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Different pool types (e.g. Weighted, Stable) have different interfaces for interacting with them, where the underlying logic can vary widely. This document outlines the common interfaces for interacting with BEX pools. In general, you will interface with the Vault contract to obtain information on pools. Specific nuances of interacting with different pool types are also detailed below.

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Using poolId

To interface with a pool, you will need its poolId, which is its unique identifier in BEX (32 bytes in length).

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Example:

  • A pool might have an id 0x5c6ee304399dbdb9c8ef030ab642b10820db8f56000200000000000000000014
  • The first 20-bytes of the poolId represent the pool’s address 0x5c6ee304399dbdb9c8ef030ab642b10820db8f56

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Obtaining poolId

You can get a poolId from:
  • The pool details page on Bera Hub: /pools/<poolId>/details/
  • The SDK
  • Calling getPoolId() on the pool contract itself if you already have it

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Common pool interfaces

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Pool balances (Vault)

The Vault can be queried for a particular pool’s token balances using getPoolTokens. For example, calling: 
vault.getPoolTokens(0x8353157092ed8be69a9df8f95af097bbf33cb2af0000000000000000000005d9)
returns something resembling: 
tokens:
[[0x40D16FC0246aD3160Ccc09B8D0D3A2cD28aE6C2f]
[0x8353157092ED8Be69a9DF8F95af097bbF33Cb2aF]
[0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48]
[0xdAC17F958D2ee523a2206206994597C13D831ec7]]

balances: [794569830111428445878272,2596148429278955607828401901927006,4333829907765,4422662782925]

lastChangeBlock:  20728927

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Swap fee

Swap fees are stored at the pool level, which can be obtained using: 
pool.getSwapFeePercentage()
This returns an 18 decimal value like: 
500000000000000 // corresponds to a 0.05% swap fee

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Emergency pause state

In the unlikely case that there is an issue with the pools, swaps and pool joins can be paused. Withdrawals are not paused, so you can always exit a pool. To check if a pool is paused, calling: 
pool.getPausedState()
returns something resembling: 
paused :  False
pauseWindowEndTime :  1627668973
bufferPeriodEndTime :  1630260973

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Rate providers

Returns the rate providers configured for each token (in the same order as registered). Zero-address entries means there’s no rate provider for that token. 
function getRateProviders() external view returns (address[]);

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Pool token supply

Because certain pool types (Stable Pools) pre-mint BPT to the Vault contract, the following function should be used to get the total supply of pool tokens: 
function getActualSupply() external view returns (uint256);

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Weighted pools

The following section documents functions specific to Weighted Pools.

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getNormalizedWeights

Returns all normalized weights, in the same order as the Pool’s tokens. 
function getNormalizedWeights() external view returns (uint256[] memory)

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Stable pools

The following section documents functions specific to Stable Pools.

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getRate

This function returns the appreciation of LP tokens relative to the underlying tokens. The rate is a monotonically increasing function as long as the tokens in the pool do not lose value. 
function getRate() external view virtual override returns (uint256)