Weslang

Weslang: is a standalone WEb Service to detect the LANGuage of a given piece of text.

It works by executing both CLD2 and Language-Detection.

The exposed API is very simple:

host:8080/detect?q=<TEXT>

The endpoint also supports POST requests in case longer payloads are required.

The response will be a JSON document like the following:

{
    "language": "en",
    "confidence": 0.99
}

Where language is the ISO_639-1 code of the language (except for Chinese in which the locale is also returned, that is the result would be either zh-cn or zh-tw).

Additional endpoints for checking the health of the webservice will be exposed at localhost:9001.

Among the endopoints one can find

• http://localhost:9001/health
• http://localhost:9001/metrics
• http://localhost:9001/env
• http://localhost:9001/info
• http://localhost:9001/mappings
• http://localhost:9001/trace

This is done automatically by the Spring-Boot framework, via the Actuator plugin.

Components

This project includes two components that could easily be a project on their own.

Java Bindings for CLD2

Using JNA a Java interface is exposed for getting the language via the CLD2 library.

The code lives in //java/com/deezer/research/cld2

Fork of Language-Detection

In //third-party/java/language-detection-v2 we have a fork of language-detection.

The main changes we did, was to remove the randomization and some performance improvements. See the file THIRD_PARTY.yaml in that folder for a comprehensive list of changes.

Building and Testing

To build and test this project BUCK is required and also Java 7. That means that it cannot be built under Windows.

$ buck test --all
$ buck build //java/com/deezer/research/language:detection_app

Running

The build command generated a file called buck-out/gen/java/com/deezer/research/language/detection_app.jar, which is a self contained binary.

To run it just execute:

$ java -jar detection_app.jar

If for some reason you don't want or can't execute both detectors, you could run:

$ java -jar detection_app.jar --spring.profiles.active=java_only
$ java -jar detection_app.jar --spring.profiles.active=cld2
$ java -jar detection_app.jar --spring.profiles.active=both

Currently the Cld2 bindings are only generated for linux-x86-64, so if your machine is different it probably won't work. In such a case, just execute it with the java_only profile.

Launch service using docker

The service can be also launched using docker. It requires the installation of docker and docker-compose. See docker home page for installation references.

Once docker is installed execute

$ docker-compose up -d

this will build the image of the service and launch it. To see on which port the service is exposed, execute docker-compose ps. This will display a table similar to the example below:

$ docker-compose ps
    Name                   Command               State                        Ports
----------------------------------------------------------------------------------------------------
weslang_api_1   java -jar buck-out/gen/jav ...   Up      0.0.0.0:32774->8080/tcp

in above example, the service on port 8080 is exposed on port 32774.

On Mac OsX, docker runs on a VM. To know the actual ip, it can be executed the following command:

$ boot2docker ip
192.168.59.103

in above example, the service can be queried by executing:

$ python -c "import urllib;\
print(urllib.urlopen('http://192.168.59.103:32774/detect?q=hello%20world').read());" | \
python -m json.tool
{
    "confidence": 0.7706013715278043,
    "language": "en"
}

The health endpoint running on port 9001 can be accessed by executing the following command:

$ docker exec CONTAINER_ID python -c "import urllib;\
print(urllib.urlopen('http://127.0.0.1:9001/health').read());" | \
python -m json.tool
{
    "status": "UP"
}

the container id can be obtained by executing docker ps. For example:

$ docker ps
CONTAINER ID        IMAGE                COMMAND                CREATED             STATUS ...
a88826098461        weslang_api:latest   "java -jar buck-out/   21 hours ago        Up 21 hours

which outputs a CONTAINER_ID equals to a88826098461.

Credits

This project is possible to several Open Source Projects

• Spring-Boot: Java Framework.
• CLD2: The language detector built into Chrome.
• Language-Detection: Language detector provided by Cybozu Labs.
• BUCK: build system released by Facebook.
• Guava: Additional Java libraries provided By Google.
• JNA: Libary to easily integrate C libraries with Java.

License

This project is released under the Apache 2.0 License.