Groovy on Google App Engine with Gaelyk

Groovy on Google App Engine with Gaelyk

Transcript

1. Groovy on Google App Engine with Gaelyk
2. Google App Engine • Platform as a Service (PaaS) • For Python, and Java (sandboxed JVM, customed Jetty servlet container)
3. What’s Good about GAE? • No OS image • Scaling aspect being handled by Google eg database/session replication, loading balancing etc.
4. Problem • Grails app can’t be deployed to GAE as is, because of the proprietary components of GAE.
5. What is Gaelyk • Lightweight Groovy toolkit for App Engine Java
6. Why Gaelyk? • Groovy programming language goodness, eg dynamic features • Gradle compliance as of version 2.0 • Layout templating and includes • Caching mechanism
7. Pros • It runs on Google App Engine • Cold startup time is faster • Lightweight, not meant to be a full blown web framework
8. Cons • Locked down to one single cloud platform without being able to move out since made specifically for GAE • No generation of views and controllers for admin interface (you have to programmatically generate it yourself)
9. Project Template • https://gaelyk.appspot.com/download
10. How it works • Groovy files act as scripts instead of classes, except for POGOs (plain old Groovy objects)
11. Project Structure Overview
12. View • .gtpl extension, very similar to JSPs or PHP
13. View • Example <html> <body> <p><%def message = "Hello World!" print message %> </p>
 <p><%= message %></p> <p>${message}</p> <ul>
 <% 3.times { %> <li>${message}</li> <% } %> </ul> </body> </html>
14. View • Output <html> <body> <p>Hello World!</p> <p>Hello World!</p> <p>Hello World!</p> <ul> <li>Hello World!</li> <li>Hello World!</li> <li>Hello World!</li> </ul> </body> </html>
15. View • Markup Builder Write Groovy scripts instead of full blown servlets html.html { body { [1, 2, 3, 4].each { number ‐> p number } def now = new Date() p now } }
16. Controller • Simple Groovy scripts in WEB-INF/groovy/ • Script based, not class based.
17. Tips on Groovy Scripts • Injected variables datastore, memcache, urlFetch etc. (GAE variables) request, response, context etc. (Eager variables) and more… Check out the Gaelyk documentation…
18. URL Mapping/Routing • /webapp/WEB-INF/routes.groovy
19. URL Mapping/Routing get "/article/@year/@month/@day/@title",
 forward: "/article.groovy? year=@year&month=@month&day=@day&title=@title", validate: { year ==~ /\d{4}/ && month ==~ /\d{2}/ && day ==~ /\d{2}/ }
20. URL Mapping/Routing • Capability-aware Routing eg get "/update", forward: {
 to "/update.groovy" to("/ maintenance.gtpl").on(DATASTORE) .not(ENABLED) to(“/ readonly.gtpl") .on(DATASTORE_WRITE).not(ENABLED) }
21. URL Mapping/Routing BLOBSTORE DATASTORE DATASTORE_WRITE IMAGES MAIL MEMCACHE TASKQUEUE URL_FETCH XMPP
22. URL Mapping/Routing • Namespace scope routing
23. Model @ToString @Entity(unindexed = false) class Person { String name @Unindexed String tagline String email }
24. CRUD • @Entity annotation gives you basic CRUD operations for FREE! def person = new Person(name:’kevintan’, email:’kevin@kevin.com’, tagline:’Android Developer’) person.save()
25. Datastore • App engine data store def entity = new Entity(‘person’) entity.name = ‘kevintan’ entity.email = ‘kevin@kevin.com’ entity.save()
26. Datastore • For debugging purposes • http://localhost:8080/_ah/admin/datastore
27. Response Rendering • JSON rendering by default json(person: person, message: ‘whateverlah’) (person is an object) More info : http://vladimir.orany.cz/everyday%20gaelyk/ 2013/03/17/everyday-gaelyk-simplify-groovlets-flow-by- handling-its-return-value/
28. Caching • Defined in routes.groovy (URL mapping file) • Duration of caching is defined in each requests • memcache eg: get "/news", forward: "/new.groovy", cache: 10.minutes
29. Email Support mail.send from: "app‐admin‐email@gmail.com",
 to: "recipient@somecompany.com",
 subject: "Hello",
 textBody: "Hello, how are you doing? ‐‐ MrG",
 attachment: [data: "Chapter 1, Chapter 2".bytes, fileName: "outline.txt"]
30. Simple Plugin System Plugin descriptors in /WEB-INF/plugins/descriptor.groovy • provide additional groovlets and templates • contribute new URL routes • define and bind new variables in the binding (the "global" variables available in groovlets and templates) • provide any kind of static content, such as JavaScript, HTML, images, etc. • add new libraries (ie. additional JARs) • and more generally, let you do any initialization at the startup of your application
31. Bootstrap some data • By using /WEB-INF/plugins/ sampledescriptor.groovy • Register descriptor using /WEB-INF/plugins.groovy install sampledescriptor
32. Running & Deploying • ./gradlew tasks (to see available app engine related tasks) • ./gradlew appEngineRun (to run locally, accessible with http://localhost:8080) • ./gradlew appEngineStartBackend to deploy to production
33. DEMO
34. Sample Project Reference • https://github.com/glaforge/bloogaey • https://github.com/kevintanhongann/ GaelykSampleApp
35. Join Groovy User Group Malaysia in Facebook or Google+ for more knowledge sharing goodness!
36. Thank you! +KevinTanHongAnn (Google+) @s1lv3rd3m0n (Twitter)