tatsuhiro-t/spdylay

Free

The experimental SPDY protocol version 2, 3 and 3.1 implementation in C

FreeFree tier

Type

Open Source

Company

tatsuhiro-t (Tatsuhiro Tsujikawa)

Visit Website GitHub (38 stars)

About tatsuhiro-t/spdylay

Spdylay is an experimental C library implementing Google's SPDY protocol versions 2, 3, and 3.1. It provides a framing layer without performing any I/O operations, relying on application-provided callback functions. The library does not include event polling, allowing applications to choose their own event handling mechanisms. It is designed to be SSL-library agnostic (example programs require OpenSSL 1.0.1+). The project also provides SPDY client, server, and reverse proxy (shrpx) implementations built on top of the library. Currently, most SPDY/2, SPDY/3, and SPDY/3.1 features are implemented; direct server-push support is not yet available but can be achieved via low-level APIs.

Key Features

Implements SPDY framing layer for versions 2, 3, and 3.1

Callback-based design with no I/O or event polling binding

SSL library agnostic (example programs use OpenSSL 1.0.1+)

Includes example programs: spdycat (SPDY client) and shrpx (reverse proxy)

Supports building for Android via provided scripts

Provides low-level APIs to achieve server-push functionality

Pros & Cons

Pros

Lightweight and focused on framing layer, giving developers full control
Flexible callback architecture separates protocol handling from I/O
Supports multiple SPDY versions (2, 3, 3.1)
Comes with working example programs for quick testing
Open source under MIT license (from COPYING file)

Cons

Experimental status may indicate unstable or incomplete implementation
Direct server-push support is missing; requires low-level APIs
SPDY protocol is deprecated in favor of HTTP/2, limiting long-term relevance
Example programs depend on OpenSSL, which may be heavy for some use cases
Not actively maintained (last commit appears historical)

Best For

Building custom SPDY-enabled applications in CCreating SPDY clients, servers, or proxies for experimentation or researchReverse proxy setup with SPDY-to-HTTP conversion using shrpxLearning about SPDY protocol internals through a minimal implementation

FAQ

What SPDY versions does Spdylay support?

Spdylay implements SPDY version 2, 3, and 3.1 framing layers.

Does Spdylay handle I/O operations?

No, Spdylay does not perform any I/O operations; it uses callback functions provided by the application for I/O and event handling.

What are the requirements to build Spdylay?

Building the library requires pkg-config (>=0.20) and zlib (>=1.2.3). Unit tests need CUnit (>=2.1). Example programs additionally require OpenSSL (>=1.0.1), libxml2 (>=2.7.7) for some features, and libevent-openssl (>=2.0.8) for shrpx.

Is server-push supported?

Direct server-push is not yet implemented, but applications can achieve server-push using the provided primitive APIs.