Case Study: The Next Generation Online Travel Platform

Spring Experience - December, 2007

Transcript

1. The*Spring*Experience* December,'2007 Michael*Alford,*Mark*Meeker** &*Alex*Antonov ONLINE&TRAVEL NEXT GENERATION CASE'STUDY: PLATFORM
2. Agenda • Project context • Technology architecture • Building UI forms • Interesting Flows • Security and SSL • Progressive Enhancement • Composite View Pattern • Componentization • URLs and REST • State management and HTTP browser caching headers • Internationalization • Performance and concurrency • Summary • Q&A
3. Project Context
4. Tech History
5. 3 years of Spring Framework usage
7. Spring MVC experiments
11. Travel Commerce Platform
12. Increase developer productivity
20. Technology Architecture
21. Direct Connections Booking Services Travel Business Services Thin Presentation Layer (Tomcat, Spring, SWF) Distributed Business Session Cache Distributed Web Session Cache
22. Deals (REST) Shop (REST) Book (not REST) Care (mixed)
23. Spring and the UI Layer
27. Dear Java Developers, Whatever you do, don’t choose a web framework that generates its own XHTML (or worse, non- validating @#$% HTML that we wouldn’t be caught dead near). Your friends, The UI Team
28. <spring:bind path=”mymodel.myinput”> <input name=”${status.expression}” value=”${status.value}” /> </spring:bind> <spring:bind />
29. Form Custom Tags • Started pre- spring-form.tld • Full control of mark-up • Abstracts concept of binding • Limit attributes available to be set • type, maxlength, class, autocomplete • Extended scope to include <label />
30. Form Custom Tags • Additional values for inputs • label-key, label-state, required, read-only • Build in hook for JavaScript • Turn-off running against live model • Augment error handling
31. Error Display • Custom Error custom tag • Formats errors with correct styles • Support for error tag debugging • Error highlighting built into form inputs
34. Interesting Flows • Leverage framework for page navigation • Large number of special conditions in booking path • Informational pop-up flows need data from flow, but don’t affect it • “Helper” flows for RESTful Ajax calls • Requirement for a “wait page”
37. Security and SSL • Browser security alerts are bad for business! • HTTP vs. HTTPS based on URL pattern • Spring Security channel filter to enforce SSL • Custom link tag insures correct protocol • Single source of truth
38. Flow listener with flow annotations to indicate flow’s security level <action-state id=“purchase”> <attribute name=“permissions” value=“USER”/> … </action-state>
39. http://blaugh.com/2006/08/21/ajax-makes-everything-better/
40. Universality • Serve pages that will work on any and every device • Fundamental basis for the web • Goes hand-in-hand with Accessibility
41. Graded Browser Support http://developer.yahoo.com/yui/articles/gbs
47. Progressive Enhancement
48. Plain Old Semantic HTML
49. Progressive Enhancement HTML Content CSS Presentation JS Behavior “No Frills” “Dress it Up” “Make it Sing”
50. Progressive Enhancement • Separation of Layers ( HTML / CSS / JS ) • Phased development • Easier to define view model and flows • And the “good stuff” too!
