In Mirth Connect, Is there anyway to validate sequence number MSH:13 whether it is valid number in sequence with current sequence number or not ?
For e.g. if Previously processed message sequence no MSH:13 is 102.
Then current incoming message sequence no MSH:13 should be 103.
If it is not 103 then validator should reject the message.
I assume your messages are processing sequentially. In Mirth Connect that means a single-threaded source connector and a single-threaded destination connector (or a destination connector with a thread-assignment-variable set to your message sequence id).
You can set a globalChannelMap variable with your sequence number. globalChannelMap.put('lastSeqNo', msg['MSH']['MSH.13']) . Then you can simply compare your current sequence number to globalChannelMap.get('lastSeqNo') and decide to reject or filter the message.
Be aware of:
javascript types (you want to compare numbers not strings)
initializing 'lastSeqNo' to zero if it is not already set (as when a channel is deployed with "clear global channel map" selected) OR ensuring that your comparison handles the case when 'lastSeqNo' is null
what to do if the sender resets its own sequence number. Will this value increase forever or might the sender some day reset it to zero?
Related
We are currently incorporating a FIX engine (using QuickFixJ) in our application. We will be the initiator and use trade capture reports to get informed on all trades happening on the platform.
The trading (and thus the FIX session) will be running 24/7 and we are currently looking into ways to handle this properly. Our concern is that at some point we will need to reset the message sequence numbers to avoid an overflow. We would ideally not want to reset the sequence number as we need to be sure that we catch every single trade. We are worried about the following scenario:
We send a SequenceReset message
Our system crashes due to unrelated reasons
The acceptor side send us one or more TradeCaptureReport messages
Only now does the acceptor side receive our SequenceReset message
Our system has recovered and sends a ResendRequest message, with BeginSeqNo equal to 1 (because we have reset the message sequence number)
We do not get the TradeCaptureReport messages from (3.)
However, we have noticed that in case of a message sequence overflow, neither our engine nor the acceptor side seem to be troubled by this.
The example I have tested is simply sending heartbeats which will overflow the sequence number:
8=FIXT.1.19=13135=A34=149=INITIATOR50=INITIATOR52=20220901-15:26:03.40356=ACCEPTOR98=0108=10141=Y553=INITIATOR554=password1137=910=224
8=FIXT.1.19=00010235=A49=ACCEPTOR56=INITIATOR34=157=INITIATOR52=20220901-15:26:03.65498=0108=10141=Y1409=01137=910=212
8=FIXT.1.19=9035=434=249=INITIATOR50=INITIATOR52=20220901-15:26:03.71856=ACCEPTOR36=2147483646123=Y10=038
8=FIXT.1.19=00007035=049=ACCEPTOR56=INITIATOR34=257=INITIATOR52=20220901-15:26:13.79210=009
8=FIXT.1.19=7935=034=214748364649=INITIATOR50=INITIATOR52=20220901-15:26:13.78956=ACCEPTOR10=044
8=FIXT.1.19=00007035=049=ACCEPTOR56=INITIATOR34=357=INITIATOR52=20220901-15:26:23.85210=008
8=FIXT.1.19=7935=034=214748364749=INITIATOR50=INITIATOR52=20220901-15:26:23.85056=ACCEPTOR10=035
8=FIXT.1.19=00007035=049=ACCEPTOR56=INITIATOR34=457=INITIATOR52=20220901-15:26:33.89610=018
8=FIXT.1.19=8035=034=-214748364849=INITIATOR50=INITIATOR52=20220901-15:26:33.89256=ACCEPTOR10=080
8=FIXT.1.19=00007035=049=ACCEPTOR56=INITIATOR34=557=INITIATOR52=20220901-15:26:43.93310=012
8=FIXT.1.19=8035=034=-214748364749=INITIATOR50=INITIATOR52=20220901-15:26:43.93256=ACCEPTOR10=075
Is this a feature of the FIX protocol or is it undefined behaviour (and just works coincidentally)? And if this doesn't work (or is discouraged), is there a best way to handle ongoing FIX sessions? We have not found any usable information and most exchanges we have seen simply reset once a day.
I think the title of the question should rather be "how does a FIX engine handle message sequence number overflow".
As per the FIX spec the sequence number is always positive: FIX datatypes
Sequence of character digits without commas or decimals. Value must be
positive.
I can only speak for QuickFIX/J: internally the sequence number is of type java.lang.Integer which means its maximum positive value is 2147483647.
Now when QuickFIX/J (or any other engine) accepts or uses negative sequence numbers it clearly is a bug.
Maybe you should approach your Exchange how other clients handle this. I think at some point they have a time window where sequence numbers can (and should) be reset.
I guess the exchange handles it like outlined here: FIX session 24-hour connectivity
I'm using Mido for python, working on parsing midi files into <start_time, duration, program, pitch> tuples and met some problems.
Some files that I parse has multiple note_on, resulting in notes at the same pitch and same program being opened more than once.
