OS
•MS Windows Operating System (Windows 10, 11 or Windows Server 2012 or higher)
•250 MB Free Memory. See Below.
•HL7 Message Maximum Size: 128 Megabytes.
•Microsoft .Net 8 Desktop Runtime. Download from Microsoft HERE
•Versions prior to 2.1 use the .Net 6 Desktop Runtime. (Out of support) Download from Microsoft HERE
How Much System Memory Do You Need?
Your CORE HL7 Listener receives HL7 messages over TCP/IP, writes them out to your data folder, and then returns a HL7 ACK message to the sender. It does this very quickly (upwards of 80 messages per second on most systems) and most HL7 messages in the world are small (typically less than 2KB in size). When receiving a 2KB message a Listener may require 10 to 12 KB of memory during this process of receiving the message, verifying that it is a valid HL7 message, etc. From this you can calculate just how much available memory you should have for your Listener software at any given time.
For instance if you have 1 Listener with 100 clients OR 100 Listeners with 1 client each who are sending you typical ADT messages (2KB or smaller), and they ALL send you a message at the exact same instant, your machine would need (100 * 12KB = 1.23MB) of memory in that precise instant or else Windows would start using virtual memory (IE swap files) which will degrade performance. Remember that the memory used when receiving a HL7 message is released when the receive operation is complete.
This calculation is not that intimidating unless you need to receive very large HL7 messages. Take the above scenario but now you have your 100 clients each wanting to send large HL7 messages of say an average of 50MB in size. Now the calculation can become very different. A 50MB HL7 message
may require 200-300 MB of memory to handle the receive operation so 100 SIMULTANEOUS receive operations would require up to 30GB of available memory in order to efficiently process all 100 transactions in memory without swapping. Remember that this would ONLY apply to the simultaneous receipt of these messages. Starting with version 2.2 of the CORE HL7 Listener we have optimized our end of this process so that, according to our benchmarks under ideal conditions, the receipt and handling of a 70MB HL7 message takes less than 2 seconds.
Upgrading from Versions Earlier than 3.0
If you are upgrading from an earlier version of the CORE HL7 Listener to version 3.0 or higher you might see a warning message when you start the program. Starting with version 3.0 we have changed the Windows Services you have available to you, adding the Private Service as well as increasing the number of Primary Services from 4 to 20. This means that IF you have any of the 4 primary services installed from a version prior to version 3.0 they must be removed from your Windows Services list. When you start the program you will see this Message Box.
The Main Window
Just click Yes here, let the software remove the old service entries. You can then make any changes you might want and then go to the 
Windows Service(s) Status Tab and click the 
Install Services button and you are back to where you started and can immediately continue. See Running As A Service for more information.
Reinstall Services After Upgrade
Demo Mode (Trial Period) Restrictions
DEMO licenses are free for 30 days of use. With a DEMO license you cannot run the Windows Services (see Running Windows Services) and are restricted to Running Locally. You can also purchase unrestricted short-term licenses online HERE (you will have to create a HermeTech account).
Contact Customer Service for assistance if you have any questions at all.
