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 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Using the Neptune Gremlin Client in an AWS Lambda function"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "![Architecture: Using the Neptune Gremlin Client in an AWS Lambda function](https://ianrob-examples.s3-eu-west-1.amazonaws.com/images/gremlin-client-lambda.png \"Architecture: Using the Neptune Gremlin Client in an AWS Lambda function\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import boto3\n",
    "import os\n",
    "import json\n",
    "\n",
    "client = boto3.client('lambda')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## neptune-endpoint-info Lambda function\n",
    "\n",
    "This Lambda function acts as a proxy for a `ClusterEndpointsRefreshAgent`. The Lambda polls the Neptune management API on a periodic basis to fetch all the available instance endpoints. Lambda functions that use a `GremlinClient` with a `ClusterEndpointsRefreshAgent` can then use this Lambda to return specific endpoints (`All`, `Primary` or `ReadReplicas`).\n",
    "\n",
    "Use of this Lambda ensures that the management API is not throttled, irrespective of the number of concurrent application Lambdas.\n",
    "\n",
    "The source code for this function can be found [here](https://github.com/awslabs/amazon-neptune-tools/blob/master/neptune-gremlin-client/neptune-endpoints-info-lambda/src/main/java/software/amazon/lambda/NeptuneEndpointsInfoLambda.java). There's a CloudFormation template that you can use to install the Lamdba [here](https://github.com/awslabs/amazon-neptune-tools/blob/master/neptune-gremlin-client/cloudformation-templates/neptune-endpoints-info-lambda.json)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "endpoint_info = client.invoke(\n",
    "    FunctionName='neptune-endpoint-info_{}'.format(os.environ['NEPTUNE_CLUSTER_ID']),\n",
    "    InvocationType='RequestResponse',\n",
    "    Payload=b'\"All\"' # or 'Primary' or 'ReadReplicas'\n",
    ")\n",
    "\n",
    "print(endpoint_info['Payload'].read().decode(\"utf-8\"))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Return full cluster metadata from the Labda proxy\n",
    "\n",
    "The latest version of the __neptune-endpoint-info__ Lambda function can now allso return a full description of the cluster topology. Supply an empty payload (`\"\"`) to request the full cluster metadata. The Neptune Gremlin Client can now use custom endpoint selection criteria to choose endpoints sourced from a Lambda proxy.\n",
    "\n",
    "For more details on using the Neptune Gremlin Client with a Lamnda proxy, [see the documentation](https://github.com/awslabs/amazon-neptune-tools/tree/master/neptune-gremlin-client#connect-the-clusterendpointsrefreshagent-to-a-lambda-proxy-when-you-have-many-clients)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "endpoint_info = client.invoke(\n",
    "    FunctionName='neptune-endpoint-info_{}'.format(os.environ['NEPTUNE_CLUSTER_ID']),\n",
    "    InvocationType='RequestResponse',\n",
    "    Payload=b'\"\"' # empty payload\n",
    ")\n",
    "\n",
    "print(json.dumps(json.loads(endpoint_info['Payload'].read().decode(\"utf-8\")), indent=1))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## neptune-gremlin-client-example Lambda function\n",
    "\n",
    "This Lambda function uses a `GremlinClient` to query Neptune. With each invocation it creates a new vertex. The function uses a `ClusterEndpointsRefreshAgent` that is configured to retrieve the Primary endpoint from the _neptune-endpoint-info_ described above.\n",
    "\n",
    "The source code for this demo function can be found [here](https://github.com/awslabs/amazon-neptune-tools/blob/master/neptune-gremlin-client/gremlin-client-demo/src/main/java/software/amazon/lambda/NeptuneGremlinClientExampleLambda.java)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "gremlin_client_lambda_response = client.invoke(\n",
    "    FunctionName='neptune-gremlin-client-example_{}'.format(os.environ['NEPTUNE_CLUSTER_ID']),\n",
    "    InvocationType='RequestResponse'\n",
    ")\n",
    "\n",
    "print('New vertex: {}'.format(gremlin_client_lambda_response['Payload'].read().decode(\"utf-8\")))"
   ]
  }
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