Open Source Java/XML Application Server & & Web Development with Open Source Enhydra Java/XML...

Open Source Java/XML Application ServerOpen Source Java/XML Application Server

&&

Web Developmentwith Open Source Enhydra Java/XML Application Server

Web Developmentwith Open Source Enhydra Java/XML Application Server

James Murphy

UC Santa CruzJanuary 2001

Agenda

• Introduction, CGI, and Servlets

• Architecture

• Application

• Enhydra XMLC

CGI Common Gateway Interface

• First We Have Static Web Pages

• Served by a Web Server to a Browser

• For Search or Buy on Line - Dynamic Web Page

• Enter CGI - Start Process for each request

• Request on standard input

• HTML page on standard output• URL http://www.ecst.csuchico.edu/~murphy/hellop.cgi

• test.cgi (bin/sh) hello.cgi (c program)

CGI Perl script

• #!/usr/local/bin/perl

• #hello: a simple Perl example

• # TWO carriage returns after the content type.

• # This is important to end the header!

• print "Content-type: text/html\n\n";

• # Output a proper HTML document, with <head> and <body> tags.

• print "<head>\n";

• print "<title>Hello, World</title>\n";

• print "</head>\n";

• print "<body>\n";

• print "<h1>Hello, World</h1>\n";

• print "</body>\n";

• Could be cshell Script or Java or C etc. Program

HTML source Generated

• <head>

• <title>Hello, World</title>

• </head>

• <body>

• <h1>Hello, World</h1>

• </body>

HTML Forms and Java Servlets

• <HTML>

• <HEAD>

• <TITLE>Introductions </TITLE>

• </HEAD>

• <BODY>

• <FORM METHOD=GET ACTION="http://localhost:9004/">

• If you don't mind me asking, what is your name?

• <INPUT TYPE=TEXT NAME="name"><P>

• <INPUT TYPE=SUBMIT>

• </FORM>

• </BODY>

• <HTML>

• <HTML>

Java Servlet Hello.java piece

• import java.io.*;

• import javax.servlet.*;

• import javax.servlet.http.*;

• public class Hello extends HttpServlet {

• public void doGet(HttpServletRequest req, HttpServletResponse res)

• throws ServletException, IOException {

• // Set the Content-Type header

• res.setContentType("text/html");

• // Return early if this is a HEAD

• if (req.getMethod().equals("HEAD")) return;

•

Java Servlet Hello.java continued

• // Proceed otherwise

• PrintWriter out = res.getWriter();

• String name = req.getParameter("name");

• out.println("<HTML>");

• out.println("<HEAD><TITLE>Hello, " + name + "</TITLE></HEAD>");

• out.println("<BODY>");

• out.println("Hello, " + name);

• out.println("</BODY></HTML>");

• }

• public void doPost(HttpServletRequest req, HttpServletResponse res)

• throws ServletException, IOException {

• doGet(req, res);

• }

• }

Servlets and eCommerce

• The Web is Stateless

• One servlet for all hits shares data members

• Amazon.com shopper visits many pages

• Need a private shopping cart

• Need a database connection

• Enter Application Servers and Enhydra

Enhydra: #1 Open Source Application Server

• Lutris is sponsor of Enhydra.org, an Open Source Java/XML Application Server

– www.enhydra.org

• Enhydra is a true Open Source Java/XML Application Server

• Over 20,000 downloads

• Over 1000 known participating developers

Professional Services


OpenSource

Software

OpenSource

Software

Startup Incubation

Startup Incubation

Lutris

Lutris

Lutris Technologies, Inc.

Founded: July 1995

Employees: 210

Headquarters: Santa Cruz

Services

•eBusiness Analysis

•Architecture and Implementation

•Creative Design and Branding

Recently Funded by Chase, Hambrecht & Quist, Intel and Trans Cosmos

An Open Source Enterprise Software and Services Company

“Enhydra Lutris”

The EnhydraSolutions Community

Open Source

Enhydra

Open Source

Enhydra

Lutris

Support


Add-On Products

Your Company

Genesis

• Motivation for creating Enhydra:

– Commercial products weren’t ready in 1997

– Offer Lutris customers time-to-market value

– Java on the server for platform independence, group development, etc.

• First licensee: FedEx

• Second licensee: Kinko’s

• Continual pull from customers, (especially start-ups in pre-funding mode.)

