Sunday, December 3, 2017

Node-RED: Dashboard Notifications and Rate Limiting

This post builds upon the dashboard we built in the last post. In particular we will:

  1. Simplify the dashboard flow using a Function node
  2. Alert the user when specific conditions are met
  3. Examine the source code for the final dashboard


Simplify Using Function Nodes
The previous version of the dashboard included three Change nodes...

The purpose of those nodes was to extract the temperature, humidity, and barometric pressure from the incoming JSON message. The reason we did that was because the Chart and Gauge nodes required that the payload hold only a single value, the value that will be charted.

The Function node will allow us to extract those three values in one step!

Start by adding a new Function node to the "MQTT Dashboard" workspace, name it "Extract Values", set the number of outputs to 3, and enter the following code for the Function node's umm... Function field:

return [
    {payload: msg.payload.temperature}, 
    {payload: msg.payload.humidity},
    {payload: msg.payload["barometric-pressure"]}
];

What this code does is to return an array of objects, each one of which contains a single property, "payload", which has been set to the temperature, humidity, and pressure found in the incoming message.

By giving the Function node three output ports, we are sending each value in that array out into those three ports. Which output goes to each port? The output ports will be arranged top to bottom on the right side of the node, with temperature going to the topmost port, humidity to the middle port, and pressure to the bottom. To make this easier to see, we can even give labels to the output ports, as shown:

Now, remove the three Change nodes, drag the new Function node into place, and wire everything up like this:

Deploy the dashboard, view it at http://127.0.0.1:1880/ui, and it should be working fine!


Dashboard Notifications
Next, let us add some notifications within the dashboard. We want to alert the user when the temperature climbs above 80 °F. In particular, we will show a "toast" popup, and even use text-to-speech to announce that the temperature is above that value.

Now sensor readings are coming in once every second. So if we just did this, the user would be notified once every second - not a good user experience! What we must do is limit the rate that these notifications are sent, without changing the rate at which data is arriving. Node-RED has this functionality ready for our use, in Delay node, which is found in the "function" section of the palette.

Drag into the workspace one of each of the following nodes: Switch, Delay, Notification, Change, and Audio Out. The Notification and Audio Out nodes are found in the "dashboard" section. Set their properties as follows:

Node Type Property Value
Switch
Name: Check Temperature
Property: msg.payload
Condition: > 80
Delay
Action: Rate Limit
Rate: 1 msg(s) per
Interval: 1 Minute
Drop Intermediate Messages: Checked
Notification
Layout: Top Right
Timeout (S): 3
Topic: Temperature is Above 80 °F
Change
Action: Set
Object: msg.payload
To: Temperature is above 80 degrees!
Audio Out
Group: Temperature [Living Room Data]
TTS Voice: Alex (en-US)

Note that for the Notification node's topic, it is necessary to enter the degree (°) symbol directly - using the HTML escape sequence will not work!

Finally, wire up components as follows:

An easy way to test this is to (believe it or not) breathe on the BME280. Once the temperature gets sufficiently high, the "toast" popup will be displayed in the top-right corner, and the audio message will be played!


