Processes are programs that run in data centers and have the role of executing specific tasks. They can be scheduled, triggered by an event or run manually. These programs handle task such as importing and exporting, reconciliation, daily updates and calculations and thing like that. Processes usually have no user interface except they log their progress to a log file. In this lecture we create a process framework based on some of the design patterns we have covered. The idea is that this framework can be used to build processes, and as an example we create process call Import Content Process that reads RSS entries form a new site. We also look briefly at XML.

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