Lecture 06Process Design

Agenda Why Processes?

– Design Issues– Architecture Issues

RU Process Framework

Reading RuFramework source code XML Processing XML (video) Build Scripts (video)

Java Technology and XML-Part One – http://java.sun.com/developer/

technicalArticles/xml/JavaTechandXML/

Why Processes?

What is a Processes anyway? Enterprise system need to run processes

for several reasons– Manual or automatic

Things in the “background”– Nightly update of customers– Reconciliation of systems

Lengthy operations– Recalculate of all accounts

Processes have no user interface– Traditionally know as “Jobs”

Our Task We need to build a framework from

running processes. What patterns can we use?

Design Issues Each process has simple task Each process can be re-run at any time Locations are always the same Logging is always the same Customer specific functionality

can be added to generic processes Other considerations

– Must handle large amount of data– Must support multiple threads for performance

Process Framework

Generic Process

Customer Specific Plugin

RU Process Framework

RU Framework Simple Framework developed during the course

– Illustrates design ideas– Application Framework– Reduce dependence on other frameworks by

wrapping them in interfaces and classes– Builds on Spring

Package– is.ruframework

• domain• process

– All classes are prefixed with “Ru”

Process Framework The idea is that the Process Framework

starts the process Process Developers must implement some

interface Information will be in a context XML file

Process Design Let’s create an interface, RuProcess

– This is what all processes have to implement

package is.ruframework.process;

public interface RuProcess{ public void startProcess (); public void beforeProcess (); public void afterProcess ();}

Process Design Let’s implement this with

RuAbstractProcess– Processes can extend this classespackage is.ruframework.process;

import is.ruframework.domain.RuObject;

abstract public class RuAbstractProcess extends RuObject implements RuProcess{ abstract public void startProcess (); public void beforeProcess () { } public void afterProcess () { }}

Process Design We needs some context,

RuProcessContext– Processes can get information about their

process from this contextpublic class RuProcessContext{ private String processName; private String processClass; private String importFile; private String importURL; private String dataSourceFile; private Map params;

...}

Process Design Let’s change the interface, RuProcess

– Dependency Injection

package is.ruframework.process;

public interface RuProcess{ public void setProcessContext (RuProcessContext processContext); public void setParameters(String[] params); abstract public void startProcess (); public void beforeProcess (); public void afterProcess ();}

Process Design Change the RuAbstractProcess

– Let this class implement the injectionabstract public class RuAbstractProcess extends RuObject implements RuProcess{ private RuProcessContext processContext; private String contextFile; private String parameters[]; ... public void setProcessContext(RuProcessContext processContext) { this.processContext = processContext; } ...

Process Design Let’s use a factory to create the process,

RuProcessFactory– This class can load the context file

public class RuProcessFactory{ private String contextFile; private RuProcessContext processContext;

public RuProcess loadProcess(RuProcessContext ctx) throws RuProcessException public void loadProcessContext(String contextFile) throws RuProcessException ...}

Process Design Create a class to run the process

– This class puts everything together

public class RuProcessRunner extends RuObject implements Runnable{ private RuProcess process = null;

public static void main(String[] args) { } public RuProcessRunner(String contextFile) throws RuProcessException public void run() { }}

RU Process Framework Implementation

Process Framework To create process, we must

– Create the process class that implements RuProcess

– Create the Process Context XML file

Process Context XML file The framework will create the object

RuProcessContext<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" http://www.springframework.org/dtd/spring-beans.dtd><beans> <bean id="processContext” class="is.ruframework.process.RuProcessContext"> <property name="processName"> <value>RSSProcess</value> </property> <property name="importURL"> <value>http://rss.news.yahoo.com/rss/tech</value> </property> <property name="processClass"> <value>is.ru.honn.blog.process.RssReaderProcess</value> </property> </bean></beans>

RuProcessContext Class for storing the Process Context

– The environment the process runs in– Attributes line process name, class, importURL,

data source

The RuProcess Interface RuProcess is the interface for all

processes The framework will load the process

context and set with setProcessContext– Dependency Injection

The Framework will call the process methods– beforeProcess, startProcess, afterProcess

RuProcess RuProcess is the interface for all

processes– The Process Factory will call setProcessContext

public interface RuProcess{ public void setProcessContext(RuProcessContextprocessContext); public void setParameters(String[] params); public void startProcess (); public void beforeProcess (); public void afterProcess ();}

RuAbstractProcess Abstract class that implements

RuProcess– Takes care of handling Process Context– Overrides beforeProcess

and afterProcess with empty methods, allowing them to become optional

– Declares startProcessas abstract

Layered Supertype Interface defines the methods needed

– Some are generic for all derived classes Use abstract super classes to implement

some but not all of the interface methods

RuAbstractProcessabstract public class RuAbstractProcess extends RuObject implements RuProcess { private RuProcessContextprocessContext; private String contextFile; private String parameters[];

public void setProcessContext(RuProcessContextprocessContext) { this.processContext = processContext; }

public RuProcessContextgetProcessContext() { return processContext; } ... abstract public void startProcess (); public void beforeProcess () {} public void afterProcess () {} }

