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What is a CDN: Principles of Content Delivery Networks

What is a CDN: Principles of Content Delivery Networks
Hostman Team
Technical writer
Infrastructure

Latency, latency, latency! It has always been a problem of the Internet. It was, it is, and it probably will be. Delivering data from one geographic point to another takes time.

However, latency can be reduced. This can be achieved in several ways:

  • Reduce the number of intermediate nodes on the data path from the remote server to the user. The fewer the handlers, the faster the data reaches the destination. But this is hardly feasible. The global Internet continues to grow and become more complex, increasing the number of nodes. More nodes = more power. That’s the global trend. Evolution!

  • Instead of regularly sending data over long distances, we can create copies of it on nodes closer to the user. Fortunately, the number of network nodes keeps growing, and the topology spreads ever wider. Eureka!

The latter option seems like an absolute solution. With a large number of geographically distributed nodes, it's possible to create a kind of content delivery network. In addition to the main function—speeding up loading—such a network brings several other benefits: traffic optimization, load balancing, and increased fault tolerance.

Wait a second! That's exactly what a CDN is—Content Delivery Network. So, let’s let this article explain what a CDN is, how it works, and what problems it solves. 

What is a CDN?

A CDN (Content Delivery Network) is a distributed network of servers designed to accelerate multimedia content delivery (images, videos, HTML pages, JavaScript scripts, CSS styles) to nearby users.

Like a vast web, the CDN infrastructure sits between the server and the user, acting as an intermediary. Thus, content is not delivered directly from the server to the user but through the powerful "tentacles" of the CDN.

What Types of Content Exist?

Since the early days of the Internet, content has been divided into two types:

  • Static (requires memory, large in size). Stored on a server and delivered to users upon request. Requires sufficient HDD or SSD storage.

  • Dynamic (requires processing power, small in size). Generated on the server with each user request. Requires enough RAM and CPU power.

The volume of static content on the Internet far exceeds that of dynamic content. For instance, a website's layout weighs much less than the total size of the images embedded in it.

Storing static and dynamic content separately (on different servers) is considered good practice. While heavy multimedia requests are handled by one server, the core logic of the site runs on another.

CDN technology takes this practice to the next level. It stores copies of static content taken from the origin server on many other remote servers. Each of these servers serves data only to nearby users, reducing load times to a minimum.

What Does a CDN Consist Of?

CDN infrastructure consists of many geographically distributed computing machines, each with a specific role in the global data exchange:

  • User. The device from which the user sends requests to remote servers.
  • Origin Server. The main server of a website that processes user requests for dynamic content and stores the original static files used by the CDN as source copies.
  • Edge Node. A server node in the CDN infrastructure that delivers static content (copied from the origin server) to nearby users. Also called a Point of Presence (PoP).

A single CDN infrastructure simultaneously includes many active users, origin servers, and edge nodes.

What Happens Inside a CDN?

First, CDN nodes perform specific operations to manage the rotation of static content:

  • Caching. The process of loading copies of content from the origin server to a CDN server, followed by optimization and storage.
  • Purge (Cache Clearing). Cached content is cleared after a certain period or on demand to maintain freshness on edge nodes. For example, if a file is updated on the origin server, the update will take some time to propagate to the caching nodes.

Second, CDN nodes have several configurable parameters that ensure the stable operation of the entire infrastructure:

  • Time to Live (TTL). A timeout after which cached content is deleted from an edge node. For images and videos, TTL can range from 1 day to 1 year; for API responses (JSON or XML), from 30 seconds to 1 hour; HTML pages may not be cached at all. CDN nodes usually respect the HTTP Cache-Control header.
  • Caching Rule. A set of rules that determines how an edge node caches content. The primary parameter is how long the file remains in the cache (TTL).
  • Restriction. A set of rules on the edge node that moderates access to cached content for security purposes. For example, an edge node may serve requests only from nearby IP addresses or specific domains.

