Developing modular, polyglot applications with Spring (SpringOne India 2012)
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This document discusses developing modular, polyglot applications using Spring. It describes how to refactor a monolithic application into modular microservices along functional boundaries (Y-axis scaling). This improves scalability, enables independent development and deployment of each service, and allows adopting different technologies for each service. Spring is well-suited for building these types of applications since it supports a variety of languages and frameworks and its programming model aligns well with developing microservices.
![About HATEOAS
The well known
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$ curl http://cf-auto-scaler.cloudfoundry.com
{"links": [
{"rel":"autoscaledapps", "href":"http://cf-auto-scaler.cloudfoundry.com/autoscaledapps"}
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$ curl http://cf-auto-scaler.cloudfoundry.com/autoscaledapps
{"content":[
{"name":"vertx-clock",
"links":[
{"rel":"self","href":"http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock"},
{"rel":"rules","href":"http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock/rules"}
]
}],
... Links to act on this app
}](https://image.slidesharecdn.com/springonekeynoteindia2012-121218174632-phpapp02/85/Developing-modular-polyglot-applications-with-Spring-SpringOne-India-2012-77-320.jpg)
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Developing modular, polyglot applications with Spring (SpringOne India 2012)
- 1. Developing modular, polyglot applications with Spring Chris Richardson Author of POJOs in Action, Founder of the original CloudFoundry.com @crichardson [email protected] http://plainoldobjects.com/
- 2. Presentation goal Modular, polyglot applications: what, why and how? Why Spring is the ideal technology for building these applications
- 3. About Chris
- 5. About Chris - 1999 CORBA Enterprise WebLogic Server JavaBeans
- 6. About Chris - 2004
- 7. Spring programming model Dependency Injection POJO Portable Aspect- Service Oriented Abstractions Programming
- 8. Transformed how I developed software!
- 10. About Chris - 2006 Oakland JUG Cloud Computing
- 11. Transformed how I deployed software!
- 12. About Chris
- 13. About Chris http://www.theregister.co.uk/2009/08/19/ springsource_cloud_foundry/
- 14. vmc push About-Chris Developer Advocate for CloudFoundry.com Signup at http://cloudfoundry.com
- 15. Agenda • The (sometimes evil) monolith • Refactoring to a modular, polyglot architecture • Presentation layer design • Using NoSQL databases • Inter-service communication options
- 16. Let’s imagine you are building an e-commerce application
- 17. Traditional web application architecture WAR StoreFrontUI Accounting Service MySQL Browser Apache Database InventoryService Simple to Shipping Service develop test Tomcat deploy scale
- 18. But there are problems
- 19. Users expect a rich, dynamic and interactive experience h oug d en HTTP Request oo ’t g Browser e isn Java Web Application HTML/Javascript ec tur it ar ch e UI s tyl Old HTML5/JavaScript browser applications Real-time web ≅ NodeJS
- 20. Limitations of relational databases • Scalability • Distribution • Schema updates • O/R impedance mismatch • Handling semi-structured data
- 22. Scalability issues • Different components have different scalability needs but you can only scale the entire system • Some components might not be scalable can’t scale system
- 23. Obstacle to frequent deployments • Need to redeploy everything to change one component • Increases risk of failure, e.g. interrupts background jobs Fear of change • Extensive test cycle • Updates will happen less often, e.g. Makes A/B testing UI really difficult
- 24. Overloads your IDE and container Slows down development
- 25. Obstacle to scaling development But the I want to update backend is not the UI working yet! Lots of coordination and communication required
- 26. Requires long-term commitment to a technology stack
- 27. Agenda • The (sometimes evil) monolith • Refactoring to a modular, polyglot architecture • Presentation layer design • Using NoSQL databases • Inter-service communication options
- 29. The scale cube Y axis - functional decomposition ila g sim nin Scale by r ing ing tio splitting th litt r ti sp pa different things by data s ale - Sc is ax Z X axis - horizontal duplication
- 30. Y-axis scaling - application level WAR StoreFrontUI Accounting Service InventoryService Shipping Service
- 31. Y-axis scaling - application level accounting application Accounting Service Store front web application inventory application StoreFrontUI InventoryService shipping application Shipping Service Apply X axis cloning and/or Z axis partitioning to each service
- 32. Real world examples http://techblog.netflix.com/ Between 100-150 services are accessed to build a page. http://highscalability.com/amazon-architecture http://www.addsimplicity.com/downloads/ eBaySDForum2006-11-29.pdf http://queue.acm.org/detail.cfm?id=1394128
- 33. Drawbacks of Y-axis splits • Complexity • Partitioned databases and transaction management • Deciding when to use this approach
- 34. But there are many benefits • Scales development: develop, deploy and scale each service independently • Enables frequent deployments • Less for each developer to learn • Doesn’t overload IDE or container • Improves fault isolation • Easily adopt new technologies
- 35. Two levels of architecture System-level Services Inter-service glue: interfaces and communication mechanisms Slow changing Service-level Internal architecture of each service Each service can use a different technology stack Rapidly evolving - regularly rewrite Pick the best tool for the job
- 36. Modular, polyglot, applications
- 37. Lots of languages and frameworks to choose from And many more...