Dashboard Source Code
Here's the source code for the dashboard flow. There are no changes to the MQTT Subscriber, and that code can be found in the previous post.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
[
    {
        "id": "492fdf69.9cb38",
        "type": "link in",
        "z": "49d20fae.01266",
        "name": "From Subscriber",
        "links": [
            "3a476f0b.d6bea"
        ],
        "x": 195,
        "y": 220,
        "wires": [
            [
                "14f7f237.a4b53e",
                "cf06c435.a31528"
            ]
        ]
    },
    {
        "id": "14f7f237.a4b53e",
        "type": "debug",
        "z": "49d20fae.01266",
        "name": "",
        "active": false,
        "console": "false",
        "complete": "true",
        "x": 330,
        "y": 160,
        "wires": []
    },
    {
        "id": "6b80f3f4.1fdb4c",
        "type": "ui_gauge",
        "z": "49d20fae.01266",
        "name": "Humidity Gauge",
        "group": "f468b186.a264b",
        "order": 0,
        "width": 0,
        "height": 0,
        "gtype": "gage",
        "title": "",
        "label": "%",
        "format": "{{value}}",
        "min": 0,
        "max": "100",
        "colors": [
            "#00b500",
            "#e6e600",
            "#ca3838"
        ],
        "seg1": "",
        "seg2": "",
        "x": 620,
        "y": 260,
        "wires": []
    },
    {
        "id": "62dd2ada.5449a4",
        "type": "ui_chart",
        "z": "49d20fae.01266",
        "name": "Temperature Chart",
        "group": "637855dc.2229bc",
        "order": 0,
        "width": 0,
        "height": 0,
        "label": "",
        "chartType": "line",
        "legend": "false",
        "xformat": "HH:mm:ss",
        "interpolate": "linear",
        "nodata": "",
        "dot": false,
        "ymin": "",
        "ymax": "",
        "removeOlder": "5",
        "removeOlderPoints": "",
        "removeOlderUnit": "60",
        "cutout": 0,
        "useOneColor": false,
        "colors": [
            "#1f77b4",
            "#aec7e8",
            "#ff7f0e",
            "#2ca02c",
            "#98df8a",
            "#d62728",
            "#ff9896",
            "#9467bd",
            "#c5b0d5"
        ],
        "useOldStyle": false,
        "x": 630,
        "y": 140,
        "wires": [
            [],
            []
        ]
    },
    {
        "id": "4075ff77.21db8",
        "type": "ui_chart",
        "z": "49d20fae.01266",
        "name": "Pressure Chart",
        "group": "9728196c.705ff8",
        "order": 0,
        "width": 0,
        "height": 0,
        "label": "",
        "chartType": "line",
        "legend": "false",
        "xformat": "HH:mm:ss",
        "interpolate": "linear",
        "nodata": "",
        "dot": false,
        "ymin": "",
        "ymax": "",
        "removeOlder": "5",
        "removeOlderPoints": "",
        "removeOlderUnit": "60",
        "cutout": 0,
        "useOneColor": false,
        "colors": [
            "#1f77b4",
            "#aec7e8",
            "#ff7f0e",
            "#2ca02c",
            "#98df8a",
            "#d62728",
            "#ff9896",
            "#9467bd",
            "#c5b0d5"
        ],
        "useOldStyle": false,
        "x": 620,
        "y": 380,
        "wires": [
            [],
            []
        ]
    },
    {
        "id": "df80eb36.2bf648",
        "type": "ui_text",
        "z": "49d20fae.01266",
        "group": "637855dc.2229bc",
        "order": 0,
        "width": 0,
        "height": 0,
        "name": "Temperature Text",
        "label": "Temperature: ",
        "format": "{{msg.payload}} °F",
        "layout": "row-left",
        "x": 630,
        "y": 200,
        "wires": []
    },
    {
        "id": "51d9d859.dc84c8",
        "type": "ui_text",
        "z": "49d20fae.01266",
        "group": "f468b186.a264b",
        "order": 0,
        "width": 0,
        "height": 0,
        "name": "Humidity Text",
        "label": "Humidity: ",
        "format": "{{msg.payload}} %",
        "layout": "row-left",
        "x": 620,
        "y": 320,
        "wires": []
    },
    {
        "id": "919809c4.84ef18",
        "type": "ui_text",
        "z": "49d20fae.01266",
        "group": "9728196c.705ff8",
        "order": 0,