Thus, static content flows from the origin server through edge nodes to users, cached based on specific caching rules, and cleared once the TTL expires. Meanwhile, access restrictions are enforced on every edge node for security.

How Does a CDN Work?

Let's see how a CDN works from the user's perspective. We can divide the process into several stages:

  1. User Request Execution. When a user opens a website, the browser sends requests to CDN servers specified in HTML tags or within JavaScript code (such as Ajax requests). Without a CDN, requests would go directly to the origin server.
  2. Finding the Nearest Server. Upon receiving the request, the CDN system locates the server closest to the user.
  3. Content Caching. If the requested content is in the cache of the found CDN server, it is immediately delivered to the user. If not, the CDN server sends a request to the origin server and caches the content.
  4. Data Optimization. Content copies on CDN servers are optimized in various ways. For example, files can be compressed using Gzip or Brotli to reduce size.
  5. Content Delivery. The optimized and cached content is delivered to the user and displayed in their browser.

For instance, if a website’s origin server is in Lisbon and the user is in Warsaw, the CDN will automatically find the nearest server with cached static content—say, in Berlin.

If there is no nearby CDN server with cached content, the CDN will request the origin server. Subsequent requests will then be served through the CDN.

The straight-line distance from Warsaw to Lisbon is about 2800 km, while the distance from Warsaw to Berlin is only about 570 km.

Someone unfamiliar with networking might wonder: “How can a CDN speed up content delivery if data travels through cables at the speed of light—300,000 km/s?”

In reality, delays in data transmission are due to technical, not physical, limitations:

  • Routing. Data passes through many routers and nodes, each adding small delays from processing and forwarding packets.
  • Network Congestion. High traffic in some network segments can lead to delays and packet loss, requiring retransmissions.
  • Data Transmission Protocols. Protocols like TCP include features such as connection establishment, error checking, and flow control, all of which introduce delays.

Thus, the difference between 2800 km and 570 km is negligible in terms of signal propagation. But from a network infrastructure perspective, it makes a big difference.

Moreover, a CDN server in Berlin, finding no cached content, might request it not from the origin server but from a neighboring CDN node in Prague, if that node has the content cached.

Therefore, CDN infrastructure nodes can also exchange cached content among themselves.

What Types of CDN Exist?

There are several ways to classify CDNs. The most obvious is based on the ownership of the infrastructure:

  • Public. The CDN infrastructure is rented from a third-party provider. Suitable for small and medium-sized companies.
  • Private. The CDN infrastructure is deployed internally by the company itself. Suitable for large companies and IT giants.

Each type has its own pros and cons:

 

Public

Private

Connection speed

High

Low

Initial costs

Low

High

Maintenance complexity

Low

High

Cost of large-scale traffic

High

Low

Control capabilities

Low

High

Dependence on third parties

High

Low

Many CDN providers offer free access to their infrastructure resources to attract users. However, in such cases, there are limitations on:

  • Server capacity
  • Traffic volumes
  • Geographical coverage
  • Advanced configuration options

Paid CDN providers use various pricing models:

  • Pay-as-you-go. Costs depend on the volume of data transferred, measured in gigabytes or terabytes.
  • Flat-rate pricing. Costs depend on the chosen plan with a fixed amount of available traffic.
  • Request-based pricing. Costs depend on the number of user requests made.

Deploying your own CDN infrastructure is a serious step, usually justified by strong reasons:

  • Public CDN costs exceed the cost of running your own infrastructure. For example, high expenses due to massive multimedia traffic volumes.
  • The product hits technical limitations of public CDNs. For example, heavy network loads or a specific user geography.
  • The project demands higher reliability, security, and data privacy that public CDNs cannot provide. For example, a government institution or bank.

Here are a few examples of private CDN networks used by major tech companies:

  • Netflix Open Connect. Delivers Netflix’s streaming video to users worldwide.
  • Google Global Cache (GGC). Speeds up access to Google services.
  • Apple Private CDN. Delivers operating system updates and Apple services to its users.

