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Adding pubsub sample (#82)
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‎README.md

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@@ -27,6 +27,7 @@ If you are new to Dapr, you may want to review following resources first:
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| [Dapr integration in Azure APIM](./dapr-apim-integration) | Dapr configuration in Azure API Management service using self-hosted gateway on Kubernetes. Illustrates exposing Dapr API for service method invocation, publishing content to a Pub/Sub topic, and binding invocation with request content transformation. |
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| [Distributed Calendar](./dapr-distributed-calendar) | Shows use of statestore, pubsub and output binding features of Dapr to roughly create a distributed version of a MVCS architecture application. |
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| [Hello Service Fabric](./hello-service-fabric) | Shows use of statestore, pubsub and service invocation in a Service Fabric environment running the Dapr sidecar as a guest executable. |
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| [Pub-sub routing](./pub-sub-routing) | Demonstrates how to use Dapr to enable pub-sub applications with message routing. |
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## External samples
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‎pub-sub-routing/.gitignore

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node_modules

‎pub-sub-routing/Dockerfile

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FROM node:8-alpine
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WORKDIR /usr/src/app
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COPY . .
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RUN npm install
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EXPOSE 3000
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CMD [ "node", "app.js" ]

‎pub-sub-routing/README.md

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# Dapr Pub-Sub routing
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In this quickstart, you'll run a subscriber application that makes use of Pub-Sub routing. The application can be quickly changed to:
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* Toggle between programmatic and declarative subscriptions (or use both as long as there is no overlap)
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* Add other routing rules with different [CEL](https://github.com/google/cel-spec) expressions
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* Enable/disable routing (disable `PubSub.Routing` in `config.yaml`)
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> **Note**: Because this example is intended to be something to play around with, it makes use of the `in-memory` pubsub component and is not intended to be deployed to Kubernetes.
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**Install dependencies**
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<!-- STEP
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name: Install node dependencies
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working_dir: .
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-->
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```bash
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npm install
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```
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<!-- END_STEP -->
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**Run the application**
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<!-- STEP
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name: Run node subscriber
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expected_stdout_lines:
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- "WIDGET:"
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- "GADGET:"
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- "PRODUCT (default):"
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expected_stderr_lines:
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output_match_mode: substring
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working_dir: .
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background: true
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sleep: 5
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-->
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```bash
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dapr run --app-id pubsub-routing --config config.yaml --components-path ./components --app-port 3000 node app.js
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```
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<!-- END_STEP -->
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**Switch between programmatic and declarative subscriptions**
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In `app.js`, the handler for `/dapr/subscribe` returns the programmatic subscriptions. The contents are commented out to demonstrate usage of a declarative subscription in `components/subscription.yaml`.
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You can switch from declarative to programmatic subscriptions by:
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1) Changing `kind: Subscription` to `kind: Subscription_disabled` in `components/subscription.yaml` so that `daprd` does not load the file
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2) Uncommenting the JSON response for `/dapr/subscribe` in `app.js`
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3) Stop (CTRL-C) and restart the application using the `dapr run` command above
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**Publish messages to route**
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Try the following `curl` commands in a separate terminal.
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Publish a widget
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<!-- STEP
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name: Curl publish message
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expected_stdout_lines:
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- "OK"
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- "OK"
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- "OK"
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expected_stderr_lines:
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-->
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```bash
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curl -s http://localhost:3000/publish -H Content-Type:application/json --data @messages/widget.json
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```
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Publish a gadget
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```bash
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curl -s http://localhost:3000/publish -H Content-Type:application/json --data @messages/gadget.json
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```
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Publish a thingamajig
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```bash
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curl -s http://localhost:3000/publish -H Content-Type:application/json --data @messages/thingamajig.json
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```
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<!-- END_STEP -->
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<!-- STEP
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expected_stdout_lines:
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- 'app stopped successfully: pubsub-routing'
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expected_stderr_lines:
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output_match_mode: substring
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name: Shutdown dapr
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-->
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```bash
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dapr stop --app-id pubsub-routing
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```
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<!-- END_STEP -->

