Ktor 3.0: A Boost in Performance and Server-Sent EventsSupport
By Sergio De Simone, translated by Pingchuan, curated by DingXiaoyun
Ktor, the native Kotlin framework for building asynchronous HTTP server and client applications, has reached version 3.0. This release brings significantperformance improvements and new features, including support for server-sent events, CSRF protection, and serving static resources from ZIP files. However, it also introduces some breaking changesdue to the adoption of kotlinx-io.
Performance Enhancement through kotlinx-io
The core of Ktor 3.0’s performance boost lies in its integration with kotlinx-io, a low-level I/O librarybuilt around the concept of a Buffer. This mutable byte sequence functions like a queue, allowing data to be written to its tail and read from its head.
The breaking changes in Ktor 3 primarily affect the underlying IO API,impacting types like Input, Output, ByteReadChannel, and ByteWriteChannel. Developers directly using these types will need to adapt their applications to the new API.
The key benefit of kotlinx-io is its performance optimization. It eliminates unnecessary byte copying between ByteReadChannel, ByteWriteChannel, and the network interface, leading to more efficient byte conversion and parsing. This paves the way for future performance enhancements.
JetBrains, the creators of Ktor, have conducted benchmarks that demonstrate a significant reduction in time for file and socket operations, with improvements reaching up to 90% in some cases.
Server-Sent Events: A New Communication Channel
Beyond performance gains, Ktor 3.0 introduces a crucial feature: support for server-sent events. This server-push technology establishes a communication channel from the server to the client. Server-sent events are particularly advantageous in scenarios where data flows primarily in one direction, especially when dealing with firewall blocking or connection interruptions. Compared to WebSockets, server-sent events are more suitable in these situations. However, WebSockets offer higher efficiency and lower latency.
Additional Features in Ktor 3.0
Ktor 3.0 also includes other valuable features:
- CSRF Protection: This feature allows specifying CSRF protection for any given route.
- Serving Static Resources from ZIP Files: Static resources can be served directly from ZIP files, including subdirectories, which are reflected in the URL structure.
Wasm Support: Still in Alpha
It’s worth noting that Ktor 3.0 now supports Wasm as a build target for Ktor clients. However, Kotlin/Wasm is still in alpha testing, so Wasm support in Ktor 3 is not yet production-ready.
Getting Started with Ktor
To begin a new project with Ktor,visit the Ktor website and choose the most suitable starting point for your needs.
Conclusion
Ktor 3.0 represents a significant step forward for the Kotlin HTTP toolkit. Its performance improvements, support for server-sent events, and other new features make it an even more powerful and versatile framework for building asynchronousHTTP applications. While some breaking changes are present, the benefits of these updates are undeniable, paving the way for a more efficient and feature-rich development experience.
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