DAS RPC method reference

This document covers the JSON-RPC methods exposed by Arbitrum Data Availability Servers (DAS) and the newer DAProvider interface, as defined in the Arbitrum Chain SDK node configuration types NodeConfig.generated.ts

Overview

DAS servers exposed two interfaces for data storage and retrieval:

Interface	Port (typical)	Used by	Purpose
RPC	`:9876`	Batch Poster	Store batch data, obtain DACerts
REST	`:9877`	Nitro nodes	Retrieve batch data by hash

The RPC interface supports two storage modes:

Single-shot store: entire payload sent in one call (legacy, used when enable-chunked-store: false).
Chunked (streaming) store: payload sent in chunks across multiple calls (default, enable by enable-chunked-store: true).

DAS RPC methods (Legacy DAS interface)

These methods are usd by the RPC aggregator (node.data-availability.rpc-aggregator.das-rpc-client) when communicating with standalone DAS servers.

`das_startChunkedStore`

Initiates a chunked data stream for storing a large batch payload on the DAS server.

Field	Value
Default method name	`das_startChunkedStore`
Config path	`node.data-availability.rpc-aggregator.das-rpc-client.data-stream.rpc-methods.start-stream`
Config key	`start-stream`
Direction	Client (batch poster) -> DAS server

Behavior:

Called once at the beginning of a chunked store operation
Returns a stream/session identifier used by subsequent das_sendChunk calls
The server allocations resources to receive the incoming data stream

When invoked:

The batch poster calls this method on each DAS backend in the RPC aggregator's backend list
Only used when enable-chunked-store is true (default)

`das_sendChunk`

Sends a single chunk of batch data within an active chunked store session.

Field	Value
Default method name	`das_sendChunk`
Config path	`node.data-availability.rpc-aggregator.das-rpc-client.data-stream.rpc-methods.stream-chunk`
Config key	`stream-chunk`
Direction	Client (batch poster) -> DAS server

Behavior:

Called one or more times after das_startChunkedStore to transmit the payload in pieces
Each chunk must fit within max-store-chunk-body-size (default: 5,242,880 bytes / 5 MB)
Chunks are sent sequentially within a stream session

Related config:

'data-stream': {
	'max-store-chunk-body-size': 5242880, // 5 MB per chunk
}

`das_commitChunkedStore`

Finalizes a chunked store session, signaling that all chunks have been transmitted.

Field	Value
Default method name	`das_commitChunkedStore`
Config path	`node.data-availability.rpc-aggregator.das-rpc-client.data-stream.rpc-methods.finalize-stream`
Config key	`finalize-stream`
Direction	Client (batch poster) -> DAS server

Behavior:

Called once after all chunks have been sent via das_sendChunk
The DAS server assembles the chunks, stores the complete payload, and returns a signed DACert component (the server's BLS Signature over the data hash)
On success, the server commits the data to its configured storage backend

DAProvider RPC Methods (newer interface)

These methods are used by the DA provider client (node.da-provider)—the newer generalized data availability interface that can work with DAS or other DA backends.

`daprovider_startChunkedStore`

Initiates a chunked data stream on the DA provider server.

Field	Value
Default method name	`daprovider_startChunkedStore`
Config path	`node.da-provider.data-stream.rpc-methods.start-stream`
Config key	`start-stream`

Functionally equivalent to das_startChunkedStore but routed through the DAProvider abstraction.

`daprovider_sendChunk`

Sends a chunk of data to the DA provider server.

Field	Value
Default method name	`daprovider_sendChunk`
Config path	`node.da-provider.data-stream.rpc-methods.stream-chunk`
Config key	`stream-chunk`

Functionally equivalent to das_sendChunk. Max chunk body size is goverend by node.da-provider.data-stream.max-store-chunk-body-size (default: 5,242,880 bytes / 5 MB).

`daprovider_commitChunkedStore`

Finalizes a chunked store session on the DA provider server.

Field	Value
Default method name	`daprovider_commitChunkedStore`
Config path	`node.da-provider.data-stream.rpc-methods.finalize-stream`
Config key	`finalize-stream`

Functionally equivalent to das_commitChunkedStore.

`daprovider_store`

Single-shot store method—sends the entire payload in one RPC call. Used when data streaming is disabled. (use-data-streaming: false).

Field	Value
Default method name	`daprovider_store`
Config path	`node.da-provider.store-rpc-method`
Config key	`store-rpc-method`

Behavior:

Sends the complete batch data in a single request
Simpler than a chunked store but limted by HTTP body size constraints
Enabled by default. Set use-data-streaming: true to switch to the chunked protocol.

REST retrieval interface

DAS nodes also expose a REST interface for reading stored data. This is not a JSON-RPC interface—it used HTTP GET requests.

`GetByHash`

Retrieves batch data by its hash from REST DAS endpoints.

Field	Value
Protocol	HTTP REST (GET)
Port (typical)	`:9877`
Used by	Nitro nodes (via `rest-aggregator`)

Configuration:

'rest-aggregator': {
  'enable': true,
  'urls': ['http://das-server:9877'],
  'strategy': 'simple-explore-exploit',     // endpoint selection strategy
  'wait-before-try-next': '2s',             // timeout before trying next endpoint
  'max-per-endpoint-stats': 20,             // latency/success stats window
  'simple-explore-exploit-strategy': {
    'exploit-iterations': 1000,   // calls using best-performing endpoint
    'explore-iterations': 20,     // calls trying random endpoints
  },
}

Endpoint selection strategy: The simple-explore-exploit strategy alternates between:

Exploit mode (default 1000 iterations): Selects endpoints based on best latency and success rate.
Explore mode (default 20 iterations): Randomly selects endpoints to discover better options.