- 38. But there are lots of awesome, and mature Spring projects • Spring Framework • Spring Integration • Spring Security • Spring AMQP • Spring Mobile • Spring Social • Spring Data • Spring Shell • Spring Web Services • ... • Spring Batch
- 39. Spring works with Scala @Controller class TwilioController { @Autowired var surveyManagementService: SurveyManagementService = _ @RequestMapping(value = Array("/begincall.html")) @ResponseBody def beginCall(@RequestParam("From") callerId: String) = { surveyManagementService.findSurveyByCallerId(callerId) match { case None => <Response> <Say>Sorry don't recognize your number</Say> <Hangup/> </Response> case Some(survey) => <Response> <Say>{ survey.prompt }</Say> <Gather action="handleresponse.html" method="POST" numDigits="1"> { for ((choice, index) <- survey.choices zipWithIndex) yield <Say>Press { index } for { choice }</Say> } </Gather> <Say>We are sorry you could not decide</Say> <Hangup/> </Response> } }
- 40. The Spring Scala project class PersonConfiguration extends FunctionalConfiguration { val jack = bean() { new Person("Jack", "Doe") } • Scala-style “setters/getters” val jane = bean() { new Person("Jane", "Doe") } • Bean configuration DSL val john = bean() { val john = new Person("John", "Doe") john.father = jack() • Scala-style template classes john.mother = jane() john } } https://github.com/SpringSource/spring-scala
- 41. Coming in 2013 Java 8 closures = concise code! List<Album> albums = ... Predicate List<Album> sortedFavorites = albums.stream() .filter(a -> a.tracks.anyMatch(t -> (t.rating >= 4))) .sorted(comparing(a -> a.name)) .into(new ArrayList<>()); Parallelism int sum = shapes.parallel() .filter(s -> s.getColor() == BLUE) .map(s -> s.getWeight()) .sum(); http://cr.openjdk.java.net/~briangoetz/lambda/sotc3.html
- 42. Key benefits of Spring are still Modularity Productivity Portability Testability
- 43. Agenda • The (sometimes evil) monolith • Refactoring to a modular, polyglot architecture • Presentation layer design • Using NoSQL databases • Inter-service communication options
- 44. Presentation layer evolution.... WAR StoreFrontUI HTML / HTTP View Controller Browser Model
- 45. ...Presentation layer evolution Browser Web application Static content View Controller JSON-REST RESTful Endpoints Model Events Event HTML 5 - JavaScript publisher No elaborate, server-side web framework required
- 46. How to publish events to browser?
- 47. NodeJS is the fashionable technology
- 48. Why NodeJS? • Familiar JavaScript • High-performance, scalable event-driven, non-blocking I/O model • Compact runtime, e.g. 64M • Over 13,000 17,000 modules developed by the community • ManyJavaScript client frameworks have a NodeJS counterpart, e.g. socket.io and SockJS
- 49. Why not NodeJS? a.k.a. callback hell
- 50. Dealing with JavaScript “...Still the consequence of this is that we must take javascript seriously as a first-class language and concentrate on how to limit the damage its flaws cause....” http://martinfowler.com/bliki/gotoAarhus2012.html
- 51. NodeJS as a mediator... Node JS Service 1 Browser Server app Static content REST Service 2 HTML 5 Application Events Socket.io Socket.io client server ...
