Configuring the Natural Language Engine service

The Natural Language Engine (NLE) is Nuance's text-to-meaning engine, also called a semantic engine.

Management Station displays commonly-used properties on the Settings tab, and the following tables shows some of these properties. (Management Station does not display less-common parameters, but you can add them to the display at any time. For a complete list, see Speech product parameters.)

Note: NLE is packaged with a self-signed certificate and pre-configured to enable secure connections using TLS/SSL. You can use the self-signed certificates for testing and development, but for a secure production environment you need to acquire a certificate signed by a Certificate Authority (CA), and generate a new keystore and certificate. Then configure the properties described below under SSL settings.

General settings

Service property

Description

Data type

Default

nle.home

NLE base installation directory.

Default is the value of the NLE_HOME environment variable (see Data pack locations).

STRING  

nle.dataHome

Base directory for the data files downloaded and/or created by NLE.

Note: Nuance recommends that you change the value to a path outside the installation directory so that NLE does not create any files in the installation directory.

STRING ${nle.home}/data

nle.host

IP address or hostname of the machine on which the NLE instance is running. This property is used by NLE when providing model URLs to NTpE.

The value localhost can be used when NTpE and NLE are co-located on the same machine (and Nuance Resource Manager is disabled via rm.enabled).

STRING  

nle.port

Port on which NLE listens for incoming requests, either HTTP or WebSocket.

INT 9091
usingJava8

Indicates Java 8 is installed on the Natural Language Engine service host. Only relevant when using Management Station.

Note: If using Management Station and running NLE on a host with Java 17, you must set usingJava8 to false in the Natural Language Engine service properties.

BOOLEAN true

Licensing setting

Service property

Description

Data type

Default

license.path

Port and IP address of the Nuance License Manager, using the format:

port@ip_address

STRING 27000@localhost

Resource Manager settings

You must configure NLE to point to the Resource Manager for engine registration purposes.

Service property

Description

Data type

Default

rm.enabled

Allows the Natural Language Engine to register its capabilities with the Resource Manager.

When the NTpE property resourceManager : enabled is also enabled, NLE publishes its capabilities to the Resource Manager, and requests from the Resource Manager a suitable NTpE instance when it needs to perform tokenization for a given session.

BOOLEAN  

rm.uris

Hostname (or IP address) and port (usually 9001) to connect to the Nuance Resource Manager listener.

STRING  
rm.retryInterval

Specifies the time to wait, in milliseconds, before the Natural Language Engine attempts to reconnect to Resource Manager.

   

rm.hostNameVerificationEnabled

The service requests SSL validation with a CA-signed certificate when registering with Nuance Resource Manager servers when using HTTPS.

BOOLEAN false

NTpE settings

Service property

Description

Data type

Default

ntpe.uri

Hostname (or IP address) and port of the NTpE instance that NLE will use to perform tokenization. The default port is 9092.

This value is used when ntpe.resourceManagerEnabled is false.

STRING wss://localhost:9092/NTpE

ntpe.resourceManagerEnabled

When enabled, NLE will locate a suitable NTpE resource via the Nuance Resource Manager, in which case the property above is ignored.

BOOLEAN  

ntpe.hostNameVerificationEnabled

Specifies whether to use a self-signed certificate for SSL validation with NTpE or alternatively, to perform a complete validation with a CA-signed SSL certifcate.

BOOLEAN false

Resource downloading and management settings

Note that the resource.preloadOnStartup[i] is an array of modules to preload, where [i] refers to the array index.

Service property

Description

Data type

Default

resource.download.connectTimeout

Timeout, in milliseconds, when connecting to the remote server when downloading resources.

Default is 10 seconds.

INT 10000

resource.download.socketTimeout

Timeout, in milliseconds, when performing a resource download request from the remote server.

Default is 10 seconds.

INT 10000

resource.download.httpClientCache.enabled

Specifies whether the HTTP client cache for resources is used.

Note: Do not set this property to false, because it causes the NLE service to fail.

BOOLEAN true

resource.download.httpClientCache.maxEntries

Maximum number of serialized cache entries that will be stored on disk in the HTTP client cache (by default ${nle.dataHome}/httpModelCache).

Note: These caches are small so it is acceptable to have them on disk.

INT 1000
resource.download.ssl.certificateVerificationEnabled

Specifies whether NLE verifies the resource HTTPS server certificate when downloading resources.

BOOLEAN false

resource.diskCache.maximumSizeMetric

Metric to use to measure maximum size of resource files that can be stored in disk cache, either Count or Size. Determines which of the following parameters to apply. String Count

resource.diskCache.maximumFileCount

Maximum number of resource files that can be stored in the disk cache.

This parameter is ignored when resource.diskCache.maximumSizeMetric (above) is set to Size, in which case parameter below applies.

INT 1000

resource.diskCache.maximumSizeInMegabytes

Maximum size of all resource files stored in the disk cache, in megabytes (MB).

This parameter is ignored when resource.diskCache.maximumSizeMetric is set to Count, in which case parameter above applies.

INT 100
resource.preloadOnStartup.id ID of the artifact to preload . STRING  
resource.preloadOnStartup.type Type of artifact to preload. STRING application/x-nuance-semantic-model
resource.preloadOnStartup.uri URI of the artifact to preload. STRING  

Model settings

Service property

Description

Data type

Default

model.cache.maximumSize

Maximum number of semantic models that can be stored in the cache.

INT 100

model.cache.expireAfterAccess

Specifies how long a model is kept in the cache after being accessed. After this interval (expressed in seconds), models are removed the next time the cache is cleaned.

Default is 5 days.

INT 432000

model.cache.maintenancePeriodInMinutes

Delay, in minutes, between cache maintenance operations. This indicates how often the disk cache is cleaned.

Default is 1 hour.

INT 60

Wordset settings

Service property

Description

Data type

Default

wordSet.cache.maximumSize

Maximum number of wordsets that can be stored in the cache. INT 500

wordSet.cache.expireAfterAccess

Specifies how long a wordset is kept in the cache after being accessed. After this interval (expressed in seconds), wordsets are removed the next time the cache is cleaned.

Default: 5 days

INT 432000

wordSet.cache.maintenancePeriodInMinutes

Delay, in minutes, between cache maintenance operations. This indicates how often the disk cache is cleaned.

Default: 1 hour

INT 60

Watcher settings

Service property

Description

Data type

Default

watcher.enabled

Specifies whether the watcher service is enabled.

Note: Do not change unless instructed by Nuance.

BOOLEAN true

watcher.alarms.enabled

Specifies whether NLE sends alarms to the watcher service.

Note: Do not change unless instructed by Nuance.

BOOLEAN true

Trust setting

Service property

Description

Data type

Default

trust.maxClockDriftInMilliseconds

Specifies the drift tolerance (in milliseconds) between client and server hosts for security verification purposes. Based on difference in UUID timestamps, with a valid range of 1-120 seconds and default value of 10 seconds.

INT 10000

SSL settings

Service property

Description

Data type

Default

server.ssl.enabled

Specifies whether SSL (TLS) is enabled.

BOOLEAN true

https.keyStore

Path to the keystore file, which holds a valid SSL certificate.

Note: Nuance highly recommends that you generate a new keystore and certificate.

STRING ${nle.home}/config/nle_keystore.jks

https.keyStorePassword

Encrypted keystore password used to protect the keystore file.

STRING