More Related Content Similar to Ratpack - SpringOne2GX 2015 (20) More from Daniel Woods (9) Ratpack - SpringOne2GX 20151. SPRINGONE2GX
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Unless otherwise indicated, these slides are © 2013 -2015 Pivotal Software, Inc. and licensed under a Creative Commons Attributio n-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
Ratpack Web Framework
By Dan Woods
@danveloper
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About Me
• Member of the Ratpack Web core team
• Author of “Learning Ratpack”, O’Reilly
• http://shop.oreilly.com/product/0636920037545.do
• Senior Engineer, The Groundwork
• https://github.com/danveloper
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1st Four Chapters Available Today!
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Ratpack Team on Twitter
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Follow this crew!
• @ldaley
• @varzof
• @rus_hart
• @beckje01
• @marcinerdmann
• @zedar185
• @Lspacewalker
• @johnrengelman
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Brief History of Ratpack
• Ratpack started out as a Groovy DSL implementation example (2010)
• Evolved steadily into a JVM Sinatra clone (2010-2011)
• Dumped Sinatra legacy and started focusing on NIO/performance (2012)
• Under steady development in its modern form for 3 full years!
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GroovyDSLImplementation
JVMSinatraClone
Drop“Sinatra”,NIO/Perf
DropsServletsforVert.x
CorerewritteninJava
Movestoorg.ratpackpackages
ExecutionModelIntroduced
Bootstraping,Config
Registryisintroduced
MovefromVert.xtoNetty
Stable,ProductionReady–1.0
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Overview of Ratpack
• Ratpack is now at version 1.0.0
• Production-ready, API-stable
• Can safely adopt without fear of breaking API changes
• Great option for building microservices
• Can also be integrated into legacy apps through its robust test fixtures
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Overview of Ratpack
• A high performance web framework
• Built on a non-blocking network stack
• Provides low-level constructs for working with async APIs
• Core is written in Java (requires Java 8)
• Integrated support for building Groovy-based applications
• Emphasis on developer productivity
• As few opinions as possible
• Fast, self-contained, light-weight deployables
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Simplest Hello World Example
• Just a few lines of Groovy code required!
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Simplest Hello World Example
• Totally Tweetable! https://twitter.com/danveloper/status/608298173208100864
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Java Hello World Example
• Still, not very much needed at all…
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Overview of Ratpack
• Support for HTML templates with Groovy and Handlebars
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Overview of Ratpack
• Great for microservices!
• First-class support for language agnostic transport
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Overview of Ratpack
• Non-blocking HTTP client
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Overview of Ratpack
• Fault tolerance for building distributed systems
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Overview of Ratpack
• Support for metric reporting with Dropwizard Metrics
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Overview of Ratpack
• Comprehensive configuration model
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Overview of Ratpack
• Support for persistent sessions
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Overview of Ratpack
• Robust security with Pac4j
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Overview of Ratpack
• Out of the box SSL support
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Performance
• Like most frameworks, Ratpack is CPU-bound (the more CPUs, the better)
• Unlike most frameworks, Ratpack efficiently processes on each CPU
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https://gist.github.com/danveloper/db888be3519966976368
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Execution Model
• The execution model in Ratpack is borne from the fact that the JVM has no
inherent support for Continuations
• Asynchronous programming is difficult
• Async processing introduces non-determinism
• Web applications require deterministic processing
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Execution Model
• Ratpack wants to make Async processing and programming a reliable and
usable model for the JVM
• By fitting into the execution model, applications garner confidence from a
deterministic processing flow
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TPR/TPC Processing Model
• How most JVM web frameworks work
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Internet Web App
new Thread().start()
Blocking
Processing
Process and wait
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TPR/TPC Processing Model
• In the thread-per-request (or thread-per-connection) model, you are limited by
the amount of threads that you can create
• Bringing the data from a request-taking thread and placing it into a processing
thread incurs a context switch
• The processing thread is where all your work is done, and is established until
you respond
• This is not performant at all, but it is an easy model to program in, and that’s
why people use it
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Ratpack Processing Model
• How Ratpack works (4 CPU example)
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Internet Event Loop
Event Loop
Event Loop
Event Loop
Handler
Waiting for something?
(db call, call to remote)
Return thread to
request-taking pool
while we wait
Respond
One thread per CPU core
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Ratpack Processing Model
• Only establishes a single thread per CPU core
• Processing doesn’t block the thread (if it needs to, then we can schedule it to
the blocking thread pool)
• While we wait for async responses to be fulfilled, the thread is able to process
other requests
• When we get the async response, processing continues on the same thread
• No context switching in computation handlers, async processing responds when
its work is done
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Problems with Async Programming
• Callbacks are obnoxious to work with
• No good way to detect when waiting for async responses
• Represents a temporal disconnect from the processing flow
• Most async web frameworks start a timer when a request comes in, and if you
don’t respond by the time that’s over, then it assumes you’re not going to
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Problems with Async Programming
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Callback
HELL
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Problems with Async Programming
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With Ratpack Promises, you
get guaranteed execution
order without the need
scoped callbacks.