- 52. ...NodeJS as a mediator REST REST Service Node JS Events AMQP AMQP socket.io RabbitMQ Service
- 53. Example NodeJS application var express = require('express') , http = require('http') , amqp = require(‘amqp’) , server = http.createServer(app) , io = require('socket.io').listen(server) ....; server.listen(8081); Handle socket.io ... connection var amqpCon = amqp.createConnection(...); io.sockets.on('connection', function (socket) { Republish as function amqpMessageHandler(message, headers, deliveryInfo) { var m = JSON.parse(message.data.toString()); socket.io event socket.emit(‘tick’, m); }; amqpCon.queue(“”, {}, Subscribe to AMQP function(queue) { queue.bind(“myExchange”, “myBindingKey”); queue queue.subscribe(amqpMessageHandler); }); });
- 54. Example browser application <html> <body> The event is <span data-bind="text: ticker"></span> <script src="/socket.io/socket.io.js"></script> <script src="/knockout-2.0.0.js"></script> <script src="/clock.js"></script> </body> Bind to model Connect to </html> socket.io server clock.js var socket = io.connect(location.hostname); function ClockModel() { self.ticker = ko.observable(1); Subscribe to tick socket.on('tick', function (data) { event self.ticker(data); }); }; Update model ko.applyBindings(new ClockModel());
- 55. About Cujojs & s2js Dependency Injection www.cujojs.com github.com/s2js JavaScript Portable Aspect- Service Oriented Abstractions Programming
- 56. Agenda • The (sometimes evil) monolith • Refactoring to a modular, polyglot architecture • Presentation layer design • Using NoSQL databases • Inter-service communication options
- 57. Why NoSQL? Benefits Drawbacks • Higher performance • Limited transactions • Higher scalability • Limited querying • Richer data-model • Relaxed consistency • Schema-less • Unconstrained data
- 58. Example NoSQL Databases Database Key features Cassandra Extensible column store, very scalable, distributed Neo4j Graph database Document-oriented, fast, scalable MongoDB Redis Key-value store, very fast http://nosql-database.org/ lists 122+ NoSQL databases
- 59. NoSQL and the scale cube nin a ing itio dr rd r t an ha pa ss s Ca DB g go on M MongoDB replica sets Cassandra replication
- 60. The future is polyglot IEEE Software Sept/October 2010 - Debasish Ghosh / Twitter @debasishg
- 61. Polyglot persistence architecture accounting application Accounting Service MySQL storefront web application inventory application StoreFrontUI InventoryService Redis shipping application ShippingService Mongo
- 62. Spring Data = simplifying data access • Redis • MongoDB • Neo4j • JPA • REST • Apache Hadoop • Gemfire http://www.springsource.org/spring-data
- 63. Agenda • The (sometimes evil) monolith • Refactoring to a modular, polyglot architecture • Presentation layer design • Using NoSQL databases • Inter-service communication options
- 64. Inter-service communication options • Synchronous HTTP asynchronous AMQP • Formats: JSON, XML, Protocol Buffers, Thrift, ... • JSON is fashionable and easier to debug • Binary format is more efficient
- 65. Asynchronous message-based communication wgrus-billing.war Accounting Service wgrus-store.war wgrus-inventory.war RabbitMQ StoreFrontUI (Message InventoryService MySQL Broker) wgrus-shipping.war ShippingService
- 66. Benefits • Decouples caller from server • Caller unaware of server’s coordinates (URL) • Message broker buffers message when server is down/slow • Supports a variety of communication patterns
- 67. Drawbacks • Additional complexity of message broker • Request/reply using messaging is more complex • Firewall unfriendly
- 68. Spring AMQP • Encapsulates low-level Producer Consumer details • Simplifiessending and Amqp Listener receiving of messages Template Container Spring AMQP AMQP
- 69. Spring Integration • Provides the building blocks for a pipes and filters architecture • Enables development of application components that are • loosely coupled • insulated from messaging infrastructure • Messaging defined declaratively
- 70. Development time: same JVM @Service public class OrderServiceImpl { @Service public class ShippingServiceImpl { @Autowired private ShippingService shippingService; public void shipOrder(String orderId) { .... public void placeOrder() { } String orderId = generateOrderId(); … } shippingService.shipOrder(orderId); } } Order Shipping Service service shipOrder() Messaging Gateway Channel Service Activator
- 71. Test and production: distributed Application code is unchanged Order Shipping Service service Messaging Gateway RabbitMQ Channel AMQP AMQP Channel Service Activator
- 72. Synchronous REST wgrus-billing.war Accounting Service wgrus-store.war REST wgrus-shipping.war StoreFrontUI Shipping MySQL Service wgrus-inventory.war ... InventoryService
- 73. Pros and cons of REST • Pros • Cons • Simple and familiar • Only supports request/ reply • Request/reply is easy • Server must be available • Firewall friendly • Clientneeds to know • No intermediate broker URL(s) of server(s)
