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Viewkit

Viewkit is a CLI tool for creating, testing, and deploying views. It does not process or serve data (hosts do that). It packages a view into a binary bundle on your machine and submits a transaction to ShinzoHub.

What viewkit does and does not do

What it does:

• Define GraphQL SDL schemas for view output.
• Configure WASM lens transforms for data mapping.
• Pre-validate transforms locally using Wasmer runtime.
• Package everything into a ViewBundle (VWL binary format).
• Deploy to ShinzoHub.

What it does not do:

• Process data (hosts do this).
• Store data (DefraDB does this).
• Serve queries (hosts do this).
• Run as a daemon (it is a CLI tool).

View definition

A view has three pieces:

1. A query that picks which primitive data to select (e.g., "all Logs from the USDC contract").
2. An SDL, the GraphQL schema defining the output shape.
3. A lens (optional), a WASM module that transforms the data.

The @materialized directive

In the SDL, @materialized(if: true) tells DefraDB to pre-compute and store the view data. @materialized(if: false) computes it on query.

@materialized(if: true) is recommended for now. Queries are faster because data is already materialized when the query arrives. The tradeoff is more storage on the Host client.

Important: the limit parameter should be on the source query (e.g., Log(limit: 100)), not on the materialized view collection.

Command reference

Filter operators

When querying a deployed view's output collection, DefraDB supports these filter operators:

What happens during deploy

When you run viewkit view deploy, the following happens inside core/service/deploy.go:

1. Tests the view locally (builds a temporary DefraDB instance, applies the lens, validates output).
2. Derives an ECDSA private key from the wallet.
3. For each lens: reads the WASM file and base64-encodes it.
4. Calls viewbundle.NewBundler().BundleView(view) to produce compressed VWL wire bytes.
5. Computes viewID: keccak256(sender.Bytes(), wireBytes).
6. ABI-encodes the transaction: method selector keccak256("register(bytes)")[:4] + ABI-encoded bytes.
7. Sends EVM transaction to 0x0000000000000000000000000000000000000210 (View Registry precompile).
8. Polls for receipt and checks status.

VWL wire format

VWL (View Wire Language) is the binary format for view bundles.

Byte layout

The bundle is a single byte stream written in the order below. Each section is appended directly after the previous one.

WASM binaries can be 70-200+ KB each. zstd compression is applied before the bundle goes on chain. The Host client decompresses when applying.

Two implementations of the wire format exist:

Key functions:

// Encode a view into wire bytes
wireBytes := viewbundle.BundleView(view)

// Decode just the header (without loading the full WASM body)
header := viewbundle.DecodeHeader(encodedBytes)

// Re-encode a modified header
reEncoded := viewbundle.EncodeHeader(decodedValue)

There is a known issue with v0.6.2 of the Host client: it uses viewbundle.UnbundleView() with zstd decompression. Views registered before v0.6.2 may be stored in uncompressed format. If the Host client tries to decompress an uncompressed payload, it fails.

View ID computation

View IDs are deterministic. The same computation runs on the client (viewkit) and on chain (precompile):

viewID = typeName + "_" + keccak256(senderAddress, wireBytes)

Example:

TestView_0xae1bd91e83f5a71ed4c34e18470ea3c12b9ba3d4a69cfd98717e23cf27f4eccb

Because the same computation runs in both places, the client can predict the view ID before the transaction confirms.

Lens authoring

Lenses are WASM binaries, typically written in Rust or AssemblyScript, that transform raw primitive data into structured output.

A simplified Rust example:

fn transform(log: Log) -> Option<USDCTransfer> {
    if log.address != USDC_ADDRESS { return None; }
    if log.topics[0] != TRANSFER_SIG { return None; }
    Some(USDCTransfer {
        from: decode_address(log.topics[1]),
        to: decode_address(log.topics[2]),
        amount: decode_uint256(log.data),
    })
}

Lenses must be deterministic. Any Host client running the same lens on the same data should produce identical results.

LensVM supports bidirectional transforms (the inverse() function in the WASM module), though most views use one-way transforms.

Binary size by language

Smaller binaries mean less P2P overhead.

Available lenses

Stored in the wasm-bucket repository. Currently available on main:

See the Lenses guide for details on each lens, output fields, and usage examples.

Writing new lenses

• Rust SDK: source-gh/lens/sdk-rust/.
• AssemblyScript example: source-gh/lens/tests/modules/as_wasm32_simple/.
• WASM runtime paths: source-gh/lens/host-go/runtimes/wasmtime/, wasmer/, wazero/.

AssemblyScript lenses follow the same interface as Rust lenses. The Host client runtime does not care what language produced the WASM.

The view lifecycle across repos

Five repos are involved in the lifecycle from creation to query:

Generator clients are not involved in the View lifecycle. By the time a View is created and applied, the Generator client has already delivered raw data to the Host clients over P2P.

Key files