Value of Open Source to Lutris & Enhydra

• Lead Generation

• Bug Fixing

• Validate

• Features

• Development community

• Support community

• Internationalpresence

• 3rd party tools & modules

– e-mailBBS, Platypus

• Continue to be driven by real world requirements

• De facto standard

www.enhydra.orgfor the Enhydra Community

• Mail lists & Working Groups– [email protected]

• Mail Archive/Search

• Case studies, News

• On-line Demos– Shopping Cart,

Chat Room, Poker

• 3rd party Services and Products

Working Groups:EJB ContainerWeb Container

I18NWireless

ArchitectureJMX

Rocks/XMLCDODS

Working Groups:EJB ContainerWeb Container

I18NWireless

ArchitectureJMX

Rocks/XMLCDODS

Wizshop/Earthlink/Mindspring

Cisco LocalDirector

Cisco LocalDirector

•Sun E250/2CPU•500M Memory•400Mhz•Enhydra•Apache/Jserv


The

Int

erne

t

•Sun E450•Oracle DB

•Sun E450•Oracle DB•Sun

E250/2CPU•500M Memory•400Mhz•Enhydra•Apache/Jserv


Enhydra Technology

• Enhydra Multiserver

– Servlet runner

– Web Server & Web Server Connection Manager

– Management console

• Enhydra Debugger

– Graphical Servlet Monitor

• Enhydra XMLC– XML/DOM Presentations

• Enhydra Director

– Cluster Support

• Enhydra Application Framework

– “Superservlet Strategy”

• Enhydra Application Wizard (“Newapp”)

– Instant application to jumpstart development

• Enhydra DODS

– Graphical Object-to-SQL mapping application

Enhydra Architecture

Super Servlet Strategy

Enhydra Applications are Super Servlets that contain multiple presentation objects Connects URLs (*.po) and Java classes (presentation objects)

Shared session state/data across multiple URLs

Factoring of common functionality (DB Mgr, Pres Mgr, …)

Presentation objects generate HTML to produce dynamic content JDDI Compiler

XMLC Compiler (encouraged; example later)

Enhydra Multi-Server

Manages the lifecycle of Enhydra Services ServletContainer (now has embedded services)

soon: EJB Container, DatabaseManager Service, …

Establishes connections to ServletContainer

Manages the server configuration file Defines initial state of Enhydra

Connection

JVMMultiServer

<multiserv.conf>

Enhydra ServletContainer

Provides Web Server and Servlet execution HTTP server (will embed full Web Server later)

Runs existing Enhydra servlet applications

Servlet 2.2, JSP 1.1

Manages the lifecycle and connectivity of servlets and Enhydra Applications Provides custom class loader

Supports Connection via http, https, Director

Connection, Channel, Filter structure (more later)

Manages the ServletContainer configuration file section Defines initial state of each application

ServletContainer

Enhydra Director

Connects non-Java web servers to Enhydra App Server Efficient protocol to ServletContainer

Portable design to various Web Servers

Provides load direction capability Map request to available ServletContainer

Session affinity

Header cookie URL rewrite Web

Server

EnhydraDirector

ServletContainer

Connection, Channels & Filters

WebServer

EnhydraDirector

WebBrowser HTTP

WebBrowser HTTPS

WebBrowser

Channel

Connection

Servlet

RR

Servlet

RRChannel

ServletRR

Filter

ServletChannel

RR

R

Channel

Administration Manager

Graphical tool to manage resource parameters HTML interface

Remote accessibility

Management Operation (shown later) Start/Stop applications or servlets

Add/Remove applications or servlets

Modify operational attributes of applications or servlets

Check status of applications or servlets

ServletContainer

Admin Mgr

Presentation Manager Manages loading and execution of

presentation objects Translates URLs to Java classes (*.po)

Uses specified class loader to load classes

Ability to cache presentation objects

One instance per Enhydra application

Executes as a servlet HttpPresentationServlet class

One per Application

Session Manager Provides session key

Cookie URL rewriting

Provides access to session objects Maintain state and user identity across multiple URLs

Session object is passed with each request

Generalized implementation

Session working set management Basic (in memory)

Page to disk

Page to Database

Database Manager

Manages a connection pool Configurable connection pool size

Opened on an as needed basis and are reused

DBQuery Allocates connections from connection pool

Ensures integrity of connections

Manages result sets

DBTransaction Performs a commit or rollback on

inserts, updates, or deletes

DBConnection Pools

Architecture Summary

EnhydraNewApp

EnhydraXMLC

EnhydraDODS

MultiServer

ServletContainer

WebServer

EnhydraDirector

WebBrowser Admin Mgr

Connection

JVM

Overview

• Development Tools

• Development Process

• Example Application

3-Tier Architecture• Database (Back-end)