Eat these

RuProcessFactory Factory that loads processes

– Factroy and Plugin Patterns– loadProcess method returns RuProcess– Extends the generic RuFactory

RuProcessFactorypublic class RuProcessFactory extends RuFactory { private static final String PROCESS_CONTEXT = "process.xml"; private RuProcessContextprocessContext;

public RuProcessloadProcess(RuProcessContextctx) throws RuProcessException { RuProcess process = null;

// Load the process specified in the context file try { Class cls = Class.forName(ctx.getProcessClass()); process = (RuProcess)cls.newInstance(); process.setProcessContext(ctx); } catch (Exception e) { ... } return process; }

RuProcessFactorypublic void loadProcessContext(String contextFile) throws RuProcessException{ try { processContext = (RuProcessContext)getObject("processContext"); } catch (BeansException e) { String tmp = "File '" + contextFile + "' not found. Exception: " + e.getMessage(); log.severe(tmp); throw new RuProcessException(tmp, e); }

}

RuProcessRunner Class that calls the factory and runs the

process– Name of Process Context file is parameter

RuProcessRunner public static void main(String[] args) { RuProcessRunner runner;

if (args.length> 0) { runner = new RuProcessRunner(args[0]); } else { runner = new RuProcessRunner(); }

try { runner.run(); } catch (RuProcessExceptionfwpe) { System.out.println(fwpe.getMessage()); } }

RuProcessRunner public RuProcessRunner(String contextFile) throws RuProcessException { if (contextFile == null) { String tmp = "Parameter contextFile must not be null"; log.severe(tmp); throw new RuProcessException(tmp); } RuProcessFactory factory = new RuProcessFactory(contextFile); process = factory.loadProcess(); } public void run() { if (process != null) { process.beforeProcess(); process.startProcess(); process.afterProcess(); } }}

Process Framework

Process Framework

Data Transfer Object

Factory

Template Method

Plug-in

Layered Supertype

Dependency injection

Layered Supertype

Import Content Process

Import Content Process Problem

– We need to import RSS feeds into our database– Example URL:

• http://rss.news.yahoo.com/rss/tech Solution

– Use the RU Framework• ImportContentPrcess

– Use the FeedReader

Import Content Process Process that reads contents from an URL Tasks

– Creates a FeedReader to read entries– The process implements the processContent

callback– Uses ContentService from our Domain Layer to

store each content– Must log out the progress using a message

source

Import Content Process Process that reads contents from an URL Tasks

– The Process must “wire” all components together

Import Content Process Process that reads contents from an URL Solution

– Create class ImportContentProcess that extends RuAbstractProcess

• beforeProcess• startProcess• afterProcess

– Define the Process Context in process.xml– Use Spring ApplicationContext to load all the

components• Specified in app.xml

Import Content Processpublic class ImportContentProcess extends RuAbstractProcess implements FeedHandler{ protected ContentServicecontentService; FeedReader reader; MessageSourcemsg;

public void beforeProcess() { ApplicationContextctx = new FileSystemXmlApplicationContext("app.xml"); contentService = (ContentService)ctx.getBean("contentService"); reader = (FeedReader)ctx.getBean("feedReader"); reader.setFeedHandler(this); msg = (MessageSource)ctx.getBean("messageSource"); log.info(msg.getMessage("processbefore", new Object[] { getProcessContext().getProcessName() } , Locale.getDefault())); }

Import Content ProcessApplicationContextctx = new FileSystemXmlApplicationContext("app.xml");contentService = (ContentService)ctx.getBean("contentService");reader = (FeedReader)ctx.getBean("feedReader");reader.setFeedHandler(this);msg = (MessageSource)ctx.getBean("messageSource");

<beans> <bean id="messageSource“ class= "org.springframework.context.support.ResourceBundleMessageSource"> <property name="basename“><value>messages</value></property> </bean> <bean id="contentService" class="is.ru.honn.tube.service.content.ContentServiceStub"> </bean> <bean id="feedReader" class="is.ru.honn.tube.feeds.RssReader"> </bean></beans>

app.xml

Import Content Process public void startProcess() { log.info(msg.getMessage("processstart", new Object[] { getProcessContext().getProcessName() }, Locale.getDefault())); try { reader.read(getProcessContext().getImportURL()); } catch (FeedException e) { log.info(msg.getMessage("processreaderror", new Object[] { getProcessContext().getImportFile() }, Locale.getDefault())); log.info(e.getMessage()); } log.info(msg.getMessage("processstartdone", new Object[] {contentService.getContents().size()}, Locale.getDefault())); }

