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Java web hosting at CERN
Computing Seminar, 1 November 2005 Michał Kwiatek, IT-DES
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What we’ll be doing A few words about servlets and JSPs
How to deploy them at CERN Scope, SLA and architecture of J2EE Public Service Some „advanced” examples Michał Kwiatek, IT-DES
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What is a JSP? page contentType="text/html;charset=iso " %> <html><header><title>Age example</title></header> <body><h1>Age example</h1> <% String yearString = request.getParameter("year"); int year; if (yearString==null || yearString.equals("")) { out.print("Please specify your year of birth using year parameter"); } else { try { year = new Integer(yearString).intValue(); %>You are <%=2005-year%> years old.<% } catch (NumberFormatException e) { %><font color="red">Year of birth incorrect!</font><% } %> <%--static include file="footer.html" %> </body></html> Michał Kwiatek, IT-DES
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JSP implicit variables
request session application response out Michał Kwiatek, IT-DES
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What is a servlet? A java class that lives inside web container to serve client requests extends javax.servlet.http.HttpServlet defining one or more of the following methods: doGet doPost doPut doDelete service init destroy Note: the same servlet object will be used simultaneously to serve many request! Michał Kwiatek, IT-DES
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Your servlets should be thread-safe!
Javadoc: Date formats are not synchronized. It is recommended to create separate format instances for each thread. If multiple threads access a format concurrently, it must be synchronized externally. package ch.cern.example; import ... public class ServletA extends HttpServlet { SimpleDateFormat sdf = new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss" ); public void service (HttpServletRequest request, HttpServletResponse response) { response.write("Current date and time is: "); response.write(sdf.format(new Date())); } Michał Kwiatek, IT-DES
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JSP is a servlet! Declaration! <%@ page laguage="java"%>
<html><body> <%! int count=0 %> Welcome, you are visitor number <%=++count%> </body></html> package ch.cern.example; import ... public class MyServlet extends HttpServlet { int count = 0; public void service (HttpServletRequest request, HttpServletResponse response) { response.write("<html><body>Welcome, you are visitor number"+(++count)+"</body></html>"); } Michał Kwiatek, IT-DES
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Did you make a nice jack’o lantern?
Michał Kwiatek, IT-DES
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There’s more to JSP than just the pages
Object-oriented programming Java libriaries, java beans Custom tag libraries Model-View-Controler model Java Server Faces It is vendor and platform independent Michał Kwiatek, IT-DES
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How to deploy them at CERN?
Go to CERN Web Service: Choose „java web application (servlet/jsp)” as site type Michał Kwiatek, IT-DES
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So what is this WAR file? WAR file is simply a zip archive with a specific structure jar files go to WEB-INF/lib classes go to WEB-INF/classes Application configuration files The rest is regular web content Use your IDE or Ant to package your application Michał Kwiatek, IT-DES
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J2EE Public Service server-side infrastructure for deployment of java (servlet/jsp) web applications provided by IT-DES we provide: servlet/JSP container support for deployment backup, monitoring we don’t provide: an EJB container support for development telnet/ssh/ftp access to the servers SLA: aimed for medium-sized, non-critical applications; full support within CERN working hours; the support outside working hours is provided on best effort basis. Michał Kwiatek, IT-DES
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„Standard” approach ! Michał Kwiatek, IT-DES
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J2EE Public Service - approach
! Michał Kwiatek, IT-DES
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J2EE Public Server architecture
software used: Apache Tomcat 5.5 JDK 1.5 Apache httpd 2.0 jpsmanager The architecture is open! Michał Kwiatek, IT-DES
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Guess what! JDBC drivers to oracle are preinstalled (thin)
3 usage scenarios Michał Kwiatek, IT-DES
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JDBC 1. Basic example 2. Connection pooling
Connection conn = null; Statement stmt = null; ResultSet rset = null; try { Class.forName("oracle.jdbc.driver.OracleDriver"); conn = DriverManager.getConnection(url, user, password); stmt = conn.createStatement(); rset = stmt.executeQuery(query); ... } catch(SQLException e) { } finally { try { rset.close(); } catch(Exception e) { } try { stmt.close(); } catch(Exception e) { } try { conn.close(); } catch(Exception e) { } } Michał Kwiatek, IT-DES
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JDBC (cont’d) 3. Connection pooling & JNDI (1/2)
// in Servlet, JSP, or simply a class: Connection conn = null; Statement stmt = null; ResultSet rset = null; try { Context initContext = new InitialContext(); Context envContext = (Context)initContext.lookup("java:/comp/env"); DataSource ds = (DataSource)envContext.lookup("jdbc/devdb"); conn = ds.getConnection(); stmt = conn.createStatement(); rset = stmt.executeQuery(query); ... } catch(SQLException e) { } finally { try { rset.close(); } catch(Exception e) { } try { stmt.close(); } catch(Exception e) { } try { conn.close(); } catch(Exception e) { } } Michał Kwiatek, IT-DES
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JDBC (cont’d) 3. Connection pooling & JNDI (2/2)
// in META-INF/context.xml: <Context> <Resource name="jdbc/devdb" auth="Container" type="javax.sql.DataSource" driverClassName="oracle.jdbc.driver.OracleDriver" username="XXXXX" password="XXXXX" maxActive="10" maxIdle="5" /> </Context> // in WEB-INF/web.xml: <resource-ref> ... </resource-ref> Michał Kwiatek, IT-DES
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Authentication/authorisation
my identity can be confirmed using my CERN id card Authorisation using my identity and additional information (did I attend the security course?) the system will let me into the Computer Centre or not Michał Kwiatek, IT-DES
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How to do it NICEly? method for authentication and authorisation
is provided by the container uses existing mechanisms this method is NICE: NICE login and password to authenticate NICE groups to authorise (CERN Department/Group structure, or some project-specific groups) Michał Kwiatek, IT-DES
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NICE authentication NICE authentication is set up by default
in WEB-INF/web.xml you specify which areas of your application require authentication you also specify which groups of users are authorized to access these areas you can define these groups (and their members) at from your application, you may check who is logged on using: request.getUserPrincipal() Michał Kwiatek, IT-DES
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Resources http://j2ee-public-service.web.cern.ch/j2ee-public-service/
sla.html faq.html technical.html chapter 9, "Developing secure web applications" from SCWCD Exam Study Kit by Hanumant Deshmukh and Jignesh Malavia. j2ee tutorial: Michał Kwiatek, IT-DES
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Questions? Michał Kwiatek, IT-DES
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