Get Random - WASI Example

Full documentation on the OutLayer dashboard.

Simple WASM binary for testing NEAR OutLayer platform with WASI support.

Description

Generates a random number in the specified range using rand crate with WASI random source. Reads input from stdin and writes output to stdout.

Input Format

{
  "min": 0,
  "max": 100
}

Output Format

{
  "random_number": 42
}

Building

# Add WASI target
rustup target add wasm32-wasip1

# Build
cargo build --release --target wasm32-wasip1

# Output: target/wasm32-wasip1/release/random-example.wasm (~111KB)

Local Testing

# Test with wasmtime
echo '{"min":1,"max":100}' | wasmtime target/wasm32-wasip1/release/random-example.wasm

# Expected output: {"random_number":42}  (some number between 1-100)

Usage with NEAR OutLayer

1. Publish the build and deploy it as a project:

outlayer upload target/wasm32-wasip1/release/random-example.wasm
# prints SHA256 and: FastFS URL: https://test.fastfs.io/<you>/outlayer.testnet/<sha256>.wasm
outlayer deploy random-example <FastFS URL>

2. Call request_execution on the OutLayer contract. A direct run names the published file and its sha256 — here the pinned testnet build that random-contract/ uses:

near call outlayer.testnet request_execution '{
  "source": {
    "WasmUrl": {
      "url": "https://wasmhub.testnet.fastfs.io/fastfs.testnet/0bb0668611f0fa9abeabbfaabf48436a46c94aa65ae1a0d106db7212f2d5f88a.wasm",
      "hash": "0bb0668611f0fa9abeabbfaabf48436a46c94aa65ae1a0d106db7212f2d5f88a",
      "build_target": "wasm32-wasip1"
    }
  },
  "resource_limits": {
    "max_instructions": 10000000,
    "max_memory_mb": 128,
    "max_execution_seconds": 60
  },
  "input_data": "{\"min\":1,\"max\":100}",
  "response_format": "Json"
}' --accountId your-account.testnet --deposit 0.1

Your own project runs with "source": {"Project": {"project_id": "your-account.testnet/random-example", "version_key": null}}.

3. Worker will:
   • Fetch the WASM and check it against the sha256
   • Execute with wasmi (WASI P1) or wasmtime (WASI P2)
   • Return the random number as readable text (not bytes!)
   • Show result in NEAR explorer

Source: https://github.com/out-layer/random-example

Unit Tests

cargo test