access

README

Access Package

The access package implements network communication with the access nodes APIs. It also defines an access.Client interface exposing all the common API interactions.

Design

Each implementation (currently grpc and http) include the following parts:

• Base Client is the client that implements the client interface exposing all generic functionality.
• Client is the network specific client that exposes any additional options possible by the specific API implementation.
• Handler takes care of actual network communication implementing the communication protocol.

Usage

If you want to use the base client you should save the instance to the client interface, which would allow you to easily switch between network implementations like so:

General Usage

// common client interface
var flowClient access.Client

// initialize an http emulator client
flowClient, err := http.NewClient(http.EmulatorHost)

// initialize a gPRC emulator client
flowClient, err = grpc.NewClient(grpc.EmulatorHost)

Transport-Specific Features

Rather than using a generic version of the HTTP or gRPC client, you instantiate a base HTTP or gRPC client to use specific features of either API format.

For example, use grpc.NewBaseClient to set custom gRPC transport credentials. instantiate the client like so:

// initialize http specific client
httpClient, err := http.NewBaseClient(http.EMULATOR_URL)

// initialize grpc specific client
grpcClient, err := grpc.NewBaseClient(
    grpc.EMULATOR_URL,
    grpcOpts.WithTransportCredentials(insecure.NewCredentials()),
)

Read more about this in the docs.

Development

Testing

The testing suite is using mock network handlers which can be generated by running the following command in the project root directory:

make generate

Documentation

Overview

Package access contains an interface defining functions for the API clients.

The Access API provides a set of methods that can be used to submit transactions and read state from Flow. Clients are compatible with the Access API implemented by the Access Node role, as well as the mock Access API exposed by the Flow Emulator.

Index

• type Client

Types

type Client

type Client interface {
	// Ping is used to check if the access node is alive and healthy.
	Ping(ctx context.Context) error

	// GetLatestBlockHeader gets the latest sealed or unsealed block header.
	GetLatestBlockHeader(ctx context.Context, isSealed bool) (*flow.BlockHeader, error)

	// GetBlockHeaderByID gets a block header by ID.
	GetBlockHeaderByID(ctx context.Context, blockID flow.Identifier) (*flow.BlockHeader, error)

	// GetBlockHeaderByHeight gets a block header by height.
	GetBlockHeaderByHeight(ctx context.Context, height uint64) (*flow.BlockHeader, error)

	// GetLatestBlock gets the full payload of the latest sealed or unsealed block.
	GetLatestBlock(ctx context.Context, isSealed bool) (*flow.Block, error)

	// GetBlockByID gets a full block by ID.
	GetBlockByID(ctx context.Context, blockID flow.Identifier) (*flow.Block, error)

	// GetBlockByHeight gets a full block by height.
	GetBlockByHeight(ctx context.Context, height uint64) (*flow.Block, error)

	// GetCollection gets a collection by ID.
	GetCollection(ctx context.Context, colID flow.Identifier) (*flow.Collection, error)

	// SendTransaction submits a transaction to the network.
	SendTransaction(ctx context.Context, tx flow.Transaction) error

	// GetTransaction gets a transaction by ID.
	GetTransaction(ctx context.Context, txID flow.Identifier) (*flow.Transaction, error)

	// GetTransactionResult gets the result of a transaction.
	GetTransactionResult(ctx context.Context, txID flow.Identifier) (*flow.TransactionResult, error)

	// GetAccount is an alias for GetAccountAtLatestBlock.
	GetAccount(ctx context.Context, address flow.Address) (*flow.Account, error)

	// GetAccountAtLatestBlock gets an account by address at the latest sealed block.
	GetAccountAtLatestBlock(ctx context.Context, address flow.Address) (*flow.Account, error)

	// GetAccountAtBlockHeight gets an account by address at the given block height
	GetAccountAtBlockHeight(ctx context.Context, address flow.Address, blockHeight uint64) (*flow.Account, error)

	// ExecuteScriptAtLatestBlock executes a read-only Cadence script against the latest sealed execution state.
	ExecuteScriptAtLatestBlock(ctx context.Context, script []byte, arguments []cadence.Value) (cadence.Value, error)

	// ExecuteScriptAtBlockID executes a ready-only Cadence script against the execution state at the block with the given ID.
	ExecuteScriptAtBlockID(ctx context.Context, blockID flow.Identifier, script []byte, arguments []cadence.Value) (cadence.Value, error)

	// ExecuteScriptAtBlockHeight executes a ready-only Cadence script against the execution state at the given block height.
	ExecuteScriptAtBlockHeight(ctx context.Context, height uint64, script []byte, arguments []cadence.Value) (cadence.Value, error)

	// GetEventsForHeightRange retrieves events for all sealed blocks between the start and end block heights (inclusive) with the given type.
	GetEventsForHeightRange(ctx context.Context, eventType string, startHeight uint64, endHeight uint64) ([]flow.BlockEvents, error)

	// GetEventsForBlockIDs retrieves events with the given type from the specified block IDs.
	GetEventsForBlockIDs(ctx context.Context, eventType string, blockIDs []flow.Identifier) ([]flow.BlockEvents, error)

	// GetLatestProtocolStateSnapshot retrieves the latest snapshot of the protocol
	// state in serialized form. This is used to generate a root snapshot file
	// used by Flow nodes to bootstrap their local protocol state database.
	GetLatestProtocolStateSnapshot(ctx context.Context) ([]byte, error)

	// GetExecutionResultForBlockID gets the execution results at the block ID.
	GetExecutionResultForBlockID(ctx context.Context, blockID flow.Identifier) (*flow.ExecutionResult, error)

	// Close stops the client connection to the access node.
	Close() error
}