Millistream Data Feed API (MDF) version 1.0.26 released

Millistream is pleased to announce the release of version 1.0.26 of our open source Data Feed API.

  • updated mdf_fields.h to the latest version (a few new fields, including new message MDF_M_QUOTEEX).
  • new property MDF_OPT_TIMEOUT that reports the number of seconds one have to wait in maximum before having to call mdf_consume() to let it handle internal idle timers (like sending heartbeat requests). Useful if you extract the libmdf descriptor with MDF_OPT_FD and use say select/poll/epoll to manage events.
  • new property MDF_OPT_HANDLE_DELAY to enable/disable delay-mode (in delay-mode the intended delay of the message is sent on the wire by the server).
  • new function mdf_get_next_message2() that replaces mdf_get_next_message().
  • new function mdf_get_mclass() which returns the Message Class of the current received message.
  • new function mdf_get_delay() which returns the intended delay of the current received message if delay-mode is enabled on the connection.
  • new function mdf_message_set_property() which replaces mdf_message_set_utf8_validation() and mdf_message_set_compression_level() with a more generic property function. Also now supports the new property MDF_MSG_OPT_DELAY to set the intended delay of the message.
  • new function mdf_message_get_num_fields() which returns the number of added fields to the current message.
  • mdf_message_move() will now keep the old insref if both src and dst are set to UINT64_MAX.
  • the mdf_t and mdf_message_t structures have been reduced in size.
  • mdf_message_send() have been optimized and is e.g now more efficient when sending messages in bulk.
  • the internal send buffer used by mdf_message_send() have been moved from mdf_t to mdf_message_t.
  • Compatible with the new API in OpenSSL 3.0

As usual this version of MDF is binary compatible with previous versions, so there is no need to recompile client applications, so users (including users of the Java JNI wrapper) can simply upgrade by replacing the libmdf file itself.

MDF 1.0.26 is available for download from the following locations:

Linux users who have added our deb or rpm repositories can upgrade by simply issuing:

  • Debian/Ubuntu: “apt-get update && apt-get upgrade
  • Red Hat/CentOS/Amazon Linux AMI: “yum upgrade

Information on how to add these repositories are available at

And as usual, if you have any questions what so ever regarding this release or other things, don’t hesitate to contact us at