I am new to Health care domain's project. In this project I am having a batch HL7 file that contains multiple patient information in the below format.
FSH
MSH
PID
OBR
OBX
MSH
PID
OBR
OBX
OBX
SO my concern is that MSH segment can be a different in same batch file or it should be same.
Any help will be appreciated.
The MSH header would typically be different betweeen the different records as each set of segments describes one complete transaction (with some execptions). In a batched layout, where the transmission may occur because of an accumulation of records over time that is sent out to the destination on some time interval, there would be several expected differences. If you consider the link below that describes the field layout for the MSH segment, I would at a minimum expect that the date time of message in the batch to differ based on when the actual event occurred and the message control id.
It would also be possible for the message type to differ depending on what your batch reflects. I included a link to the Texas immunization batch specification that expresses a uniqueness constraint on the MSH msg control id
http://www.corepointhealth.com/resource-center/hl7-resources/hl7-msh-message-header
https://www.dshs.state.tx.us/immunize/docs/immtrac/HL7_Data_Transfer_Guide.pdf
You can have different MSH in a HL7 file containing batch results. I am developing HL7 interfaces since last 10 years. As message header can change for results it is possible to do so. You can have same MSH for all results or different MSH for every result in a batch file.
Related
To generate error on CAN, I've done change data field. But It seems just change numerical things.
I want to know how to modify ACK or CRC field to inject error.
Can I change that field with software?
No, you cannot change that from software, since that part of the message is always constructed on CAN Communication Controller level and down (Physical Layer).
Basically, the ACK field is not set in SW. It is "completed" by other nodes while the message is sent, and the bitstream arrived to the ACK bit slot.
The CRC is constructed on Communication Controler level, upon the payload the application wishes to send.
So in order to inject such faults in a CAN message, you need a special HIL (Hardware in the Loop) device, which will forcefully overwrite fields of your choosing.
One such device is a CANSTress from Vector, but there are many others.
Regarding NACK error, you can simulate that without HIL, if you have a simulation environment.Or, simply do not turn on the other nodes on the cluster, ensuring there is no other node to ACK the message. Beware, disconnecting CANH and CANL cables will result in a different error type.
After that I send different runicast messages with the function runicast_send, how can I understand which message was acknowledged when the callback sent_runicast is triggered?
The runicast.h file states:
The runicast primitive adds two packet attributes: the single-hop
packet type and the single-hop packet ID. The runicast primitive
uses the packet ID attribute as a sequence number for matching
acknowledgement packets to the corresponding data packets.
but I didn't understand how to do it in practice. Can somebody provide an example?
One way would be to look at the field sndnxt of struct runicast_conn *c before you send the packet, and then compare that value of the packetbuf_attr(PACKETBUF_ATTR_PACKET_ID) in the "sent" callback of your code.
However note that by default the runicast packet ID is just 2 bits long. Enough to demultiplex the ACK in most cases, but may be insufficient for your purposes. (The packet ID size in bits can be changed by redefining RUNICAST_PACKET_ID_BITS.)
Also Rime is obsolete. Don't use it in your code, especially production code unless you know what you're doing. runicast was never one of the highlights of Rime, I doubt there are no better alternatives (e.g. the uIPv6 stack) for what you want to do.
Getting Patient Analysis Results In HL7 V2.3-V2.3.1-V2.4.
Including analysis date|analysis|result amount|unit|reference sequence.
How could i get it?
Have a look at the ORU^R01-Messages, especially at the OBX segments
OBX/14 Datetime
OBX/3 Observation Identifer
OBX/5 Observation Value
OBX/6 Units
OBX/7 Reference Range
and do not neglect the other fields
This question is on HL7, my understanding is that any segment(sch, pv1 etc) in HL7 is independent of message type(ADT, SIU etc), that means any type of message can contain any type of segment and there are no restrictions that a particular type of message type can have only certain segments and not any segment, am I correct?
Hope my question is clear...
Not exactly. HL7 has many segments and trigger events, each having a specific purpose and action. Out of that whole lot, when someone is designing a healthcare interfacing application, they have to choose the right segments and trigger events. That is called cardinality which requires a definition of:
Mandatory segments (MSH,PID,PV1 etc)
Optional Segments (DG1,PR1,AL1 etc)
Repeating Segments (OBX)
Once cardinality is defined, then the message starts taking its shape.
A patient demographics trigger event shall include MSH, EVN, PID, PV1, IN1, GT1. But not necessarily DG1, PR1 and AL1.
Similarly, a charge message should definitely include FT1 (financial transactions) segment in the message. An order message should definitely include OBR and ORC segments.
Each segment in HL7 has a defined purpose. There isn't any point in including FT1 in demographics message or an OBR in an SIU message (just an example).
