1.
Lecture 06
Process Design

2.
Agenda
 Why Processes?
– Design Issues
– Architecture Issues
 RU Process Framework

3.
Reading
 RuFramework source code
 XML
 Processing XML (video)
 Build Scripts (video)
 Java Technology and XML-Part One
– http://java.sun.com/developer/technicalArticles/xml/Ja
vaTechandXML/

4.
Why Processes?

5.
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”

6.
Our Task
 We need to build a framework from running
processes.
 What patterns can we use?

7.
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

8.
RU Process Framework

9.
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”

10.
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

11.
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 ();
}

12.
Process Design
 Let’s implement this with RuAbstractProcess
– Processes can extend this classes
package 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 ()
{
}
}

13.
Process Design
 We needs some context, RuProcessContext
– Processes can get information about their process
from this context
public class RuProcessContext
{
private String processName;
private String processClass;
private String importFile;
private String importURL;
private String dataSourceFile;
private Map params;
...
}

14.
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 ();
}

15.
Process Design
 Change the RuAbstractProcess
– Let this class implement the injection
abstract public class RuAbstractProcess extends RuObject
implements RuProcess
{
private RuProcessContext processContext;
private String contextFile;
private String parameters[];
...
public void setProcessContext(RuProcessContext
processContext)
{
this.processContext = processContext;
}
...

16.
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
...
}

17.
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()
{
}
}

18.
RU Process Framework
Implementation

19.
Process Framework
 To create process, we must
– Create the process class that implements RuProcess
– Create the Process Context XML file

20.
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>

21.
RuProcessContext
 Class for storing the Process Context
– The environment the process runs in
– Attributes line process name, class, importURL, data
source

22.
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

23.
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 ();
}

24.
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
startProcess
as abstract

25.
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

26.
RuAbstractProcess
abstract 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

27.
RuProcessFactory
 Factory that loads processes
– Factroy and Plugin Patterns
– loadProcess method returns RuProcess
– Extends the generic RuFactory

28.
RuProcessFactory
public 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;
}

29.
RuProcessFactory
public 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);
}
}

30.
RuProcessRunner
 Class that calls the factory and runs the process
– Name of Process Context file is parameter

31.
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());
}
}

32.
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();
}
}
}

33.
Process Framework

34.
Process Framework
Data Transfer Object
Factory
Template Method
Plug-in
Layered Supertype
Dependency injection
Layered Supertype

35.
Import Content Process

36.
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

37.
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

38.
Import Content Process
 Process that reads contents from an URL
 Tasks
– The Process must “wire” all components together

39.
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

40.
Import Content Process
public 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()));
}

41.
Import Content Process
ApplicationContextctx =
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

42.
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()));
}

43.
Collecting the Entries
public void processContent(Object content)
{
contentService.addContent((Content)content);
}

44.
Running the Process
public void afterProcess()
{
Collection<Content>col = contentService.getContents();
for (Content cnt: col)
{
System.out.println(cnt);
}
}

45.
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} contents
processreaderror=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

46.
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

47.
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.ImportContentProcessstar
INFO: Starting process ImportContentProcess
Sep 28, 2008 3:09:32 PM is.ru.honn.tube.process.ImportContentProcessstar
INFO: Reading done. Read 12 contents
Japan's online social scene isn't so social
(AP)
Unlocked iPhone 3G on sale in Hong Kong

48.
Run with IntelliJ

49.
Running the Process
INFO: Starting process ImportContentProcess
Sep 24, 2012 8:43:50 AM is.ru.honn.tube.process.ImportContentProcess
startProcess
INFO: Reading done. Read 40 contents
Many US stores report being sold out of iPhone 5s
Apple supplier halts China factory after violence
Apple, Samsung demand changes to $1B verdict
This is Scary: Scientists find a way to erase frightening memories
Verizon’s iPhone 5 being sold unlocked, allowing it to be used
internationally
Why Burberry Wants to Bring the Online Experience to Stores, and Not Vice
Versa
Apple, Samsung demand changes to $1B verdict
iPhone 5 launch draws Apple fans worldwide
Verizon iPhone 5's secret feature: It's 'unlocked'
Review: iPhone evolves into jewel-like '5'

50.
Processing XML

51.
Overview

52.
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>

53.
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>

54.
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

55.
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

56.
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

57.
The DOM Concept
 Tree is built – DOM

58.
The SAX Concept
 SAX will send a message
– Calls methods in Handler

59.
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

60.
XML
 XML is universal, simple to understand
 Good when exchanging data
 There is time and space complexity

61.
Summary
 Process Framework
 Import Content Process
 XML