How to configure with Spring an api not based on Spring

HOW TO CONFIGURE WITH SPRING AN
API NOT BASED ON SPRING
Jose María Arranz Santamaría

Madrid (Spain) February 17-18, 2011
1

THE PROBLEM
• Spring was born as a tool to configure and
integrate disparate technologies
• We can not always expect such disparate
technologies be ready to be configured “out of
the box” with Spring
This is the thing Spring was invented for!

3

THE PROBLEM
• ItsNat is a Java web framework
with a custom non-Spring configuration system
• ItsNat configuration is the most powerful and
flexible approach ever invented: Calling methods!
• As of day 0 ItsNat configuration was conceived to
be “overloaded” with higher level configuration
techniques and APIs, for instance… Spring!

4

DO NOT WORRY THIS IS NOT GOING
TO BE AN ItsNat COURSE!


6

WE ARE GOING TO LEARN SOME
Spring TRICKS

7

BUT WE MUST KNOW HOW TO
CONFIGURE A WEB PROJECT BASED
ON ItsNat TO CONFIGURE IT LATER
WITH Spring

We will pick the “core” example in the
ItsNat Reference Manual

8

“PURE” ItsNat EXAMPLE: the servlet
• ItsNat does not define a concrete servlet,
developer must create one (or more)
– Configuration is done in method init
• In this example most of configuration is optional, just
used to show ItsNat configuration options
public class servlet extends HttpServletWrapper
{
public void init(ServletConfig config) throws ServletException
{
super.init(config);
ItsNatHttpServlet itsNatServlet = getItsNatHttpServlet();
ItsNatServletConfig itsNatConfig =
itsNatServlet.getItsNatServletConfig();
ItsNatServletContext itsNatCtx =
itsNatConfig.getItsNatServletContext();

9

• ItsNatHttpServlet, ItsNatServletConfig
y ItsNatServletContext are the roots (and
singletons) of ItsNat configuration
itsNatCtx.setMaxOpenDocumentsBySession(6);

String serverInfo = getServletContext().getServerInfo();
boolean gaeEnabled = serverInfo.startsWith(
"Google App Engine");

itsNatCtx.setSessionReplicationCapable(gaeEnabled);
itsNatCtx.setSessionSerializeCompressed(false);
itsNatCtx.setSessionExplicitSerialize(false);

10

itsNatConfig.setDebugMode(true);
itsNatConfig.setClientErrorMode(
ClientErrorMode.SHOW_SERVER_AND_CLIENT_ERRORS);
itsNatConfig.setLoadScriptInline(true);
itsNatConfig.setFastLoadMode(true);
itsNatConfig.setCommMode(CommMode.XHR_ASYNC_HOLD);
itsNatConfig.setEventTimeout(-1);
itsNatConfig.setOnLoadCacheStaticNodes("text/html",true);
itsNatConfig.setOnLoadCacheStaticNodes("text/xml",false);
itsNatConfig.setNodeCacheEnabled(true);

11

itsNatConfig.setDefaultEncoding("UTF-8");
itsNatConfig.setUseGZip(UseGZip.SCRIPT);
itsNatConfig.setDefaultDateFormat(
DateFormat.getDateInstance(DateFormat.DEFAULT,Locale.US));
itsNatConfig.setDefaultNumberFormat(
NumberFormat.getInstance(Locale.US));
itsNatConfig.setEventDispatcherMaxWait(0);
itsNatConfig.setEventsEnabled(true);
itsNatConfig.setScriptingEnabled(true);
itsNatConfig.setUsePatternMarkupToRender(false);
itsNatConfig.setAutoCleanEventListeners(true);

12

• Now we register in the servlet an ItsNat template
core_example.xhtml and associated document loader
CoreExampleLoadListener
– Just a simple example of HTML page with AJAX
String pathPrefix = getServletContext().getRealPath("/");
pathPrefix += "/WEB-INF/pages/manual/";

ItsNatDocumentTemplate docTemplate;
docTemplate = itsNatServlet.registerItsNatDocumentTemplate(
"manual.core.example","text/html",
pathPrefix + "core_example.xhtml");
docTemplate.addItsNatServletRequestListener(
new CoreExampleLoadListener());

13

• Another example, in this case a page with XML
docTemplate = itsNatServlet.registerItsNatDocumentTemplate(
"manual.core.xmlExample","text/xml",
pathPrefix + "xml_example.xml");
new CoreXMLExampleLoadListener());

• This XML example inserts an ItsNat “template
fragment”
– Template fragments have not “loaders/processors”
ItsNatDocFragmentTemplate docFragTemplate;
docFragTemplate = itsNatServlet.registerItsNatDocFragmentTemplate(
"manual.core.xmlFragExample","text/xml",
pathPrefix + "xml_fragment_example.xml");

