Glossary
Catalyst #
Catalyst is the name given to the Decentraland Service Bundle, each Catalyst node exposes a set of services that work as the backbone for the platform and also exposes a public API .
Bootstrap #
When the Catalyst is started, the node will have a Bootstrapping state while fetching content from other catalysts until it catches up with the others. And then it transitions to the next state Syncing in which it is ready to serve content.
Catalyst Client #
Library that can be used to interact with the Catalyst servers. It allows both fetching data and deploying new entities to the specified server.
Entity #
Data Type, defined with schemas , that cannot be stored in the blockchain because of its size. Some of the current supported types are the following:
Deployment #
Instances of Entities created on the Content Server and identified with a unique EntityId . Deployments can be of any Entity Type .
Failed Deployment #
Instance of an Entity deployed to a Content Server that failed to pass the Content Validations . Validations are implemented on the content validator library.
Active Entity #
An entity that is currently deployed on a pointer, thus all active entities represent the live content of Decentraland: scenes, profiles, wearables, etc.
Pointer #
Pointers are the ids or locations to which a Deployment belongs. Their format is different based on the Entity Type, for example:
- Wearables: Uses URN as pointers
urn:decentraland:ethereum:collections-v1:dg_atari_dillon_francis:gerald_patchwork_knit_sweater - Scenes: Uses parcels or array of parcels as pointers, for example
--10,20or[(0,0), (0,1), (0,-1)] - Profiles: Uses a Wallet address as pointer
0xb01ddb6d4c89314f74a32dfc2f3bd0f8311a6d75 - Stores: Uses a URN as pointer
urn:decentraland:off-chain:marketplace-stores:{wallet} - Outfits: Uses a Wallet address as pointer suffixed by
:outfits,0xb01ddb6d4c89314f74a32dfc2f3bd0f8311a6d75:outfits
URN #
URN stands for Uniform Resource Name. They are used as global unique identifiers for assets across the Metaverse projects.
- URN Resolver: https://github.com/decentraland/urn-resolver
- URN Namespace: https://github.com/common-metaverse/urn-namespaces
Content Server #
The Content Server is a part of the Catalyst node in charge of managing the Decentralized storage of Entitiy Deployments. Currently, all content stored in a Content Server is synchronized with the rest of the DAO Catalysts.
Lambdas #
The Lambdas Service is a part of the Catalyst node that works as a reconciliation layer between the Content Servers and the Blockchain, sanitizing content, validating ownership and helping retrieve information for the Catalyst clients.
Synchronization #
Content Servers offer the ability to deploy content on them. They also ensure that any content deployed on the other Catalysts from the DAO is available there too. Resolving this is called synchronization.
Content SNAPSHOT #
A set of all the Active Entities of a specific type in a content server . This content snapshots are used to synchronize content between Catalyst nodes.
Realm #
When connected to Decentraland, you would only be able to interact with Peers connected to the same Realm. As friendly-names Realms make use of Greek Gods names such as Hela or Loki. Each realm is determined by a single Catalyst Node .
Peer #
A user connected to Decentraland.
Lighthouse #
The Lighthouse is the name used to reference the previous version of the Communications Service hosted on the Catalyst nodes and used for grouping users in a P2P network. Main responsibilities were to determine which are the candidates for a P2P connection and do the WebRTC signaling to establish the connection. Most of this logic was done through two external components: the PeerJS Server (connects WebRTC peers) and Archipelago (receives users positions and groups them in islands).
Backend for Frontend (aka BFF) #
The BFF Service was created to resolve client needs and to enable faster development of new features without breaking the existing APIs. In the context of the Catalyst Communication Service, it will be in charge of managing the P2P signaling and thus replacing the Lighthouse.
Catalyst Owner #
A Catalyst Owner is an individual or organization running a Catalyst node. To add a Catalyst node to the DAO network a proposal needs to be submitted and the DAO nodes represent the trusted Decentraland Network.
Archipelago Service #
The Archipelago Service previously was a library used by the Lighthouse. This service will have the same responsibility that the library did: group peers into clusters so they can communicate efficiently between them. Each cluster is called an island. On the other hand, the service also needs to be able to balance islands using the available communications transports and following a set of Catalyst Owner defined rules, in order to, for example, use LiveKit for an island in the Casino scene and P2P in a Genesis Plaza.
Island #
Cluster of connected peers.
Communication Transport #
Transport is the technology used to share updates between Peers connected to an Island.
P2P Transport #
Uses WebRTC connections between Peers, no extra infrastructure needed to scale as the load is on the client side and the Servers only manage the signaling. Latency increases as more Peers are added to an Island. There is a limit on the amount of WebRTC connections a client can have thus in order to have bigger islands, more indirect connections (jumps) between peers are needed.
LiveKit Transport #
LiveKit is an open source project that provides scalable, multi-user conferencing over WebRTC. Instead of doing a P2P network, Peers are connected to a Selective Forwarding Unit (SFU) in charge of managing message relay and different quality aspects of the communication. The SFUs are the added infrastructure needed in order to provide high-performance / high-quality communications between crowds on designated scenes.
WebSocket Transport #
The WebSocket Transport is lighter than LiveKit, it also requires a Server that manages the relay of messages through WebSocket rooms. Rooms are equivalent to islands. This transport provides less latency and better performance than P2P islands but also requires the extra infrastructure.
NATS #
NATS is a message broker that enables the data exchange and communication between services. In the context of the Catalyst Server it is used to communicate some of the internal services.
DAO #
DAO stands for “Decentralized Autonomous Organization”. The Decentraland DAO owns the most important smart contracts and assets that make up Decentraland – the LAND Contract, the Estates Contract, Wearables, Content Servers and the Marketplace. It also owns a substantial purse of MANA which allows it to be truly autonomous as well as subsidize various operations and initiatives throughout Decentraland.