To ensure the consistency and integrity of data stored on Layer 2, all data is governed by the Hellar Platform Protocol (HPP). Hellar Platform Protocol describes serialization and validation rules for the platform’s 3 core data structures: data contracts, documents, and state transitions. Each of these structures are briefly described below.
A data contract is a database schema that a developer needs to register with the platform in order to start using any decentralized storage functionality. Data contracts are described using the JSON Schema language and must follow some basic rules as described in the platform protocol repository.
📘 Contract updates
Hellar’s data contracts support backwards-compatible modifications after their initial deployment unlike many smart contract based systems. This provides developers with additional flexibility when designing applications.
For additional detail, see the Data Contract explanation.
Document
A document is an atomic entity used by the platform to store user-submitted data. It resembles the documents stored in a document-oriented DB (e.g. MongoDB). All documents must follow some specific rules that are defined by a generic document schema. Additionally, documents are always related to a particular application, so they must comply with the rules defined by the application’s data contract. Documents are submitted to the platform API (HAPI) by clients during their use of the application.
For additional detail, see the Document explanation.
State Transition
A state transition represents a change made by a user to the application and platform states. It consists of:
The user signature is made for the binary representation of the state transition using a private key associated with an identity. A state transition is constructed by a client-side library when the user creates documents and submits them to the platform API.
For additional detail, see the State Transition explanation.