14

“PURE” ItsNat EXAMPLE
• <root>/WEB-INF/pages/manual/core_example.xhtml
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><title>ItsNat Core Example</title></head>
<body>
<h3>ItsNat Core Example</h3>
<div itsnat:nocache="true"
xmlns:itsnat="http://itsnat.org/itsnat">
<div id="clickableId1">Clickable Elem 1</div>
<br />
<div id="clickableId2">Clickable Elem 2</div>
</div>
</body>
</html>

15

• CoreExampleLoadListener is just a simple
launcher of document processors, called per page
loaded
public class CoreExampleLoadListener
implements ItsNatServletRequestListener
{
public CoreExampleLoadListener() {}

public void processRequest(ItsNatServletRequest request,
ItsNatServletResponse response)
{
ItsNatHTMLDocument itsNatDoc =
(ItsNatHTMLDocument)request.getItsNatDocument();
new CoreExampleDocument(itsNatDoc);
}
}

16

• CoreExampleDocument manages the page
(document) state receiving AJAX events
public class CoreExampleDocument implements EventListener
{
protected ItsNatHTMLDocument itsNatDoc;
protected Element clickElem1;
protected Element clickElem2;

public CoreExampleDocument(ItsNatHTMLDocument itsNatDoc)
{
this.itsNatDoc = itsNatDoc;
load();
}
...

17


18

• <root>/WEB-INF/pages/manual/xml_example.xml
<?xml version='1.0' encoding='UTF-8' ?>
<discs>
<itsnat:include name="manual.core.xmlFragExample"
xmlns:itsnat="http://itsnat.org/itsnat" />
<cdList>
<cd>
<title>Tittle</title>
<artist>Artist</artist>
<songs>
<song>Song Pattern</song>
</songs>
</cd>
</cdList>
</discs>

19

• <root>/WEB-INF/pages/manual/xml_fragment_example.xml

<?xml version='1.0' encoding='UTF-8' ?>
<root>
<title>CD List</title>
<subtitle>in XML</subtitle>
</root>

20

• CoreXMLExampleLoadListener : in this case
(XML page) there is no AJAX events, we do not need a
class wrapping the document. This example includes the
template fragment "manual.core.xmlFragExample"
public class CoreXMLExampleLoadListener
implements ItsNatServletRequestListener
{
public CoreXMLExampleLoadListener() { }

ItsNatServletResponse response)
{
ItsNatDocument itsNatDoc = request.getItsNatDocument();
Document doc = itsNatDoc.getDocument();
Element discsElem = doc.getDocumentElement();
...

21


22

ItsNat Springization

23

OBJETIVES
1. Build a single reused generic servlet :
itsnatspring.itsnatservlet
2. Configuration is fully done in a XML
configuration file of Spring in classpath:
itsnatex/spring.xml
3. The only user defined Java classes will be the
document wrappers/containers:
itsnatex.CoreExampleDocument
itsnatex.CoreXMLExampleDocument

24

CONSEQUENCES
• Besides the generic servlet we will need some
utility classes also generic and reusable for
other ItsNat+Spring projects
• These classes are not completed, just to cover
the needs of this example
– ItsNat has more configuration options

25

THE SERVLET
package itsnatspring;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import org.itsnat.core.http.HttpServletWrapper;
import org.itsnat.core.http.ItsNatHttpServlet;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.support.GenericApplicationContext;

public class itsnatservlet extends HttpServletWrapper
{
public void init(ServletConfig config) throws ServletException
{
super.init(config);
ItsNatHttpServlet itsNatServlet = getItsNatHttpServlet();
GenericApplicationContext rootContext = new GenericApplicationContext();
ItsNatBeansRegistryUtil.registerSingletons(rootContext, itsNatServlet);
rootContext.refresh();

26

THE SERVLET
String springXMLPath = config.getInitParameter("spring_config");
if (springXMLPath == null)
throw new RuntimeException("spring_config initialization
parameter is not specified in web.xml");
ApplicationContext context =
new ClassPathXmlApplicationContext(
new String[] {springXMLPath},rootContext);
}
}

• ItsNat configuration objects are registered into a
generic ApplicationContext (the root), our
XML with Spring configuration is loaded by
another (child) Spring context

