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Wassily Kandinsky - Composition IV, 1911

K. Wassily Kandinsky - Composition IV, 1911. Web Publishing using PL/SQL and Java. Eric Grancher eric.grancher@cern.ch CERN (Geneva), IT/DB European Organization for Nuclear Research. EOUG 2000, paper 60. Plan. About server side web applications,

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Wassily Kandinsky - Composition IV, 1911

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  1. K Wassily Kandinsky - Composition IV, 1911

  2. Web Publishing using PL/SQL and Java Eric Grancher eric.grancher@cern.chCERN (Geneva), IT/DBEuropean Organization for Nuclear Research EOUG 2000, paper 60

  3. Plan About server side web applications, not to conclude Java (or PL/SQL) is better… • Introduction (what technology, where is it used ?) • Special features • Security features and pitfalls • Transaction handling • Manageability • Performance • Suggestions and Conclusion

  4. The PL/SQL “cartridge” • The original method, since 1995 • Has proven to be fast, reliable • Embraced a lot in the Oracle “community”, including CERN • Has almost not changed a lot for 5 years (transactions, file upload…) • Used • In Oracle Application Server • In WebDB • As the target for Designer Web generation

  5. How the PL/SQL cartridge works • Based on Oracle PL/SQL stored objects • Few simple PL/SQL packages, the PL/SQL Web toolkit • OAS makes the mapping between the URL and the database account • Procedure is executed, it fills up a buffer, returns it and commits /app1/plsql/pa.pr?l_a1_num=3 PACKAGE PA IS PROCEDURE PR(l_a1_num NUMBER); END; browser execute pa.pr(l_a1_num=>3); owa.get_page; commit; HTTP Net8 <HTML><BODY>… </HTML> OAS PL/SQL table

  6. PL/SQL example arguments procedure t1 (p_a1_num number default 100) is cursor c is select t1,t2 from t where rownum<p_a1_num; begin htp.print('<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN“"http://www.w3.org/TR/REC-html40/loose.dtd">'); htp.htmlopen; htp.headopen; htp.title(p_a1_num); htp.headclose; htp.bodyopen; forc1 in cloop htp.print(c1.t1||'--'||c1.t2); end loop; htp.bodyclose; htp.htmlclose; end; specify DOCTYPE loop around the cursor

  7. The Java techniques • Java introduced by Sun, object orientation, no pointer arithmetic, compilation into an OS neutral VM • Java2 Enterprise Edition, Java Servlet and Java Server Pages • Used in • “All” web servers, Oracle Application Server • Oracle iFS • The RDBMS itself (8.1.7)

  8. How the Java techniques work • Server side Java execution • Java Server Pages and SQLJ are all “transformed” into plain Java code with JDBC access to the database, we will concentrate on Servlets • Java class writes to a stream that is sent back to the browser • Init, service/doGet/doPost and destroy “main” methods /app1/java/TestServlet browser www listener & JVM HTTP JDBC HTML

  9. Standard Java Servlet code public class BasicServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = new PrintWriter (response.getOutputStream()); out.println("<html>");out.println("<head><title>Title</title></head>");out.println("<body>some text in the body");out.println("</body></html>");out.flush();} } arguments and output set MIME & get out send page to out

  10. Java code with Oracle extensions public class BasicOracle extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{ ServletOutputStream out_str=response.getOutputStream(); out_str.println("Content-type: text/html"); out_str.println(); HtmlHead head = new HtmlHead("Title !"); HtmlBody body = new HtmlBody(); HtmlPage page = new HtmlPage(head, body); body.addItem(new SimpleItem("Some body text")); page.print(out_str); out_str.flush();} } arguments and output set MIME & get out create page send page to out

  11. Special features • Non HTML • Specify a non “text/html” mime-type like CSV = application/msexcel • Return “raw” data • Return XML data, to be handled by a local XSL preprocessor or used in another program • (Java only) • Non textual: images… • Networking access: e-mail, ftp… • LDAP access • Servlet chaining • External or remote processing (Enterprise Java Beans)

  12. Security • Encryption, use of SSL at the listener level. With OAS4, no possibility to restrict access to an application to a set of TCP ports ! • Access control • Before or within the application (simplicity vs. extensibility) • Source of users • configuration file • LDAP • Oracle users for the PL/SQL cartridge (WebDB 2.x) • Custom run-time protection with the PL/SQL cartridge (authorize function) • Pitfall with small vs. capital letters (PL/SQL cartridge)  good practice is to protect everything and “unprotect” the few URLs to be made more widely available /app1/plsql/private* = Basic(admin) /app1/plsql/ = Basic(admin)/app1/plsql/public* = IP(allip) /app1/plsql/priVate.admin !!!

  13. Transaction and session handling • One of the biggest issues for a dynamic site: transaction, locking and contexts (session and application) • HTTP is basically stateless  one has to workaround • Solutions for context, inter web page communication • Hidden fields • Cookies • Servlet-only: place variables in the context • Application context • Session context (uses URL rewriting or cookies) HttpSession session = request.getSession (true); Integer ItemCount = (Integer) session.getValue("itemcount"); if (ItemCount == null) { ItemCount=new Integer (0); }else { ItemCount = new Integer(ItemCount.intValue()+1); }session.putValue("itemcount",ItemCount); get session reference retrieve the value put the value

  14. Application Transactions • Pseudo locking can be implemented with the help of PL/SQL owa_opt_lock • Real transactions • PL/SQL can make use of declarative URLs with the transaction service, no control on the transaction, easy to setup but some issues with the session handling • JDBC/Java Transaction Service, programmatic approach, more code, more control DistributedTransactionCoordinator Instance

  15. Manageability • Packaging systems • Packages in PL/SQL • Object Orientation, packages with Java • Coding conventions • Sun “Code Conventions” • PL/SQL reference books • N accounts architecture (data, API, logic, presentation…) • N tier architecture, for Java applications, place the Java logic in EJB • PL/SQL dependencies  make calls to PL/SQL stored procedures from Java

  16. Performance • As usual, database design and SQL are the most common sources of the bottlenecks ! • Use parameterized statements, avoid dynamic SQL • Java  place as much as possible in the init/destroy • Java  manage a connection pool, see JDBC 2.0 • Java  use StringBuffer or the oracle.html classes • This is done by the PL/SQL cartridge “for free”

  17. Performance tests Relative times. Sun E450, RDBMS 8.1.6, OAS 4.0.8.15 connections at the same time

  18. Mixing technologies • Basic idea: “Avoid to use many different technologies, it makes more complex applications”… at least do it in a N tier architecture • Java as the presentation layer (JSP, Servlets) + database access in PL/SQL • Benefits of new features (session and application contexts, TCP connection like e-mail, binary types…) • PL/SQL dependencies • PL/SQL as the presentation layer + Java stored procedures to extend PL/SQL (e-mail, TCP connections, specific functions…) • Easy management of code, simpler code • New features via the Java calls

  19. Conclusions ? • Java techniques provide very interesting features (session context…), they still evolve very fast, Java2 EE, JDBC 2.0. • No need to rush on Servlets/Java Server Pages, PL/SQL programming is most of the time simpler, needs less tuning and is very well integrated with the database. • Servlet in the database  will help to have highly-performing, centrally maintained Java code. Some issues are opened, will you open your DB server through the firewall ? • Mixing Java and PL/SQL (dependencies) can be a solution. Keep access to database objects with PL/SQL.

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