51. Progressive Enhancement 1 2 3 4 HTML CSS JS            
53. 1 HTML  CSS  JS 
54. <img src=”/map/image” /> <ul> <li><a href=”/map/move?dir=n”>North</a></li> <li><a href=”/map/move?dir=e”>East</a></li> <li><a href=”/map/move?dir=s”>South</a></li> <li><a href=”/map/move?dir=w”>West</a></li> ... </ul> <ul> <li><a href=”/map/zoom?level=1”>Zoom Level 1</a></li> <li><a href=”/map/zoom?level=2”>Zoom Level 2</a></li> <li><a href=”/map/zoom?level=3”>Zoom Level 3</a></li> ... </ul>
55. 2 HTML  CSS  JS 
56. 3 HTML  CSS  JS 
57. 4 HTML  CSS  JS 
62. Select from known list: Free form input:
64. 2 HTML  CSS  JS  4 HTML  CSS  JS 
65. 2 HTML  CSS  JS  4 HTML  CSS  JS 
66. XHR
67. Hijax • Term coined by Jeremy Keith • Bulletproof Ajax (http://bulletproofajax.com/) • Pull in portion of page via Ajax when XHR is supported • Re-use same portion when a full page refresh is required • Requires UI Componentization
68. Header Footer Rail Module 1 Module 2
69. Header Footer Rail Module 1 Login Module Module 2 JS-Enabled XHR noscript page transition Login Module
75. JS-Enabled XHR no-script page transition
78. 4 HTML  CSS  JS 
79. • Separates “layout” of page from content • Allows to plug in different modules into page • Used in Apache Tiles • Leverage in-house framework • Try and gain as much re-use of JSP code Composite View Pattern
85. Componentization
86. Webapp Multi-Model • Webflow definition • Reusable components • Form
87. Reusable Component • View Module (JSP) • Model • Validator [optional] • Executor (Component Action) [optional] • Tests
88. Model = POJO
89. public class ShipperSelection implements Serializable { private List<ShipperOption> shipperOptions; private ShipperOption shipperOption; private COUNTRY country; public COUNTRY getCountry() { return country; } public void setCountry(COUNTRY country) { this.country = country; } public ShipperOption getShipperOption() { return shipperOption; } public void setShipperOption(ShipperOption shipperOption) { this.shipperOption = shipperOption; } public List<ShipperOption> getShipperOptions() { return shipperOptions; } public void setShipperOptions(List<ShipperOption> shipperOptions) { this.shipperOptions = shipperOptions; } public void addShipperOption(ShipperOption shipperOption) { this.shipperOptions.add(shipperOption); } }
90. /** * @spring.bean id="shipperSelectionExecutor" * */ public class ShipperSelectionExecutor { private static PRODUCT_TYPE[] productTypes = {PRODUCT_TYPE.AIR}; public PRODUCT_TYPE[] getApplicableProductTypes() { return productTypes; } public boolean supports(Class clazz) { return ClassUtils.isAssignable(ShipperSelection.class, clazz); } public void setupBookComponent(ShipperSelection shipperSelection, BookState newParam) { List<ShipperOption> shipperOptions = getShipperOptions(); shipperSelection.setShipperOptions(shipperOptions); } private List<ShipperOption> getShipperOptions() { … return shipperOptions; } }
91. /** * @spring.bean id="shipperSelectionValidator" * */ public class ShipperSelectionValidator implements Validator { private List<COUNTRY> restrictedCountries; public ShipperSelectionValidator(List<COUNTRY> restrictedCountries) { this.restrictedCountries = restrictedCountries; } public boolean supports(Class clazz) { return ClassUtils.isAssignable(ShipperSelection.class, clazz); } public void validate(Object obj, Errors errors) { ShipperSelection c = (ShipperSelection) obj; if (restrictedCountries.contains(c.getCountry()) { errors.rejectValue("country", "1535"); } } }
92. <bean id="shipperSelectionExecutor" class="com.orbitz.wl.web.book.air.action.ShipperSelectionExecutor" /> <bean id="shipperSelectionValidator" class="com.orbitz.wl.web.book.air.validator.ShipperSelectionValidator" /> <bean id="shipperSelectionComponent" class="com.orbitz.webframework.component.ComponentFactoryBean"> <property name="singleton" value="false" /> <property name="id" value="WL_UBP310.110" /> <property name="name" value="shipperSelection" /> <property name="modelClass" value="com.orbitz.wl.web.book.air.model.ShipperSelection" /> <property name="executor" ref="shipperSelectionExecutor"/> <property name=”validator” ref=”shipperSelectionValidator” /> </bean>
93. /** * @spring.bean id="travelerInfoAction" * @spring.property name="formObjectName" value="travelerInfoForm" * @spring.property name="formObjectClass" *value="com.orbitz.webframework.component.Form" * @spring.property name="formObjectScope" value="FLOW" * @spring.property name="validator" ref="formValidator" * @spring.property name="propertyEditorRegistrators" ref="propertyEditorRegistrators" */ public class TravelerInfoAction extends Action { private static final String SHIPPER_SELECTION = "shipperSelection"; private static final String TRAVELERS_INPUT = "travelersInput"; @Override protected String[] getComponentIds() { return new String[] { SHIPPER_SELECTION + "Component", TRAVELERS_INPUT + "Component",}; } @Override public Event setupComponents(RequestContext context) { ShipperSelectionExecutor flightTicketExecutor = getComponentExecutor(context, SHIPPER_SELECTION); flightTicketExecutor.setupComponent(shipperSelection.getModel(), getBookState(context)); return success(); } public Event postProcess(RequestContext context) { TravelersInput travelersInput = getComponentModel(context, TRAVELERS_INPUT); TravelersInputExecutor whosTravelingExecutor = getComponentExecutor(context, TRAVELERS_INPUT); whosTravelingExecutor.executePostProcess(travelersInput, getBookState(context)); return success(); } }
94. URLs and REST
95. Fundamental nature of the web
96. RESTful URL represents all the state necessary to reference a particular resource
97. long-lived backwards compatible
98. benefits?
