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A Scala Fix Engine implementation. It is a full implementation of the session level protocol, tested using the sackfix tester project, supporting acceptor and initiators using AKKA and Scala.

To get started simply download the examples project and start the acceptor and then the initiator. The SackFix suite consists of

  • Examples: This is all you need!
  • Tester: A very simple test suite to stress out any Session level implementation.
  • Session: All of the statemachines and message handling for the Fix Session. ie the business logic lives here.
  • Messages: Code generated Fix Messages for all versions of fix.
  • Common: The code generator and common classes - including all the code generated Fields.

Full documentation is at


Upgraded in 2021 to akka typed and scala 2.13.

Version Year built with
0.1.0 2017 JDK 1.8, Scala 2.11, SBT 0.13.12, Akka 2.4.16
0.1.3 2021 JDK 1.8, Scala 2.13.5, SBT 1.4.7, Akka 2.6.13

Feel free to upgrade and generate your own version.

Does your server need to do anything special?

The tests require that should you receive a NewOrderSingle then you should reply with an ExecutionReport. For instance, see T8_ResendRequestSpec.

You also need a persistent message store so that replay of business messages works.

What is not tested?

Well, SackFix will not implement login, or encryption, or data content. It will also not insist on the ordering of fields within the message or header as experience shows there are too many implementations which do not do that correctly.

Due to the above, tests that focus on these items were not written.

In particular:

  • A tests of ordering of fields in a group,
  • A test that all header fields preceed all body fields

What is tested?

Pretty much all the session level validation and message flows for login, logout and resend requests.

How does it work?

There is a really straight forward Fix sender and receiver based on the old Java sockets - this is very deliberately not straying into NIO, Netty or etc. Its as simple as I could do it, with little thought or effort.

So the simple fix package does key value tuples, and sockets. It provides the handy utils for logging in, logging out and creating headers using the values from application.conf.

Why SackFix tests?

As I said, I've been learning Scala and wanted to know the session level spec, and writing the tests seemed like a fine way to learn.

All the best,


2017 & updated in 2021

How to run it

Edit application.conf with the IP address of your server.

cd into the base dir of the project

Expected output

> test
[info] Compiling 39 Scala sources to C:\all_dev\sackfix\sackfixtests\sf-fix-tester\target\scala-2.11\test-classes...
[info] T14_h_DuplicateTag:
[info] Receive application or administrative message
[info] - should Send message with missing value
[info] T4_b_SendThemTestReqSpec:
[info] Send heartbeat message
[info] - should If send a test request expect heartbeat reply
[info] T2_q_InvalidMessageType:
[info] Receive Message Standard Header
[info] - should Reject invalid message type
[info] T10_2_ReceiveSeqResetSeqGapFillDupLowerSpec:
[info] Receive SequenceReset Message
[info] - should If msgSeqsend time, disconnect
[info] - should logon has low seq num and poss dup flag=y, disconnect and close socket after 2 secs
[info] T10_4_ReceiveSeqResetSeqGapFillSpec:
[info] Receive SequenceReset Message
[info] - should Reset the sequence number!
[info] T10_3_ReceiveSeqResetSeqGapFillLowerSpec:
[info] Receive SequenceReset Message
[info] - should If msgSeqexpected then gap fill
[info] T2_b_SeqNumResend:
[info] Receive Message Standard Header
[info] - should accept first message and then resend request
[info] T1S_a_LoginResendRequestSpec:
[info] Receive Logon message
[info] - should Receive a logon and a resend request
[info] T1S_c_BadCompIdSpec:
[info] Receive Logon message
[info] - should Close the socket
[info] T1S_b_LoginTwiceSpec:
[info] Receive Logon message
[info] - should 2nd Logon should just get socket closed
[info] T14_b_MissingMandTag:
[info] Receive application or administrative message
[info] - should Send message with missing mand tag
[info] T3_e_GarbledChecksumBadLen:
[info] Receive Message Standard Trailer
[info] - should Garbled checsum of 2 chars ignored
[info] Run completed in 1 minute, 32 seconds.
[info] Total number of tests run: 40
[info] Suites: completed 39, aborted 0
[info] Tests: succeeded 40, failed 0, canceled 0, ignored 0, pending 0
[info] All tests passed.
[success] Total time: 99 s, completed


A fix session layer test suite written in Scala. It acts as an initiator and looks for the correct responses.




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