Implementation FAQ:Use of Transports with HL7 v3

Removable Media over a network

Usecase

For retinal screening there is a requirement in some implementations to work with laptops that are synchronised once a week with the data stored on a central server to collect requests for screening to be done and results of screening.

The same information may be conveyed in other situations over a permanent network connection, or using removable media (pen drive or CD).

For laptop synchronisation using messaging to transfer and individually acknowledge a few thousand messages proved too slow -- and so it was proposed that the removable media specification be used -- with the directory structure transferred using the network.

Discussion

Acks can be sent by a different media

The Abstract Transport Specification document explicitly states that there is no requirement that a response be transported using the same transmission infrastructure as the initial interaction .. things like accept acks and receiver responsibilities make statements about communications between HL7 Applications, never about layers below that.

This means that there could be a transport protocol defined that uses the Removable Media specification for conveying the information, and includes transport level acknowledgement using a network connection.

Use a database or version control system to synchronise

If it's basically about synchronizing a central directory structure with (many) laptops, I'd either use a versioning system such as [|SVN] with appropriate clients on the laptops, or store the stuff-to-be-exchanged in a database and use database replication, which is widely supported. I'd see no need to reinvent such functionality on the HL7 level. On that level, the requirement that a transport must always leave both ends in a consistent state should be sufficient - probably the ATS already requires this. Marc -- www.marcdegraauw.com

The requirement is that the entire directory structure is either fully replicated, or not replicated at all - but I agree that this could be done using version control software or database replication. Charliemccay 11:25, 6 June 2007 (CDT)