Gaelyk: Lightweight Groovy on the Google App Engine

Lightweight on the by Tim Berglund

Tell me about aGreat Application Language

Tell me a Happy Tale of Deployment

and Make it Fast

Tell me about the Googl eApp Engine

An App Server

In the CLoud

Google Infrastructure

Usually Free!

Quotas http://code.google.com/appengine/docs/quotas.html

Pricing

Languages

Services

Services It’s an app server

Services With a few extra features

Services

Services Datastore

Services Datastore Authentication

Services Datastore Authentication Caching

Services Datastore Authentication Caching XMPP

Services Datastore Authentication Caching XMPP Email

Services Datastore Task Queue Authentication Caching XMPP Email

Services Datastore Task Queue Authentication Image API Caching XMPP Email

Services Datastore Task Queue Authentication Image API Caching URL Fetching XMPP Email

Services Datastore Task Queue Authentication Image API Caching URL Fetching XMPP OAuth Email

Services Datastore Task Queue Authentication Image API Caching URL Fetching XMPP OAuth Email Blobstore

But It’s not Perfect

Limitations

Limitations The JDK whitelist

Limitations The JDK whitelist http://code.google.com/appengine/docs/java/jrewhitelist.html

Limitations The JDK whitelist http://code.google.com/appengine/docs/java/jrewhitelist.html No Hibernate

Limitations The JDK whitelist http://code.google.com/appengine/docs/java/jrewhitelist.html No Hibernate Only JPA and JDO

Limitations The JDK whitelist http://code.google.com/appengine/docs/java/jrewhitelist.html No Hibernate Only JPA and JDO Grails is limited

Limitations The JDK whitelist http://code.google.com/appengine/docs/java/jrewhitelist.html No Hibernate Only JPA and JDO Grails is limited Performance problems?

Tell me about

Groovy-based

Groovy-based Lightweight

Groovy-based Lightweight Page-centric

Groovy-based Lightweight Page-centric Tightly coupled to the Google App Engine

Groovy-based Lightweight Page-centric Tightly coupled to the Google App Engine A better GAE than the GAE

Setting up Gaelyk

Serving Content

Serving Content Static content (like in a WAR)

Serving Content Static content (like in a WAR) Groovy templates

Templates <% include '/WEB-INF/includes/header.gtpl' %> <h1>Look Up an Artist</h1> <form action="/artistLookup.groovy" method="POST"> <input type="text" size="50" name="artist"/> <input type="submit" value="Lookup"/> </form> <ul> <% request.artists.each { artist -> %> <li>${artist.name}</li> <% } %> </ul> <% include '/WEB-INF/includes/footer.gtpl' %>

Templates

Templates Lightweight, Groovy JSPs

Templates Lightweight, Groovy JSPs Downside: Scriptlets

Templates Lightweight, Groovy JSPs Downside: Scriptlets Request attributes bound from Groovlets

Groovlets import java.net.URLEncoder if(params.artist) { def response = urlFetch.fetch(new URL("http://musicbrainz.org/ ws/1/artist/?type=xml&name=${URLEncoder.encode(params.artist)}")) def text = new String(response.content) def xml = new XmlSlurper().parseText(text) request.artists = xml.'artist-list'.artist } else { request.artists = [] } forward '/artistLookup.gtpl'

Groovlets

Groovlets Groovy script, meet Servlet

Groovlets Groovy script, meet Servlet Intrinsic variables

Groovlets Groovy script, meet Servlet Intrinsic variables Forwarding

Groovlets Groovy script, meet Servlet Intrinsic variables Forwarding Redirecting

Groovlets Groovy script, meet Servlet Intrinsic variables Forwarding Redirecting MarkupBuilder

import java.net.URLEncoder if(params.artist) { def response = urlFetch.fetch(new URL("http:// musicbrainz.org/ws/1/artist/?type=xml&name=$ {URLEncoder.encode(params.artist)}")) def text = new String(response.content) def xml = new XmlSlurper().parseText(text) request.artists = xml.'artist-list'.artist } else { request.artists = [] } forward '/artistLookup.gtpl'

import com.google.appengine.api.datastore.* import static com.google.appengine.api.datastore.FetchOption if(!user) { redirect users.createLoginURL(request.requestURL.toString( return } def query = new Query("project") query.addSort("dateCreated", Query.SortDirection.ASCENDING) PreparedQuery preparedQuery = datastore.prepare(query) request.projects = preparedQuery.asList( withOffset(0) ) forward "/WEB-INF/views/project/list.gtpl"

URL Mapping

URL Mapping Templates in war/*.gtpl

URL Mapping Templates in war/*.gtpl Groovlets in war/WEB-INF/groovy/*.groovy

URL Mapping Templates in war/*.gtpl Groovlets in war/WEB-INF/groovy/*.groovy Pretty URLs with war/WEB-INF/routes.groovy

The Datastore

The Datastore Google’s BigTable infrastructure

The Datastore Google’s BigTable infrastructure Schemaless

The Datastore Google’s BigTable infrastructure Schemaless Named entities (property bundles)

The Datastore Google’s BigTable infrastructure Schemaless Named entities (property bundles) Indexed, queryable, sortable

The Datastore Google’s BigTable infrastructure Schemaless Named entities (property bundles) Indexed, queryable, sortable Transactional

The Datastore Google’s BigTable infrastructure Schemaless Named entities (property bundles) Indexed, queryable, sortable Transactional Great Groovy wrapper

Datastore Indexes

Datastore Indexes Automatically generated by default

Datastore Indexes Automatically generated by default Override in WEB-INF/datastore-indexes.xml

Datastore Indexes Automatically generated by default Override in WEB-INF/datastore-indexes.xml <?xml version="1.0" encoding="utf-8"?> <datastore-indexes autoGenerate="true"> <datastore-index kind="Employee" ancestor="false"> <property name="lastName" direction="asc" /> <property name="hireDate" direction="desc" /> </datastore-index> <datastore-index kind="Project" ancestor="false"> <property name="dueDate" direction="asc" /> </datastore-index> </datastore-indexes>

Tell me about Other Services

Email in Java

Email with Gaelyk mail.send sender: 'story-admin@augusttechgroup.com', to: 'tlberglund@gmail.com', subject: 'Story Complete', textBody: "A story you edited has increased in priority. Check it out."

