FEATURE EXPECTATIONS AND REQUIREMENTS GATHERING [5 min]

1. Use cases
   1. As a X, I want to Y so that Z
   2. Scenarios that will not be covered (Edge cases)
2. Who will use?
3. How many will use?
4. How will they use it? (Usage patterns)

ESTIMATIONS [5 min]

1. Throughput (QPS for read and write queries)
2. Latency expected from the system (for read and write queries)
3. Read/Write ratio
4. Traffic estimates - Write (QPS, Volume of data) - Read (QPS, Volume of data)
5. Storage estimates
6. Memory estimates - If we are using a cache, what is the kind of data we want to store in cache - How much RAM and how many machines do we need for us to achieve this? - Amount of data you want to store in disk/SSD

DESIGN GOALS [5 min]

1. Latency and Throughput requirements
2. Consistency vs Availability [Weak/strong/eventual => consistency | Failover/replication => availability]

HIGH LEVEL DESIGN [5-10 min]

1. APIs for Read/Write scenarios for crucial components
2. Database schema
3. Basic algorithm
4. High level design for Read/Write scenario

DEEP DIVE [15-20 min]

1. Scaling the algorithm
2. Scaling individual components:
   • Availability, Consistency and Scale story for each component
   • Consistency and availability patterns
3. Think about the following components, how they would fit in and how it would help
   • DNS
   • CDN [Push vs Pull]
   • Load Balancers [Active-Passive, Active-Active, Layer 4, Layer 7]
   • Reverse Proxy - Application layer scaling [Microservices, Service Discovery]
   • DB [RDBMS, NoSQL]
     • RDBMS
       • Master-slave, Master-master, Federation, Sharding, Denormalization, SQL Tuning
     • NoSQL
       • Key-Value, Wide-Column, Graph, Document
         • Fast-lookups:
           • RAM [Bounded size] => Redis, Memcached
           • AP [Unbounded size] => Cassandra, RIAK, Voldemort - CP [Unbounded size] => HBase, MongoDB, Couchbase, DynamoDB
   • Caches
     • Client caching, CDN caching, Webserver caching, Database caching, Application caching, Cache @Query level, Cache @Object level
     • Eviction policies:
       • Cache aside
       • Write through
       • Write behind
       • Refresh ahead
     • Asynchronism
       • Message queues
       • Task queues
       • Back pressure
     • Communication
       • TCP
       • UDP
       • REST
       • RPC

JUSTIFY [5 min]

1. Throughput of each layer
2. Latency caused between each layer
3. Overall latency justification