Architecture

This document describes, in detail, the architecture of plasma-core. If you’re a new contributor to plasma-core, welcome! Hopefully this document will help you better understand how plasma-core works under the hood.

plasma-core 101

plasma-core is composed of a set of services that, when woven together, form (almost) a complete node! Each of these services performs a very specific role. A more in-depth explanation of each individual service is available in the Service API Reference section of our documentation.

Architecture Diagram

This diagram shows the basic architecture of plasma-core:

src/./_static/images/architecture/architecture.png

PG Plasma Architecture Diagram

External services

plasma-core talks to three external services: Ethereum, the plasma chain Operator, and user applications. These three services are outside of the scope of plasma-core. Instead, plasma-core provides interfaces through which it can talk to and hear from these external services.

ContractService

ContractService handles interactions with the plasma chain contract, like submitting deposits or starting withdrawals. Non-contract specific Ethereum interactions are handled by ETHService.

ETHService

ETHService exposes the functionality necessary to read information from Ethereum. ETHService is used for non-contract specific interactions.

OperatorService

As its name suggests, OperatorService handles all communication with the plasma chain operator. This includes sending and receiving plasma chain transactions.

JSONRPCService

The JSONRPCService acts as a handler for commands sent by user applications. By default, applications must interact directly with JSONRPCService. plasma-core can be extended to expose additional interfaces to JSONRPCService, such as an HTTP API.

Internal services

The remaining services of plasma-core manage things internally.

SyncService

Possibly the most important internal service, SyncService ensures that your node always has the latest transactions. SyncService watches Ethereum for any new plasma chain blocks and automatically pulls any necessary information from the Operator. SyncService makes sure your balances are always up-to-date and that you can always send transactions when you need to!

ChainService

ChainService is another extremely important internal service. ChainService manages plasma-core’s internal blockchain. This includes storing any necessary transaction and block information. ChainService also handles returning information about the stored local state with convenient wrapper functions.

GuardService

GuardService takes on the important role of keeping your funds safe at all times. The GuardService keeps a constant eye on Ethereum and blocks others from trying to move funds without your permission. GuardService queries Ethereum through the ETHService and pulls other relevant user data from ChainService.

DBService

DBService simply provides a database that ChainService uses to store user data. Currently, we support two database backends, LevelDB and an in-memory ephemeral database (EphemDB). Most services talk to ChainService to retrieve data from DBService instead of talking to DBService directly.