37 lines
2.0 KiB
Markdown
37 lines
2.0 KiB
Markdown
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# Middlewares
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In ethers-rs, middleware is a way to customize the behavior of certain aspects of the library by
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injecting custom logic into the process of interacting with the Ethereum JSON-RPC API.
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Middlewares act in a chain of responsibility and can be combined to achieve the desired behavior.
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The library allows developers to create [custom middlewares](./custom.md), going beyond
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standard operations and unlocking powerful use cases.
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A JSON-RPC client instance can be constructed as a stack of middlewares, backed by a common instance of `Provider` of one specific type among `JsonRpcClient` and `PubSubClient`.
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```mermaid
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{{#include ../mermaid-style.txt}}
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flowchart TB
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subgraph ide1 [Client]
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middleware2--inner-->middleware1--inner-->middleware0--inner-->provider
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end
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subgraph ide2 [Transport]
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provider--PubSubClient-->ws
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provider--PubSubClient-->ipc
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provider--JsonRpcClient<br>PubSubClient-->http
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provider--JsonRpcClient<br>PubSubClient-->retry
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provider--JsonRpcClient<br>PubSubClient-->quorum
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provider--JsonRpcClient<br>PubSubClient-->rw
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end
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```
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The following middlewares are currently supported:
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- [Gas Escalator](./gas-escalator.md): Avoids transactions being stucked in the mempool, by bumping the gas price in background.
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- [Gas Oracle](./gas-oracle.md): Allows retrieving the current gas price from common RESTful APIs, instead of retrieving it from blocks.
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- [Nonce Manager](./nonce-manager.md): Manages nonces of transactions locally, without waiting for them to hit the mempool.
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- [Policy](./policy.md): Allows to define rules or policies that should be followed when submitting JSON-RPC API calls.
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- [Signer](./signer.md): Signs transactions locally, with a private key or a hardware wallet.
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- [Time lag](./time-lag.md): Poses a block delay on JSON-RPC interactions, allowing to shift the block number back of a predefined offset.
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- [Transformer](./transformer.md): Allows intercepting and
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transforming a transaction to be broadcasted via a proxy wallet.
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