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welshman/docs/dvm/request.md
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2025-02-25 14:07:44 -08:00

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# DVM Request
The DVM Request module provides utilities for making requests to Data Vending Machines (DVMs) and handling their responses.
It includes support for progress tracking and result handling.
## Core Types
### DVMRequestOptions
```typescript
type DVMRequestOptions = {
event: SignedEvent // The event to send to the DVM
relays: string[] // Relays to use
timeout?: number // Request timeout in milliseconds
autoClose?: boolean // Auto-close subscription after result
reportProgress?: boolean // Listen for progress events
}
```
### DVMEvent Enum
```typescript
enum DVMEvent {
Progress = "progress", // DVM progress updates (kind 7000)
Result = "result" // Final DVM result
}
```
## Making DVM Requests
### Basic Usage
```typescript
import { makeDvmRequest, DVMEvent } from '@welshman/dvm'
const request = makeDvmRequest({
event: signedEvent,
relays: ["wss://relay.example.com"],
timeout: 30000, // 30 seconds
})
// Handle results
request.emitter.on(DVMEvent.Result, (url, event) => {
console.log('Received result:', event)
})
// Handle progress updates
request.emitter.on(DVMEvent.Progress, (url, event) => {
console.log('Progress update:', event)
})
```
## Response Handling
### Result Events
```typescript
request.emitter.on(DVMEvent.Result, (url: string, event: TrustedEvent) => {
// Handle the DVM result
const result = JSON.parse(event.content)
// Process tags
const requestTag = event.tags.find(t => t[0] === 'request')
const expirationTag = event.tags.find(t => t[0] === 'expiration')
})
```
### Progress Updates
```typescript
request.emitter.on(DVMEvent.Progress, (url: string, event: TrustedEvent) => {
// Handle progress update (kind 7000)
const progress = JSON.parse(event.content)
console.log(`Progress: ${progress.percentage}%`)
})
```
## Complete Example
```typescript
import { makeDvmRequest, DVMEvent } from '@welshman/dvm'
import { createEvent, finalizeEvent } from '@welshman/util'
async function queryDVM() {
// Create the request event
const event = createEvent(5001, {
content: JSON.stringify({
query: "search terms"
})
})
// Sign the event
const signedEvent = finalizeEvent(event, privateKey)
// Make the request
const dvmRequest = makeDvmRequest({
event: signedEvent,
relays: ["wss://relay.example.com"],
timeout: 30000,
reportProgress: true
})
// Handle progress updates
dvmRequest.emitter.on(DVMEvent.Progress, (url, event) => {
console.log('Progress:', event.content)
})
// Return a promise that resolves with the result
return new Promise((resolve, reject) => {
const timeout = setTimeout(() => {
dvmRequest.sub.close()
reject(new Error('DVM request timeout'))
}, 30000)
dvmRequest.emitter.on(DVMEvent.Result, (url, event) => {
clearTimeout(timeout)
resolve(event)
})
})
}
```
This module simplifies the process of making requests to DVMs while providing flexibility in handling responses and progress updates.