Subscription samples. README.

.gitignore

@@ -37,3 +37,6 @@ node_modules
 .vscode
 
 lib/
+.eslintrc.json
+jsconfig.json
+

README.md

@@ -69,9 +69,21 @@ npm install eventstore-node
 node app.js
 ```
 
-## Porting .Net Task to Node.js
+### Example: Subscribing to events
 
-.Net Task have been replace with Promise. When executing an async command, i.e. appendToStream you can use then/catch to wait for result/error.
+```cd samples```
+
+To subscribe to all events from now on (includes example of a filter which ignores events which we aren't interested in):
+
+```node subscribe-all-events.js```
+
+To catch up on all events ever and subscribe to all new ones from now on:
+
+```node subscribe-catchup-all-events.js```
+
+To generate a test event, open a separate console and run:
+
+```node store-event.js```
 
 ## Running the tests
 
@@ -83,6 +95,10 @@ To execute the tests suites simply run
 
     npm test
 
+## Porting .Net Task to Node.js
+
+.Net Task have been replace with Promise. When executing an async command, i.e. appendToStream you can use then/catch to wait for result/error.
+
 ## License
 
 Ported code is released under the MIT license, see [LICENSE](https://github.com/nicdex/eventstore-node/blob/master/LICENSE). 

samples/store-event.js

@@ -0,0 +1,40 @@
+var esClient = require('../src/client');      // When running in 'eventstore-node/samples' folder. 
+// var esClient = require('eventstore-node'); // Otherwise
+var uuid = require('uuid');
+
+var esConnection = esClient.createConnection({}, {"hostname": "localhost", "port": 1113});
+esConnection.connect();
+esConnection.once('connected', function (tcpEndPoint) {
+    console.log('Connected to eventstore at ' + tcpEndPoint.hostname + ":" + tcpEndPoint.port);
+    var userId = uuid.v4();
+    // This event could happen as a result of (e.g.) a 'CreateUser(id, username, password)' command.
+    var userCreatedEvent = {
+        id: userId,      
+        username: "user" + uuid.v4().substring(0,6),  // Hard-to-spell exotic username.
+        password: Math.random().toString()                      // Hard-to-guess password. 
+    };
+    var eventId = uuid.v4();
+    var event = esClient.createJsonEventData(eventId, userCreatedEvent, null, "UserCreated");
+    // Every user has her/his own stream of events:
+    var streamName = "user-" + userId;
+    console.log("Storing event. Look for it at http://localhost:2113/web/index.html#/streams/user-" + userId);
+    esConnection.appendToStream(streamName, esClient.expectedVersion.any, event)
+        .then(function(result) {
+            console.log("Event stored.");
+            process.exit(0);
+        })
+        .catch(function(err) {
+            console.log(err);
+            process.exit(-1);
+        });
+});
+
+esConnection.on('error', function (err) {
+  console.log('Error occurred on connection:', err);
+  process.exit(-1);  
+});
+
+esConnection.on('closed', function (reason) {
+  console.log('Connection closed, reason:', reason);
+  process.exit(-1);
+});

samples/subscribe-all-events.js

@@ -0,0 +1,48 @@
+// Subscribe to all new events on the $all stream. Filter out any which aren't about "user" aggregates.
+
+var esClient = require('../src/client');      // When  running in 'eventstore-node/samples' folder.
+// var esClient = require('eventstore-node'); // Otherwise
+
+const credentialsForAllEventsStream = new esClient.UserCredentials("admin", "changeit");
+const resolveLinkTos = false;
+
+var esConnection = esClient.createConnection({}, {"hostname": "localhost", "port": 1113});
+esConnection.connect();
+esConnection.once('connected', function (tcpEndPoint) {
+    console.log('Connected to eventstore at ' + tcpEndPoint.hostname + ":" + tcpEndPoint.port);
+    esConnection.subscribeToAll(resolveLinkTos, eventAppeared, subscriptionDropped, credentialsForAllEventsStream)
+        .then(function(subscription) {
+        console.log("subscription.isSubscribedToAll: " + subscription.isSubscribedToAll);
+        console.log("(To generate a test event, try running 'node store-event.js' in a separate console.)")
+        });
+});
+
+function belongsToAUserAggregate(event) {
+    return event.originalEvent.eventStreamId.startsWith("user-")
+}
+
+function eventAppeared(subscription, event) {
+    // Ignore all events which aren't about users:
+    if(belongsToAUserAggregate(event)) {
+        var aggregateId = event.originalEvent.eventStreamId;
+        var eventId = event.originalEvent.eventId;
+        var eventType = event.originalEvent.eventType;
+        console.log(aggregateId, eventType, eventId);
+        console.log(event.originalEvent.data.toString() + "\n");
+    }
+}
+
+function subscriptionDropped(subscription, reason, error) {
+    if (error) {
+        console.log(error);
+    }
+    console.log('Subscription dropped.');
+}
+
+esConnection.on('error', function (err) {
+  console.log('Error occurred on connection:', err);
+});
+
+esConnection.on('closed', function (reason) {
+  console.log('Connection closed, reason:', reason);
+});

samples/subscribe-catchup-all-events.js

@@ -0,0 +1,51 @@
+// Subscribe to all events on the $all stream. Catch up from the beginning, then listen for any new events as they occur.
+// This can be used (e.g.) for subscribers which populate read models. 
+
+var esClient = require('../src/client');      // When  running in 'eventstore-node/samples' folder.
+// var esClient = require('eventstore-node'); // Otherwise
+
+const credentialsForAllEventsStream = new esClient.UserCredentials("admin", "changeit");
+
+var esConnection = esClient.createConnection({}, {"hostname": "localhost", "port": 1113});
+esConnection.connect();
+esConnection.once('connected', function (tcpEndPoint) {
+    console.log('Connected to eventstore at ' + tcpEndPoint.hostname + ":" + tcpEndPoint.port);
+    var subscription = esConnection.subscribeToAllFrom(null, true, eventAppeared, liveProcessingStarted, subscriptionDropped, credentialsForAllEventsStream);
+    console.log("subscription.isSubscribedToAll: " + subscription.isSubscribedToAll);    
+});
+
+function eventAppeared(subscription, event) {
+    // This is where to filter out events which the subscriber isn't interested in.
+    // For an example, see 'subscribe-all-events.js'.
+    console.log(event.originalEvent.eventStreamId);
+}
+
+function subscriptionDropped(subscription, reason, error) {
+    if (error) {
+        console.log(error);
+    }
+    console.log('Subscription dropped.');
+}
+
+function liveProcessingStarted() {
+    console.log("Caught up with previously stored events. Listening for new events.");
+    console.log("(To generate a test event, try running 'node store-event.js' in a separate console.)")
+}
+
+function eventAppeared(stream, event) {
+    console.log(event.originalEvent.eventStreamId, event.originalEvent.eventId, event.originalEvent.eventType);
+    // Data:
+    // console.log(event.originalEvent.data.toString());
+
+    // Position in the event stream. Can be persisted and used to catch up with missed events when re-starting subscribers instead of re-reading
+    // all events from the beginning. 
+    // console.log(event.originalPosition);
+}
+
+esConnection.on('error', function (err) {
+  console.log('Error occurred on connection:', err);
+});
+
+esConnection.on('closed', function (reason) {
+  console.log('Connection closed, reason:', reason);
+});