Collecting the Entries public void processContent(Object content) { contentService.addContent((Content)content); }

Running the Process public void afterProcess() { Collection<Content>col = contentService.getContents(); for (Content cnt: col) { System.out.println(cnt); } }

Message Source

log.info(msg.getMessage("processstart", new Object[] { getProcessContext().getProcessName() }, Locale.getDefault()));

processbefore=The process {0} is starting (beforeProcess).processstart=Starting process {0}processstartdone=Reading done. Read {0} contentsprocessreaderror=Unable to read file ''{0}''.

messages.properties

msg = (MessageSource)ctx.getBean("messageSource");

<bean id="messageSource“ class="org.springframework.context.support.ResourceBundleMessageSource"><property name="basename“><value>messages</value></property></bean>

app.xml

startProcess in ImportContentProcess.java

beforeProcess in ImportContentProcess.java

Using the ContentService

public void processContent(Content content) { contentService.addContent(content); }

public interface ContentService{ public void addContent(Content content); public Collection<Content>getContents();}

while (i.hasNext()) { ent = (SyndEntry)i.next(); content = new Content(); content.setTitle(ent.getTitle()); ... handler.processContent(content); }

read in RssReader.java

ImportContentProcess.java

ContentService.java

Printing out values public void afterProcess() { Collection<Content>col = contentService.getContents(); for (Content cnt: col) { System.out.println(cnt); } }INFO: The process ImportContentProcess is starting (beforeProcess).Sep 28, 2008 3:09:31 PM is.ru.honn.tube.process.ImportContentProcessstartProcessINFO: Starting process ImportContentProcessSep 28, 2008 3:09:32 PM is.ru.honn.tube.process.ImportContentProcessstartProcessINFO: Reading done. Read 12 contentsJapan's online social scene isn't so social (AP)

Unlocked iPhone 3G on sale in Hong Kong (AP)

Run with IntelliJ

Running the ProcessINFO: Starting process ImportContentProcessSep 24, 2012 8:43:50 AM is.ru.honn.tube.process.ImportContentProcess startProcessINFO: Reading done. Read 40 contentsMany US stores report being sold out of iPhone 5sApple supplier halts China factory after violenceApple, Samsung demand changes to $1B verdictThis is Scary: Scientists find a way to erase frightening memoriesVerizon’s iPhone 5 being sold unlocked, allowing it to be used internationallyWhy Burberry Wants to Bring the Online Experience to Stores, and Not Vice VersaApple, Samsung demand changes to $1B verdictiPhone 5 launch draws Apple fans worldwideVerizon iPhone 5's secret feature: It's 'unlocked'Review: iPhone evolves into jewel-like '5'

Processing XML

Overview

XML Example<?xml version="1.0" encoding=”UTF-8"?><teams> <team> <id>ENG001</id> <name>Arsenal</name> <league>ENG001</league> <sport>FOOTBALL</sport> <country>England</country> </team> ...</teams>

XML RSS Example<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:media="http://search.yahoo.com/mrss"><channel><title>YouTube :: Recently Added Videos</title><link>http://youtube.com/rss/global/recently_added.rss</link><description>Recently Added Videos</description><item><author>rss@youtube.com (lokipsa)</author><title>Profile pic test</title><link>http://youtube.com/?v=1mpDAAMwoQo</link><description><![CDATA[<img src="http://sjl-static2.sjl.youtube.com/vi/1mpDAAMwoQo/2.jpg" align="right" ...</p>]]></description><guid isPermaLink="true">http://youtube.com/?v=1mpDAAMwoQo</guid><pubDate>Sun, 10 Sep 2006 10:11:02 -0700</pubDate><media:player url="http://youtube.com/?v=1mpDAAMwoQo" />...

Valid and well-formed docments XML document is well-formed if it is

according to the XML standard– Correct according to the rules

XML document is valid if it is according to some specific Document Definition (DTD) or Schema– Correct according to DTD or Schema

XML document that is not well-formed is not usable– Unlike HTML

XML Properties XML documents are tree Each node is also a tree or a leaf Benfits

– Easy to traverse the document– Easy to build new documents– Allows for XSLT transformation– Easy to work with parts of the

document XML parser can use these properties

Parsing To use XML document it must be parsed XML Parser

– Reads in the XML document– Provides data to tree form to work with

Two basic methods– DOM – Document Object Model– SAX – Simple API of XML

JDom is a library that simplifies both

The DOM Concept Tree is built – DOM

The SAX Concept SAX will send a message

– Calls methods in Handler

JDom DOM and SAX are low-level APIs

– Cumbersome to use JDom is a simple class library for XML

parsing– Supports both DOM and SAX– Goal is to simplify using XML

Packages– org.jdom

XML XML is universal, simple to understand Good when exchanging data There is time and space complexity

Summary Process Framework Import Content Process XML