27

ItsNatBeansRegistryUtil
import org.itsnat.core.ItsNatServletConfig;
import org.itsnat.core.ItsNatServletContext;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.context.support.AbstractApplicationContext;

public class ItsNatBeansRegistryUtil
{
public final static String itsNatHttpServletBean = "itsNatHttpServlet";
public final static String itsNatServletConfigBean = "itsNatServletConfig";
public final static String itsNatServletContextBean = "itsNatServletContext";

public static ItsNatHttpServlet getItsNatHttpServlet(ApplicationContext context) {
return context.getBean(itsNatHttpServletBean,ItsNatHttpServlet.class);
}
public static ItsNatServletConfig getItsNatServletConfig(ApplicationContext context){
return context.getBean(itsNatServletConfigBean,ItsNatServletConfig.class);
}
public static ItsNatServletContext getItsNatServletContext(ApplicationContext context){
return context.getBean(itsNatServletContextBean,ItsNatServletContext.class);
}
28

ItsNatBeansRegistryUtil
public static void registerSingletons(AbstractApplicationContext context,
ItsNatHttpServlet itsNatServlet)
{
ItsNatServletConfig itsNatServletCofig =
itsNatServlet.getItsNatServletConfig();
ItsNatServletContext itsNatServletContext =
itsNatServletCofig.getItsNatServletContext();

ConfigurableListableBeanFactory beanFact = context.getBeanFactory();
beanFact.registerSingleton(itsNatHttpServletBean,itsNatServlet);
beanFact.registerSingleton(itsNatServletConfigBean,itsNatServletCofig);
beanFact.registerSingleton(itsNatServletContextBean,itsNatServletContext);
}
}

• ItsNat configuration objects are manually
registered as singletons in Spring context

29

web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<servlet>
<servlet-name>itsnatservlet</servlet-name>
<servlet-class>itsnatspring.itsnatservlet</servlet-class>
<init-param>
<param-name>spring_config</param-name>
<param-value>itsnatex/spring.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>itsnatservlet</servlet-name>
<url-pattern>/itsnatservlet</url-pattern>
</servlet-mapping>
<session-config>
<session-timeout>30</session-timeout>
</session-config>
</web-app> 30

spring.xml
<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/util
http://www.springframework.org/schema/util/spring-util-3.0.xsd">

<bean class="itsnatspring.ItsNatServletContextBean">
<property name="maxOpenDocumentsBySession" value="10" />
<property name="sessionReplicationCapable" value="false" />
<property name="sessionSerializeCompressed" value="false" />
<property name="sessionExplicitSerialize" value="false" />
</bean>

31

ItsNatServletContextBean
• This utility class is used as a singleton to save the
specified flags and in the end of bean configuration
they are registered calling methods of
ItsNatServletContext
– Because we need the ApplicationContext
we will implement
ApplicationContextAware
– Because we must to save in ItsNat context our
configuration data in the end of bean
configuration we need to implement
InitializingBean
32


import org.itsnat.core.ItsNatServletContext;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContextAware;

public class ItsNatServletContextBean
implements InitializingBean,ApplicationContextAware
{
protected ApplicationContext context;
protected Integer maxOpenDocumentsBySession;
protected Boolean sessionReplicationCapable;
protected Boolean sessionSerializeCompressed;
protected Boolean sessionExplicitSerialize;

public ItsNatServletContextBean() { }

33

public int getMaxOpenDocumentsBySession() {
return maxOpenDocumentsBySession;
}
public void setMaxOpenDocumentsBySession(int maxOpenDocumentsBySession){
this.maxOpenDocumentsBySession = maxOpenDocumentsBySession;
}
public boolean getSessionReplicationCapable() {
return sessionReplicationCapable;
}
public void setSessionReplicationCapable(
boolean sessionReplicationCapable) {
this.sessionReplicationCapable = sessionReplicationCapable;
}
public boolean getSessionSerializeCompressed() {
return sessionSerializeCompressed;
}
public void setSessionSerializeCompressed(
boolean sessionSerializeCompressed) {
this.sessionSerializeCompressed = sessionSerializeCompressed;
}
34

public boolean getSessionExplicitSerialize() { return sessionExplicitSerialize; }
public void setSessionExplicitSerialize(boolean sessionExplicitSerialize){
this.sessionExplicitSerialize = sessionExplicitSerialize;
}
@Override
public void setApplicationContext(ApplicationContext context) throws BeansException {
this.context = context; }
@Override
public void afterPropertiesSet() throws Exception {
ItsNatServletContext itsNatServletContext =
ItsNatBeansRegistryUtil.getItsNatServletContext(context);
if (maxOpenDocumentsBySession != null)
itsNatServletContext.setMaxOpenDocumentsBySession(maxOpenDocumentsBySession);
if (sessionReplicationCapable != null)
itsNatServletContext.setSessionReplicationCapable(sessionReplicationCapable);
if (sessionSerializeCompressed != null)
itsNatServletContext.setSessionSerializeCompressed(sessionSerializeCompressed);
if (sessionExplicitSerialize != null)
itsNatServletContext.setSessionExplicitSerialize(sessionExplicitSerialize);
}
}
35

spring.xml (cont.)
<bean id="defaultLocale" class="itsnatspring.LocaleBean" >
<property name="language" value="en" />
<property name="country" value="US" />
</bean>

