#HL7 Processor

This library provides a simple way to accept and process LLP/HL7 messages. At the moment only an object model is provided, but an easy-to-use DSL will be added later.

The following features will be implemented during the RMU course:

• Build a server to accept HL7 messages
• Expose a plugin model for building message handlers
• Persist incoming messages to a message queue
• Easily store messages to a database
• Build a DSL to easily configure the host

The bin directory provides a few example scripts, but here are a few examples:

Starts a host on port 5900

require 'hl7-processor'

class LoggingChannel
  extend HL7Processor::Channels::Logging

  log_file "hl7.txt"

  for_all_messages do |hl7|
    log.info("Received a message:#{hl7}")
  end

end

host = HL7Processor::Host.new do |config|
  config.port      = 5900
  config.processor = HL7Processor::Processors::Immediate
  config.channels  = [LoggingChannel]
end

host.start

HL7 is transmitted via a protocol called LLP. To send an LLP message to the host, use the following code:

require 'hl7-processor'
require 'socket'

llp = HL7Processor::LLPMessage.from_hl7("hello!")

socket = Socket.tcp("127.0.0.1", 5900)
socket.write(llp.to_s)
socket.close

Processors

A 'processor' defines how each incoming LLP message will be processed. At the moment there are two processors: Immediate and Background.

The Immediate processor synchronously handles incoming messages. The Background processor uses Resque to place the message on a queue named 'hl7_jobs' so that it can be handled later. In production, the Background processor is preferred as it provides greater fault tolerance and performance can be scaled as needed by adding more Resque workers.

Please see the Resque project page for more information.

Channels

A 'channel' defines a unit of work for a single unpacked HL7 message. The message can be handled by as many channels as are specified in the Configuration object.

To be functional, a channel merely needs to respond to a 'handle(hl7)' method, but a series of helper modules (Basic, Logging) have been created in the HL7Processor::Channels namespace that provide a DSL for creating custom channels easily.