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Connector blueprints

Introduced 2.9

Every connector is specified by a connector blueprint. The blueprint defines all the parameters you need to provide when creating a connector.

For example, the following blueprint is a specification for an Amazon SageMaker connector:

{
  "name": "<YOUR CONNECTOR NAME>",
  "description": "<YOUR CONNECTOR DESCRIPTION>",
  "version": "<YOUR CONNECTOR VERSION>",
  "protocol": "aws_sigv4",
  "credential": {
    "access_key": "<YOUR AWS ACCESS KEY>",
    "secret_key": "<YOUR AWS SECRET KEY>",
    "session_token": "<YOUR AWS SECURITY TOKEN>"
  },
  "parameters": {
    "region": "<YOUR AWS REGION>",
    "service_name": "sagemaker"
  },
  "actions": [
    {
      "action_type": "predict",
      "method": "POST",
      "headers": {
        "content-type": "application/json"
      },
      "url": "<YOUR SAGEMAKER MODEL ENDPOINT URL>",
      "request_body": "<YOUR REQUEST BODY. Example: ${parameters.inputs}>"
    }
  ]
}

OpenSearch-provided connector blueprints

OpenSearch provides connector blueprints for several machine learning (ML) platforms and models. For a list of all connector blueprints provided by OpenSearch, see Supported connectors.

As an ML developer, you can build connector blueprints for other platforms. Using those blueprints, administrators and data scientists can create connectors for models hosted on those platforms.

Configuration parameters

The following configuration parameters are required in order to build a connector blueprint.

The action parameter supports the following options.

Built-in pre- and post-processing functions

Call the built-in pre- and post-processing functions instead of writing a custom Painless script when connecting to the following text embedding models or your own text embedding models deployed on a remote server (for example, Amazon SageMaker):

• OpenAI models
• Cohere models

OpenSearch provides the following pre- and post-processing functions:

• OpenAI: connector.pre_process.openai.embedding and connector.post_process.openai.embedding
• Cohere: connector.pre_process.cohere.embedding and connector.post_process.cohere.embedding
• Amazon SageMaker default functions for neural search: connector.pre_process.default.embedding and connector.post_process.default.embedding

Amazon SageMaker default pre- and post-processing functions for neural search

When you perform vector search using neural search, the neural search request is routed first to ML Commons and then to the model. If the model is one of the pretrained models provided by OpenSearch, it can parse the ML Commons request and return the response in the format that ML Commons expects. However, for a model hosted on an external platform, the expected format may be different from the ML Commons format. The default pre- and post-processing functions translate between the format that the model expects and the format that neural search expects.

For the default functions to be applied, the model input and output must be in the format described in the following sections.

Example request

The following example request creates a SageMaker text embedding connector and calls the default post-processing function:

POST /_plugins/_ml/connectors/_create
{
  "name": "Sagemaker text embedding connector",
  "description": "The connector to Sagemaker",
  "version": 1,
  "protocol": "aws_sigv4",
  "credential": {
    "access_key": "<YOUR SAGEMAKER ACCESS KEY>",
    "secret_key": "<YOUR SAGEMAKER SECRET KEY>",
    "session_token": "<YOUR AWS SECURITY TOKEN>"
  },
  "parameters": {
    "region": "ap-northeast-1",
    "service_name": "sagemaker"
  },
  "actions": [
    {
      "action_type": "predict",
      "method": "POST",
      "url": "sagemaker.ap-northeast-1.amazonaws.com/endpoints/",
      "headers": {
        "content-type": "application/json"
      },
      "post_process_function": "connector.post_process.default.embedding",
      "request_body": "${parameters.input}"
    }
  ]
}

The request_body template must be ${parameters.input}.

Preprocessing function

The connector.pre_process.default.embedding default preprocessing function parses the neural search request and transforms it into the format that the model expects as input.

The ML Commons Predict API provides parameters in the following format:

{
  "parameters": {
    "input": ["hello", "world"]
  }
}

The default preprocessing function sends the input field contents to the model. Thus, the model input format must be a list of strings, for example:

["hello", "world"]

Post-processing function

The connector.post_process.default.embedding default post-processing function parses the model response and transforms it into the format that neural search expects as input.

The remote text embedding model output must be a two-dimensional float array, each element of which represents an embedding of a string from the input list. For example, the following two-dimensional array corresponds to the embedding of the list ["hello", "world"]:

[
  [
    -0.048237994,
    -0.07612697,
    ...
  ],
  [
    0.32621247,
    0.02328475,
    ...
  ]
]

Custom pre- and post-processing functions

You can write your own pre- and post-processing functions specifically for your model format. For example, the following Amazon Bedrock connector definition contains custom pre- and post-processing functions for the Amazon Bedrock Titan embedding model:

POST /_plugins/_ml/connectors/_create
{
  "name": "Amazon Bedrock Connector: embedding",
  "description": "The connector to the Bedrock Titan embedding model",
  "version": 1,
  "protocol": "aws_sigv4",
  "parameters": {
    "region": "<YOUR AWS REGION>",
    "service_name": "bedrock"
  },
  "credential": {
    "access_key": "<YOUR AWS ACCESS KEY>",
    "secret_key": "<YOUR AWS SECRET KEY>",
    "session_token": "<YOUR AWS SECURITY TOKEN>"
  },
  "actions": [
    {
      "action_type": "predict",
      "method": "POST",
      "url": "https://bedrock-runtime.us-east-1.amazonaws.com/model/amazon.titan-embed-text-v1/invoke",
      "headers": {
        "content-type": "application/json",
        "x-amz-content-sha256": "required"
      },
      "request_body": "{ \"inputText\": \"${parameters.inputText}\" }",
      "pre_process_function": "\n    StringBuilder builder = new StringBuilder();\n    builder.append(\"\\\"\");\n    String first = params.text_docs[0];\n    builder.append(first);\n    builder.append(\"\\\"\");\n    def parameters = \"{\" +\"\\\"inputText\\\":\" + builder + \"}\";\n    return  \"{\" +\"\\\"parameters\\\":\" + parameters + \"}\";",
      "post_process_function": "\n      def name = \"sentence_embedding\";\n      def dataType = \"FLOAT32\";\n      if (params.embedding == null || params.embedding.length == 0) {\n        return params.message;\n      }\n      def shape = [params.embedding.length];\n      def json = \"{\" +\n                 \"\\\"name\\\":\\\"\" + name + \"\\\",\" +\n                 \"\\\"data_type\\\":\\\"\" + dataType + \"\\\",\" +\n                 \"\\\"shape\\\":\" + shape + \",\" +\n                 \"\\\"data\\\":\" + params.embedding +\n                 \"}\";\n      return json;\n    "
    }
  ]
}

Next steps

• To learn more about connecting to external models, see Connecting to externally hosted models.
• For connector examples, see Connectors.