Domain Name Server
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enables WWW
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changes domain name to ip address
Load Balancer
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Horizontal scaling is always better than vertical scaling
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prevent service interruption
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even you can scale server vertically, there is an limit
•
enables horizontal scaling
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by distributing requests to the duplicated server
Web Application Server
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executes business logic and sends responds through HTML
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Should choose proper server language (Node.js, Ruby, PHP, Scala, Java, C#, .NET, ...) and its web MVC framework (Express for Node.js, Ruby on Rails, Play for Scala, Laravel for PHP)
Database Server
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struct, insert, find, modify, delete, and compute data
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Each backend service could have distinct different database
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SQL vs NoSQL
Cache Service
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provide key-value data that could be found in O(1)
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Instead of re-calculation, application retrieves result from cache
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Redis / Memcache
Job Queue & Server
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application should do background task asynchronously
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For example, google crawling and indexing data from internet
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Job Queue architecture has two components
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Queue consists of Jobs that is FIFO (First-in-first-out)
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Job server that runs job in queue