- 74. Spring MVC makes REST easy URL matching @Controller & public class AccountController { object destructuring @Autowired XML/JSON private MoneyTransferService moneyTransferService; @RequestMapping(value = "/accounts/{accountId}", method = RequestMethod.GET) @ResponseBody public AccountInfo getAccount(@PathVariable String accountId) { Account account = moneyTransferService.findAccountByid(accountId); return makeAccountInfo(account); } @RequestMapping(value = "/accounts", method = RequestMethod.POST) @ResponseStatus( HttpStatus.CREATED ) public void createAccount(@RequestBody AccountInfo accountInfo, UriComponentsBuilder builder, HttpServletResponse response) { ... } XML/JSON object
- 75. Not all APIs are RESTful From http://martinfowler.com/articles/richardsonMaturityModel.html
- 76. About Hypertext As The Engine Of Application State • Single well known URL • Entity representation has typed relationship links • Client discovers what it can do to an entity via those links See http://roy.gbiv.com/untangled/2008/rest-apis-must-be-hypertext-driven
- 77. About HATEOAS The well known URL $ curl http://cf-auto-scaler.cloudfoundry.com {"links": [ {"rel":"autoscaledapps", "href":"http://cf-auto-scaler.cloudfoundry.com/autoscaledapps"} ]} Link link type $ curl http://cf-auto-scaler.cloudfoundry.com/autoscaledapps {"content":[ {"name":"vertx-clock", "links":[ {"rel":"self","href":"http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock"}, {"rel":"rules","href":"http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock/rules"} ] }], ... Links to act on this app }
- 78. Spring HATEOAS @Controller @RequestMapping(value = "/autoscaledapps") public class AutoscaledAppController { @RequestMapping(value = "/{appName}", method = RequestMethod.GET) public HttpEntity<AutoscaledAppResource> get(@PathVariable String appName) { AutoscaledAppResource ar = new AutoscaledAppResource(appName); ar.add(linkTo(AutoscaledAppController.class) .slash(appName).withSelfRel()); ar.add(linkTo(AutoscaledAppController.class) .slash(appName).slash("rules").withRel("rules")); return new HttpEntity<AutoscaledAppResource>(ar); } ... public class AutoscaledAppResource } extends ResourceSupport { private String name; https://github.com/SpringSource/spring-hateoas
- 79. Consuming RESTful WS RestTemplate restTemplate = new RestTemplate(); AccountInfo accountInfo = new AccountInfo(...); URI accountUrl = restTemplate.postForLocation("http://localhost/accounts", accountInfo); ResponseEntity<AccountInfo> accountInfoResponse = restTemplate.getForEntity(accountUrl, AccountInfo.class); Assert.assertEquals(HttpStatus.SC_OK, accountInfoResponse.getStatusCode()); AccountInfo accountInfo2 = accountInfoResponse.getBody(); ...
- 80. The Spring REST shell $ rest-shell http://localhost:8080:> baseUri http://cf-auto-scaler.cloudfoundry.com http://cf-auto-scaler.cloudfoundry.com:> discover rel href ======================================================================= autoscaledapps http://cf-auto-scaler.cloudfoundry.com/autoscaledapps http://cf-auto-scaler.cloudfoundry.com:> follow --rel autoscaledapps http://cf-auto-scaler.cloudfoundry.com/autoscaledapps:> post --from src/test/resources/examplejson/createapp1.json --follow true 1 files uploaded to the server using POST http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock:> discover rel href ================================================================================ self http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock rules http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock/rules http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock:> follow --rel rules http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock/rules:> post --from src/test/resources/examplejson/createrule1.json --follow true 1 files uploaded to the server using POST http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock/rules/idle:> up http://cf-auto-scaler.cloudfoundry.com/autoscaledapps/vertx-clock/rules:> up
- 81. Original architecture WAR StoreFrontUI Accounting Service MySQL Browser Apache Database InventoryService Simple to Shipping Service develop test Tomcat deploy scale
- 82. Modular, polyglot architecture Desktop Browser Native Mobile application HTML5 mobile application oy StoreUI StoreUI StoreUI pl NodeJS !?! e Asynchronous, NodeJS Javascript scalable is d StoreUI communication th we RabbitMQ Spring/Scala do web application Inventory Standalone Inventory Shipping Service Service Shipping “headless” Service Spring ow Integration/Java applications Billing Service Redis Inventory Mongo Order H Database Database MySQL Customer Database
- 83. OSS community vFabric Postgres Ap Private Clouds p Data Services lica 'o n S vFabric Public erv RabbitMQTM ice Msg Services Clouds In ter fac Micro e Other Services Clouds Additional partners services …
- 84. Cloud Foundry simplifies the deployment of modular, polyglot applications
- 85. Spring makes it easy to consume Cloud Foundry services
- 86. Many Spring applications run on Cloud Foundry unchanged
- 87. Summary • Modern applications have a modular, polyglot architecture • Springis the ideal technology for building these applications • Cloud Foundry is the ideal way to deploy these applications
- 88. @crichardson [email protected] http://plainoldobjects.com Thank you! www.cloudfoundry.com @cloudfoundry