Google App Engine and Java

Application: Clustering Internet search results for a person

19.04.23 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)

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

2/14

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

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

3/14

Architecture overview

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

4/14

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

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

5/14

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, …

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

6/14

App Engine’s request handling

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

7/14

Building applications

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

8/14

App engine dashboard

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

9/14

App engine dashboard

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

10/14

Clustering search results

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

11/14

Clustering search results

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

12/14

EC2 vs GAE vs Azure

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

13

EC2 vs GAE vs Azure

19.04.23 Aleksandar Karteljkartelj@matf.bg.ac.rs

14

Thank you.

Aleksandar Kartelj

Faculty of Mathematics, University of Belgrade

kartelj@matf.bg.ac.rs

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