<bean id="defaultDateFormat" class="itsnatspring.DateFormatBean" >
<property name="style" value="2" /> 
<property name="locale">
<bean factory-bean="defaultLocale" factory-method="getLocale"/>
</property>
</bean>

<bean id="defaultNumberFormat" class="itsnatspring.NumberFormatBean" >
<property name="locale">
<bean factory-bean="defaultLocale" factory-method="getLocale" />
</property>
</bean>
... 36

LocaleBean
• This “factory bean” allows configuring a Locale and
made public calling the “factory method”
getLocale()
import java.util.Locale;

public class LocaleBean implements InitializingBean
{
protected String language;
protected String country;
protected Locale locale;

public LocaleBean() { }
public String getCountry() { return country; }
public void setCountry(String country) { this.country = country; }
public String getLanguage() { return language; }

37

LocaleBean
public void setLanguage(String language) { this.language = language; }
public Locale getLocale() { return locale; }

@Override
public void afterPropertiesSet() throws Exception
{
Locale[] availablelocales = Locale.getAvailableLocales();
for(Locale locale : availablelocales)
if (locale.getLanguage().equals(language) &&
locale.getCountry().equals(country))
{
this.locale = locale;
return;
}
this.locale = new Locale(language,country);
}
}

38

• Some other utility classes are very similar to the
previous shown, from now we are just to show
only the most interesting
• From Spring XML you can figure out how they
work under the hood
– ItsNat singletons are got through
ItsNatBeansRegistryUtil and the Spring
ApplicationContext
– This context is got implementing
ApplicationContextAware

39

spring.xml (cont.)
<bean class="itsnatspring.ItsNatServletConfigBean">
<property name="debugMode" value="true" />
<property name="clientErrorMode" value="4" />
<!– ClientErrorMode.SHOW_SERVER_AND_CLIENT_ERRORS -->
<property name="defaultEncoding" value="UTF-8" />
<property name="onLoadCacheStaticNodes"> <!– backed by a Properties attr -->
<value>
text/html=true
text/xml=false
</value>
</property>
<property name="defaultDateFormat">
<bean factory-bean="defaultDateFormat" factory-method="getDateFormat"/>
</property>
<property name="defaultNumberFormat">
<bean factory-bean="defaultNumberFormat" factory-method="getNumberFormat"/>
</property>
</bean>
...
40

spring.xml (cont.)
<bean id="coreExamplePath" class="itsnatspring.WebPathBean">
<property name="relativePath" value="/WEB-INF/pages/manual/core_example.xhtml"/>
</bean>

<bean id="coreExampleDoc" class="itsnatex.CoreExampleDocument" scope="prototype" >

</bean>

<bean id="coreExampleDocTemplate" class="itsnatspring.ItsNatDocumentTemplateBean">
<property name="name" value="manual.core.example" />
<property name="mime" value="text/html" />
<property name="source">
<bean factory-bean="coreExamplePath" factory-method="getAbsolutePath"/>
</property>
<property name="itsNatServletRequestListener" >
<bean class="itsnatspring.ItsNatServletRequestListenerBean" >
<property name="documentBeanName" value="coreExampleDoc" />
</bean>
</property>
</bean>
...

41

ItsNatServletRequestListenerBean
• This “local singleton bean” is very interesting becase it works
like a generic “ItsNat document loader listener”
implementing ItsNatServletRequestListener
• To be generic we must invent a simple interface
ItsNatDocumentInitialize for the document
processors/wrappers:

import org.itsnat.core.ItsNatServletRequest;
import org.itsnat.core.ItsNatServletResponse;

public interface ItsNatDocumentInitialize
{
public void load(ItsNatServletRequest request,
ItsNatServletResponse response);
}

42


import org.itsnat.core.ItsNatServletRequest;
import org.itsnat.core.ItsNatServletResponse;
import org.itsnat.core.event.ItsNatServletRequestListener;
import org.springframework.context.support.AbstractApplicationContext;

public class ItsNatServletRequestListenerBean implements
ItsNatServletRequestListener,ApplicationContextAware,InitializingBean
{
protected AbstractApplicationContext context;
protected String documentBeanName;

public ItsNatServletRequestListenerBean() { }
43

ItsNatServletResponse response) {
ItsNatDocumentInitialize docWrapper =
context.getBean(documentBeanName,ItsNatDocumentInitialize.class);
docWrapper.load(request, response);
}

public String getDocumentBeanName() { return documentBeanName; }

public void setDocumentBeanName(String documentBeanName) {
this.documentBeanName = documentBeanName;
}

