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Version: v3.x alpha

Hasura DDN Glossary

Data Delivery Network (DDN)

Hasura DDN is a globally distributed and always-available cloud for APIs and data connectivity which enables blazingly-fast and secure delivery of real-time data over GraphQL or REST APIs. It is powered by innovations in Hasura version 3 including a serverless runtime.

Serverless Runtime System

The new runtime engine in Hasura DDN which accesses metadata on a per-request basis, enabling improved isolation and scalability. The serverless runtime also eliminates shared state and cold start issues for enhanced performance.

Metadata Authoring

The process of defining and creating metadata files using the CLI, LSP, and Native Data Connector specifications in Hasura DDN. It involves specifying data types, models, commands, data source and API configurations. Learn more.

Data Sources

Any external data source, database, or service that can be connected to Hasura DDN using a Data Connector agent. Every data source must have connector URL and schema. Learn more.

Native Data Connector Specification (NDC Spec)

A standardized specification that allows you to extend the functionality of the Hasura server by providing web services which can resolve new sources of data that defines the metadata structure for APIs in Hasura DDN. All data backends in Hasura DDN conform to this backend and use types defined by this specification such as collections, functions and procedures. Learn more.

Native Data Connector Agents

Data connector agents that integrate Hasura with various external data sources and services and are based on the native data connector specification. Native data connectors can be either official Hasura connectors, verified by Hasura or a non-verified connector. Learn more.

Push-Down Capabilities

The ability in Hasura DDN to delegate certain query operations including Authorization to the underlying data source. This can improve query optimization and performance and is the reason why data connectors in Hasura DDN are called 'native'.

Connector Hub

Refers to the public site where all Native Data Connectors for Hasura DDN are listed. Users can discover connectors, get more information about their specific features and find documentation on how to use each connector with Hasura DDN. Learn more.

Model

A metadata object that is fundamental to API design in Hasura DDN. The model is the entity that has a direct mapping to the underlying native data connector schema object or collection.

A model includes reference to the data type and includes configuration details related to API configuration, arguments and global ids.

It supports select, insert, update and delete operations. Within the select operation the different query operations include filtering, aggregating, paginating and limiting. Learn more.

Command

The Hasura entity that helps encapsulate business logic and represents an action that can be performed which returns back some type of result. It directly maps to the native data connector object's functions and procedures. Learn more.

Relationships

A metadata object in Hasura DDN that defines the relationship between two models or between a model and a command. This facilitates data interconnection. Learn more.

Permissions

A metadata object in Hasura DDN that defines the access control or authorization rules on models and commands. Learn more.

Global ID

Refers to the Relay global ID that encodes the type and ID of an object in a single string. In Hasura this is defined per model and enables fetching any object directly, regardless of what kind of object it is. A result of this is that you get the node root field in the GraphQL API schema to use with a Relay client. Learn more.

Collection

A collection is a native data connector spec object that maps one-to-one with the underlying data source object. Tracking a collection results in the creation of a model object in Hasura metadata.

It can be queried or mutated and contains name, arguments and object types. Learn more.

Function

A function is a native data connector specification object and is a special type of collection. It only returns a single row and a single column, can contain arguments and cannot be mutated.

Tracking a function results in the creation of a Command object in Hasura metadata. Learn more.

Procedure

A procedure is a native data connector specification object, and it defines an action that the data connector implements. Each procedure has arguments and a return type.

Tracking a procedure results in the creation of a Command object in Hasura metadata. Learn more.

Builds

Each metadata change in Hasura DDN represents an immutable build. Every build has a unique GraphQL Endpoint that can be tested independently. Builds are tied to projects and there is a one-to-many mapping between projects and builds. Learn more.

Subgraphs

In Hasura DDN, Subgraphs provide autonomy, separation and security to teams for working with project metadata and allow them to organize and structure metadata as per team and business requirements. There can be multiple subgraphs in a project.

All subgraphs contribute to one build at any given time, ie: one subgraph can be used create a build only when it does not introduce a breaking change at the project level. Learn more.

Hasura CLI (Command-Line Interface)

A tool in Hasura DDN that enables developers to interact with Hasura from the command line. It supports various commands for creating builds, deploying projects, creating tunnels and managing secrets. Learn more.

LSP (language server protocol)

The Hasura Language Server Protocol (LSP) enables the integration of language features such as tracking data source objects, validation of metadata, providing diagnostics at the time of authoring and helping autocomplete metadata.

It supports .hml files which are a Hasura variant of .yaml files. We have used the Hasura LSP to build our VSCode extension which you can download to help you write metadata. We have plans to provide extensions such as these for other text editors.

Hasura Secure Connect

A feature in Hasura DDN that creates secure tunnels to connect with local resources, aiding local development while ensuring data security. It requires a local daemon to be run via the CLI.

Hasura Console

An interface in Hasura DDN that provides tools for metadata visualizing, API testing and deployment, and team collaboration. It offers tools to validate metadata before creating builds and metrics and traces to determine the usage and health of the API.

Secrets

A secret is an object that contains small amounts of sensitive information such as database connection strings. It is best practice to first create secrets using the Hasura CLI or Console and then use those secrets in the metadata.

Cloud PAT

This refers to a personal authentication token that Hasura Cloud creates automatically for you on every new project creation. This ensures that your GraphQL API always has a security mechanism. The auto-generated PAT is included in the API header cloud_pat.