• Business Logic (Middle-tier)

• Presentation Logic (User Interface)

• Example Code

• Application Deployment

Overview

Enhydra Development Tools

• JBuilder 3 "Foundation"

+ XMLC Wizard

• vi/emacs + xmlc + javac

+ newapp (Utility) + make

• Run-time Debugging– with JBuilder (monitor Java threads, watch values)

– with multiserver (monitor HTTP request/response)

Development Tools


• JBuilder Foundation+ XMLC Wizard


• Command line tools

– The newapp utility generates "empty" Enhydra project:Directory structure

Stub application classes

make file

– The xmlc utility generates Java classes from HTML or XML templates (more on this later)

Form.html FormHTML.java


• What is XMLC?– A compiler for converting an HTML or XML

document into a DOM-compliant Java Object

• What is DOM?– Document Object Model

– W3C specification (www.w3c.org/DOM)

– A standard API to represent a structured document as a traversable tree with branches, nodes, and leaves

– Each markup element in the document becomes a node in the DOM, nested markup elements become child nodes

– Allows HTML documents to be traversed as a tree; nodes can be added, removed, modified, or cloned

http://www.w3c.org/DOM


• Debugging

– In JBuilder+ Multiserver Administration Console

Dynamic

HTML

Dynamic

HTML

Enhydra Development Process

• Typical development steps involve:

• Create database schema


• Create data access objects


• Create business objects


• Create presentation objects


Enhydra Multiserver

Enhydra Example Application

• Goal:

Display rows from a SQL query in an HTML table.

• Objects:– Application: App.java– Data: Data.java– Business: Biz.java– Presentation: Pres.java– Template: Table.html

(XMLC generates TableHTML.java)

HTTP Request

HTML Table

Example Java code…

Example Code:

public class App extends StandardApplication {

private Biz biz = null;

public void startup(Config appConfig) throws ApplicationException { super.startup(appConfig);

logChannel.write(Logger.INFO,"Starting up the Example Application");

biz = new Biz(); //Instantiate the "Business" Object. }

public Biz getBiz() { return biz; //Return a reference to the Biz Object. }

} //end class App

App.java

public class App extends StandardApplication {

private Biz biz = null;

public void startup(Config appConfig) throws ApplicationException { super.startup(appConfig);

logChannel.write(Logger.INFO,"Starting up the Example Application");

biz = new Biz(); //Instantiate the "Business" Object. }

public Biz getBiz() { return biz; //Return a reference to the Biz Object. }

} //end class App

Example Code:

public class Biz {

private int requests = 0; //Number of requests serviced.

public String[] getList() { requests++; //Increment the request count. return new Data().query(); //Return list of employee names. }

//Expose number of times a request has been made

public int getRequestCount() { return requests; //Return request count. }

} //end class Biz

Biz.java

public class Biz {

private int requests = 0; //Number of requests serviced.

public String[] getList() { requests++; //Increment the request count. return new Data().query(); //Return list of employee names. }

//Expose number of times a request has been made

public int getRequestCount() { return requests; //Return request count. }

} //end class Biz

Example Code:

public class Data extends Vector {

public String[] query() { //Perform SQL database query.

try { //Use Enhydra database connection pool. DBConnection c = Enhydra.getDatabaseManager().allocateConnection(); ResultSet r = c.executeQuery("select ENAME from EMP"); while (r.next()) add(r.getString(1)); c.reset(); c.release(); // Be sure to release DBConnection... } catch (Exception e) { //...back into the connection pool! e.printStackTrace(); } //Explicit cast is required by compiler. return (String[])toArray(new String[] {}); }

} //end class Data

Data.java

public class Data extends Vector {

public String[] query() { //Perform SQL database query.

try { //Use Enhydra database connection pool. DBConnection c = Enhydra.getDatabaseManager().allocateConnection(); ResultSet r = c.executeQuery("select ENAME from EMP"); while (r.next()) add(r.getString(1)); c.reset(); c.release(); // Be sure to release DBConnection... } catch (Exception e) { //...back into the connection pool! e.printStackTrace(); } //Explicit cast is required by compiler. return (String[])toArray(new String[] {}); }

} //end class Data

Example Code:

<html>

<head> <title>Employee Names</title> </head>

<body>

<table id="exampleTable" border="1" > <tr id="tableRow"> <td><span id="name">Employee Name<span></td> </tr> </table>