99. usability
100. agility and runtime isolation
101. Cache: performance and hardware savings
102. exponential growth of network effects
103. diffusion of innovation
104. search engine optimization
105. implementation?
106. Spring Webflow versus Spring MVC
107. one framework to rule them all
109. public interface Action { public Event execute(RequestContext context) throws Exception; } public interface RequestContext { public MutableAttributeMap getRequestScope(); public MutableAttributeMap getFlashScope(); public MutableAttributeMap getFlowScope(); public MutableAttributeMap getConversationScope(); … } requestContext.getExternalContext().getSessionMap() Session scope obfuscated
110. RESTful stateless flows
111. Deals (REST) Shop (REST) Book (not REST) Care (mixed)
112. <flow …> <attribute name=”stateless” value=”true”/> … </flow>
113. no view state no pause no continuation enforce with customization at XMLFlowBuilder level & made easier by SWF-310
114. separate model from the URL
115. Internet Explorer’s URL limit: 2083 characters source: Source: http://support.microsoft.com/kb/208427 http://www.ebookers.com/shop/home? type=air&ar.type=roundTrip&ar.rt.leaveSlice.orig.key=L HR&ar.rt.leaveSlice.dest.key=FLL&ar.rt.leaveSlice.date =12%2F12%2F07&ar.rt.leaveSlice.time=Anytime&ar.rt.retu rnSlice.date=15%2F12%2F07&ar.rt.returnSlice.time=Anyti me&ar.rt.numAdult=1&ar.rt.numSenior=0&ar.rt.numChild=0 &ar.rt.child%5B0%5D=&ar.rt.child%5B1%5D=&ar.rt.child %5B2%5D=&ar.rt.child%5B3%5D=&ar.rt.child %5B4%5D=&ar.rt.child%5B5%5D=&ar.rt.child %5B6%5D=&ar.rt.child%5B7%5D=&search=Search+Flights
116. input mapper
117. <flow …> … <subflow-state id=”executeSearch” flow=”search”/> <attribute-mapper> <input-mapper> <input-attribute name=”dealsModel.searchAttr1”/> <input-attribute name=”dealsModel.searchAttr2”/> </input-mapper> </attribute-mapper> <transition on=”someOutcome” to=”someView”/> </subflow-state> </flow> AttributeMapper config
118. SWF-297 will also allow the input-mapper to also record validation error messages, providing a better alternative to the FormAction generally used for this purpose now.
