Why does ethereum uses RLP encoding

Question

Why does ethereum uses RLP encoding encoding for serialising data i mean is there are specific reason for not using already existing formats ?? other than RLP being really compact and space efficient.

Answer 1

RLP is a deterministic scheme, whereas other schemes may produce different results for the same input, which is not acceptable on any blockchain. Even a small change will lead to a totally different hash and will result in data integrity problems that will render the entire blockchain useless.

From here

Recursive Length Prefix (RLP) serialization is used extensively in Ethereum's execution clients. RLP standardizes the transfer of data between nodes in a space-efficient format. The purpose of RLP is to encode arbitrarily nested arrays of binary data, and RLP is the primary encoding method used to serialize objects in Ethereum's execution layer. The only purpose of RLP is to encode structure; encoding specific data types (e.g. strings, floats) is left up to higher-order protocols; but positive RLP integers must be represented in big-endian binary form with no leading zeroes (thus making the integer value zero equivalent to the empty byte array). Deserialized positive integers with leading zeroes get treated as invalid. The integer representation of string length must also be encoded this way, as well as integers in the payload.

Answer 2

1. simplicity of implementation, it build on ASCII Encoding.
2. guaranteed absolute byte-perfect consistency. Especially for Key/Value Map data structure, we can represent it as [[k1, v1], [k2, v2], ...], but the sort of key is not stable, which mean use the same value(Map) in different implement will output different result. So RLP guaranteed the ethereum tx hash need consistency.

Answer 3

The purpose of RLP (Recursive Length Prefix) is to encode arbitrarily nested arrays of binary data, and RLP is the main encoding method used to serialize objects in Ethereum. See this RLP

RLP is just an option as you mentioned, someone may be familiar with this format while others don't, but once you choose this tech, it's better to be consistent in one project for not confusing others.