Kafka Connect REST API: Easy Configuration with 2 Use Cases and Features

Real-time Big Data Solutions use their systematic framework to provide the best outcomes that Businesses require. In our Digital Era, Business Servers need Real-time Data Processing Services like Apache Kafka which are fast, resilient and allow their Customers to see data in “real-time” without any lag.

Companies can develop Real-time Data Feeds using Apache Kafka, a popular Distributed Streaming Platform used by over 30% of Fortune 500 companies. Apache Kafka has low latency and high throughput, and Kafka Connect REST APIs, which may be used to link different systems for executing administrative operations and make message production and consumption easier.

In this article, we’ll highlight Apache Kafka’s utility in the Business Data Handling, the Kafka Connect functionality, Kafka Connect REST APIs and how you can configure them to use and integrate with other systems. 

What is Apache Kafka?

Apache Kafka is an Open Source, Distributed Streaming Platform that allows for the development of Real-time Event-Driven Applications. It enables Developers to create Applications that consistently produce and consume streams of Data Records, relying on a message broker that relays messages from the Publishers (systems that transform data into the desired format from Data Producers) to the Subscribers (systems that manipulate or analyze data in order to find alerts and insights and deliver them to Data Consumers). 

Also Read: Apache Kafka Logs

As a result, Apache Kafka has a fault-tolerant and resilient architecture. Kafka copies the partitions to other Brokers (also known as replicas) from the elected Broker (leader) to ensure robustness. A Broker is a working Server or Node; like a facilitator between Data Producer and Data Consumer Groups.

Also, read an in-depth article on Kafka replication.

Business Benefits of Using Apache Kafka

Low Latency Publish-Subscribe Messaging Service

• For huge amounts of data, Apache Kafka has very low end-to-end latency, up to 10 milliseconds.
• This means that the time it takes for a data record produced for Kafka to be retrieved by the consumer is quite quick. It is because it decouples the message, allowing the Consumer to retrieve it at any moment.

Seamless Messaging and Streaming Functionality

• Apache Kafka provides a unique capacity to publish, subscribe, store, and process Data Records in real-time, thanks to its special ability to decouple messages and store them in a highly efficient manner.
• With such seamless messaging functionality, dealing with huge volumes of data becomes simple and easy, giving Business Communications and Scalability a considerable edge over conventional communication approaches.

Consumer Friendly

• Kafka may be used to integrate with a wide range of Consumers.
• The best thing about Kafka is that it may behave or act differently depending on the Consumer with whom it connects because each Customer has a varied ability to manage the messages that come out of Kafka.
• Furthermore, Kafka integrates nicely with a wide range of consumers who write in a wide range of languages.

What is Kafka Connect?

Kafka Connect is a robust tool for streaming data between Apache Kafka and other systems. It enables scalable and reliable data movement in and out of Kafka with ease, making it simple to define connectors and handle massive volumes of data efficiently.

Key Features of Kafka Connect:

• Reduced Custom Development: Eliminates the need to build custom producer or consumer applications or third-party data collectors.
• Streamlined Architecture: Simplifies setting up connectors, allowing rapid data transfer to and from Kafka.
• Data Integration: Supports both legacy and modern data stores like databases, data warehouses, and HDFS.

Kafka Connect REST API Execution Modes

Standalone Mode

• In Standalone Mode all work is performed in a single process. It is easier to set up and helpful in cases when just one worker is required (e.g., collecting log files), but it lacks some of Kafka Connect’s capabilities, such as fault tolerance. 
• This mode is helpful for obtaining status information, adding and deleting Connectors without interrupting the operation, as well as for testing and troubleshooting.

Distributed Mode

• The other mode of execution, Distributed mode handles automatic balancing of work, allows you to scale up (or down) dynamically, and offers fault tolerance both in the active tasks and for configuration and offset commit data. 
• In Distributed Mode, Kafka Connect REST API is the primary interface for automatically forwarding requests to Kafka Clusters. 

Kafka Connect REST API Content Types

• The REST API only supports application/json as both the request and response entity content type. Your requests should specify the expected content type of the response via the HTTP Accept header:

Accept: application/json

• And should specify the content type of the request entity (if one is included) via the Content-Type header:

Content-Type: application/json

Kafka Connect REST API Configuration

• Kafka Connect REST API can be configured using the listeners’ configuration option. This field should contain a list of listeners in the following format: 

protocol://host:port,protocol2://host2:port2. 