What an application can or cannot send out is called specification of that application.
It is required to understand message cardinality. One cannot create an HL7 message on the fly. It is neither technically feasible nor logically correct.
There is one more segment type called “Z” segment which carries the user defined information and is not defined by HL7. For example, ZDS contains additional ID for the imaging study. The number and coding of Z segments are also user defined.
In order to process such segments both sending and receiving applications must agree on the format, which potentially leads to errors.
I am about to write a message protocol going over a TCP stream. The receiver needs to know where the message boundaries are.
I can either send 1) fixed length messages, 2) size fields so the receiver knows how big the message is, or 3) a unique message terminator (I guess this can't be used anywhere else in the message).
I won't use #1 for efficiency reasons.
I like #2 but is it possible for the stream to get out of sync?
I don't like idea #3 because it means receiver can't know the size of the message ahead of time and also requires that the terminator doesn't appear elsewhere in the message.
With #2, if it's possible to get out of sync, can I add a terminator or am I guaranteed to never get out of sync as long as the sender program is correct in what it sends? Is it necessary to do #2 AND #3?
Please let me know.
Thanks,
jbu
You are using TCP, the packet delivery is reliable. So the connection either drops, timeouts or you will read the whole message.
So option #2 is ok.
I agree with sigjuice.
If you have a size field, it's not necessary to add and end-of-message delimiter --
however, it's a good idea.
Having both makes things much more robust and easier to debug.
Consider using the standard netstring format, which includes both a size field and also a end-of-string character.
Because it has a size field, it's OK for the end-of-string character to be used inside the message.
If you are developing both the transmit and receive code from scratch, it wouldn't hurt to use both length headers and delimiters. This would provide robustness and error detection. Consider the case where you just use #2. If you write a length field of N to the TCP stream, but end up sending a message which is of a size different from N, the receiving end wouldn't know any better and end up confused.
If you use both #2 and #3, while not foolproof, the receiver can have a greater degree of confidence that it received the message correctly if it encounters the delimiter after consuming N bytes from the TCP stream. You can also safely use the delimiter inside your message.
Take a look at HTTP Chunked Transfer Coding for a real world example of using both #2 and #3.
Depending on the level at which you're working, #2 may actually not have an issues with going out of sync (TCP has sequence numbering in the packets, and does reassemble the stream in correct order for you if it arrives out of order).
Thus, #2 is probably your best bet. In addition, knowing the message size early on in the transmission will make it easier to allocate memory on the receiving end.
Interesting there is no clear answer here. #2 is generally safe over TCP, and is done "in the real world" quite often. This is because TCP guarantees that all data arrives both uncorrupted* and in the order that it was sent.
*Unless corrupted in such a way that the TCP checksum still passes.
Answering to old message since there is stuff to correnct:
Unlike many answers here claim, TCP does not guarantee data to arrive uncorrupted. Not even practically.
TCP protocol has a 2-byte crc-checksum that obviously has a 1:65536 chance of collision if more than one bit flips. This is such a small chance it will never be encountered in tests, but if you are developing something that either transmits large amounts of data and/or is used by very many end users, that dice gets thrown trillions of times (not kidding, youtube throws it about 30 times a second per user.)
Option 2: size field is the only practical option for the reasons you yourself listed. Fixed length messages would be wasteful, and delimiter marks necessitate running the entire payload through some sort of encoding-decoding stage to replace at least three different symbols: start-symbol, end-symbol, and the replacement-symbol that signals replacement has occurred.
In addition to this one will most likely want to use some sort of error checking with a serious checksum. Probably implemented in tandem with the encryption protocol as a message validity check.
As to the possibility of getting out of sync:
This is possible per message, but has a remedy.
A useful scheme is to start each message with a header. This header can be quite short (<30 bytes) and contain the message payload length, eventual correct checksum of the payload, and a checksum for that first portion of the header itself. Messages will also have a maximum length. Such a short header can also be delimited with known symbols.
Now the receiving end will always be in one of two states:
Waiting for new message header to arrive
Receiving more data to an ongoing message, whose length and checksum are known.
This way the receiver will in any situation get out of sync for at most the maximum length of one message. (Assuming there was a corrupted header with corruption in message length field)
With this scheme all messages arrive as discrete payloads, the receiver cannot get stuck forever even with maliciously corrupted data in between, the length of arriving payloads is know in advance, and a successfully transmitted payload has been verified by an additional longer checksum, and that checksum itself has been verified. The overhead for all this can be a mere 26 byte header containing three 64-bit fields, and two delimiting symbols.
(The header does not require replacement-encoding since it is expected only in a state whout ongoing message, and the entire 26 bytes can be processed at once)
There is a fourth alternative: a self-describing protocol such as XML.