</body>

</html>

+ XMLC

Table.html

= TableHTML.java

DOM

HTMLTableRowElement getElementTableRow();

HTMLTableElement getElementExampleTable();

void setTextName();

+"Convenience methods":

Example Code:

public class Pres implements HttpPresentation {

public void run(HttpPresentationComms c) throws HttpPresentationException { TableHTML tableDOM = new TableHTML(); //Generated by XMLC. Biz b = ((example.App)c.application).getBiz(); //Business object. fillTable(tableDOM, b.getList()); //Populate the table. c.response.writeHTML(tableDOM.toDocument()); //Display the table! }

private void fillTable(TableHTML tableDOM, String[] list) { //Manipulate table related elements of DOM. HTMLTableElement table = tableDOM.getElementExampleTable(); // Add new row... for (int i = 0 ; i < list.length ; i++) //...elements to DOM table.appendChild(createNewRow(tableDOM, list[i])); }…

Pres.java

TableHTML tableDOM = new TableHTML();

fillTable(tableDOM, b.getList()); c.response.writeHTML(tableDOM.toDocument());

private void fillTable(TableHTML tableDOM, String[] list)

HTMLTableElement table = tableDOM.getElementExampleTable();

HTMLTableElement table = tableDOM.getElementExampleTable();

Example Code:Pres.java

…

private HTMLTableRowElement createNewRow(TableHTML tableDOM, String name ) { tableDOM.setTextName(name); //Set the <SPAN> text.

return (HTMLTableRowElement) //Return the row element. tableDOM.getElementTableRow().cloneNode(true);

}

} //end class Pres

(cont)

…



}

} //end class Pres

…



}

} //end class Pres

Enhydra Application Development

• make

(…and then a miracle occurs…)

Enhydra Application Deployment

• Example.conf

Server.ClassPath[] = "/enhydra/classes/example.jar"

Server.AppClass = "example.App"

Server.PresentationPrefix = "example/presentation"

Application.DefaultUrl = "Pres.po"

• Created by JBuilder Application Wizard

• …or by running newapp

• …automagically!


• Example.conf (cont.)DatabaseManager.Databases[] = "Example"

DatabaseManager.DefaultDatabase = "Example"

DatabaseManager.DB.Example.ClassType = "Oracle"

DatabaseManager.DB.Example.JdbcDriver = "oracle.jdbc.driver.OracleDriver"

DatabaseManager.DB.Example.Connection.Url = "jdbc:oracle:thin:@artemis:1521:SID2"

DatabaseManager.DB.Example.Connection.User = "scott"

DatabaseManager.DB.Example.Connection.Password = "tiger"

DatabaseManager.DB.Example.ObjectId.CacheSize = 0


• multiserver.conf

Application.Example.ConfFile = "Example.conf"Application.Example.Description = "Example Enhydra Application"Application.Example.Running = "yes"

Connection.Http8001.Type = "http"Connection.Http8001.Port = 8001

Channel.Http8001.ExampleChannel.Servlet = "Example"Channel.Http8001.ExampleChannel.Url = "/"Channel.Http8001.ExampleChannel.Enabled = "yes"

• Created by Enhydra Administration utility

• …automagically!

Enhydra Application Deployment Adding "Example"• Enhydra Administration:

Example

Enhydra XMLC

Separate Graphics from Code

What is XMLC?

• XMLC = XML Compiler

• XMLC - Compiles an HTML or XML document into a DOM (Document Object Model)-compliant tree that can then be used as a java object which can reconstruct that document

• Provides object-oriented access to HTML or XML document templates

• Convenience getElement...() and setText…() direct accessor methods are additionally compiled into the document to facilitate common tasks

...Enhydra XMLC Overview

• Programmer adds dynamic content to the document by adding and manipulating DOM objects

• Static page URLs can be replaced with dynamic ones

• Prototype table rows can be used as templates for other rows.

Embedded Page Languages: Bad Idea!• HTML is developed by graphic artists

– Authoring programs can break the code

– Pages with mocked-up data are not final mockup

– Most graphic artists cannot program

• Code is developed by programmers

– They use source code editors

– Code added to HTML is difficult to maintain

– Most programmers cannot draw

Embedded Page Languages: Bad Idea!• Embedded page languages are not legal

HTML

– Can’t parse the pages with standard parsers

– Standards are a good thing.

