Quick guide on how to write functions on vitalpointz IoT Core Platform

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Flow Processing

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vitalpointz IoT Core Lite v1.3 and above
Flow Processing in
vitalpointz IoT Core Lite

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 Flow Processing signifies the processing of messages
received from Devices / Fog Nodes
 In flow processing, users can implement their own
functions, one or more to process the messages.
 Functions are invoked to incoming messages
 Functions can be implemented in two ways
 Using Hosted NodeRED, the built-in NodeRED tool
with vitalpointz helper nodes
 Using Workload Containers
 Deployment of end-to end flow processing in vitalpointz
IoT Core is largely of 2 steps, no specific order
 Specify the function name while Adding Devices
 Define the Function
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Overview

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Receiving messages from Devices into Function
 Navigate to NodeRED tab, scroll down left-hand
pane
 Under vitalpointz directory, helper nodes are
provided
 Use Service In node and double click to enter
the function names
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Writing Function in NodeRED – (1)
Double
Click
Function
Name

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Sending a message from a Functions to Devices
 Step1: create a message
 Navigate to NodeRED
 Create a function node with below Code
{
topic:’<device allowed device topic>’,
payload:"Message to be sent to Device”
};
 Wire to vitalpointz Service Out Node
 Provide name & Source name
 Step2: create a Rule to forward the message
to Device
 See Next Slide
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Writing Function in NodeRED – (2)
Connect
Service-Out
to Function
Node
Write the js
code into
the function
node

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Sending messages from Functions to Devices
 Navigate to Rules Engine, click Add New
Rule
 Select Events to Forward ‘User Defined’
 Enter custom Event = device topic entered in
Node RED function
 Enter Source= Source name entered in Node
RED Service Out Node
 Select Forward to ‘User Defined Service
Name’
 Enter Service name = ‘TO_DEVICE’
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Writing Function in NodeRED – (2)

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Broadcasting to all Devices/FogNodes
When a function generated event needed to be received by all device or all fog nodes or both, follow
below mentioned procedure
 Step 1: Create a Function that generates message to be broadcasted
 Step 2: Wire it to Service Out Node in NodeRED
 Step 3: Create a Rule to Broadcast
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Writing Function in NodeRED – (3)

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 Step 1: Create a Function that generates a
message to be broadcasted
 Message must be in JSON format
 Topic: define your own topic, starting with ‘app/abcde’
 Payload: this could be JSON object or a String.
 If payload is a string, all devices and fog nodes will
receive this message as is
 If payload is a JSON object and if a key called
‘broadcast’ is found, the message broadcast can be
controlled
 broadcast:’device’ - forces broadcast service to send
the message only to devices (i.e, No Fog Node will
receive this message)
 broadcast:’fognode’ - forces broadcast service to send
the message only to devices (i.e, no Device will receive
this message)
 If this key is missing or the payload is JSON, the
message is delivered to every device and fog nodes
 Note: The device will receive this message in their
<allowed device topic>/fromcloud
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Broadcasting
Payload
defined in
the function

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 Step 2: Wire it to Service Out Node in NodeRED
 Double click on Service Out Node,
 Provide any string/name as Source
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Broadcasting

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 Step 3: Create a Rule to Broadcast
 Navigate to Rules Engine, click ‘Add a
new Rule’
 Select Events to Forward ‘User Defined’
 Enter custom Event = topic entered in
Node RED function e.g, ‘app/abcde’
 Enter Source= Source name entered in
Node RED Service Out Node
 Select Forward to ‘Broadcast Service’
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Broadcasting
Forward To:
Broadcast
Service

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 Pro
 Easy to write and test a function
 Quick to debug or visualize the device
messages
 User can leverage the community NodeRED
nodes to quickly build dashboards, write
business logics & much more
 Cons
 Hosted NodeRED is not multi-user supported,
this means flows created by one user is visible
to others
 JavaScript is the primary language to develop
over NodeRED
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Caveats of Hosted NodeRED
 Recommended Best practice
 NodeRED container image identical to in-built
Hosted NodeRED is available in Workload
 By spinning up one or many NodeRED
containers, user can create their own container
to process their data in an isolated manner
 This way multi-user problem can be solved
 User can leverage the community NodeRED
nodes to quickly build dashboards or business
logics etc

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 Functions can be implemented in following
workload containers
 VPZ-nodered
 helloworld-js
 helloworld-py
 Spinning a vpz-nodered workload brings up
another NodeRed instance
 helloworld-js / hellowold-py
 This container implements basic hello world
program that listens on a specific user defined topic
(called Topic In)
 Sends the message back using user defined topic
called Topic Out
 This container also implements a REST server that
listens on 3005 port
 This port runs configuration service
 Configuration service accepts 3 parameters namely
SSH to be enabled or not , Topic IN and Topic Out
 This can be invoked using ‘Configure’ menu item
on workload tab
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Writing Function in workload containers

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 User can enable SSH access on configure
menu
 Login to container using ‘SSH Access’ menu
item
 User can modify the code, save and commit
as new image
 Then spin up their own container as
production workload
 See quick guide in workload tab from details
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Writing Function in workload containers

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 Device messages can be connected to a
function in Device Add form
 When a Group of devices is added, all the
messages from the devices will be sent to the
same function
 Navigate to Device Tab, click on Add IoT
Device
 Enter a name of function in Message
Decoder/Processing Function
 Writing Function using
 NodeRED Option: Use Service In Node under
vitalpointz directory, enter the same function
name entered in above step
 Workload option : use helloworld-js/helloworld-
py and enter the same function name in TopicIn
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Connecting Device to Functions

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