        "width": 0,
        "height": 0,
        "name": "Pressure Text",
        "label": "Barometric Pressure:",
        "format": "{{msg.payload}} InHg",
        "layout": "row-left",
        "x": 620,
        "y": 440,
        "wires": []
    },
    {
        "id": "d29db2b5.f8ddb",
        "type": "delay",
        "z": "49d20fae.01266",
        "name": "",
        "pauseType": "rate",
        "timeout": "5",
        "timeoutUnits": "seconds",
        "rate": "1",
        "nbRateUnits": "1",
        "rateUnits": "minute",
        "randomFirst": "1",
        "randomLast": "5",
        "randomUnits": "seconds",
        "drop": true,
        "x": 840,
        "y": 60,
        "wires": [
            [
                "6e7140a1.07b05",
                "1e27bbe.febf544"
            ]
        ]
    },
    {
        "id": "6e7140a1.07b05",
        "type": "ui_toast",
        "z": "49d20fae.01266",
        "position": "top right",
        "displayTime": "3",
        "highlight": "",
        "outputs": 0,
        "ok": "OK",
        "cancel": "",
        "topic": "Temperature is Above 80 °F",
        "name": "",
        "x": 1070,
        "y": 40,
        "wires": []
    },
    {
        "id": "bb4a13de.4faaa",
        "type": "switch",
        "z": "49d20fae.01266",
        "name": "Check Temperature",
        "property": "payload",
        "propertyType": "msg",
        "rules": [
            {
                "t": "gt",
                "v": "80",
                "vt": "num"
            }
        ],
        "checkall": "true",
        "outputs": 1,
        "x": 630,
        "y": 60,
        "wires": [
            [
                "d29db2b5.f8ddb"
            ]
        ]
    },
    {
        "id": "3f251d1e.167872",
        "type": "ui_audio",
        "z": "49d20fae.01266",
        "name": "",
        "group": "637855dc.2229bc",
        "voice": "en-US",
        "always": false,
        "x": 1040,
        "y": 180,
        "wires": []
    },
    {
        "id": "1e27bbe.febf544",
        "type": "change",
        "z": "49d20fae.01266",
        "name": "",
        "rules": [
            {
                "t": "set",
                "p": "payload",
                "pt": "msg",
                "to": "Temperature is above 80 degrees!",
                "tot": "str"
            }
        ],
        "action": "",
        "property": "",
        "from": "",
        "to": "",
        "reg": false,
        "x": 1060,
        "y": 80,
        "wires": [
            [
                "3f251d1e.167872"
            ]
        ]
    },
    {
        "id": "cf06c435.a31528",
        "type": "function",
        "z": "49d20fae.01266",
        "name": "Extract Values",
        "func": "return [\n    {payload:msg.payload.temperature}, \n    {payload:msg.payload.humidity},\n    {payload:msg.payload[\"barometric-pressure\"]}\n];",
        "outputs": "3",
        "noerr": 0,
        "x": 360,
        "y": 280,
        "wires": [
            [
                "bb4a13de.4faaa",
                "62dd2ada.5449a4",
                "df80eb36.2bf648"
            ],
            [
                "6b80f3f4.1fdb4c",
                "51d9d859.dc84c8"
            ],
            [
                "4075ff77.21db8",
                "919809c4.84ef18"
            ]
        ],
        "outputLabels": [
            "Temperature",
            "Humidity",
            "Barometric Pressure"
        ]
    },
    {
        "id": "f468b186.a264b",
        "type": "ui_group",
        "z": "",
        "name": "Humidity",
        "tab": "d376d602.4e3538",
        "order": 2,
        "disp": true,
        "width": "6"
    },
    {
        "id": "637855dc.2229bc",
        "type": "ui_group",
        "z": "",
        "name": "Temperature",
        "tab": "d376d602.4e3538",
        "order": 1,
        "disp": true,
        "width": "6"
    },
    {
        "id": "9728196c.705ff8",
        "type": "ui_group",
        "z": "",
        "name": "Barometric Pressure",
        "tab": "d376d602.4e3538",
        "order": 3,
        "disp": true,
        "width": "6"
    },
    {
        "id": "d376d602.4e3538",
        "type": "ui_tab",
        "z": "",
        "name": "Living Room Data",
        "icon": "dashboard",
        "order": 2
    }
]

1 comment: