gateway-hl7-listener

This is a Python service that does the following:

• Listen/receive MLLP HL7 messages from the configured port.
• Publish (NATS Publish-Subscribe mode) the received HL7 messages to either the configured NATS JetStream server "Subject" (e.g., "hl7.") or configured SQS queue. Note that the "Subject" is associated with a JetStream "Stream" (e.g., "hl7") and the stream's "Consumer" (e.g.,"queue").
• The published NATS messages are acknowledge by the server. If messages publishes start to fail or acknowledges do not occur, listening for HL7 messages will halt.

Diagram:

Development

Setup

poetry install # Create venv and install dependencies

poetry run pytest # Run unit tests

poetry build -f wheel # Build the wheel file under dist directory

Env Vars

To run locally via docker you'll need to set a couple of env variables, be sure to set your dd api key

export DD_AGENT_HOST="datadog-agent"
export DD_TRACE_ENABLED=1
export DD_ENV=local
export DD_DOGSTATSD_NON_LOCAL_TRAFFIC=true
export DD_SITE="datadoghq.com"
export DD_APM_ENABLED=true
export DD_APM_NON_LOCAL_TRAFFIC=true
export DD_API_KEY="your-super-special-key"

Update pyproject.toml as needed.

poetry update # update the poetry.lock file after making changes to pyproject.toml

Adding Dependencies

Update the pyproject.toml file to add dependencies.

Install NATS Jetstream server and NATS CLI

You can find the instructions for the NATS Jetstream server (via docker) here: https://hub.docker.com/_/nats/

You can find the instructions for the NATS Cli here: https://github.com/nats-io/natscli

A docker-compose file is also available for standing up NATS Jetstream server.

Create the stream and consumer

Create the hl7 stream with wildcard/unspecified subjects:

nats str add hl7 --subjects "hl7.*" --ack --max-msgs=-1 --max-bytes=-1 --max-age=1y --storage file --retention limits --max-msg-size=-1 --discard=old --max-msgs-per-subject=-1 --dupe-window=2m --replicas=1

Create the queue consumer for the hl7 stream and filter to a subject named "hl7.queue":

nats con add hl7 queue --filter hl7.queue --ack explicit --pull --deliver all --max-deliver=-1 --sample 100 --max-pending=1 --replay=instant --wait=1s

Environment variables

You will need to override these if you are not running locally.

HL7_MLLP_HOST = HL7 MLLP host server

HL7_MLLP_PORT = HL7 MLLP host server port to listen for incoming HL7 messages

PILOT_MODE = Flag that delineate whether to skip membership check

NATS_OUTGOING_SUBJECT = NATS subject to use

NATS_SERVER_URL = NATS Jetstream connection info

OUTBOUND_QUEUE_TYPE = one of: NATS, SQS

SQS_OUTBOUND_QUEUE_URL = URL of SQS queue to send to

Creating the docker image

Create the container using the docker build command below.

docker build -t qcc-gateway-hl7-listener:1.0.0 .

If the steps completed successfully, the image specified by the -t option should now exist.

Testing

With NATS Config

Install nats cli

brew tap nats-io/nats-tools
brew install nats-io/nats-tools/nats

Set local context

nats context add local --description "Localhost"
nats context ls
nats context select local

Make sure your NATS-specific environment vars are set. They are:

• NATS_OUTGOING_SUBJECT
• NATS_SERVER_URL
• OUTBOUND_QUEUE_TYPE

Start the services

docker-compose up

Create a stream (hl7) and a consumer (hl7.queue) for that stream

nats str add hl7 --subjects "hl7.*" --ack --max-msgs=-1 --max-bytes=-1 --max-age=1y --storage file --retention limits --max-msg-size=-1 --discard=old --max-msgs-per-subject=-1 --dupe-window=2m --replicas=1

nats con add hl7 queue --filter hl7.queue --ack explicit --pull --deliver all --max-deliver=-1 --sample 100 --max-pending=1 --replay=instant --wait=1s

Send a sample HL7 using HL7 Inspector tool. Samples are available under src/test/resources. Import a sample file in Hl7 inspector. Set the send option to the following:

Hit the send button and confirm success in the logs:

Confirm the message was processed by the service and sent to hl7.queue consumer ("Unprocessed Messages": 1)

nats con info hl7 queue

With SQS Config

Make sure your SQS-specific environment vars are set. They are:

• SQS_OUTBOUND_QUEUE_URL
• OUTBOUND_QUEUE_TYPE

Start the services

docker-compose up

Send a sample HL7 using HL7 Inspector tool. Samples are available under src/test/resources. Import a sample file in Hl7 inspector. Set the send option to the following:

Hit the send button and confirm success in the logs:

Confirm the message was processed by the service and sent to SQS queue your environment points to.