cd Opus-MT/install
make all
sudo make install
cd ../..

Install the MT-server (for Finnish-English):

cd Opus-MT
sudo make all

Make sure that the services are running (change language IDs in the name if necessary):

service marian-opus-fi-en status
service opusMT-opus-fi-en status
service opusMT status

marian-opus-fi-en is the service that runs the actual translation using marian-server. This is implemented as a websocket service that expects plain text input that has been pre-processed according to the model behind the server (i.e. may require tokenized, normalized and text segmented into BPE or other kinds of subword units). opusMT-opus-fi-en status does this kind of pre-processing also including sentence boundary detection. opusMT is a routing server that makes it possible to connect several translation servers. Translation servers need to be defined in a JSON file that is used as configuration.

If any of those servers do not run then try to restart them in this order:

sudo service marian-opus-fi-en restart
sudo service opusMT-opus-fi-en restart
sudo service opusMT restart

The translation service is provided as a websocket service. The opusMT-client.py implements a script that demonstrates how to call the API. Youe can test the service by piping plain text to the client script using the socket of the running server:

echo "Mitä kuuluu? Käännös on hauskaa." | ./opusMT-client.py -H localhost -P 20000 -s fi -t en

This should return something like

{
    "alignment": [
        "0-0 0-2 1-1 2-3",
        "0-0 1-1 3-2 4-3 5-4"
    ],
    "result": "How are you? The translation is fun.",
    "server": "192.168.1.18:20001",
    "source": "fi",
    "source-segments": [
        "Mit\u00e4 kuuluu ?",
        "K\u00e4\u00e4@@ nn\u00f6@@ s on hauskaa ."
    ],
    "source-sentences": [
        "Mit\u00e4 kuuluu?",
        "K\u00e4\u00e4nn\u00f6s on hauskaa."
    ],
    "target": "en",
    "target-segments": [
        "How are you ?",
        "The translation is fun ."
    ],
    "target-sentences": [
        "How are you?",
        "The translation is fun."
    ]
}

The final translation is returned in the result field. source-segments and target-segments show the individual sentences after pre-processing and before post-processing, respectively. The client script sends the request in JSON with text including the plain source language tect to be translated, source and target specifying the source and the target language (typically, iso-639-1 language IDs). source can also be set to detect or DL in order to use language identification to detect the input language.

The same format can be used to request translations from the opusMT routing server. If this service is running, several trabslation services can be connected via the same API. The service listens on port 8080 by default.

echo "Mitä kuuluu? Käännös on hauskaa." | ./opusMT-client.py -H localhost -P 8080 -s fi -t en

It returns an error message in the result field if the language pair is not supported.

Set SRC_LANGS, TRG_LANGS, MARIAN_PORT and OPUSMT_PORT. For example, for installing a server that handles English input and translates to Finnish:

sudo make SRC_LANGS=en TRG_LANGS=fi MARIAN_PORT=10001 OPUSMT_PORT=20001 opusMT-server

You can also look at the other exampels in the Makefile. Edit opusMT-servers.json by adding the additional services and re-install the opusMT service:

sudo make opusMT-router
sudo service marian-opus-en-fi restart
sudo service opusMT-opus-en-fi restart
sudo service opusMT restart

Multilingual models are possible as well. For example, to install a model that is able to translate from German, Afrikaans, Frisian and Dutch to either Estonian or Finnish can be installed by running:

sudo make SRC_LANGS="de+af+fy+nl" TRG_LANGS="et+fi" MARIAN_PORT=10002 OPUSMT_PORT=20002 opusMT-server
sudo service marian-opus-de+af+fy+nl-et+fi restart
sudo service opusMT-opus-de+af+fy+nl-et+fi restart

Edit the server configuration file opusMT-servers.json again to add the new service and restart the service. Each entry in the configuration file specifies a server running on some accessible machine. localhost is the local machine but other IP addresses can be listed here together with the port the translation server is listening at:

{
    "localhost:20000" : {
	"source-languages" : "fi",
	"target-languages" : "en"
    },
    "192.168.1.14:21100" : {
	"source-languages" : "fr",
	"target-languages" : "et+fi"
    }
}

Multilingual models are specified with language IDs separated by + characters. If certain language pairs are served with multiple services then you will need to specify model names to make it possible to select specific models in the request:

{
    "192.168.1.19:20004" : {
	"source-languages" : "de",
	"target-languages" : "fi"
    },
    "192.168.1.12:20008" : {
        "model" : "wmt",
	"source-languages" : "de",
	"target-languages" : "fi"
    }
}

The default name of a model is default (if no name is given) and each language pair should have at least one default model that will be called if no specific model is specified. Finally, update the installation and restart the service after editing the configuration file.

sudo make opusMT-router
sudo service opusMT restart

The default location of the configuration file is /usr/local/share/opusMT/.

• SentencePiece does not compile within MarianNMT for Ubuntu 20.04 (problem in makefile)
• multi-core translation does not work (need to send batches of text instead)