Symbol in many ways, has similarities with Polkadot.
Commonly, Polkadot is described as a heterogeneous multichain protocol, even non-blockchain systems or data structures can become a parachain if they fulfill a set of criteria.
Let’s look at some distinct similarities and differences between Polkadot and Symbol.
Relay Chain vs. Mainnet
Polkadot uses the relay chain to enable arbitrary message passing between blockchains in its ecosystem. The relay chain is generic enough to allow adjacent chains — we call them parachains — to have their own application logic. — https://medium.com/polkadot-network/
Polkadot’s Relay Chain was launched in May 2020. It is like the mainnet of Symbol, yet, different in many ways. Polkadot relay chain and Symbol mainnet are both built as “chain of chains” or “network of networks”, and both running on Proof-of-Stake variations.
As for the differences, it would be easier to explain by talking about “parachain”.
Parachains vs. Private Chain
Parachain is like a private chan in Symbol (Symbol’s “private chain” could be a permissionless chain. ) While Symbol’s private chains are considered forks from Symbol’s technology, having their own consensus, tokenomics and independent from Symbol, Polkadot’s parachains are sharing infrastructure and security from the relay chain. Parachains produce their own blocks but do not have their own consensus mechanism. If you want to set up a blockchain with your own consensus mechanism and connect to the replay chain, you can use parachain as a bridge.
Comparing to shards, which are homogenous, parachains are heterogeneous, Each parachain is different from each other, having different logics, and serves different functions. While it provides strong security, scalability has to give in. It is estimated “that the relay chain will be able to host about one hundred parachains, but anything between ten and one thousand slots is imaginable.”
As there are limited slots available, to connect to the relay chain, a parachain needs to win an auction. Connection to the relay chain is not permanent. When it expires, and the parachain fails to win another auction, it will disconnect from the relay chain and becomes a parathread (to be discussed another time).
Both parachain and private chain do not need to have native currencies of Polkadot (DOT) and Symbol (XYM).
Substrate vs. Catapult Server
It is easy to set up a parachain using Substrate. Substrate is a framework to build modular and upgradable blockchains. It has pre-designed Substrate Node and its genesis block configurable.
Substrate is, “a set of libraries for doing all the things that are really annoying about writing blockchains.” — Robert Habermeier
Private chain in Symbol is easy to set up by following the instructions to compile Catapult Server or using Symbol-Boostrap. They are highly customizable with configurable genesis block, consensus mechanism and functions.
Pallet vs. Plug-in
In building parachains with Substrate, the modules included are called pallets. For Symbol, the customizable and configurable features are called plugins.
Author vs. Harvester
Block producer in Polkadot is called an “author” while Symbol’s is called a “harvester”.
Consensus Protocols
Polkadot hybrid consensus mechanism uses Aura (Authority Round) for block production and probabilistic finality, and uses GRANDPA for deterministic finality. BABE (Blind Assignment for Block Extension) is in place to make sure of block creation.
Symbol uses PoS+ and its finality models after GRANDPA.
Another interesting feature of Polkadot is it can upgrade without hard forks to integrate new features or fix bugs. A feature in Substrate is used to circumvent the fork and update the relay chain.
As it is not advisable to have your 3 meals for the day in one sitting and stay full the whole day, as you will get indigestion. So, here is where I will stop now, and dip my finger into it again another time.
“The world, in some sense, belongs to the coders.” — Dr. Gavin Wood.
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