• Currently, supported protocols are HTTP and HTTPS. For example:

 listeners=http://localhost:8080,https://localhost:8443

Note: Kafka Connect REST API is useful for managing connectors; by default, it runs on port 8083 if no listeners are specified. The REST API returns standards-compliant HTTP statuses for status and errors. Clients should check the HTTP status, especially before attempting to parse and use response entities.l

• All endpoints will utilize a common error message format for all errors with status codes in the 400 or 500 range. For example, requesting an entity that omits a required field may generate the following response:

HTTP/1.1 422 Unprocessable Entity
Content-Type: application/json

{
    "error_code": 422,
    "message": "config may not be empty"
}

• The following are the currently supported Kafka Connect REST API endpoints:

HTTP	URI	Description
GET	/connectors	Gets a list of active connectors.
POST	/connectors	Creates a new connector, returning the current connector information is successful.
GET	/connectors/(string:name)	Gets information about the connector.
GET	/connectors/(string:name)/config	Gets the configuration for the connector.
PUT	/connectors/(string:name)/config	Creates a new connector using the given configuration or updates the configuration for an existing connector.
GET	/connectors/(string:name)/tasks	Gets a list of tasks current running for the connector.
DELETE	/connectors/(string:name)/	Deletes a connector, halting all tasks and deleting its configuration.
GET	/connector-plugins	Lists the connector plugins available on this worker,
POST	/connectors/(string:name)/restart	Restarts a connector and its tasks.
GET	/connectors/(string:name)/tasks/(int:taskId)/status	Gets the status for a task.
POST	/connectors/(string:name)/tasks/(int:number of tasks)/restart	Restarts an individual task.
PUT	/connectors/(string:name)/pause	Pauses the connector and its tasks, which stops message processing until the connector is resumed.
PUT	/connectors/(string:name)/resume	Resumes a paused connector or do nothing if the connector is not paused.
GET	/connectors/(string:name)/status	Get the current status of the connector, including whether it is running, failed or paused, which worker it is assigned to, error information if it has failed, and the state of all its tasks.

• Requests sent to the REST API of the follower nodes will be routed to the REST API of the leader node. If the URI under which the given host is reachable differs from the URI on which it listens, the configuration options,

rest.advertised.host.name, 
rest.advertised.port and 
rest.advertised.listener

can be used to change the URI which will be used by the follower nodes to connect with the leader.

Kafka Connect REST API Use Cases

Kafka Connect REST APIs finds various use cases for producing and consuming messages to/from Kafka, such as in:

Natural Request-Response Applications

• Mobile Applications require an integration framework via HTTP and request-response.  WebSockets, Server-Sent Events (SSE), and similar concepts are a better fit for Event Streaming with Kafka.
• They are in the Client Framework, though often not supported. This is where Kafka Connect REST APIs come in handy.

Legacy Applications and Third-Party Integration Tools

• Legacy Applications, Standard Software, and Traditional Middlewares often integrate only using HTTPS/REST APIs.
• For Event Streaming to Kafka, Extract Transform Load (ETL) Services or Enterprise Service Bus (ESB) Services and other third-party tools are complementary. 

Check out the best Kafka connectors in 2024 that suit your use case.

Kafka Connect REST API Features

Security

• When compared to TCP ports of the Kafka-native protocol used by clients from programming languages such as Java, Go, C++, or Python, HTTP ports are much easier for security teams to open.
• In the case of DMZ pass-through requirements, for example, InfoSec owns the DMZ F5 proxies. The use of REST Proxy simplifies integration.

Domain-driven design (DDD)

• HTTP/REST and Kafka are frequently combined to take advantage of the best of both worlds: decoupling with Kafka and synchronous client-server communication with HTTP.
• A common architecture is a service mesh that uses Kafka in conjunction with REST APIs.

For more information on the strengths and weaknesses of the Kafka Connect REST APIs, you may refer to the following article- A Comprehensive REST Proxy for Kafka.

Conclusion

This blog covered Apache Kafka, the Distributed Publish-Subscribe Messaging System, Kafka Connect and Kafka Architecture along with Kafka Connect REST API and its configuration, with use cases and features. Explore Kafka Connect’s powerful REST API for seamless integration and data pipeline management.

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