Google App Engine and Java

Google App Engine and Java

Application: Clustering Internet search results for a person

20.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

Faculty of Mathematics, University of Belgrade

Google App Engine

• Web application hosting service

• Designed for real-time dynamic apps

• Many simultaneous users

• Scalable

• Paying resources monthly

• Free account (5 million page views a month)

20.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

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Sandboxing

• App can only read its own files

• App cannot manipulate environment variables

• App cannot access network facilities

• Distributing request non-deterministically

• Consequence: run multiple apps on the same server, or one app on multiple servers safely

20.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

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Architecture overview

20.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

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Features

• The static file servers

• The Datastore– Not join-query database– Most resembling to object database

• Entities and properties– Entity has 1..* properties– Not to be confused with rows in RDBMS

20.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

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Features

• Queries and indexes– Index in made for every simple query– Query performance affected only by the size

of the result set

• Transactions– Optimistic concurrency control– Entity groups (entities updated in one trans.)

• Services: memcache, URL fetch , Mail, …

20.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

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App Engine’s request handling

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Building applications

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App engine dashboard

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App engine dashboard

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Clustering search results

20.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

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Clustering search results

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EC2 vs GAE vs Azure

20.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

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EC2 vs GAE vs Azure

20.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

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Thank you.

Aleksandar Kartelj

Faculty of Mathematics, University of Belgrade

kartelj@matf.bg.ac.rs

www.matf.bg.ac.rs/~kartelj