‎pub-sub-routing/app.js

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// ------------------------------------------------------------
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// Copyright (c) Microsoft Corporation.
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// Licensed under the MIT License.
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// ------------------------------------------------------------
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const daprPort = process.env.DAPR_HTTP_PORT || "3500";
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// The Dapr endpoint for the state store component to store the tweets.
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const pubsubEndpoint = `http://localhost:${daprPort}/v1.0/publish/pubsub/inventory`;
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const express = require('express');
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const axios = require('axios');
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const app = express();
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// Dapr publishes messages with the application/cloudevents+json content-type
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app.use(express.json({ type: ['application/json', 'application/*+json'] }));
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const port = 3000;
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app.get('/dapr/subscribe', (_req, res) => {
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// Programmatic subscriptions
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// See ./components/subscription.yaml for declarative subscription.
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//
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res.json([
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// Previous subscription structure.
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// {
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// pubsubname: "pubsub",
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// topic: "inventory",
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// route: "products"
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// }
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//
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// Subscription with routing rules and default route.
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// {
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// pubsubname: "pubsub",
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// topic: "inventory",
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// routes: {
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// rules: [
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// {
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// match: `event.type == "widget"`,
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// path: "widgets"
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// },
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// {
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// match: `event.type == "gadget"`,
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// path: "gadgets"
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// }
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// ],
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// default: "products"
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// }
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// }
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]);
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});
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// Default product handler.
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app.post('/products', (req, res) => {
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console.log("🤔 PRODUCT (default): ", req.body);
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console.log();
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res.sendStatus(200);
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});
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// Specific handler for widgets.
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app.post('/widgets', (req, res) => {
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console.log("🪛 WIDGET: ", req.body);
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console.log();
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res.sendStatus(200);
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});
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// Specific handler for gadgets.
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app.post('/gadgets', (req, res) => {
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console.log("📱 GADGET: ", req.body);
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console.log();
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res.sendStatus(200);
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});
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// Allow publishing freeform cloud events to the topic.
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app.post('/publish', async (req, res) => {
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console.log("publishing", req.body);
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console.log();
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axios.post(pubsubEndpoint, req.body, {
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headers: {
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'content-type': 'application/cloudevents+json'
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}
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})
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.then(() => { res.sendStatus(200); })
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.catch(error => {
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res.sendStatus(500);
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console.error('There was an error!', error);
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});
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});
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app.listen(port, () => console.log(`Node App listening on port ${port}!`));

‎pub-sub-routing/components/in-memory.yaml

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apiVersion: dapr.io/v1alpha1
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kind: Component
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metadata:
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name: pubsub
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namespace: default
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spec:
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type: pubsub.in-memory
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version: v1

‎pub-sub-routing/components/subscription.yaml

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apiVersion: dapr.io/v2alpha1
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kind: Subscription
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metadata:
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name: mysubscriptions
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namespace: default
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spec:
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pubsubname: pubsub
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topic: inventory
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routes:
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rules:
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- match: "event.type == 'widget'"
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path: widgets
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- match: "event.type == 'gadget'"
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path: gadgets
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default: products

‎pub-sub-routing/config.yaml

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apiVersion: dapr.io/v1alpha1
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kind: Configuration
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metadata:
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name: pubsubroutingconfig
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spec:
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features:
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- name: PubSub.Routing
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enabled: true

‎pub-sub-routing/messages/gadget.json

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{
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"type": "gadget",
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"source": "routing-demo",
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"data": {
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"description": "Hello, Gadget!",
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"price": 75.00,
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"gadgetField": "gadgets only"
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}
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}

‎pub-sub-routing/messages/thingamajig.json

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{
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"type": "thingamajig",
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"source": "routing-demo",
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"data": {
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"description": "Hello, Thingamajig!",
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"price": 5.00
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}
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}

‎pub-sub-routing/messages/widget.json

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{
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"type": "widget",
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"source": "routing-demo",
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"data": {
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"description": "Hello, Widget!",
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"price": 25.00,
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"widgetField": "widgets only"
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}
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}

‎pub-sub-routing/package.json

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{
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"name": "node-pubsub-routing",
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"version": "1.0.0",
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"private": true,
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"description": "A routing subscriber sample",
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"main": "app.js",
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"scripts": {
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"test": "echo \"Error: no test specified\" && exit 1"
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},
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"author": "Phil Kedy",
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"license": "ISC",
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"dependencies": {
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"axios": "^0.21.4",
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"express": "^4.17.1"
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}
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}

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