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2. Decode images

In this part of the tutorial you decode the base64 encoded images coming from the webcam.

Create the base64 decoder service

Follow these steps to deploy the base64 decoder service:

  1. Navigate to the Code Samples and locate the Python Starter transformation.


    You can use the filters on the left hand side to select Python and Transformation then select Starter transformation in the resulting filtered items.

  2. Click Edit code.

  3. Enter base64 decoder service as the name for the project.

  4. Select or enter image-base64 for the input.

  5. Select or enter image-raw for the output.

  6. Click Save as project.

Update the code

The code is now saved to your workspace and you can edit it to perform any actions you need it to.

Using the following steps, update the default code so it decodes the web cam images being received on the image-base64 topic. Then publish the decoded images to the image-raw topic.

  1. Add import base64 to the imports at the top of

  2. Update the on_dataframe_received_handler method by adding the following line to base64 decode the images.

    df['image'] = df["image"].apply(lambda x: base64.b64decode(x))

    This should go immediately before this line:

The completed should look like this
import quixstreams as qx
import os
import pandas as pd
import base64 # Added import (1)

client = qx.QuixStreamingClient()

topic_consumer = client.get_topic_consumer(os.environ["input"], consumer_group = "empty-transformation")
topic_producer = client.get_topic_producer(os.environ["output"])

def on_dataframe_received_handler(stream_consumer: qx.StreamConsumer, df: pd.DataFrame):

    # Transform data frame here in this method. You can filter data or add new features.
    # Pass modified data frame to output stream using stream producer.
    # Set the output stream id to the same as the input stream or change it,
    # if you grouped or merged data with different key.
    stream_producer = topic_producer.get_or_create_stream(stream_id = stream_consumer.stream_id)
    df['image'] = df["image"].apply(lambda x: base64.b64decode(x)) # Added code (2)

# Handle event data from samples items that emit event data
def on_event_data_received_handler(stream_consumer: qx.StreamConsumer, data: qx.EventData):
    # handle your event data here

def on_stream_received_handler(stream_consumer: qx.StreamConsumer):
    # subscribe to new DataFrames being received
    # if you aren't familiar with DataFrames there are other callbacks available
    # refer to the docs here: = on_event_data_received_handler # register the event data callback
    stream_consumer.timeseries.on_dataframe_received = on_dataframe_received_handler

# subscribe to new streams being received
topic_consumer.on_stream_received = on_stream_received_handler

print("Listening to streams. Press CTRL-C to exit.")

# Handle termination signals and provide a graceful exit
  1. Import base64 which will be used to decode the images
  2. Call base64.b64decode and store the resulting data in the dataframe


Now it's time to deploy this microservice.

Follow these steps:

  1. Tag the code by clicking add tag at the top of the code panel. Enter v1.0 for your tag.

  2. Click Deploy near the top right hand corner of the screen.

  3. Select the v1.0 from the verison tag drop down.

  4. Click Deploy.

    You will be redirected to the homepage and the code will be built and deployed and your microservice will be started.

Part 3 - Object detection