Configuration quick reference

DAS RPC client (Legacy—`das-rpc-client`)

Full config path: node.data-availability.rpc-aggregator.das-rpc-client

'das-rpc-client': {
  'enable-chunked-store': true,       // default: true
  'server-url': 'http://...',         // DAS server URL
  'data-stream': {
    'max-store-chunk-body-size': 5242880,  // 5 MB
    'rpc-methods': {
      'start-stream':    'das_startChunkedStore',       // customizable
      'stream-chunk':    'das_sendChunk',               // customizable
      'finalize-stream': 'das_commitChunkedStore',      // customizable
    },
  },
}

DAProvider client (newer—`da-provider`)

Full config path: node.da-provider

'da-provider': {
  'enable': true,
  'store-rpc-method': 'daprovider_store',   // single-shot store
  'use-data-streaming': true,                // use chunked protocol
  'with-writer': true,                       // server supports writes
  'data-stream': {
    'max-store-chunk-body-size': 5242880,    // 5 MB
    'rpc-methods': {
      'start-stream':    'daprovider_startChunkedStore',
      'stream-chunk':    'daprovider_sendChunk',
      'finalize-stream': 'daprovider_commitChunkedStore',
    },
  },
  'rpc': {
    'url': 'http://...',
    'retries': 3,
    'retry-delay': '...',
    'timeout': '...',
    'connection-wait': '...',
    'jwtsecret': '...',                      // JWT auth (optional)
    'arg-log-limit': 2048,
    'websocket-message-size-limit': 268435456,
  },
}

RPC aggregator backend entry

Full config path: node.data-availability.rpc-aggregator.backends (JSON string)

// Type: NodeConfigDataAvailabilityRpcAggregatorBackendsJson
// Source: src/types/NodeConfig.ts:23-29
[
  {
    url: 'http://das-member-0:9876', // DAS RPC endpoint
    pubkey: '<base64 BLS public key>', // member's BLS key
  },
  // Additional members go here. Each backend's signer bit is auto-derived from
  // its index in this array (index i -> mask 1 << i) and must line up with
  // the member's position in the onchain keyset.
];

Method Summary Table

Method	Interface	Default Name	Purpose	Config Key
Start chunked store	DAS	`das_startChunkedStore`	Begin streaming session	`start-stream`
Send chunk	DAS	`das_sendChunk`	Transmit data chunk	`stream-chunk`
Commit chunked store	DAS	`das_commitChunkedStore`	Finalize and store	`finalize-stream`
Start chunked store	DAProvider	`daprovider_startChunkedStore`	Begin streaming session	`start-stream`
Send chunk	DAProvider	`daprovider_sendChunk`	Transmit data chunk	`stream-chunk`
Commit chunked store	DAProvider	`daprovider_commitChunkedStore`	Finalize and store	`finalize-stream`
Single-shot store	DAProvider	`daprovider_store`	Store entire payload at once	`store-rpc-method`
Get by hash	REST	N/A (HTTP GET)	Retrieve data by hash	N/A

Config Key	Default	Description
`data-availability.enable`	`false`	Enable AnyTrust DA mode
`data-availability.request-timeout`	`5s`	Store request timeout
`data-availability.panic-on-error`	`false`	Crash on DAS errors (not recommended)
`data-availability.sequencer-inbox-address`	—	SequencerInbox contract address
`data-availability.parent-chain-node-url`	—	Parent chain RPC URL
`batch-poster.das-retention-period`	`360h`	How long DAS retains stored batches
`rpc-aggregator.assumed-honest`	—	H value for quorum (K=N+1-H)
`das-rpc-client.enable-chunked-store`	`true`	Use streaming protocol
`rest-aggregator.strategy`	`simple-explore-exploit`	Endpoint selection strategy
`rest-aggregator.wait-before-try-next`	`2s`	Timeout before next endpoint
`sync-to-storage.retention-period`	`360h`	Synced data retention period

Overview​

DAS RPC methods (Legacy DAS interface)​

das_startChunkedStore​

das_sendChunk​

das_commitChunkedStore​

DAProvider RPC Methods (newer interface)​

daprovider_startChunkedStore​

daprovider_sendChunk​

daprovider_commitChunkedStore​

daprovider_store​

REST retrieval interface​

GetByHash​

Configuration quick reference​

DAS RPC client (Legacy—das-rpc-client)​

DAProvider client (newer—da-provider)​

RPC aggregator backend entry​

Method Summary Table​

Related Configuration​

Overview

DAS RPC methods (Legacy DAS interface)

`das_startChunkedStore`

`das_sendChunk`

`das_commitChunkedStore`

DAProvider RPC Methods (newer interface)

`daprovider_startChunkedStore`

`daprovider_sendChunk`

`daprovider_commitChunkedStore`

`daprovider_store`

REST retrieval interface

`GetByHash`

Configuration quick reference

DAS RPC client (Legacy—`das-rpc-client`)

DAProvider client (newer—`da-provider`)

RPC aggregator backend entry

Method Summary Table

Related Configuration