Add forward-to-logger service and requester sample

This commit adds a new service called "forward-to-logger" to the docker-compose.yml file. It also includes a new requester sample that demonstrates how to request data from another service and publish it on a different subject. This allows for forwarding data to the logger service.

backend-deno/samples/docker-compose.yml

@@ -43,6 +43,20 @@ services:
     environment:
       - SERVICE_NAME=sample-publisher
       - DATA_SUBJECT=data.sample
+  forward-to-logger:
+    build:
+      context: ../
+      dockerfile: samples/Dockerfile
+    command: ["requester/mod.ts"]
+    depends_on:
+      - nats
+    env_file:
+      - .common.env
+    environment:
+      - SERVICE_NAME=forward-to-logger
+      - REQUEST_SUBJECT=latest.data.sample
+      - FREQUENCY=3000
+      - OUTPUT_SUBJECT=log.sample-data
   logger:
     build:
       context: ../

backend-deno/samples/requester/README.md

@@ -0,0 +1,13 @@
+# Requester Sample
+
+This sample shows how to request data from another service.
+
+In a given frequency, the service will request the value from a given subject (with an empty request) and re-publish it on a different subject.
+
+## Configuration Options
+
+| Option | Description | Default |
+| ------ | ----------- | ------- |
+| `REQUEST_SUBJECT` | The subject to request data from. | (required) |
+| `PUBLISH_SUBJECT` | The subject to publish the requested data on. | (required) |
+| `FREQUENCY` | The frequency to request data from the `REQUEST_SUBJECT` in milliseconds. | `5000` |

backend-deno/samples/requester/mod.ts

@@ -0,0 +1,27 @@
+import { startService } from "https://deno.land/x/telestion/mod.ts";
+import { z } from "https://deno.land/x/[email protected]/mod.ts";
+
+const { messageBus, config } = await startService();
+
+const { FREQUENCY, REQUEST_SUBJECT, OUTPUT_SUBJECT } = z.object({
+  FREQUENCY: z.coerce.number().positive().default(5000),
+  REQUEST_SUBJECT: z.string(),
+  OUTPUT_SUBJECT: z.string(),
+}).parse(config);
+
+console.log("Request started with config", {
+  FREQUENCY,
+  REQUEST_SUBJECT,
+  OUTPUT_SUBJECT,
+});
+
+setInterval(async () => {
+  try {
+    const data = await messageBus.request(REQUEST_SUBJECT);
+    console.log("Requester received requested data", data.data);
+    messageBus.publish(OUTPUT_SUBJECT, data.data);
+    console.log("Data forwarded to", OUTPUT_SUBJECT);
+  } catch (e) {
+    console.warn("Couldn't retrieve data", e);
+  }
+}, FREQUENCY);