119. re-use flows as subflows without changing the URL
121. State Management
122. infinite memory
123. used smallest scope possible
124. avoided session and conversation usage
125. request scope not for redirect-after-post
126. flow and flash scopes
127. <flow:executor id="flowExecutor" registry-ref="flowRegistry"> <flow:repository type="continuation" max-conversations="1" max-continuations="30"/> </flow:executor> continuation limits
128. stateless flows, continuations, and form value history
130. no-cache no-store
131. /** * Prevent the response from being cached. * See www.mnot.net.cache docs. */ protected final void preventCaching(HttpServletResponse response) { response.setHeader(HEADER_PRAGMA, "No-cache"); if (this.useExpiresHeader) { // HTTP 1.0 header response.setDateHeader(HEADER_EXPIRES, 1L); } if (this.useCacheControlHeader) { // HTTP 1.1 header: "no-cache" is the standard value, // "no-store" is necessary to prevent caching on FireFox response.setHeader(HEADER_CACHE_CONTROL, "no-cache"); response.addHeader(HEADER_CACHE_CONTROL, "no-store"); } } Spring source when cacheSeconds == 0
132. <bean name="dealsFlowController" class="org.springframework.webflow.…"> … <property name="cacheSeconds" value="1"/> </bean> workaround #1
133. <bean name="dealsFlowController" class="org.springframework.webflow.…"> … <property name=“useCacheControlHeader" value=“false"/> <property name="cacheSeconds" value=“0"/> </bean> workaround #2
134. Internationalization
135. third-party libraries
136. Joda-time (what JDK Date/Calendar/DateFormat should be)
137. International Components for Unicode (ICU)
138. JScience’s Units JSR-275
139. immutable / thread-safe domain models & formatters
140. point-of-sale and locale parameterization
141. URL pattern POS
142. POS defaultLocale
143. <pos> <posCode>EBCH</posCode> <description>Ebookers Switzerland Point of Sale</description> … <supportedLocales> <defaultLocale>de_CH</defaultLocale> <locale>de_CH</locale> <locale>fr_CH</locale> … </supportedLocales> … </pos> POS config
144. locale selection
145. <property name="interceptors"> <list> … <bean id="localeChangeInterceptor" class=“ org.springframework.web.i18n. localeChangeInterceptor"> <property name="paramName"> <value>locale</value> </property> </bean> … </list> <property>
146. <bean id="localeResolver" class="org.springframework.web.servlet.i18n. cookieLocaleResolver"/> locale persistence <bean id="localeResolver" class="org.springframework.web.servlet.i18n. sessionLocaleResolver"/> OR
147. <spring:bind /> versus <format />
148. editors.put(Currency.class, new CurrencyEditor()); editors.put(Scalar.class, new ScalarEditor()); editors.put(DateTime.class, new JodaDateTimeEditor(true)); editors.put(YearMonthDay.class, new JodaYearMonthDayEditor(true)); editors.put(LocalDate.class, new JodaLocalDateEditor(true)); … register PropertyEditors
149. format:dateTime format:distance format:distanceVector format:interval format:money format:number format:period format:address format:creditCard format:emailAddress format:location format:name format:phoneNumber format tags for data types
150. content access
151. <bean id="messageSource“ class="com.orbitz.webframework.ContentMessageSource"> <constructor-arg> <ref bean="contentMessageConfig"/> </constructor-arg> <property name="useCodeAsDefaultMessage" value="true"/> </bean> MessageSource
152. content access • <format:message /> • supports tokens of custom type
153. Spring’s dependency on JDK’s MessageFormat
154. open-source
155. performance and concurrency
156. good performance from Spring & Spring Web Flow
157. "http-8585-Processor39" daemon prio=1 tid=0x081634c8 nid=0x65b7 waiting for moni tor entry [0x9d41a000..0x9d41e0b0] at org.springframework.beans.factory.support.DefaultSingletonBeanRegistr y.getSingleton(DefaultSingletonBeanRegistry.java:114) - waiting to lock <0xb0d85828> (a java.util.LinkedHashMap) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean (AbstractBeanFactory.java:187) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean (AbstractBeanFactory.java:156) lock contention
159. cached results of Spring’s getBeansOfType (circa March 2007 – Juergen says it may be fixed in Spring v2.0.5)
160. SWF, registerCustomEditors, PropertyEditor issues
162. Other lock contentions • JDK RMIClassLoaderSpi • JDK java.security.* • Tomcat • 3000 tag invocations in search results page view • Log4j • ICU
163. ConcurrentHashMap JDK 1.5 Emory backport for JDK 1.4
164. concurrency is hard (see Rob Harrop’s “Practical Enterprise Concurrency” presentation)
165. Scala: JVM language Erlang-style message passing
166. Summary • Project context • Technology architecture • Building UI forms • Managing Flows • Security and SSL • Progressive Enhancement • Composite View Pattern • Componentization • URLs and REST • State management and HTTP browser caching headers • Internationalization • Performance and concurrency • Summary • Q&A
167. Slides & Contact Slides: http://markmeeker.com/events/tse2007 Emails: Michael Alford - malford@orbitz.com Mark Meeker - mmeeker@orbitz.com We are Hiring: http://www.orbitz.com/startmycareer