<1> - definitely happens 1st
<2> - definitely happens 2nd
<3> - definitely happens 3rd
<4> - definitely happens 4th
<5> - definitely happens 5th
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Problems with Async Programming
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In other async web
frameworks:
The clock is ticking for you
to get that response out
before the framework
shuts you down
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Problems with Async Programming
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Execution
|__stream
|__marker
|__flatMap(..)
|__findByUsername
|__stream
|__marker
|__flatMap(..)
|__loadProfile
|__stream
|__marker
|__flatMap(..)
|__loadFriends
|__stream
|__marker
|__flatMap(..)
|__loadFriendPhotos
|__stream
|__marker
|__render(..)
|__then(..)
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Execution Model
• The overall execution is a parallel to the construct of a continuation
• Each of the calls to a Promise represent a frame in the execution
• Each of the Promise types represents a new processing stream in the
execution
• While async processing is taking place (ie. Promise is not fulfilled), the
execution is suspended
• When the execution is suspended, the processing thread is given back to the
event loop to continue processing requests
• When an async call returns, the execution is resumed
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Execution Model
• Most importantly, we know that when we hit the marker on a processing stream
that the stream is done computing
• The processing streams are supervised by Ratpack to know that a request is
still processing
• If your code doesn’t respond to a request, we don’t need to wait until the
request times out to inform the client
• If all the streams are done computing but no response has been sent, we are
aware of that and can send an appropriate error back (no response sent) to the
client
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Execution Model
• Ratpack’s execution model gives you much higher confidence in working with
async programming
• The Promise type makes async programming easier
• Deterministic async processing gives added benefits for concurrency
• You have better confidence when programming to async APIs with Ratpack
• Fun fact: any API can be made asynchronous in Ratpack
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Blocking Done Right
• To make use of most 3rd party Java libraries, blocking will need to take place at
some point
• A prime example here is using JDBC
• Since you can’t block on the request-taking thread, you will need to do blocking
on a separate thread
• Any non-trivial application will need to do blocking at some point…
• Ratpack provides easy fixtures for Promise types to be scheduled for
computation or blocking
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Blocking Done Right
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Dependency Injection
• Ratpack is not tied to any particular dependency injection framework
• DI is an abstract concept in Ratpack, components are registered via a Registry
• Ratpack apps can be built entirely without any DI
• Framework modularity is accomplished via Guice
• 1st class support for Guice and Spring Boot
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Registry
• There are multiple registries in Ratpack
• Provide components at different layers of the framework
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Server Registry
User Registry
Context Registry
Request Registry
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Registry
• Components can be bound to the user registry at start time
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Registry
• Registries can be built and cascaded at request time, and according to request
attributes
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Registry
• Registries can be backed by Guice…
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Registry
• … or by Spring Boot…
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Registry
• … or both …
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Dependency Injection
• In Groovy, dependency injection can be accomplished by simply specifying the
type as a closure argument
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Dependency Injection
• Taking a completely unopinionated approach to dependency injection allows
implementations to be flexible
• Can support nearly every component-providing backend
• Gives you the ability to leverage the best parts of all available ecosystems
• New Ratpack apps can readily fit into legacy infrastructures that do have
opinions about this stuff
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Build System Support
• Ratpack is just a set of libraries, so any Java build system can build your project
• Advanced integration with Gradle is provided through the ratpack-gradle plugin
• Using Gradle is the easiest way to get started
• Gradle plugin provides version-proper dependency resolution, so you don’t
need to update versions as you upgrade your project
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Build System Support
• Just a set of libraries…
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Build System Support
• Advanced integration with Gradle…
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Build System Support
• Ratpack apps can be easily packaged for deployment with Gradle
• Multiple options: fat jar, tarball, zip file
• Gradle plugin applies the application plugin, so distributions and dependencies
can easily be built and shipped with os start scripts
• Fat JAR building is accomplished via the ShadowJar plugin
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Developer Productivity
• Development time hot reloading is provided via Gradle’s “continuous build”
mode
• Standalone Ratpack Groovy scripts are able to be reloaded when the
development serverConfig option is true
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The Handler Chain
• Denotes the edge of your application
• Requests flow through the chain until reaching a handler than can provide a
response
• Two types of handlers: request flow and terminal
• Request Flow handlers manage the direction the request takes through the
chain
• Terminal handlers process a request and respond to it
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The Handler Chain
• Request flow handler
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The Handler Chain
• Terminal handler
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The Handler Chain
• Chain API provides semantic methods to bind a handler to an HTTP verb and
optionally a path
• get(..), post(..), put(..), patch(..), delete(..) methods will bind accordingly
• Can also bind a handler that will be called for every incoming request with the
all(..) and path(..) chain methods
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Live Coding Demo Time
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Questions?
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Join the Community
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http://slack-signup.ratpack.io/
Editor's Notes We provide a comprehensive integration with NetflixOSS’s Hystrix project
Hystrix is a circuit breaker library where you can safely buil
Hystrix helps you better build fault tolerant systems
We even provide the ability to stream Non-blocking networking and asynchronous programming go hand-in-hand
Demo: fatjar Demo: app.groovy Demo: app.groovy Demo: app.groovy Demo: app.groovy Demo: app.groovy Demo: app.groovy Demo: app.groovy Demo: app.groovy