Some files contains multiple note_off resulting in trying to close notes that is no longer on due to being closed before (assuming only one note at the same program and same pitch can be on).
Some tracks does not have a program_change in the beginning of the track (or even worse, not even having one in the whole track).
Some files has more than one track containing set_tempo messages.
What should I do in each of these cases to ensure I get the correct interpretation?
In general, to get a correct MIDI message stream, you have to merge all tracks in a type 1 file. What matters for a synthesizer are not tracks, but channels.
The MIDI specification says:
ASSIGNMENT OF NOTE ON/OFF COMMANDS
If an instrument receives two or more Note On messages with the same key number and MIDI channel, it must make a determination of how to handle the additional Note Ons. It is up to the receiver as to whether the same voice or another voice will be sounded, or if the messages will be ignored. The transmitter, however, must send a corresponding Note Off message for every Note On sent. If the transmitter were to send only one Note Off message, and if the receiver in fact assigned the two Note On messages to different voices, then one note would linger. Since there is no harm or negative side effect in sending redundant Note Off messages this is the recommended practice.
The General MIDI System Level 1 Developer Guidelines say that in response to a “GM System On” message, a device should set Program Change to 0. So you can assume this to be the initial value for channels that have notes without a preceding Program Change.
The Standard MIDI Files specification says that
tempo information should always be stored in the first MTrk chunk.
But "should" is not "must".
I am receiving a large number of correlated HL7 messages in Mirth. They contain an ID which is always the same for all correlated messages and they always come within a minute. Multiple batches can be received at the same time. It's hard to say when the batch ends, but when there are no more messages for a minute, it's safe to assume that the batch has finished.
How could I implement an aggregator pattern in Mirth that would keep reading and completing correlated messages and send the completed message after it didn't receive any new messages with the same ID within a defined time interval?
You may drop all incoming message to a folder and store the message ID in a Global Map. Once new messages start to arrive with the message ID different than the one stored in the map (meaning that the next sequence is started), trigger another channel either by sending the message ID it needs to look for or in some other way. After that replace the message ID in the Global Map with the message ID of a new sequence.
If that sounds too complicated, you may do the same, but the second channel will constantly scan the folder (File Reader) and grab only files having the same message ID and older than a minute from a current time (which is in my mind is too vague qualifier).
I've implemented this by saving all messages in a folder using an ID inside the message (that identifies the sequence) as the file name. The file gets updated with each new message. Several sequences live together in the same folder.
The next channel is using a simple file reader that only fetches the files that are a minute or more old.
I am doing a project involving finding a suffix string given a prefix --for instance, "aaa", so that that its hashed value (SHA256) has a certain pattern -- for example, starting with "123".
My method of finding the required hash key is to generate the suffix string in an ordered way: first try all the string with one character -- basically it goes through the ASCII printable code chart, 95 trials in total. If the required hash key is not found, then try all the string with two characters (95*95 trails)... and so on so forth.
I am also required to use akka actor model to let multiple actors get involved in solving this problem concurrently. (The number of actors is an input)
Any idea about how to efficiently divide the total problem to multiple actors using this pattern? Or anyone has a better solution to this problem?
You can group your workers under a BalancingPool which will automatically distribute work to idle actors, with the manager and worker actors using work pulling to prevent the mailbox from growing too large.
The manager accepts two message types: work-request and work-complete. Work-request is called by a worker when it has completed X tasks (where X is, say, 10), signalling the manager to add X more tasks to the BalancingPool. Work-complete is called when a worker has found an appropriate string prefix, at which point the manager sends out a stop command to the BalancingPool instructing it to immediately terminate and to also terminate its workers. Aside from this, the manager is responsible for initially filling the BalancingPool with sufficient prefixes for the workers to test (say, 20 * workerCount), and refilling the pool every time it receives a work-request message.
The workers accept one message type: test-prefix, which contains a string prefix for the worker to test. It also needs to maintain a count of messages that it has received and processed, and when this count reaches X then it is zeroed and the worker sends a work-request message to the manager.
I have few question on FIX protocol sequence number:
What is the benefit of setting ResetOnLogon=N?
Does initiator and acceptor both can send Resend request?
How message sequence helps in session recovery/error handling?
it means that sequence numbers are reset by the protocol on a logon message. This keeps sequence numbers low which can be useful. The sell side usually defines whether this should be done or not.
Yes, as long as the engine thinks that, due to out of synch sequence numbers, a message may have been lost it may request a resend.
If sequence numbers are out of synch between a message and its predecessor, and the number is higher than expected then the engine may assume that some messages have been lost in the connection. This means that it needs to recover these meaasges.
If you have any more questions or want more information I would be happy to reply.
ResetOnLogon determines if sequence numbers should be reset when recieving a logon request. (please find documentation here: http://www.quickfixengine.org/quickfix/doc/html/configuration.html)
Yes, both can send a Resend Request, but you must follow the specs between your side and the counterparty.
The message sequence numbers tell that no messages were lost during the current session. If there is a mismatch, actions must be taken in order to establish the correct sync between the 2 sides.