Intro to App Engine and AppScale

introTo

Googleapp engine

&Appscale

build apps faster and easier

developer innovation

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rapid releases

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scale on any cloud

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Chris [email protected]

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a common pattern

One of several recurring problems seen in the real world today.

• You have a cool idea

• To make it into an app, you need to:

• Setup hardware

• Configure, deploy app services

• And you have to do this for every app!

www.appscale.comPhone: +1(805) 845 0010 | e-mail: [email protected] PAGE

Why not Amazon?

3

• You don’t want to deploy and maintain:

• Servers

• Load balancers

• App Servers

• Databases

• And you don’t want to hire people to do it!

mailto:[email protected]



google app engine

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• A web application hosting service

• Never log into a server

• Crystallizes web service best practices

• Share common services between apps

• Focus on writing your app




Supported Languages

5

Go

Python

Go

Java



PAGEwww.appscale.comPhone: +1(805) 845 0010 | e-mail: [email protected]

Programming Model

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Everything is a web request

Stateless, scalable web server, meaning:

• No filesystem access

• Persistence via Datastore / memcache

• 60 second time limit on requests

• APIs from whitelist only




The DATAstore

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• Not a relational database, but resembles an object database

• You define Kinds of data you want to store

• Each object stored is an Entity

• Entities can be arranged into Groups




Defining a kind

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class Person(ndb.Model):

user = ndb.UserProperty()

balance = ndb.FloatProperty()

phone = ndb.StringProperty()

last_login = ndb.DateTimeProperty()




EXTENDING a kind

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user = ndb.UserProperty()

balance = ndb.FloatProperty()

phone = ndb.StringProperty()

last_login = ndb.DateTimeProperty()

login_location = ndb.GeoPt()




Kind, entities

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...

new_person = Person()

new_person.put()




transactions

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• Updating an Entity happens in a Transaction

• Apps tell App Engine which Entities will be updated together by putting them into an Entity Group

• Transactions can only occur within an Entity Group*

def f():

person = db.get(key1)

person.balance = 100.00

person.put()

db.run_in_transaction(f)


memcache

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data = memcache.get(‘key’)

if data:

return data

else:

data = db.get(‘key’)

memcache.set(‘key’, data, 300)

return data




users

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user = users.get_current_user()

if user:

return user.nickname()

else:

return None




mail

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from = “Chris Bunch <[email protected]>”

to= “You <[email protected]>”

subject = “Try out AppScale!”

body = “http://download.appscale.com”

mail.send_mail(sender=from, to=to, subject=subject, body=body)







http://download.appscale.com

http://download.appscale.com


task queue

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taskqueue.add(url=“/path/to/worker”)

cron:- description: sends friendly emails url: /path/to/worker schedule: every 24 hours




url fetch

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r = urlfetch.fetch(“http://www.google.com/”)

if r.status_code == 200:

do_something_with_result(r.content)

else:

# retry later




xmpp

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user = “[email protected]”

msg = “Hello there!”

status = xmpp.send_message(user, msg)

if status != xmpp.NO_ERROR:

# decide what to do with the failed msg




enter appscale

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• But what if you need:

• To fail over to a private cloud?

• To run your App Engine app in-house?

• To use APIs App Engine doesn’t support?

• Then you need AppScale!




run anywhere

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datastore

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• Supports NoSQL datastores via a database agnostic API:

• get

• put

• range_query

• delete




we have supported

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now focusing on...

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load balancing + app servers

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API Services

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the development cycle

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• App Engine SDK for rapid development

• Limitations:

• Many APIs are stubbed out (XMPP, Mail)

• Not designed for production workloads

• Use AppScale!



Demo

Technology

Intro to App Engine and AppScale