What Problems Does a CDN Solve?

CDN technology has evolved to address several key tasks:

  • Faster load times. Files load more quickly (with less latency) because CDN servers with cached static content are located near the user.
  • Reduced server load. Numerous requests for static content go directly to the CDN infrastructure, bypassing the origin server.
  • Global availability. Users in remote regions can access content more quickly, regardless of the main server’s location.
  • Protection against attacks. Properly configured CDN servers can block malicious IP addresses or limit their requests, preventing large-scale attacks.
  • Traffic optimization. Static content is compressed before caching and delivery to reduce size, decreasing transmitted data volumes and easing network load.
  • Increased fault tolerance. If one CDN server fails or is overloaded, requests can be automatically rerouted to other servers.

The CDN, being a global infrastructure, takes over nearly all core responsibilities for handling user requests for static content.

What Are the Drawbacks of Using a CDN?

Despite solving many network issues, CDNs do have certain drawbacks:

  • Costs. In addition to paying for the origin server, you also need to pay for CDN services.
  • Privacy. CDN nodes gain access to static data from the origin server for caching purposes. Some of this data may not be public.
  • Availability. A site’s key traffic may come from regions where the chosen CDN provider has little or no presence. Worse, the provider might even be blocked by local laws.
  • Configuration. Caching requires proper setup. Otherwise, users may receive outdated data. Proper setup requires some technical knowledge.

Of course, we can minimize these drawbacks by carefully selecting the CDN provider and properly configuring the infrastructure they offer.

What Kind of Websites Use CDNs?

In today’s cloud-based reality, websites with multimedia content, high traffic, and a global audience are practically required to use CDN technology. Otherwise, they won’t be able to handle the load effectively.

Yes, websites can function without a CDN, but the question is, how? Slower than with a CDN.

Almost all major websites, online platforms, and services use CDNs for faster loading and increased resilience. These include:

  • Google
  • Amazon
  • Microsoft
  • Apple
  • Netflix
  • Twitch
  • Steam
  • Aliexpress

However, CDNs aren’t just for the big players — smaller websites can benefit too. Several criteria suggest that a website needs distributed caching:

  • International traffic. If users from different countries or continents visit the site. For example, a European media site with Chinese readers.
  • Lots of static content. If the site contains many multimedia files. For example, a designer’s portfolio full of photos and videos.
  • Traffic spikes. If the site experiences sharp increases in traffic. For example, an online store running frequent promotions or ads.

That said, there are cases where using a CDN makes little sense and only complicates the web project architecture:

  • Local reach. If the site is targeted only at users from a single city or region. For example, a website for a local organization.
  • Low traffic. If only a few dozen or hundreds of users visit the site per day.
  • Simple structure. If the site is a small blog or a minimalist business card site.

Still, the main indicator for needing a CDN is a large volume of multimedia content.

Where Are CDN Servers Located?

While each CDN’s infrastructure is globally distributed, there are priority locations where CDN servers are most concentrated:

  • Capitals and major cities. These areas have better-developed network infrastructure and are more evenly spaced worldwide.
  • Internet exchange points (IXPs). These are locations where internet providers exchange traffic directly. Examples include DE-CIX (Frankfurt), AMS-IX (Amsterdam), LINX (London).
  • Data centers of major providers. These are hubs of major internet backbones that enable fast and affordable data transmission across long distances.

The smallest CDN networks comprise 10 to 150 servers, while the largest can include 300 to 1,500 nodes.

Popular CDN Providers

Here are some of the most popular, large, and technologically advanced CDN providers. Many offer CDN infrastructure as an add-on to their cloud services:

  • Akamai
  • Cloudflare
  • Amazon CloudFront (AWS CDN)
  • Fastly
  • Google Cloud CDN
  • Microsoft Azure CDN

There are also more affordable options:

  • BunnyCDN
  • KeyCDN
  • StackPath

Some providers specialize in CDN infrastructure for specific content types, such as video, streams, music, or games:

  • CDN77
  • Medianova

Choosing the right CDN depends on the business goals, content type, and budget. To find the optimal option, you should consider a few key factors:

  • Goals and purpose. What type of project needs the CDN: blog, online store, streaming service, media outlet?
  • Geography. The provider's network should cover regions where your target audience is concentrated.
  • Content. The provider should support caching and storage for the type of content used in your project.
  • Pricing. Which billing model offers the best value for performance?

