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Decomposing applications for deployability and scalability #gluecon

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Today, there are several trends that are forcing application architectures to evolve. Users expect a rich, interactive and dynamic user experience on a wide variety of clients including mobile devices. Applications must be highly scalable, highly available and run on cloud environments. Organizations often want to frequently roll out updates, even multiple times a day. Consequently, it’s no longer adequate to develop simple, monolithic web applications that serve up HTML to desktop browsers.

In this talk we describe the limitations of a monolithic architecture. You will learn how to use the scale cube to decompose your application into a set of narrowly focused, independently deployable back-end services and an HTML 5 client. We will also discuss the role of technologies such as NodeJS and AMQP brokers. You will learn how a modern PaaS such as Cloud Foundry simplifies the development and deployment of this style of application.

Read articles based on the presentation here: http://plainoldobjects.com/2012/05/31/decomposing-applications-for-deployability-and-scalability-part-1/

Publié dans : Technologie, Formation

Decomposing applications for deployability and scalability #gluecon

  1. 1. Decomposing applications fordeployability and scalability Chris Richardson Author of POJOs in Action Founder of the original CloudFoundry.com @crichardson crichardson@vmware.com 1
  2. 2. Presentation goal How decomposing applications improves deployability and scalability and How Cloud Foundry helps 2
  3. 3. About Chris 3
  4. 4. (About Chris) 4
  5. 5. About Chris() 5
  6. 6. About Chris 6
  7. 7. About Chris http://www.theregister.co.uk/2009/08/19/springsource_cloud_foundry/ 7
  8. 8. vmc push About-Chris Developer Advocate for CloudFoundry.comSignup at http://cloudfoundry.com Promo code: Gluecon12 8
  9. 9. Agenda The (sometimes evil) monolith Decomposing applications into services How do services communicate? Presentation layer design How Cloud Foundry helps 9
  10. 10. Let’s imagine you are building an e- commerce application 10
  11. 11. Traditional web application architecture WAR StoreFrontUI Accounting Service MySQL Browser Apache InventoryService Database Shipping ServiceSimple to Tomcat develop test deploy scale 11
  12. 12. But there are problems 12
  13. 13. Users expect a rich, dynamic andinteractive experience on mobiledevices and desktop h oug d en oo ’t g HTTP Request e isn r ctu Java Web Browser e hit HTML/Javascript Application c I ar ty le U s Old Real-time web ≅ NodeJS 13
  14. 14. Obstacle to frequent deployments Need to redeploy everything to change one component Interrupts long running background (e.g. Quartz) jobs Increases risk of failure Fear of change Updates will happen less often e.g. Makes A/B testing UI really difficult 14
  15. 15. Large application Slow IDESlow start times for web container 15
  16. 16. Scaling development WAR StoreFrontUI Accounting Scalable != InventoryService development Shipping Forces teams to synchronize development efforts Teams need to coordinate updates 16
  17. 17. Long-term commitment to a single technology stack Let’s suppose you go with the JVM • Some polyglot support • Many (but not all) JVM languages interoperate easily • e.g. Scala, Groovy modules within a Java application • But you can’t use non-JVM languages Application depends on a particular: • Framework - e.g. Spring or Java EE • Container - e.g. Tomcat Switching technology stack touches entire application • Painful • Rarely done 17
  18. 18. Agenda The (sometimes evil) monolith Decomposing applications into services How do services communicate? Presentation layer design How Cloud Foundry helps 18
  19. 19. 3 dimensions to scalingY axis -functionaldecompositionScale by s ngsplitting ila g n hi g s oni rtdifferent things iti rt im pa ta in da ittl s- sp i ax by Z ale X axis - horizontal duplication Sc Scale by cloning 19
  20. 20. Y axis scaling - functional partitioning Splits monolithic application into a set of services Each service implements a set of related functionality Partitioning schemes: • Partition functionality by noun or by verb • Single Responsibility Principle • Unix utilities - do one focussed thing well 20
  21. 21. Y axis scaling - application level billing web application Accounting Service Store front web application inventory web application Store Front InventoryService shipping web application ShippingServiceApply X axis cloning and/or Z axis partitioning to each service 21
  22. 22. 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 22
  23. 23. There are drawbacks Complexity: • Architectural • Development • Deployment • Application management Deciding when to use it • In the beginning: you don’t need it and it will slow you down • When you do need it: refactoring existing code is painful See Steve Yegge’s Google Platforms Rant re Amazon.com 23
