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K Wassily Kandinsky - Composition IV, 1911 Web Publishing using PL/SQL and Java Eric Grancher [email protected] CERN (Geneva), IT/DB European Organization for Nuclear Research EOUG 2000, paper 60 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 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 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 browser HTTP OAS PACKAGE PA IS PROCEDURE PR(l_a1_num execute pa.pr(l_a1_num=>3); NUMBER); END; owa.get_page; commit; Net8 PL/SQL table <HTML> <BODY> … </HTML> 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; for c1 in c loop htp.print(c1.t1||'--'||c1.t2); end loop; htp.bodyclose; htp.htmlclose; end; specify DOCTYPE loop around the cursor 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 “All” in web servers, Oracle Application Server Oracle iFS The RDBMS itself (8.1.7) 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 /app1/java/TestServlet browser HTML HTTP and destroy “main” methods www listener & JVM JDBC Standard Java Servlet code arguments and output public class BasicServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); set MIME & get out 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(); send page to out Java code with Oracle extensions public class BasicOracle extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{ arguments and output ServletOutputStream out_str=response.getOutputStream(); out_str.println("Content-type: text/html"); out_str.println(); set MIME & get out HtmlHead head = new HtmlHead("Title !"); HtmlBody body = new HtmlBody(); create page HtmlPage page = new HtmlPage(head, body); body.addItem(new SimpleItem("Some body text")); page.print(out_str); out_str.flush(); } } send page to out 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) 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/priVate.admin !!! /app1/plsql/ = Basic(admin) /app1/plsql/public* = IP(allip) 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 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 Application Distributed Transaction Coordinator Instance Manageability Packaging systems Coding conventions Packages in PL/SQL Object Orientation, packages with Java 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 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” Performance tests Relative times. Sun E450, RDBMS 8.1.6, OAS 4.0.8.1 5 connections at the same time Method Response Throughput PL/SQL reference reference J1 = DB connection within code + 776% - 23 % J2 = DB connection within init/destroy + 8% - 8% J3 = J2 using Oracle packages + 20 % - 394 % J4 = J2 using StringBuffer + 16 % - 24 % J5 = J2 using a PreparedStatement + 20 % + 7%, size(code)=4* 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 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 highlyperforming, 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.