In practice, it’s best to test several suitable CDN providers to find the right one for long-term use.

In a way, choosing a CDN provider is like choosing a cloud provider. They all offer similar services, but the implementation always differs.

Conclusion

It’s important to understand that a CDN doesn’t fully store static data; it only distributes copies across its nodes to shorten the distance between the origin server and the user.

Therefore, the main role of a CDN is to speed up loading and optimize traffic. This is made possible through the caching mechanism for static data, which is distributed according to defined rules between the origin server and CDN nodes.

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DDoS protection cuts off malicious traffic before it enters the infrastructure, reducing server load and preventing downtime that easily turns into tangible losses. Automation: How to Reduce Operating Costs Even perfectly selected infrastructure can remain expensive if managed manually. Creating test environments, updating configurations, scaling, backup rotation, server management—all this turns into a long chain of manual actions that take hours of work and lead to errors. Automation reduces maintenance costs through repeatability, predictability, and the elimination of human error. Why Manual Infrastructure Is More Expensive Manual operations always mean: Risk of forgetting to delete a temporary environment Inconsistent settings between servers Unpredictable downtime due to errors Developer time spent on routine instead of the product These are direct and indirect costs that easily hide in the process but noticeably increase the final budget. Which Processes Are Most Profitable to Automate From a savings perspective, three areas provide the most benefit: Environment Deployment. Quick creation of environments for development, testing, preview, and load tests. The environment is spun up automatically, works for the required time, and is deleted when no longer needed. Infrastructure Scaling. Load peaks can be handled automatically: spin up additional resources based on metrics, then shut them down. This way, you pay only for the peak, not for maintaining a constant reserve. Unified Configuration Description. When the environment is described as code, it can be reproduced at any stage, from development to production. This reduces the number of errors and eliminates "manual magic." Infrastructure as Code: An Economic Tool IaC solves the main problem of the manual approach: unpredictability. Configuration is stored in Git, changes are tracked, environments are created identically. The team spends less time on maintenance, plans the budget more easily, and responds to load changes faster. As a result, operating costs are reduced, and infrastructure becomes more transparent and manageable. Hostman Tools for Automation Hostman provides a set of tools that help build automation around the entire infrastructure: Public API. Automatic management of servers, networks, databases, and storage. Terraform provider, for a complete IaC approach: the entire infrastructure is described as code. cloud-init. Allows deploying servers immediately with preconfigured settings, users, and packages. Together, they create infrastructure that can be spun up, modified, and scaled automatically, without unnecessary actions and costs. This is especially important for teams that need to move quickly but without constant overspending. Conclusion Optimizing infrastructure costs is about building a mature approach to working with resources. At each stage, it seems that costs are quite justified, but in total they turn into a tangible burden on the budget—especially if the team scales quickly. To keep spending under control, it's important not to cut resources blindly, but to understand how infrastructure works and which elements the product really needs here and now. An audit helps find inefficient parts of the system. Correct work with computing power and databases reduces costs without loss of performance. Transition to object storage makes the architecture more flexible and reliable. Containerization and Kubernetes remove dependence on manual actions. Automation frees the team from routine and prevents errors that cost money. Proper network organization increases resilience—and simultaneously reduces costs. For many projects, it makes sense to rent a VPS instead of investing in dedicated hardware. VPS hosting for rent gives you predictable performance, root access, and the freedom to scale resources as your workload grows—without overpaying upfront. Rational architecture is not about saving for saving's sake. It's about resilience, speed, and the project's ability to grow without unnecessary technical and financial barriers. And the earlier the team transitions from chaotic resource accumulation to a thoughtful management model, the easier it will be to scale the product and budget together.
09 December 2025 · 16 min to read
Infrastructure

