Add Canton EA to read from Canton participant node

.changeset/fair-geese-beam.md

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+---
+'@chainlink/canton-functions-adapter': major
+---
+
+This EA enables us to read data from Canton participant nodes via the Ledger API

packages/sources/canton-functions/README.md

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+# Chainlink External Adapter for canton-functions
+
+This README will be generated automatically when code is merged to `main`. If you would like to generate a preview of the README, please run `yarn generate:readme canton-functions`.

packages/sources/canton-functions/package.json

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+{
+  "name": "@chainlink/canton-functions-adapter",
+  "version": "1.0.0",
+  "description": "Chainlink canton-functions adapter.",
+  "keywords": [
+    "Chainlink",
+    "LINK",
+    "blockchain",
+    "oracle",
+    "canton-functions"
+  ],
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "files": [
+    "dist"
+  ],
+  "repository": {
+    "url": "https://github.com/smartcontractkit/external-adapters-js",
+    "type": "git"
+  },
+  "license": "MIT",
+  "scripts": {
+    "clean": "rm -rf dist && rm -f tsconfig.tsbuildinfo",
+    "prepack": "yarn build",
+    "build": "tsc -b",
+    "server": "node -e 'require(\"./index.js\").server()'",
+    "server:dist": "node -e 'require(\"./dist/index.js\").server()'",
+    "start": "yarn server:dist"
+  },
+  "devDependencies": {
+    "@sinonjs/fake-timers": "9.1.2",
+    "@types/jest": "^29.5.14",
+    "@types/node": "22.14.1",
+    "@types/sinonjs__fake-timers": "8.1.5",
+    "nock": "13.5.6",
+    "typescript": "5.8.3"
+  },
+  "dependencies": {
+    "@chainlink/external-adapter-framework": "2.7.1",
+    "tslib": "2.4.1"
+  }
+}

packages/sources/canton-functions/src/config/index.ts

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+import { AdapterConfig } from '@chainlink/external-adapter-framework/config'
+
+export const config = new AdapterConfig({
+  AUTH_TOKEN: {
+    description: 'JWT token for Canton JSON API authentication',
+    type: 'string',
+    required: true,
+    sensitive: true,
+  },
+  BACKGROUND_EXECUTE_MS: {
+    description:
+      'The amount of time the background execute should sleep before performing the next request',
+    type: 'number',
+    default: 1_000,
+  },
+})

packages/sources/canton-functions/src/endpoint/canton-data.ts

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+import { AdapterEndpoint } from '@chainlink/external-adapter-framework/adapter'
+import { InputParameters } from '@chainlink/external-adapter-framework/validation'
+import { config } from '../config'
+import { cantonDataTransport } from '../transport/canton-data'
+
+export const inputParameters = new InputParameters(
+  {
+    url: {
+      description: 'The Canton JSON API URL',
+      type: 'string',
+      required: true,
+    },
+    templateId: {
+      description: 'The template ID to query contracts for (format: packageId:Module:Template)',
+      type: 'string',
+      required: true,
+    },
+    contractId: {
+      description: 'The contract ID to exercise choice on',
+      type: 'string',
+      required: false,
+    },
+    choice: {
+      description: 'The non-consuming choice to exercise on the contract',
+      type: 'string',
+      required: true,
+    },
+    argument: {
+      description: 'The argument for the choice (JSON string)',
+      type: 'string',
+      required: false,
+    },
+    contractFilter: {
+      description: 'Filter to query contracts when contractId is not provided (JSON string)',
+      type: 'string',
+      required: false,
+    },
+  },
+  [
+    {
+      url: 'http://localhost:7575',
+      templateId: 'example-package-id:Main:Asset',
+      contractId: '00e1f5c6d8b9a7f4e3c2d1a0b9c8d7e6f5a4b3c2d1e0f9a8b7c6d5e4f3a2b1c0',
+      choice: 'GetValue',
+    },
+  ],
+)
+
+export type BaseEndpointTypes = {
+  Parameters: typeof inputParameters.definition
+  Response: {
+    Data: {
+      result: string
+      exerciseResult: any
+      contract?: any
+    }
+    Result: string
+  }
+  Settings: typeof config.settings
+}
+
+export const endpoint = new AdapterEndpoint({
+  name: 'canton-data',
+  aliases: [],
+  transport: cantonDataTransport,
+  inputParameters,
+})

