The purpose of sender-jid-from-mam-message.escript

This script may be used as a part of migration from MongooseIM 3.3.0 (or older). It is able to extract a JID of a groupchat message sender from an XML payload. This piece of information is essential for GDPR commands (retrieve data and remove user) to work properly, as without it the operations on MAM MUC data in DB would be extremely inefficient.

Please consult "3.3.0 to..." migration guide for details. DB-specific sections describe where the payloads are stored and what you should do with the extracted JID.


This script may be executed in every *nix environment which has OTP 19.0 (or newer) installed and escript executable is in PATH.

It doesn't depend on any MongooseIM code or library, so it may be used as a standalone file.

How to use?

sender-jid-from-mam-message.escript (eterm | xml)

The only parameter required by the script is the input format.

You should use eterm if (in MongooseIM config file):

  • You haven't set db_message_format option for MAM at all.
  • db_message_format is set to mam_message_compressed_eterm or mam_message_eterm

You should use the xml option if:

  • db_message_format is set to mam_message_xml.

Once started, the script will run in an infinite loop (until killed or interrupted), expecting a stream of inputs. For every provided payload, a JID will be returned immediately. All communication with the script is done via stdio.

Input format

For both eterm and xml mode, the script expects an input in a very similar format. The high-level overview is:

  • LENGTH is the PAYLOAD length in bytes; if the data retrieved from a DBMS is a Unicode string, LENGTH is equal to the number of bytes used to encode this string
  • PAYLOAD is a sequence of bytes; if a DBMS returns binary data encoded as hex, then it has to be decoded to raw bytes
  • LENGTH and PAYLOAD are separated with a newline character (ASCII code 10 / 0x0a)

Output format

The script output format is very similar to the input:

  • LENGTH is the number of bytes in a JID
  • JID is a sequence of bytes, which encodes a Unicode string
  • LENGTH and PAYLOAD are separated with a newline character (ASCII code 10 / 0x0a)

In case of an error (that is not a critical error, like I/O failure), script will print -N\n (where N is an error code) and will continue to work. Technically it's -N for LENGTH, followed by a newline character and no PAYLOAD part (or 0-length PAYLOAD if you like). The following error codes are supported: * -1\n - Unknown error. Something went wrong with the JID extraction (most likely malformed input). * -2\n - Invalid message type. The message / stanza has been decoded successfully, but it's not a groupchat message.


tools/migration folder contains two files: sender-jid-from-mam-message.example.eterm and sender-jid-from-mam-message.example.xml. They are input samples for the script and may be used as a reference for the script usage.

You can test them by running:

  • tools/migration/sender-jid-from-mam-message.escript eterm < sender-jid-from-mam-message.example.eterm > out
  • tools/migration/sender-jid-from-mam-message.escript xml < sender-jid-from-mam-message.example.xml > out

In both cases the out file should have the following content:



If an environment variable DEBUG is set to 1, the script will store error messages in a /tmp/script-debug file.