Streamlit PubSub¶
Overview¶
This is a demonstration of pulling real-time streaming data from Pub/Sub into Streamlit.
Subscriber behaviour:
- Subscriptions will be created on demand. This is to allow scaling across multiple processes. It is expected to only pull newly published data in the general case.
- There is a configurable fixed buffer of messages it retains. Clients will receive all messages back in time up to this buffer size.
- Each client session will receive messages as fast as possible asynchronously.
- Only one subscription is shared (for the subscription) across all user sessions in a single proces.
Note that asyncio isn't officially supported by Streamlit (see this), but this use of it should be safe. Each rendering of the page has its own async loop, with the loop shutting down if the page is reloaded.
Please provide feedback to any issues when using this.
Creating topic¶
It is necessary to create an initial topic. In this case, echo-json is the
topic name.
Initializing Python Environment¶
The Python environment needs to be initialized. You can use the following or your favourite tools.
python3 -m venv .venv
.venv/bin/python3 -m ensurepip
.venv/bin/python3 -m pip install --require-hashes -r requirements.txt
source .venv/bin/activate
Running Streamlit¶
Start Streamlit to show a dashboard, connecting to the subscription and topic.
Replace PROJECT_ID with the project you created the subscription in.
Publishing data to PubSub (Optional)¶
Start publishing messages to the topic. Replace PROJECT_ID with the project
you created the topic in.