Introduction to Kafka WebSocket

The Kafka WebSocket is defined as it is a simple WebSocket server that can interface with the Kafka dispersed message server easily. Therefore, we can say that the WebSocket can function as a persistent connection joining the clients and server. A WebSocket can work as the persistent connection linking the client and server. This can give back the Bi-directional full-duplex communication channel, which means that the data transmission can simultaneously be done in both directions on a single carrier. WebSocket can authorize us to construct a real-time application without utilizing the long-polling.

Overview of Kafka WebSocket

Kafka WebSocket is the simple WebSocket server that interfaced with the Kafka distributed message server. It can manage clients subscribing to various topics at one time by sending messages to the topics. The messages can be binary or text; the Kafka WebSocket is mainly used when we require real-time interactions and we need to send the same message to multiple users.

WebSocket can hold up due to the control of the HTTP technology, which can be the strict unidirectional protocol which means the client must request any data transferred by the server to the client. In contrast, the WebSocket can authorize to carry the idea, which can be based on data such as UDP but with the responsibility of TCP, and WebSocket can utilize the HTTP to start the transfer process. Still, it can retain the TCP connection by moving after an HTTP reaction is collected.

How to Use Kafka WebSocket?

WebSocket does not utilize the ‘http://’ and ‘https://’ plan of action, which means they do not answer to the HTTP protocol; instead, it can utilize the URI plan (ws://, wss://), and after that, the client and server require to must answer the WebSocket protocol for the WebSocket specifications.

“ws:” “//” host [ “:”port] path [ “?” query]

“wss:” “//” host [ “:”port] path [ “?” query]

A WebSocket connection can be accepted by improving the HTTP request and a client that can manage the WebSocket.

1. Connection: Upgrade

The connection headers can manage the network connection which needs to be put up unlocked or not after completion of the current transaction; at the time of the WebSocket opening handshake then, we can able to put a header to the improvement specifying that we have to retain moving connection which is utilizing it for the non-HTTP work/request.

2. Upgrade: WebSocket

The clients utilize the upgrade header to query the server to control one of the listed protocols it can clarify in the descending order; we mentioned the Upgrade to WebSocket to indicate that client wants to accept the WebSocket connection.

3. Sec-WebSocket Key

The sec WebSocket key is the arbitrarily generated value of 16 bytes encoded as base64; the client has generated that value.

4. Sec-WebSocket Version:13

Version 13 is the only trusted version of the WebSocket protocol; aside from this obtainable version is not trusted, and the header can manifest that has an infirm version. Once the clients transfer starting request for the opening of the WebSocket connection, it can hold up for the server to give feedback which can be the HTTP 101 diverting protocols response code; the HTTP 101 diverting protocol specifies that the server is diverting to the protocol for which client has been solicited.

HTTP/1.1 101 Switching Protocols
Upgrade: WebSocket
Connection: Upgrade
Sec-WebSocket-Accept: fA9dggdnMPU79lJgAE3W4TRnyDM=

5. Connection: Upgrade

It confirms that the connection has been successfully upgraded.

6. Upgrade: WebSocket

It confirms that the connection has been successfully upgraded.

7. Sec-WebSocket Accept

The sec-WebSocket uses the base64 encoded; although the sec-WebSocket key and the sec-WebSocket accept seem complicated, they exist, so both the clients and server know their counterpart supports WebSocket.

After the client receives the server’s response, the WebSocket connection is open to start transmitting data.

Creating a Messaging Kafka WebSocket

The WebSocket can subscribe to topics involving varied topics at one time and can also convey ideas to the topics, which can be in text or binary format as described below.
The client can consume or produce messages from the same connection.
The client can acquire ideas described in the query specification when connecting to the Kafka WebSocket.
/v2/broker/?topics = my_topic,my_other_topic
If topics are not introduced, then it will not gain the ideas; the format of the idea is sent to the client arranged by the subprotocol; the format can be Kafka-text or the Kafka-binary if the sub-protocol is not set.
By default, the unique group.id generated as per session and that group. id of consumers can be managed by the passing group.id.

Message Transform

Kafka WebSocket can move the idea from Kafka; if our applications need to modify ideas in the conveyance, for example, to append the current-time field in the body, then we can execute a custom-modified class.

For alteration, it needs to enlarge ‘us.b3k.kafka.ws.transforms’, and the modification can be set aside the particular method also, the modification can be put into the clients before accepting the idea by Kafka then the idea has been taken by Kafka prior transferring to the clients.

Binary Messages: The Binary message can be formatted as:
[topic name length bytes] [topic name bytes (UTF-8)] [message bytes]
Text Messages: The text messages are the JSON object which consists of the two mandatory things: Topics and Messages, which may also include some more attributes:
{“topic”: “my_topic”, “message”: “my amazing message”}
{“topic”: “my_topic”, “key”: “my_key123”, “message”: “my amazing message”}

Conclusion

In this article, we have concluded that the Kafka WebSocket can allow us to reply to messages quickly; we also discussed detailed information about the Kafka WebSocket, how it can be helpful, and how it is a better option than HTTP; also we have seen the use of Kafka WebSocket.

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