44

@Override
public void setApplicationContext(ApplicationContext context)
throws BeansException {
this.context = (AbstractApplicationContext)context;
}
@Override
// Checking correctly defined:
if (documentBeanName == null)
throw new RuntimeException("docBeanName property is mandatory");
if (!context.getBeanFactory().isPrototype(documentBeanName))
throw new RuntimeException("Bean " + documentBeanName +
" must be "prototype" scoped");
}
}

45

ItsNatDocumentTemplateBean
• Finally this bean registers the template and the
associated “ItsNat document loader listener” configured
import org.itsnat.core.event.ItsNatServletRequestListener;
import org.itsnat.core.tmpl.ItsNatDocumentTemplate;

public class ItsNatDocumentTemplateBean
implements InitializingBean,ApplicationContextAware {
protected String name;
protected String mime;
protected Object source;
protected ItsNatServletRequestListener itsNatServletRequestListener;

46

public ItsNatServletRequestListener getItsNatServletRequestListener(){
return itsNatServletRequestListener;
}
public void setItsNatServletRequestListener(
ItsNatServletRequestListener itsNatServletRequestListener) {
this.itsNatServletRequestListener = itsNatServletRequestListener;
}

public String getName() { return name; }
public void setName(String name) { this.name = name; }
public String getMime() { return mime; }
public void setMime(String mime) { this.mime = mime; }
public Object getSource() { return source; }
public void setSource(Object source) { this.source = source; }

@Override
public void setApplicationContext(ApplicationContext context)
throws BeansException {
this.context = context;
}

47

@Override
public void afterPropertiesSet() throws Exception
{
// name, mime and source are mandatory
ItsNatHttpServlet itsNatHttpServlet =
ItsNatBeansRegistryUtil.getItsNatHttpServlet(context);
ItsNatDocumentTemplate docTemplate =
itsNatHttpServlet.registerItsNatDocumentTemplate(name,mime,source);
if (itsNatServletRequestListener != null)
itsNatServletRequestListener);
// More config here...
}
}

48

spring.xml (cont.)
<bean id="coreXMLDocExamplePath" class="itsnatspring.WebPathBean">
<property name="relativePath" value="/WEB-INF/pages/manual/xml_example.xml" />
</bean>
<bean id="coreXMLExampleDoc" class="itsnatex.CoreXMLExampleDocument“
scope="prototype">

</bean>
<bean id="coreXMLExampleDocTemplate"
class="itsnatspring.ItsNatDocumentTemplateBean">
<property name="name" value="manual.core.xmlExample" />
<property name="mime" value="text/xml" />
<bean factory-bean="coreXMLDocExamplePath"
factory-method="getAbsolutePath"/>
</property>
<property name="itsNatServletRequestListener" >
<bean class="itsnatspring.ItsNatServletRequestListenerBean" >
<property name="documentBeanName" value="coreXMLExampleDoc" />
</bean>
</property>
</bean> ...

49

spring.xml (cont.)
<bean id="coreXMLFragExamplePath" class="itsnatspring.WebPathBean">
<property name="relativePath"
value="/WEB-INF/pages/manual/xml_fragment_example.xml" />
</bean>

<bean id="coreXMLExampleFragTemplate"
class="itsnatspring.ItsNatDocFragmentTemplateBean">
<property name="name" value="manual.core.xmlFragExample" />
<property name="mime" value="text/xml" />
<bean factory-bean="coreXMLFragExamplePath"
factory-method="getAbsolutePath"/>
</property>
</bean>

</beans>

50

ItsNatDocFragmentTemplateBean
• With this class the template fragment is registered
...
public class ItsNatDocFragmentTemplateBean
implements InitializingBean,ApplicationContextAware
{
protected String name;
protected String mime;
protected Object source;
...
@Override
// name, mime and source are mandatory
ItsNatHttpServlet itsNatHttpServlet =
ItsNatBeansRegistryUtil.getItsNatHttpServlet(context);
ItsNatDocFragmentTemplate fragTemplate;
fragTemplate = itsNatHttpServlet.registerItsNatDocFragmentTemplate(
name,mime,source);
// More config here...
}
} 51

CONCLUSION
Can you use Spring to configure “any”
API?

52

How to configure with Spring an api not based on Spring

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