Inbound Email

Inbound Email Enable in appengine-web.xml

Inbound Email Enable in appengine-web.xml Enable built-in servlet in web.xml

Inbound Email Enable in appengine-web.xml Enable built-in servlet in web.xml email.groovy Groovlet

Inbound Email Enable in appengine-web.xml Enable built-in servlet in web.xml email.groovy Groovlet The “message” intrinsic variable

Memcache in Java

Memcache with Gaelyk def countryFr = new Country(name: 'France') memcache['FR'] = countryFr if ('FR' in memcache) { countryFromCache = memcache['FR'] }

URL Fetch in Java

URL Fetch with Gaelyk def response = urlFetch.fetch(new URL("http://example.com")) def text = new String(response.content)

Task Queues queue.add countdownMillis: 10000, url: '/task/emailTaskList', taskName: 'Email current story assignments', method: 'PUT', params: [date: new Date()]

Task Queues

Task Queues Timed HTTP requests

Task Queues Timed HTTP requests Conﬁgure in war/WEB-INF/queue.xml

Task Queues Timed HTTP requests Conﬁgure in war/WEB-INF/queue.xml http://code.google.com/appengine/docs/java/conﬁg/queue.html

Task Queues Timed HTTP requests Conﬁgure in war/WEB-INF/queue.xml http://code.google.com/appengine/docs/java/conﬁg/queue.html Can update without redeploying

Task Queues Timed HTTP requests Conﬁgure in war/WEB-INF/queue.xml http://code.google.com/appengine/docs/java/conﬁg/queue.html Can update without redeploying Can be secured

XMPP User notiﬁcation

XMPP User notiﬁcation XML payloads for distributed communication

XMPP User notiﬁcation XML payloads for distributed communication Send messages with a Groovier API

XMPP User notiﬁcation XML payloads for distributed communication Send messages with a Groovier API Receive messages through a servlet

XMPP Sending in Java

XMPP Sending with Gaelyk

XMPP Sending with Gaelyk def recipient = 'tlberglund@gmail.com' if (xmpp.getPresence(recipient).isAvailable()) { def status = xmpp.send(to: recipient, body: "Glad you're into Gaelyk!") if (!status.isSuccessful()) {

XMPP Sending with Gaelyk def recipient = 'tlberglund@gmail.com' if (xmpp.getPresence(recipient).isAvailable()) { def status = xmpp.send(to: recipient, body: "Glad you're into Gaelyk!") if (!status.isSuccessful()) { // ...

XMPP Sending with Gaelyk def recipient = 'tlberglund@gmail.com' if (xmpp.getPresence(recipient).isAvailable()) { def status = xmpp.send(to: recipient, body: "Glad you're into Gaelyk!") if (!status.isSuccessful()) { // ... } }

XMPP Receiving

XMPP Receiving Enable in appengine-web.xml

XMPP Receiving Enable in appengine-web.xml Enable built-in servlet in web.xml

XMPP Receiving Enable in appengine-web.xml Enable built-in servlet in web.xml /war/WEB-INF/groovy/jabber.groovy

XMPP Receiving Enable in appengine-web.xml Enable built-in servlet in web.xml /war/WEB-INF/groovy/jabber.groovy The “message” intrinsic variable

Plugins

Plugins Analogous to Grails plugins

Plugins Analogous to Grails plugins Mini Gaelyk apps

Plugins Analogous to Grails plugins Mini Gaelyk apps plugins/xxxPluginDescriptor.groovy

Plugins Analogous to Grails plugins Mini Gaelyk apps plugins/xxxPluginDescriptor.groovy Bundled as ZIP ﬁles

Plugins Analogous to Grails plugins Mini Gaelyk apps plugins/xxxPluginDescriptor.groovy Bundled as ZIP ﬁles Ad-hoc discovery and distribution

Development

What about Services in development?

GAE Emulation

GAE Emulation Datastore simulated in ﬁlesystem

GAE Emulation Datastore simulated in ﬁlesystem General Administration

GAE Emulation Datastore simulated in ﬁlesystem General Administration http://localhost:8080/_ah/admin

GAE Emulation Datastore simulated in ﬁlesystem General Administration http://localhost:8080/_ah/admin Authentication

GAE Emulation Datastore simulated in ﬁlesystem General Administration http://localhost:8080/_ah/admin Authentication http://localhost:8080/_ah/login

GAE Emulation Datastore simulated in ﬁlesystem General Administration http://localhost:8080/_ah/admin Authentication http://localhost:8080/_ah/login http://localhost:8080/_ah/logout

On github git@github.com:tlberglund/august-stories.git git@github.com:tlberglund/august-demo.git

Thank You Tim Berglund www.augusttechgroup.com tim.berglund@augusttechgroup.com @tlberglund Using Your Existing Team

Photo Credits Parchment Background http://www.photoshopstar.com/effects/recreate-indiana-jones-text-effect/

Gaelyk: Lightweight Groovy on the Google App Engine

by Tim Berglund

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