Summary: Dolos – A Lightweight Cardano Data Node in Rust
In the 63rd edition of the Developers Office Hour, host Disa speaks with Santiago Carmuega, CEO and founder of TxPipe, about their open-source project Dolos. Dolos is a lightweight Cardano data node alternative built entirely in Rust, designed to dramatically improve the developer experience.
The Problem: Resource-Heavy Infrastructure
For newcomers to the Cardano ecosystem, extracting data from a node can be highly cumbersome, as it traditionally requires implementing custom binary protocols. While solutions like DB Sync provide a comprehensive SQL database of on-chain activity, they are highly resource-intensive and can be considered overkill for applications that only require specific API lookups. Most DApp developers simply need a fast data access layer and do not need their nodes to participate in block production or heavy consensus validation.
The Solution: The Data Node Concept
Dolos serves as a complementary data node. It is specifically optimized to provide a rich, flexible query layer for developers without the overhead of a full-blown block-producing node. To achieve this low-resource footprint, Dolos does not validate full consensus; instead, it connects to a trusted upstream relay node to pull its data.
Flexible APIs and Seamless Interoperability
A major value proposition of Dolos is its ability to mimic existing popular interfaces. It exposes a gRPC client using the UTxO RPC specification for high-performance, low-latency streaming. Additionally, it offers a Kupo-compatible API and a Blockfrost-compatible API. The Blockfrost endpoint passes roughly 900 of their official conformance tests, meaning developers can seamlessly point their existing DApp transaction builders or wallets to Dolos without rewriting their code.
Sliding Window Storage
To further reduce resource requirements, Dolos introduces a “sliding window” feature. Developers can choose to store the entire history of the blockchain, or they can configure Dolos to only retain data from a specific recent time period. This drastically reduces the disk space needed to run the node while still providing immediate transaction updates.
Bootstrapping and Performance
When starting a new Dolos node, developers have three options: syncing from scratch via a relay node, importing a verified Mithril snapshot (which requires some time to migrate data formats), or downloading a trusted snapshot directly from TxPipe for near-instant initialization. Thanks to its Rust architecture, LSM trees, and Bloom filters, Dolos is incredibly fast, achieving a median response latency of around four to five milliseconds for typical requests.
Top Five Q&A (FAQ) about Dolos
Question 1: What is Dolos, and why was it created?
Answer: Dolos is a lightweight Cardano data node written in Rust by the TxPipe team. It was created to provide DApp developers with a fast, low-resource query layer to easily extract data from the blockchain without having to manage heavy infrastructure.
Question 2: How does Dolos differ from running a traditional Cardano node or DB Sync?
Answer: Unlike traditional nodes, Dolos does not participate in heavy consensus validation or block production, and unlike DB Sync, it does not rely on a massive SQL database. Instead, it connects to a trusted relay node to fetch data, making it highly resource-efficient.
Question 3: What APIs does Dolos support for developers?
Answer: Dolos acts as a drop-in replacement for several existing services. It supports a high-performance gRPC client, standard Ouroboros node-to-client protocols, and exposes APIs that are strictly compatible with both Kupo and Blockfrost.
Question 4: What is the “sliding window” feature in Dolos?
Answer: The sliding window allows node operators to configure Dolos to only store data from a recent, specific time period. This saves a massive amount of disk space for applications that only care about recent transaction states and do not need to query historical data going back to the Byron era.
Question 5: How can a developer bootstrap a new Dolos node quickly?
Answer: Developers can bootstrap Dolos in three ways: syncing from scratch, using a secure Mithril snapshot (which requires migrating the Haskell-specific data into the Dolos format), or downloading a trusted snapshot directly from TxPipe to bypass migration and start running almost immediately.
Dolos: A Lightweight Cardano Node
Intro to TxPipe & the context behind Dolos
Friday, 29 May
14:00 UTC