org.agent.slang.in.google

Class GoogleASRComponent

java.lang.Object

MixedComponent

org.agent.slang.in.google.GoogleASRComponent

public class GoogleASRComponent
extends MixedComponent

This component enables the use of Google's Speech Recognition engine.

Using the Google Speech API directly is no longer an ideal solution because it is limited to 50 requests/day (even with an API key). However, the implementation of the Web Speech API in Google Chrome is exempt from this limit, hence the dirty workaround that this component implements.

The component works by setting up a WebSocket server and having a Web page open in Chrome connect to it and send it the results of the Web Speech API. Unfortunately, for Chrome to authorize the Web page to access the microphone and remember the authorization, the page has to be served via an HTTPS server. The page, in turn, needs to access the WebSocket server via TLS too. It is thus necessary to create a self-signed certificate and tell Chrome to accept it as valid. The process is described below.

Setting up the component

Creating the certificate

The following command can be used to create the certificate. When asked for the certificate information, enter localhost for the Common Name/CN; the other values do not matter as much.

 openssl req -new -newkey rsa:4096 -days 5000 -nodes -x509 -sha512 -out cert.crt -keyout cert.key
 

The resulting files must then be converted into a PKCS #12 file. This can be done by issuing the following command and entering an empty password (adjust the output path as needed):

 openssl pkcs12 -export -in cert.crt -inkey cert.key -out $PATH_TO_AGENTSLANG/data/org/agent/slang/in/google/cert.p12
 

The resulting .p12 file can actually be installed anywhere, but this location is where the default configuration files point to.

Making Chrome accept the certificate

Under Microsoft Windows

If the component is used as-is, Chrome will complain that the certificate is invalid. To solve this problem, open Chrome's settings, go to Advanced → HTTPS/SSL → Manage certificates, import the cert.crt file previously created and choose "Trusted Root Certification Authorities" as the destination.

Finally, restart Chrome (this is a very important part of the process).

Under GNU/Linux

Open Chrome, go to its Settings, then Advanced → HTTPS/SSL → Manage Certificates, go to the "Authorities" tab and import cert.crt .

Usage

Configuration

The certificate parameter of the component must point to a valid *.p12 file (as created in the previous section). In addition, the language parameter must contain the language code corresponding to the language that should be used for recognition.

Running

Once AgentSlang is running with a configuration file that makes use of this component, the URL https://localhost:8149/ should be opened in Chrome (this should happen automatically) and permission to use the microphone should be granted, if Chrome asks.

Communication protocol

This section describes the exact protocol used over the WebSocket.

Note that the AgentSlang component being the WebSocket server, it must be started before the Web browser.

Initialization

Once the connection between the browser and the AgentSlang component is established, the component sends the browser the language code that should be used for speech recognition.

(Technically, the component could send the language code at any moment, even though it currently does not.)

Recognition loop

After it has received the language code, the browser starts speech recognition. Once a result is available, it is sent through the WebSocket.

After each iteration, recognition is started again, allowing for continuous recognition. (The SpeechRecognition object natively supports a continuous mode, but it seems slower than using the non-continuous mode repeatedly.)

At any moment, the AgentSlang component can send either stop or start to stop or resume recognition. (It is currently used for suspending recognition while the agent speaks, so that it does not hear itself.)

End

If the AgentSlang component is closed, the Web browser automatically stops the recognition engine. If the AgentSlang component is restarted, the Web page must be reloaded.

Conversely, if the Web page is closed while the AgentSlang component is still active, it can simply be reopened. OS Compatibility: Windows and Linux

Version:

1, 2/14/13, 2, 4/14/15

Author:

Ovidiu Serban, ovidiu@roboslang.org, Sami Boukortt, sami.boukortt@insa-rouen.fr

Constructor Summary

Constructors

Constructor and Description
GoogleASRComponent(java.lang.String outboundPort, ComponentConfig config)

Method Summary

Modifier and Type	Method and Description
void	close() Closes and stops the connection with google ASR port.
void	definePublishedData() Checking type of output data.
void	defineReceivedData() Checking type of input data

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GoogleASRComponent

public GoogleASRComponent(java.lang.String outboundPort,
                          ComponentConfig config)

Method Detail

definePublishedData

public void definePublishedData()

Checking type of output data.

defineReceivedData

public void defineReceivedData()

Checking type of input data

close

public void close()

Closes and stops the connection with google ASR port.