latjug. google app engine

Google AppEngine

First experience

Java and Python on Google infrastructure

No need for own server, no electricity and ISP bills

Stable, cheap, scalable, fast to setup and easy to use

Administration, logs, statistics, all in one place

Greet and meet

• Take some war file and deploy it

Greet and meet

• Take some war file and deploy it• Discover that JDBC is blacklisted• Discover that actually a lot of stuff is blacklisted

Greet and meet

• Take some war file and deploy it• Discover that JDBC is blacklisted• Discover that actually a lot of stuff is blacklisted• Application instances are started on demand• Stopped after 2-3 minutes if not used• Url like: myapp.appspot.com• Only 10 applications per account

Startup time matters

• No activity = application stopped• First load = more time and resources

Datastore

• Upload 20 000 records in Datastore• Discover that data is wrong and you want to delete it• DELETE FROM ...

Datastore

• Upload 20 000 records in Datastore• Discover that data is wrong and you want to delete it• DELETE FROM ... oh, wait• GQL can only query for data• Create, update, delete only with code• Get used to it, write small utilities, agents

So, Datastore

• NoSQL, BigTable from Google

So, Datastore

• NoSQL, BigTable from Google• Because in most cases reads are often, writes are rare• Trade fast reads for slow writes

So, Datastore

• NoSQL, BigTable from Google• Because in most cases reads are often, writes are rare• Trade fast reads for slow writes• Denormalization is favored• Partial JPA and JDO support

So, Datastore

• NoSQL, BigTable from Google• Because in most cases reads are often, writes are rare• Trade fast reads for slow writes• Denormalization is favored• Partial JPA and JDO support• Record → Entity• Table → Kind• Column → Property• Entities of same kind can have different set of properties

No index = no query

• Each query has its own index

No index = no query

• Each query has its own index• Query without index = exception or empty result• Index must have all fields from "WHERE" clause• Even ASC and DESC order matter

Index takes space

• Example: 70MB of data

Index takes space

• Example: 70MB of data can have 300MB of indexes

Index takes space

• Example: 70MB of data can have 300MB of indexes• Do not index everything (to avoid situation above)• Index fields only used for queries• Reindex after index creation

Everything counts

• There is free quota

Everything counts

• There is free quota, which is good enough

Everything counts

• There is free quota, which is good enough• Use bulk operations

Getting used to limits

• 30 seconds per request• 1MB per request

Getting used to limits

• Currently:• 30 seconds per request• 10 minutes for TaskQueue/Cron requests• 10MB per request

Versions

• Multiple application versions at same time

Versions

• Multiple application versions at same time• One database though

Versions

• Multiple application versions at same time• One database though• Be careful• Useful in various ways• Easy switch

Services

• URLFetch• Memcache• TaskQueue• Mail• Images• Blobstore

OpenID

• Google Accounts by default• Possible Federated login

OpenID

• Google Accounts by default• Possible Federated login• @gmail.com• @hotmail.com• @yahoo.com• @yandex.ru• @rambler.ru

OpenID

• Google Accounts by default• Possible Federated login• @gmail.com• @hotmail.com• @yahoo.com• @yandex.ru• @rambler.ru• @mail.ru, @live.co.uk @a42.ru, @bk.ru, @schuett-nms.de,

@partreg.lg.ua, @neglect.us, @saikonet.org, @clear.net.nz, @meta.ua, @gmx.de, @mchsi.com, @tut.by, @pp.inet.fi

• ...

Sometimes there is just bad weather

Pricing

• Resource-based• Free quota• Pay for surplus

Developing applications for AppEngine

Future of AppEngine

• Google AppEngine for Business

Demo

EveManagehttp://code.google.com/p/evemanage/

EveDbhttp://code.google.com/p/evedb/