What this custom route will do is it will get a message from the device and send the message to all the devices that are connected to the WebSocket API. Now that we have tested our two routes, let us look into the custom route onMessage. To check whether our lambda function is working, we can go to DynamoDB and look in the table for the connection id of the connected terminal.Īs above, we can test the disconnect as well by pressing CTRL + C which will simulate a disconnection. When the connection is successful, a connected message will be displayed on the terminal. Make sure to replace the WebSocket URL with the correct URL provided to you. To connect to our WebSocket API, issue the following command. After installing, we can use the tool using wscat command.
#Aws dynamodb client configuration js install#
To install it, we need to just issue the npm install -g wscat command in the command line. To call through WebSockets we can use the wscat tool. Since we have not yet configured call back to devices, let’s first only test the $connect and $disconnect routes. And the second URL, which is Connection URL, is the URL which we will use to call back to the devices which are connected. The WebSocket URL is the URL that is used to connect through WebSockets to our API by devices. The first URL is called WebSocket URL and the second is called Connection URL. Give a stage name such as Test since we are only deploying the API for testing.Īfter deploying, we will be presented with two URLs. In the Actions button, click on Deploy API to deploy. To do that we must first to deploy the API. Now that we have configured our $connect and $disconnect routes, we can actually test whether out WebSocket API is working. We can do the same on $disconnect route as well where the lambda function will be ChatRoomDisconnectionFunction: As integration type, select Lambda function and select the ChatRoomConnectionFunction. Before creating the third lambda function, let us go back again to API Gateway and configure the routes using our created lambda functions. Now we have created the DynamoDB table and two lambda functions. For example, if our JSON messages contain a property call action, and you want to perform different actions based on this property, your route selection expression might be $ The expression is evaluated against an inbound request to produce a value that corresponds to one of your route’s routeKey values. A route selection expression is there to determine which route a particular inbound request should use, which will be provided in the inbound request. WebSocket API ConceptsĪ WebSocket API is composed of one or more routes. Before we start implementing our chat application, there are some concepts that we need to understand regarding real-time applications and API Gateway. In this post, we are going to create a simple chat application using API Gateway WebSockets. So now using AWS infrastructure we are able to create real-time applications using API Gateway. Later in December, they launched it in the API Gateway. This functionality can be done through real-time applications.Īmazon announced that they are going to support WebSockets in API Gateway at AWS re:Invent 2018. What is more efficient is if the server sends data to client chat applications when a chat is received. In this situation, it is a waste if all the chat clients request data from the server like every second. Assume we have a chat application where two chat clients can communicate via a server. Real-time applications are applications where the server gets the ability to push to the clients without the client requesting data first. So what if the server wants to start off the communication and push responses without the client requesting them first? That is where real-time applications come into the play. So first the client initiates the communication and the server responds to the request sent by the server. Here you can see that it is the client that starts off the communication with the server. In client-server architecture, the client sends the requests over the Internet using network communication and then the server processes that request and sends the response back to the client. Most of the applications that are currently operational use client-server architecture. This brings up the question: what are real-time applications? So let’s first answer that question. With WebSockets, we are able to create a two-way communication line which can be used in many scenarios like real-time applications. Recently AWS has announced the launch of a widely-requested feature: WebSockets for Amazon API Gateway.
#Aws dynamodb client configuration js how to#
By Janitha Tennakoon How to build real-time applications using WebSockets with AWS API Gateway and Lambda
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