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Test Streaming Lite Project

Intermediate
15 min.
SAP HANA streaming analytics, Intermediate, Internet of Things, SAP HANA, express edition, Tutorial
Test the Streaming Lite Project by using the `streamingsubscribe` command line utility to see the flow of events through the project.
You will learn
  • How to subscribe for the isFreezerTemperatureReading stream to show the individual events entering the project
  • How to subscribe for the FilterEveryFifteenthRow stream to show the final output after the project has processed the events
  • How to send event records into our Streaming Lite project
  • To wrap up our Streaming Lite projects

Prerequisites

Open three more PuTTY/SSH sessions connected to our Raspberry Pi. You will need to run a separate command line utility in each session to see the flow of events through the project.

Using the streamingsubscribe command line utility, we will be subscribing to two streams in our project.

The first subscribe will be for theisFreezerTemperatureReading stream. This will be used to show the individual events entering the project.

The second subscribe will be for the FilterEveryFifteenthRow stream of our project. This will be used to show the final output after the project has process the events through all three elements.

  • Step 1

    In the first PuTTY/SSH session, run this command to subscribe to the isFreezerTemperatureReading stream:

    Note: Don’t forget to replace <Raspberry Pi IP Address> with our Raspberry Pi’s IP Address

    Bash
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    $STREAMING_HOME/bin/streamingsubscribe -s isFreezerTemperatureReading -p <Raspberry Pi IP Address>:9230/freezer_monitoring_lite
    Is Freezer Temperature Reading

    For the question below, select the correct answer, and click Validate.

    Which streaming command line utility is used to subscribe to a stream in our project?

  • Step 2

    In the second PuTTY/SSH session, run this command to subscribe to the FilterEveryFifteenthRow stream:

    Note: Don’t forget to replace <Raspberry Pi IP Address> with our Raspberry Pi’s IP Address

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    $STREAMING_HOME/bin/streamingsubscribe -s FilterEveryFifteenthRow -p <Raspberry Pi IP Address>:9230/freezer_monitoring_lite
    Filter Every Fifteenth Row

    You will now be able to see when data passes through either stream. streamingsubscribe is a binary executable which subscribes to our stream of choice, in a running instance of any streaming project.

  • Step 3

    We will now send a single event record into our Streaming Lite project. The first part of this command prints out a record in a delimited format. This output is then piped into streamingconvert, which converts the delimited record into 32-bit binary records compatible with Streaming Lite. Finally, this output is piped again into streamingupload, which writes the row into our stream.

    To represent our record in a delimited format, we will use the following string: "isFreezerTemperatureReading,i,RaspberryPi,90,2014-06-03T12:00:00.000,218". This string is made up of six parts. First, we state the stream name. Next, we define the opcode to be i for insert. The subsequent four values correspond to the four fields as defined in the stream schema, in consecutive order. SensorId is set as Raspberry Pi, Temperature is set to "90", ReadingDate is set to "2014-06-03 12:00:00.000", and Id is set to "218". (Id is arbitrary since it will be autogenerated inside the project)

    Run the command in our third PuTTY/SSH window:

    Note: Don’t forget to replace <Raspberry Pi IP Address> with our Raspberry Pi’s IP Address

    Bash
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    echo "isFreezerTemperatureReading, i, RaspberryPi, 90, 2014-06-03T12:00:00.000,218" | $STREAMING_HOME/bin/streamingconvert -d "," -p <Raspberry Pi IP Address>:9230/freezer_monitoring_lite | $STREAMING_HOME/bin/streamingupload -p <Raspberry Pi IP Address>:9230/freezer_monitoring_lite
  • Step 4

    After running the send row command, you should now see something in the first PuTTY/SSH window, which is subscribed to isFreezerTemperatureReading:

    Is Freezer Temperature Reading Results

    Note that nothing has yet appeared in our second PuTTY/SSH window, which is subscribed to the FilterEveryFifteenthRow stream.

    Run the send row command 14 more times. You will see each row appear in our first isFreezerTemperatureReading PuTTY/SSH window.

    After 15 rows have been sent, check our second PuTTY/SSH window, which is subscribed to the FilterEveryFifteenthRow stream.

    Filter Every Fifteenth Row Results

    Our "FilterEveryFifteenthRow" stream has finally passed a row, after averaging the last 15 rows of temperature values.

  • Step 5

    In summary, Streaming Lite runs on remote devices to collect data, and processes the bulk of the information before sending it off. By pushing computation into the edge, more data can be processed without hindering the central nodes.

    In the future, we will be adding a Streaming Web Service output adapter onto this stream, to send records into a Streaming Analytics project.

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