Apache Kafka and Real-Time Data Stream Processing

Apache Kafka is a high-performance server-based message broker capable of processing enormous volumes of events, measured in millions per second. Kafka's distinctive features include exceptional fault tolerance, the ability to store data for extended periods, and ease of infrastructure expansion through the simple addition of new nodes. The project's development began within LinkedIn, and in 2011, it was transferred to the Apache Software Foundation. Today, Kafka is widely used by leading global companies to build scalable, reliable data transmission infrastructure and has become the de facto industry standard for stream processing. Kafka solves a key problem: ensuring stable transmission and processing of streaming data between services in real time. As a distributed broker, it operates on a cluster of servers that simultaneously receive, store, and process messages. This architecture allows Kafka to achieve high throughput, maintain operability during failures, and ensure minimal latency even with many connected data sources. It also supports data replication and load distribution across partitions, making the system extremely resilient and scalable. Kafka is written in Scala and Java but supports clients in numerous languages, including Python, Go, C#, JavaScript, and others, allowing integration into virtually any modern infrastructure and use in projects of varying complexity and focus. How the Technology Works To work effectively with Kafka, you first need to understand its structure and core concepts. The system's main logic relies on the following components: Messages: Information enters Kafka as individual events, each representing a message. Topics: All messages are grouped by topics. A topic is a logical category or queue that unites data by a specific characteristic. Producers: These are programs or services that send messages to a specific topic. Producers are responsible for generating and transmitting data into the Kafka system. Consumers: Components that connect to a specific topic and extract published messages. To improve efficiency, consumers are often organized into consumer groups, thereby distributing the load among different instances and allowing better management of parallel processing of large data volumes. This division significantly improves overall system performance and reliability. Partitions: Any topic can be divided into partitions, enabling horizontal system scaling and increased performance. Brokers: Servers united in a Kafka cluster perform functions of storing, processing, and managing messages. The component interaction process looks as follows: The producer sends a message to a specified topic. The message is added to the end of one of the topic's partitions and receives its sequential number (offset). A consumer belonging to a specific group subscribes to the topic and reads messages from partitions assigned to it, starting from the required offset. Each consumer independently manages its offset, allowing messages to be re-read when necessary. Thus, Kafka acts as a powerful message delivery mechanism, ensuring high throughput, reliability, and fault tolerance. Since Kafka stores data as a distributed log, messages remain available for re-reading, unlike many queue-oriented systems. Key Principles Append-only log: messages are not modified/deleted (by default), they are simply added. This simplifies storage and replay. Partition division for speed: one topic is split into parts, and Kafka can process them in parallel. Thanks to this, it scales easily. Guaranteed order within partition: consumers read messages in the order they were written to the partition. However, there is no complete global ordering across the entire topic if there are multiple partitions. Messages can be re-read: a consumer can "rewind" at any time and re-read needed data if it's still stored in Kafka. Stable cluster operation: Kafka functions as a collection of servers capable of automatically redirecting load to backup nodes in case of broker failure. Why Major Companies Choose Apache Kafka There are several key reasons why large organizations choose Kafka: Scalability Kafka easily handles large data streams without losing performance. Thanks to the distributed architecture and message replication support, the system can be expanded simply by adding new brokers to the cluster. High Performance The system can process millions of messages per second even under high load. This level of performance is achieved through asynchronous data sending by producers and efficient reading mechanisms by consumers. Reliability and Resilience Message replication among multiple brokers ensures data safety even when part of the infrastructure fails. Messages are stored sequentially on disk for extended periods, minimizing the risk of their loss. Log Model and Data Replay Capability Unlike standard message queues where data disappears after reading, Kafka stores messages for the required