> For the complete documentation index, see [llms.txt](https://avinandanbanerjee99.gitbook.io/system-design-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://avinandanbanerjee99.gitbook.io/system-design-notes/examples/template.md).

# Template

#### (1) FEATURE EXPECTATIONS \[5 min]

```
(1) Use cases
(2) Scenarios that will not be covered
(3) Who will use
(4) How many will use
(5) Usage patterns
```

#### (2) 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
```

#### (3) DESIGN GOALS \[5 min]

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

#### (4) 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
```

#### (5) 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
a) DNS
b) CDN [Push vs Pull]
c) Load Balancers [Active-Passive, Active-Active, Layer 4, Layer 7]
d) Reverse Proxy
e) Application layer scaling [Microservices, Service Discovery]
f) 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
g) 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
h) Asynchronism
        > Message queues
        > Task queues
        > Back pressure
i) Communication
        > TCP
        > UDP
        > REST
        > RPC
```

#### (6) JUSTIFY \[5 min]

```
	(1) Throughput of each layer
	(2) Latency caused between each layer
	(3) Overall latency justification
```