  24. 24. But there are many benefits Scales development: focussed two pizza devops teams Deploy services independently Scale services independently Improves fault isolation Enforces well defined interfaces between components Eliminates long-term commitment to a single technology stack Modular, polyglot applications 24
  25. 25. Two levels of architecture System level • Defines the inter-service glue: interfaces and communication mechanisms • Slow changing Versus Service level • Defines the internal architecture of each service • Far fewer constraints on technology • Each service could use a different technology stack • Rapid evolving 25
  26. 26. If services are small... Regularly rewrite using a better technology stack Pick the best developers rather than best <pick a language> developers polyglot culture Adapt system to changing requirements and better technology without a total rewrite Fred George “Developer Anarchy” 26
  27. 27. Moreover: you are not the same you ... Cell lifetimes: Can we build software • hours - some white blood cells systems with these characteristics? • days - stomach lining cells • years - bone cells Too much technical debt • lifetime - brain cells component death? 50 to 70 billion of your cells die each day Yet you (the system) remains intact http://dreamsongs.com/Files/ DesignBeyondHumanAbilitiesSimp.pdf http://dreamsongs.com/Files/WhitherSoftware.pdf 27
  28. 28. Agenda The (sometimes evil) monolith Decomposing applications into services How do services communicate? Presentation layer design How Cloud Foundry helps 28
  29. 29. Inter-service communication options Multiple collaborating services need a communication mechanism Many choices: • Synchronous asynchronous • Transports: HTTP, AMQP, ... • Formats: JSON, XML, Protocol Buffers, Thrift, ... • Even via the database Distributed application error handling strategies Asynchronous is preferred JSON is fashionable but binary format is more efficient 29
  30. 30. Asynchronous message-based communication wgrus-billing.war Accounting Servicewgrus-store.war RabbitMQ wgrus-inventory.war StoreFrontUI (Message MySQL Broker) Widget InventoryService wgrus-inventory.war InventoryService 30
  31. 31. Benefits and drawbacks Benefits • Decouples caller from server • Caller unaware of server’s coordinates (URL) • Message broker buffers message when server is down/slow Drawbacks • Additional complexity of message broker • RPC using messaging is more complex 31
  32. 32. Writing code that calls services 32
  33. 33. Composable futures Problem: • Service A needs to call services B and C and then D • Makes sense to call B and C parallel • Yet most concurrency APIs are low-level, error-prone etc Solution: • Use Akka composable futures = really nice abstraction val futureB = callB() Two calls execute in parallel val futureC = callC() val futureD = for { b <- futureB.mapTo[SomeType] c <- futureC.mapTo[SomeType] d <- callD(b, c) And then invokes D } yield d val result = Await.result(futureD, 1 second). asInstanceOf[SomeOtherType] Get the result of D http://doc.akka.io/docs/akka/2.0.1/scala/futures.html http://en.wikipedia.org/wiki/Futures_and_promises 33
  34. 34. Spring Integration Builds on Spring framework Implements EAI patterns = high-level of abstraction for building message based applications Provides the building blocks for a pipes and filters architecture • Pipes = message channels • Filters = endpoints that filter, transform, route messages and integrate with external messaging infrastructure Enables development of components that are • loosely coupled • insulated from underlying messaging infrastructure 34
  35. 35. Handling failure Errors happen (especially in distributed systems) Use timeouts and retries • Never wait forever • Some errors are transient so retry Use per-dependency bounded thread pool with bounded queue • Limits number of outstanding requests • Fails fast if service is slow or down Use circuit breaker • High rate of errors stop calling temporarily • Avoids calling service that has issues On failure • Returned cached or default data • Invoke custom error handler http://techblog.netflix.com/2012/02/fault-tolerance-in-high-volume.html 35
  36. 36. Agenda The (sometimes evil) monolith Decomposing applications into services How do services communicate? Presentation layer design How Cloud Foundry helps 36
  37. 37. Modular applicationChoice of presentation layer technology + Redeploy UI frequently/independently 37
  38. 38. NodeJS is the fashionable technologyMany JavaScript client frameworks have a NodeJS counterparte.g. socket.io 38
  39. 39. NodeJS isn’t the only game in town JVM-based http://vertx.io/ 39
  40. 40. A modern web application Service 1 RESTful WS Node JSBrowser HTML 5 Server Application Application Service 2 Events Socket.io Socket.io client server ... 40
  41. 41. NodeJS - using RESTful WS and AMQP REST ServiceRESTRequests Node JS Events socket.io AMQP AMQP RabbitMQ Service 41
  42. 42. Updating the UI is easy Update the UI independently of rest of system Easily run A/B tests Enables fast iteration of the UI http://theleanstartup.com/principles 42
