New Chain Integration

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Chains can bring subgraph support to their ecosystem by starting a new graph-node integration. Subgraphs are a powerful indexing tool opening a world of possibilities for developers. Graph Node already indexes data from the chains listed here. If you are interested in a new integration, there are 2 integration strategies:

1. EVM JSON-RPC
2. Firehose: All Firehose integration solutions include Substreams, a large-scale streaming engine based off Firehose with native graph-node support, allowing for parallelized transforms.

If the blockchain is EVM equivalent and the client/node exposes the standard EVM JSON-RPC API, Graph Node should be able to index the new chain.

For Graph Node to be able to ingest data from an EVM chain, the RPC node must expose the following EVM JSON-RPC methods:

• eth_getLogs
• eth_call (for historical blocks, with EIP-1898 - requires archive node)
• eth_getBlockByNumber
• eth_getBlockByHash
• net_version
• eth_getTransactionReceipt, 在JSON-RPC批量请求中
• trace_filter (optionally required for Graph Node to support call handlers)

Firehose is a next-generation extraction layer. It collects history in flat files and streams in real time. Firehose technology replaces those polling API calls with a stream of data utilizing a push model that sends data to the indexing node faster. This helps increase the speed of syncing and indexing.

The primary method to integrate the Firehose into chains is to use an RPC polling strategy. Our polling algorithm will predict when a new block will arrive and increase the rate at which it checks for a new block near that time, making it a very low-latency and efficient solution. For help with the integration and maintenance of the Firehose, contact the StreamingFast team. New chains and their integrators will appreciate the fork awareness and massive parallelized indexing capabilities that Firehose and Substreams bring to their ecosystem.

For EVM chains, there exists a deeper level of data that can be achieved through the geth live-tracer, a collaboration between Go-Ethereum and StreamingFast, in building a high-throughput and rich transaction tracing system. The Live Tracer is the most comprehensive solution, resulting in Extended block details. This enables new indexing paradigms, like pattern matching of events based on state changes, calls, parent call trees, or triggering of events based on changes to the actual variables in a smart contract.

While the JSON-RPC and Firehose are both suitable for subgraphs, a Firehose is always required for developers wanting to build with Substreams. Supporting Substreams allows developers to build Substreams-powered subgraphs for the new chain, and has the potential to improve the performance of your subgraphs. Additionally, Firehose — as a drop-in replacement for the JSON-RPC extraction layer of graph-node — reduces by 90% the number of RPC calls required for general indexing.

• All those getLogs calls and roundtrips get replaced by a single stream arriving into the heart of graph-node; a single block model for all subgraphs it processes.

Configuring Graph Node is as easy as preparing your local environment. Once your local environment is set, you can test the integration by locally deploying a subgraph.

1. Clone Graph Node

2. Modify this line to include the new network name and the EVM JSON-RPC compliant URL

   Do not change the env var name itself. It must remain ethereum even if the network name is different.

3. Run an IPFS node or use the one used by The Graph: https://api.thegraph.com/ipfs/

1. Install graph-cli
2. 创建一个简单的示例子图。以下是一些选项：
   1. The pre-packed Gravitar smart contract and subgraph is a good starting point
   2. Bootstrap a local subgraph from any existing smart contract or solidity dev environment using Hardhat with a Graph plugin
3. Adapt the resulting subgraph.yaml by changing dataSources.network to the same name previously passed on to Graph Node.
4. Create your subgraph in Graph Node: graph create $SUBGRAPH_NAME --node $GRAPH_NODE_ENDPOINT
5. Publish your subgraph to Graph Node: graph deploy $SUBGRAPH_NAME --ipfs $IPFS_ENDPOINT --node $GRAPH_NODE_ENDPOINT

如果没有错误，Graph Node应该正在同步部署的子图。给它一些时间来同步，然后向API端点发送一些GraphQL查询。

For StreamingFast-led Firehose/Substreams integrations, basic support for foundational Substreams modules (e.g. decoded transactions, logs and smart-contract events) and Substreams codegen tools are included. These tools enable the ability to enable Substreams-powered subgraphs. Follow the How-To Guide and run substreams codegen subgraph to experience the codegen tools for yourself.