• Flow-of-control is obscured

• Little compile-time type checking available

• Does not integrate well with debuggers, profilers

• Poor support for I18N

JSP Example

<HTML><%@ page language==“java”

imports==“com.wombat.JSP.*” %><H1>Welcome</H1><P>Today is </P><jsp:useBean id==“clock”

class==“calendar.jspCalendar” /><UL><LI>Day: <%==clock.getDayOfMonth() %><LI>Year: <%==clock.getYear() %></UL><% if (Calendar.getInstance().get(Calendar.AM_PM)

== Calendar.AM) { %>Good Morning<% } else { %>Good Afternoon<% } %><%@ include file==“copyright.html” %></HTML>

An HTML Example

<TABLE> <TBODY> <TR> <TH>Name</TH> <TH>City</TH> </TR> <TR> <TD>John Doe</TD> <TD>Atlanta</TD> </TR> </TBODY> </TABLE>

DOM Representation

ID=custName ID=city

Adding ID Attributes

<TABLE> <TBODY> <TR> <TH>Name</TH> <TH>City</TH> </TR> <TR> <TD ID=“custName”>John Doe</TD> <TD ID=“city”>Atlanta</TD> </TR> </TBODY> </TABLE>

Enhydra XMLC

Java DOM Package

• Document: Root of tree

– Provides factory methods for other DOM classes

• Node: Base class of all DOM tree objects

– Contains children and parent links

– Provides methods for manipulating the tree

• Element: Interface for XML tag classes

– Extends Node

– Specific applications may define classes that extend Element (e.g., HTMLTableElement, etc.)

• Text: Nodes that contain the document text

Java DOM HTML Package

• org.w3c.dom.html

– DOM Interfaces for HTML

• HTMLDocument - Root of the HTML hierarchy• HTMLHeadElement - <HEAD>• HTMLBodyElement - <BODY>• HTMLParagraphElement - <P>• HTMLAnchorElement - <A>• HTMLTableElement - <TABLE>• HTMLFontElement - <FONT>• …more…

Simple XMLC ExampleHTML - Hello.html

<H1><FONT ID=“HeadFont” SIZE=“4” COLOR=“red”>Hello World</FONT></H1><P>Hello, my name is <SPAN ID=“CustName”>John Doe</SPAN>

Using the Generated Class HelloHTMLHelloHTML hello = new HelloHTML();HTMLFontElement hfont = hello.getElementHeadFont();hfont.setColor(“Green”);hello.setTextCustName(“Barney Blake”);out.println(hello.toDocument());

Work Flow using Enhydra XMLC

• HTML designer creates a working storyboard/demo page

• The designer tags dynamic elements with HTML 4.0 ID tags, e.g.,

<TD ID=“CustName”>…</TD>

and hands off the page to the programmer

• The programmer compiles the page into a java class which is a DOM tree that can reproduce the document

Development with Enhydra XMLC

welcome.html

xmlc -class myapp.WelcomeHTML welcome.html

javac

myapp.WelcomeHTML

… Work Flow ...

• XMLC generates “getElement<IDName>()” and “setText<IDName>()”methods in the document object, e.g.

getElementCustName()and setTextCustName() for each ID-tagged HTML page element

• At run-time the programmer instantiates the HTML page as an object and manipulates its properties

…Work Flow

• The programmer can use the XMLC-generated methods like getElementCustName()to clone, remove, or otherwise manipulate page elements

• The programmer can also traverse the DOM tree to manipulate its other nodes directly if desired

• Finally toDocument() is called on the page object to stream the page to the web client as a string

Advantages of XMLC

• Object-oriented control of documents

• Layout and flow of control are completely separated

• Page designers and programmers only intersect on defining the dynamic page elements

• Programmers are largely unaware of page layout

...Advantages

• HTML storyboard can be demo’d and modified in parallel with the server-side code

• Business logic and user interface can be developed and tested completely independently of each other

• Enhydra XMLC can serve the presentation layer in any multi-tier java environment, such as BEA WebLogic

XMLC for XML

• XMLC compiles any XML document

– Generic DOMs

– DTD-specific DOMs

• XML intended for display

• XML as data interchange format

• WML - Wireless Markup Language

– HTML-like DTDs for wireless devices

– Many companies using Enhydra XMLC for developing WML applications

Toward J2EE Enhydra

Other Open Source contributions,including on-going Enhydra evolution

JOnAS,BullSoft

Jonathan,France Telecom

Open Source Java/XML Application ServerOpen Source Java/XML Application Server

Open Source Java/XML Application Server & & Web Development with Open Source Enhydra Java/XML...

Documents

Transcript of Open Source Java/XML Application Server & & Web Development with Open Source Enhydra Java/XML...