Tianpan.co: Crack the System Design Interview

 Here is the page. 

My study notes:

RPC vs RESTful style 

Generally speaking, RPC is internally used by many tech companies for performance issues, but it is rather hard to debug and not flexible. So for public APIs, we tend to use HTTP APIs, and are usually following the RESTful style.

• REST (Representational state transfer of resources)
  • Best practice of HTTP API to interact with resources.
  • URL only decides the location. Headers (Accept and Content-Type, etc.) decide the representation. HTTP methods(GET/POST/PUT/DELETE) decide the state transfer.
  • minimize the coupling between client and server (a huge number of HTTP infras on various clients, data-marshalling).
  • stateless and scaling out.
  • service partitioning feasible.
  • used for public API.

Db Proxy 

What if we want to eliminate single point of failure? What if the dataset is too large for one single machine to hold? For MySQL, the answer is to use a DB proxy to distribute data, either by clustering or by sharding.

Clustering is a decentralized solution. Everything is automatic. Data is distributed, moved, rebalanced automatically. Nodes gossip with each other, (though it may cause group isolation).

Sharding is a centralized solution. If we get rid of properties of clustering that we don’t like, sharding is what we get. Data is distributed manually and does not move. Nodes are not aware of each other.