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pre-checklist

Basic Stationery Box​

Design interviews mostly talk about choice the right solution for the problem in hand, but most of solutions are picked up from a box of several choices. In-order for someone to choose from a box, somene must put something in the box , and this is where the box of tools comes into picture.

Mostly in interviews a few things are common amongst which you need to make a choice.

  • Services
  • Databases
  • Networks
  • Caches
  • Languages
  • Protocols
  • Security Options
  • Operating Systems
  • Memory Managements
  • Data Structures
  • Messaging
  • Algorithms
  • integration patterns

etc.

These can be considered as subsection in your tool-box and you will see you have a pool of choices within each sub-section and you need to make a choice , and in order to do that you need to understand the basic requirement of the problem and then basic capability of that tool , for example to make a hole in a wall you will not take out a pin-hole bit.

CAP​

Always Remember Cap theorem: Choose between availability and scalability

Most of the questions will be targeted towards understanding the data ingestion pipelines, and that involve focusing on below issues

  • How various requests to service will be coming ( single/buffered/batch)
  • How will timeouts be considered depending on type of requests
  • What will API look like
  • How does client – implement a re-try mechanism
  • Where data is getting stored temporary
  • How do you deal with duplicates
  • How do you scale a single service
  • How the increase in database though through
  • Which type of database is required.
  • How the incoming requests will be processed and stored.
  • Fault handling and tolerance of the system
  • Error Handling
  • What happens when something goes wrong , bottle necks etc.

Concepts while implementing a client

  1. Blocking vs Non-blocking calls (threads/ asyncs )
  2. Buffering/ batching ? ( example logger client)
  3. timeouts (request timeouts 1% of slowest requests times)
  4. retries ( retry storm events , overload server with too many request )
  5. exponential backoff and jitter algorithms
  6. circuit breaker

Below diagram talks a 1 key info you should know about you tools inside the tool box