period and allows their repeated reading. Ecosystem Support and Maturity Kafka has a broad ecosystem: it supports connectors (Kafka Connect), stream processing (Kafka Streams), and integrations with analytical and Big Data systems. Open Source Kafka is distributed under the free Apache license. This provides numerous advantages: a huge amount of official and unofficial documentation, tutorials, and reviews; a large number of third-party extensions and patches improving basic functionality; and the ability to flexibly adapt the system to specific project needs. Why Use Apache Kafka? Kafka is used where real-time data processing is necessary. The platform enables development of resilient and easily scalable architectures that efficiently process large volumes of information and maintain stable operation even under significant loads. Stream Data Processing When an application produces a large volume of messages in real time, Kafka ensures optimal management of such streams. The platform guarantees strict message delivery sequence and the ability to reprocess them, which is a key factor for implementing complex business processes. System Integration For connecting multiple heterogeneous services and applications, Kafka serves as a universal intermediary, allowing data transmission between them. This simplifies building microservice architecture, where each component can independently work with event streams while remaining synchronized with others. Data Collection and Transmission for Monitoring Kafka enables centralized collection of logs, metrics, and events from various sources, which are then analyzed by monitoring and visualization tools. This facilitates problem detection, system state control, and real-time reporting. Real-Time Data Processing Through integration with stream analytics systems (such as Spark, Flink, Kafka Streams), Kafka enables creation of solutions for operational analysis and rapid response to incoming data. This allows for timely informed decision-making, formation of interactive monitoring dashboards, and instant response to emerging events, which is critically important for applications in finance, marketing, and Internet of Things (IoT). Real-Time Data Analysis Through interaction with stream analytics tools (for example, Spark, Flink, Kafka Streams), Kafka becomes the foundation for developing solutions ensuring fast processing and analysis of incoming data. This functionality enables timely important management decisions, visualization of indicators in convenient interactive dashboards, and instant response to changing situations, which is extremely relevant for financial sector companies, marketers, and IoT solution developers. Use Case Examples Here are several possible application scenarios: Web platforms: any user action (view, click, like) is sent to Kafka, and then these events are processed by analytics, recommendation system, or notification service. Fintech: a transaction creates a "payment completed" event, which the anti-fraud service immediately receives. If suspicious, it can initiate a block and pass data further. IoT devices: thousands of sensors send readings (temperature, humidity) to Kafka, where they are processed by streaming algorithms (for example, for anomaly detection), and then notifications are sent to operators. Microservices: services exchange events ("order created," "item packed," etc.) through Kafka without calling each other directly. Log aggregation: multiple services send logs to Kafka, from where analytics systems, SIEM, or centralized processing systems retrieve them. Logistics: tracking delivery statuses or real-time route distribution. Advertising: collection and analysis of user events for personalization and marketing analytics. These examples demonstrate Kafka's flexibility and its application in various areas. When Kafka Is Not Suitable It's important to understand the limitations and situations when Kafka is not the optimal choice. Several points: If the data volume is small (for example, several thousand messages per day) and the system is simple, implementing Kafka may be excessive. For low traffic, simple queues like RabbitMQ are better. If you need to make complex queries with table joins, aggregations, or store data for very long periods with arbitrary access, it's better to use a regular database. If full ACID transactions are important (for example, for banking operations with guaranteed integrity and relationships between tables), Kafka doesn't replace a regular database. If data hardly changes and doesn't need to be quickly transmitted between systems, Kafka will be excessive. Simple storage in a database or file may be sufficient. Kafka's Differences from Traditional Databases Traditional databases (SQL and NoSQL) are oriented toward storing structured information and performing fast retrieval operations. Their architecture is optimized for reliable data storage and efficient extraction of specific records on demand. In turn, Kafka is designed to