packages/sources/canton-functions/src/endpoint/index.ts

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+export { endpoint as cantonData } from './canton-data'

packages/sources/canton-functions/src/index.ts

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+import { expose, ServerInstance } from '@chainlink/external-adapter-framework'
+import { Adapter } from '@chainlink/external-adapter-framework/adapter'
+import { config } from './config'
+import { cantonData } from './endpoint'
+
+export const adapter = new Adapter({
+  defaultEndpoint: cantonData.name,
+  name: 'CANTON_FUNCTIONS',
+  config,
+  endpoints: [cantonData],
+})
+
+export const server = (): Promise<ServerInstance | undefined> => expose(adapter)

packages/sources/canton-functions/src/shared/canton-client.ts

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+import { Requester } from '@chainlink/external-adapter-framework/util/requester'
+
+export interface CantonClientConfig {
+  AUTH_TOKEN: string
+}
+
+export interface QueryContractByTemplateRequest {
+  templateIds: string[]
+  filter?: string | Record<string, any>
+}
+
+export interface ExerciseChoiceRequest {
+  contractId: string
+  templateId: string
+  choice: string
+  argument: Record<string, any>
+}
+
+export interface Contract {
+  contractId: string
+  templateId: string
+  payload: Record<string, any>
+  signatories: string[]
+  observers: string[]
+  agreementText: string
+  createdAt?: string
+}
+
+export interface ExerciseResult {
+  exerciseResult: any
+  events: any[]
+}
+
+export class CantonClient {
+  private requester: Requester
+  private config: CantonClientConfig
+  private static instance: CantonClient
+
+  constructor(requester: Requester, config: CantonClientConfig) {
+    this.requester = requester
+    this.config = config
+  }
+
+  static getInstance(requester: Requester, config: CantonClientConfig): CantonClient {
+    if (!this.instance) {
+      this.instance = new CantonClient(requester, config)
+    }
+
+    return this.instance
+  }
+
+  /**
+   * Query contracts by template ID with an optional filter
+   */
+  async queryContractsByTemplate(
+    url: string,
+    request: QueryContractByTemplateRequest,
+  ): Promise<Contract[]> {
+    const baseURL = `${url}/v1/query`
+
+    const requestData: any = {
+      templateIds: request.templateIds,
+    }
+
+    if (request.filter) {
+      requestData.query =
+        typeof request.filter === 'string' ? JSON.parse(request.filter) : request.filter
+    }
+
+    const requestConfig = {
+      method: 'POST',
+      baseURL,
+      headers: {
+        'Content-Type': 'application/json',
+        Authorization: `Bearer ${this.config.AUTH_TOKEN}`,
+      },
+      data: requestData,
+    }
+
+    const response = await this.requester.request<{ result: Contract[] }>(baseURL, requestConfig)
+
+    if (response.response?.status !== 200) {
+      throw new Error(`Failed to query contracts: ${response.response?.statusText}`)
+    }
+
+    return response.response.data.result
+  }
+
+  /**
+   * Exercise a non-consuming choice on a contract
+   */
+  async exerciseChoice(url: string, payload: ExerciseChoiceRequest): Promise<ExerciseResult> {
+    const baseURL = `${url}/v1/exercise`
+
+    const requestConfig = {
+      method: 'POST',
+      baseURL,
+      headers: {
+        'Content-Type': 'application/json',
+        Authorization: `Bearer ${this.config.AUTH_TOKEN}`,
+      },
+      data: payload,
+    }
+
+    const response = await this.requester.request<ExerciseResult>(baseURL, requestConfig)
+
+    if (response.response?.status !== 200) {
+      throw new Error(`Failed to exercise choice: ${response.response?.statusText}`)
+    }
+
+    return response.response.data
+  }
+}