In the last blog we discussed 4 major file types/documents that are used in healthcare data exchange: HL7, DICOM, CCD and CCR. In order to exchange these data types, application interfaces need to be deployed to allow for the integration of disparate healthcare systems.
Today, we will cover how applications communicate or interface with each other.
Interfaces typically use what is called a transport protocol, which “provides end-to-end communication services for applications within a layered architecture of network components and protocols.”
The most common transport protocol in use is TCP or Transmission Control Protocol. Sometimes referred to as TCP/IP, it allows for applications to stream data to each other. For example, if you have a Patient Management System that generates HL7 SIU messages (scheduling messages) and that application interfaces to an HL7 routing engine, it is likely that the two interfaces would communicate via TCP.
In healthcare, there is a subset of TCP known as MLLP which adds specific delimeters to messages to denote the beginning and end of a message. The receiving application needs to know where one message ends and another begins in order to deliver the correct information to the system. In TCP, you would do this by specifying a length header, or more simply put, the details about where messages start and end. With MLLP, specifiying length headers is not necessary as the transport protocol inserts the delimiters for applications to know where the messages begin and end. Confusing, I know!
Sometimes, it may not be necessary or preferred to use TCP/MLLP for streaming data, and applications will use Simple File Transfer or file drop. This is accomlished by outputing the messages and storing them in a directory on the computer or server. Another application or interface checks the folder for new messages and consumes them when they are written to the directory.
Interfaces need transport protocols to exchange information and it is common for systems to need to communicate over various connectivity services, making integration somewhat challenging. Talking with your health information service provider and/or your integration specialist can help you understand the best method for interfacing healthcare applications together.