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Rate limits

For security reasons, you are limited to a maximum of requests when using Mix services. This is to prevent Distributed Denial of Service (DDOS) attacks. When the limit is reached, a rate limit error is returned.

The following table describes the default rate limits for Mix services.

Service Limits
Authorization 50 requests/minute per IP address
ASRaaS 2 requests/second per IP address
2 requests/second per App ID
NLUaaS 2 requests/second per IP address
2 requests/second per App ID
DLGaaS 3 requests/second per App ID
TTSaaS 2 requests/second per IP address
2 requests/second per App ID
Event logs 10 requests/second per consumer group

gRPC rate limit error

When a rate limit is exceeded, the rate limiting service returns the gRPC status code UNAVAILABLE as well as the following header in the gRPC metadata:

x-envoy-ratelimited: true

Recover from rate-limit errors

Nuance recommends using the exponential backoff strategy to recover from rate-limit errors, where your application retries the requests and increases the wait time between retries exponentially.

For example:

Data limits

The following table describes the current data limits for Mix projects:

Data Limit
Number of samples sentences in your model1 60,000
Characters per sample 500
Number of literals per entity1 55,000
Number of bytes per entity literal value 256 (see Entity literal values)
Number of entity literals per model1 100,000

1. Please contact Nuance if you need to increase limit values for an application.

The limits are assessed when you build a project. Therefore, for all data except characters per sample, even if you reach one or more of these limits, you can continue to add them, work in your model, train the model, import data from the Discover tab, and make new configurations. However, you will not be able to build the model if it has exceeded one or more of these limits.

For characters per sample, you will not be able to add the sample if you exceed the character count limit. In addition, if you import a TRSX file that includes a sample that exceeds the character count, the sample will not be imported.

Entity literal values

An entity literal value can include a maximum of 256 bytes. For languages such as English, where a single byte is required to encode one character, this means that the value can include a maximum of 256 characters. For other languages, such as Japanese and Korean, two or more bytes are required to encode some characters; in these cases, the maximum number of characters available will be lower.

Importing data into your project

Importing data into your project, whether by importing a prebuilt domain or uploading a TRSX domain file, is an additive operation: any new data will be added, and each duplicate sample that exists in both your current project and in the imported prebuilt domain will be counted.

Depending on your project and the size of the data you are importing, it's good practice to check the Details tab, under the Content section, to keep track of values for your project.