperature in a given U.S. zipcode region. SOAP Implementation:Apache SOAPApache SOAP

82 20 Maart 2006ISS - Internet Applications Part 282 Sample SOAP service Found at

83 20 Maart 2006ISS - Internet Applications Part 283 RPC Profile for Service See sample: TempClient.java

84 20 Maart 2006ISS - Internet Applications Part 284 Client program samples See samples in client folder: – TempClient.java – StockQuoteClient.java –CurrencyClient.java

85 20 Maart 2006ISS - Internet Applications Part 285 SOAP data types SOAP Data TypesSOAP Data Types, 2/webservices/datatypes.html 2/webservices/datatypes.html Uses XML Schema data types Primitive Types string, boolean, decimal, float, double, duration, dateTime, time, date, gYearMonth, gYear, gMonthDay, gDay, gMonth, hexBinary, base64Binary, anyURI, QName, NOTATION

86 20 Maart 2006ISS - Internet Applications Part 286 SOAP data types Derived Types Simple types (derived from a single primitive type) * integer is derived from decimal * int ( <= int <= ) is derived from long which is derived from integer * 5-digit zip code can be derived from int * may use regular expressions to specify derived types, such as ([A-Z]){2,3}-\d{5}

87 20 Maart 2006ISS - Internet Applications Part 287 Complex Type Complex types (struct or array) Struct example Ed Donley Array example 10452C 10454C 11123T

88 20 Maart 2006ISS - Internet Applications Part 288 Creating Web Services (server-side SOAP) O'Reilly Network: Using SOAP with Tomcat [Feb. 27, 2002] 7/tomcat.htmO'Reilly Network: Using SOAP with Tomcat [Feb. 27, 2002] Apache SOAP allows you to create and deploy a SOAP web service. You must install some.jar files on your system and set the CLASSPATH to them: Algorithm: 1.Write a class for providing the service. 2.Create a deployment descriptor in XML. 3.Deploy the service with the service manager.

89 20 Maart 2006ISS - Internet Applications Part 289 The Apache SOAP service manager The service manager is itself implemented as a SOAP service. To see what services are deployed on your system: java org.apache.soap.server.ServiceManagerClient list To deploy a service: java org.apache.soap.server.ServiceManagerClient deploy foo.xml

90 20 Maart 2006ISS - Internet Applications Part 290 Creating a SOAP Service O'Reilly Network: Using SOAP with Tomcat [Feb. 27, 2002] O'Reilly Network: Using SOAP with Tomcat [Feb. 27, 2002] A SOAP service can be just about any Java class that exposes public methods for invocation. The class does not need to know anything about SOAP, or even that it is being executed as a SOAP service. The method parameters of a SOAP service must be serializable. The available types that can be used as SOAP service parameters are shown in (Listing 2) (shown on next slide)

91 20 Maart 2006ISS - Internet Applications Part 291 SOAP Service Parameter Types All Java primitive types and their corresponding wrapper classes Java arrays java.lang.String java.util.Date java.util.GregorianCalendar java.util.Vector java.util.Hashtable java.util.Map

92 20 Maart 2006ISS - Internet Applications Part 292 SOAP Service Parameter Types java.math.BigDecimal javax.mail.internet.MimeBodyPart java.io.InputStream javax.activation.DataSource javax.activation.DataHandler org.apache.soap.util.xml.QName org.apache.soap.rpc.Parameter java.lang.Object (must be a JavaBean)

93 20 Maart 2006ISS - Internet Applications Part 293 Sample SOAP Service Implementations See sample in SOAP folder: TempService: A temperature service Exchange: currency exchange service and client

94 20 Maart 2006ISS - Internet Applications Part 294 Sample SOAP Service Class // A sample SOAP service class // source: package onjava; public class CalcService { public int add(int p1, int p2) { return p1 + p2; } public int subtract(int p1, int p2) { return p1 - p2; }

95 20 Maart 2006ISS - Internet Applications Part 295 Deployment Descriptor org.apache.soap.server.DOM FaultListener

96 20 Maart 2006ISS - Internet Applications Part 296 SOAP Summary SOAP is a protocol that makes use of HTTP requests and responses to effect remote method calls to web services. A SOAP method call is encoded in XML and is embedded in an HTTP request The return value of a method call is likewise embedded and encoded in an HTTP response A number of SOAP APIs are available for programming web services and client method calls. The Apache API was introduced.

97 20 Maart 2006ISS - Internet Applications Part 297 References (1) Programming Web Services with SOAP, by Snell et al, O’Reilly SOAP Tutorial, Tutorial SoapRPC.com: Tutorials, (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1SoapRPC.com: Tutorials DaveNet : XML-RPC for Newbies, ForNewbiesDaveNet : XML-RPC for Newbies ForNewbies SoapRPC.com: Other resources, Other resources

98 20 Maart 2006ISS - Internet Applications Part 298 References (2) Aloso,Casati, Kuno, Machiraju “Web Services - Concepts, Architectures and Applications” Liu “Distributed Computing - principles and applications”

99 20 Maart 2006ISS - Internet Applications Part 299 Self Study Exercises Chapter 11 –Applet exercises: 4 –General Servlet Exercises: 1 & 2 –SOAP Exercises: 2 & 3


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