  43. 43. But coordination with backend changes required Let’s imagine that you are deploying an advanced search feature: • Enhancements to search service • Enhancements to UI Before • Deploy new war Now: • Some coordination required • Deploy updated backend service • Deploy updated NodeJS and browser code • Enable feature using feature switch 43
  44. 44. Agenda The (sometimes evil) monolith Decomposing applications into services How do services communicate? Presentation layer design How Cloud Foundry helps 44
  45. 45. Traditional tools: monolithic applications 45
  46. 46. Developing modular apps is more difficult Many more moving parts to manage • Platform services: SQL, NoSQL, RabbitMQ • Application services: your code Who is going to setup the environments: • the developer sandbox? • ... • QA environments? But Cloud Foundry helps... 46
  47. 47. Easy polyglot application deployment and service provisioning OSS community vFabricPostgres Ap p lica Data Private   o Services Clouds   n  S erv ice  In vFabric ter fac RabbitMQTM Msg Public e Services Clouds Micro Other Clouds Services Additional partners services …
  48. 48. Creating a platform service instance$ vmc create-service mysql --name mysql1Creating Service: OK$ vmc services......=========== Provisioned Services ============+-------------+---------+| Name | Service |+-------------+---------+| mysql1 | mysql |+-------------+---------+
  49. 49. Multi-application manifest - part 1 --- applications: inventory/target: Path to application name: inventory url: cer-inventory.chrisr.cloudfoundry.me framework: name: spring info: mem: 512M description: Java SpringSource Spring Application exec: mem: 512M instances: 1 services: Required platform services si-rabbit: type: :rabbitmq si-mongo: type: :mongodb si-redis: type: :redis 49
  50. 50. Multi-application manifest - part 2 store/target: Path to application name: store url: cer-store.chrisr.cloudfoundry.me framework: name: spring info: mem: 512M description: Java SpringSource Spring Application exec: mem: 512M instances: 1 services: Required platform services si-mongo: type: :mongodb si-rabbit: type: :rabbitmq 50
  51. 51. One command to create platform services and deployapplication $ vmc push Would you like to deploy from the current directory? [Yn]: Pushing application inventory... Creating Application: OK Creating Service [si-rabbit]: OK Binding Service [si-rabbit]: OK Creating Service [si-mongo]: OK Binding Service [si-mongo]: OK Creating Service [si-redis]: OK Binding Service [si-redis]: OK Uploading Application: Checking for available resources: OK Processing resources: OK Packing application: OK vmc push: Uploading (12K): OK Push Status: OK •Reads the manifest file Staging Application inventory: OK Starting Application inventory: OK •Creates the required platform services Pushing application store... Creating Application: OK •Deploys all the applications Binding Service [si-mongo]: OK Binding Service [si-rabbit]: OK Uploading Application: Checking for available resources: OK Processing resources: OK Packing application: OK Uploading (5K): OK Push Status: OK Staging Application store: OK 51 Starting Application store: ...
  52. 52. Micro Cloud Foundry: new developer sandbox App Instances Services Open source Platform as a Service project 10.04 A PaaS packaged as a VMware Virtual Machine Use as a developer sandbox • Use the services from Junit integration tests • Deploy your application for functional testing • Remote debugging from STS 52
  53. 53. Using Caldecott…$ vmc tunnel1: mysql-135e02: mysql1Which service to tunnel to?: 2Password: ********Stopping Application: OKRedeploying tunnel application caldecott.Uploading Application: Checking for available resources: OK Packing application: OK Uploading (1K): OKPush Status: OKBinding Service [mysql1]: OKStaging Application: OKStarting Application: OKGetting tunnel connection info: OKService connection info: username : uMe6Apgw00AhS password : pKcD76PcZR7GZ name : d7cb8afb52f084f3d9bdc269e7d99ab50Starting tunnel to mysql1 on port 10000.1: none2: mysqlWhich client would you like to start?: 2
  54. 54. …Using CaldecottLaunching mysql --protocol=TCP --host=localhost --port=10000 -- user=uMe6Apgw00AhS --password=pKcD76PcZR7GZ d7cb8afb52f084f3d9bdc269e7d99ab50Welcome to the MySQL monitor. Commands end with ; or g.Your MySQL connection id is 10944342Server version: 5.1.54-rel12.5 Percona Server with XtraDB (GPL), Release 12.5, Revision 188Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type help; or h for help. Type c to clear the current input statement.mysql>
  55. 55. Running JUnit test with Caldecott Configure your test code to use port + connection info 55
  56. 56. Summary Monolithic applications are simple to develop and deploy BUT applying the scale cube Decomposes your application into services Enables scaling for transactions and data volumes Tackles application complexity Enables scaling for development Enables frequent, independent deployments Make it easy to leverage other technologies AND Cloud Foundry simplifies the development and deployment of modular, service-based applications 56
  57. 57. @crichardson crichardson@vmware.com Questions?www.cloudfoundry.com promo code Gluecon12