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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
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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
19.04.23 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
19.04.23 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, …
19.04.23 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
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