solve different tasks: Working with streaming data: Kafka focuses on managing continuous data streams, while traditional database management systems are designed primarily for processing static information arrays. Parallelism and scaling: Kafka scales horizontally through partitions and brokers, and is designed for very large stream data volumes. Databases (especially relational) often scale vertically or with horizontal scaling limitations. Ordering and stream: Kafka guarantees order within a partition and allows subscribers to read from different positions, jump back, and replay. Latency and throughput: Kafka is designed to provide minimal delays while simultaneously processing enormous volumes of events. Example Simple Python Application for Working with Kafka If Kafka is not yet installed, the easiest way to "experiment" with it is to install it via Docker. For this, it's sufficient to create a docker-compose.yml file with minimal configuration: version: "3" services: broker: image: apache/kafka:latest container_name: broker ports: - "9092:9092" environment: KAFKA_NODE_ID: 1 KAFKA_PROCESS_ROLES: broker,controller KAFKA_LISTENERS: PLAINTEXT://0.0.0.0:9092,CONTROLLER://0.0.0.0:9093 KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://localhost:9092 KAFKA_CONTROLLER_LISTENER_NAMES: CONTROLLER KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT KAFKA_CONTROLLER_QUORUM_VOTERS: 1@localhost:9093 KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1 KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 1 KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 1 KAFKA_GROUP_INITIAL_REBALANCE_DELAY_MS: 0 KAFKA_NUM_PARTITIONS: 3 Run: docker compose up -d Running Kafka in the Cloud In addition to local deployment via Docker, Kafka can be run in the cloud. This eliminates unnecessary complexity and saves time. In Hostman, you can create a ready Kafka instance in just a few minutes: simply choose the region and configuration, and the installation and setup happen automatically. The cloud platform provides high performance, stability, and technical support, so you can focus on development and growth of your project without being distracted by infrastructure. Try Hostman and experience the convenience of working with reliable and fast cloud hosting. Python Scripts for Demonstration Below are examples of Producer and Consumer in Python (using the kafka-python library), the first script writes messages to a topic and the other reads. First, install the Python library: pip install kafka-python producer.py This code sends five messages to the test-topic theme. from kafka import KafkaProducer import json import time # Create Kafka producer and specify broker address # value_serializer converts Python objects to JSON bytes producer = KafkaProducer( bootstrap_servers="localhost:9092", value_serializer=lambda v: json.dumps(v).encode("utf-8"), ) # Send 5 messages in succession for i in range(5): data = {"Message": i} # Form data producer.send("test-topic", data) # Asynchronous send to Kafka print(f"Sent: {data}") # Log to console time.sleep(1) # Pause 1 second between sends # Wait for all messages to be sent producer.flush() consumer.py This Consumer reads messages from the theme, starting from the beginning. from kafka import KafkaConsumer import json # Create Kafka Consumer and subscribe to "test-topic" consumer = KafkaConsumer( "test-topic", # Topic we're listening to bootstrap_servers="localhost:9092", # Kafka broker address auto_offset_reset="earliest", # Read messages from the very beginning if no saved offset group_id="test-group", # Consumer group (for balancing) value_deserializer=lambda v: json.loads(v.decode("utf-8")), # Convert bytes back to JSON ) print("Waiting for messages...") # Infinite loop—listen to topic and process messages for message in consumer: print("Received:", message.value) # Output message content These two small scripts demonstrate basic operations with Kafka: publishing and receiving messages. Conclusion Apache Kafka is an effective tool for building architectures where key factors are event processing, streaming data, high performance, fault tolerance, and latency minimization. It is not a universal replacement for databases but excellently complements them in scenarios where classic solutions cannot cope. With proper architecture, Kafka enables building flexible, responsive systems. When choosing Kafka, it's important to evaluate requirements: data volume, speed, architecture, integrations, ability to manage the cluster. If the system is simple and loads are small—perhaps it's easier to choose a simpler tool. But if the load is large, events flow continuously, and a scalable solution is required, Kafka can become the foundation. Despite certain complexity in setup and maintenance, Kafka has proven its effectiveness in numerous large projects where high speed, reliability, and working with event streams are important.
08 December 2025 · 12 min to read

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