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Pallets

FRAME, or the Framework for Runtime Aggregation of Modularized Entities, essentially heavily simplifies runtime development for us. It allows us to combine different runtime modules to customize our blockchain. Consensus, staking, governance, balances, and the like are all pallets covered under FRAME.

These modules are called pallets. In short, they contain the business logic for custom blockchain functionality and are added and managed by the runtime. In theory, you can build a Substrate based chain without them. However, they contain a lot of core functionality that serves as a valuable base for a new Substrate based chain.

We’ll create a custom pallet later in this course, where you will see how to mix and match pallets to create your own blockchain. The pallets handle the signing and submission of extrinsics on Substrate, allowing us to implement custom functionality directly into the chain.

Common Pallets in FRAME​

Several standard pallets built using FRAME are used in many networks and relay chains like Polkadot or Kusama. The standard pallet naming convention is pallet_ followed by the actual name. Here are a few standard pallets that you might often encounter as a developer:

  • pallet_balances - The Balances pallet provides account and balance functionality.
  • pallet_system - The System pallet provides low-level access to core types and cross-cutting utilities. It is the base layer for other pallets interacting with the Substrate framework components.
  • pallet_referenda - The Referenda pallet handles the administration of general stakeholder voting. This pallet along with other pallets like pallet_conviction_voting drives Polkadot OpenGov - the next generation of decentralized on-chain governance.

To view all pallets included with FRAME, look at the repository on GitHub.

Our Pallet: pallet_connect​

As a part of this course, the pallet you will build and modify is called pallet_connect. It is a basis for a simple, Sybil-resistant social network, demonstrating several vital functionalities and practices for building pallets using FRAME.

Below you may find a list of the exact features this pallet provides:

  • Create the equivalent of a social network, but with only profiles. The user must meet a set of prerequisites (balance) to join.
  • Account for Sybil attacks by requiring an amount of currency to be locked (an existential deposit) for each user.
  • Each profile picture is generated on-chain using on-chain randomness - forming a gradient image associated with every user.
  • All handles are unique. No two usernames can be the same.
  • Bounded metadata for each account.