Example: Sse Server

Demonstrates sseServer.zig using the canonical HTTPX API.

Complete Example

const std = @import("std");
const httpx = @import("httpx");

pub fn main() !void {
    var gpa: std.heap.DebugAllocator(.{}) = .init;
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();
    const io = std.Io.Threaded.global_single_threaded.io();

    var server = try httpx.Server.init(allocator, io, .{
        .host = "127.0.0.1",
        .port = 0,
        .maxConnections = 5,
    });
    defer server.deinit();

    try server.get("/events", sseHandler);

    const port = server.localPort();
    std.debug.print("SSE server running on http://127.0.0.1:{d}\n", .{port});

    const ServerThread = struct {
        fn run(s: *httpx.Server) void {
            s.run();
        }
    };
    const t = try std.Thread.spawn(.{}, ServerThread.run, .{&server});

    var client = httpx.Client.init(allocator, io, .{});
    defer client.deinit();

    var urlBuf: [128]u8 = undefined;
    const urlEvents = try std.fmt.bufPrint(&urlBuf, "http://127.0.0.1:{d}/events", .{port});
    var res = try client.get(urlEvents, .{});
    std.debug.print("GET /events -> status={d}, body={s}\n", .{ res.status, res.body });
    res.deinit();

    server.requestShutdown();
    t.join();
    std.debug.print("SSE server verification completed successfully.\n", .{});
}

fn sseHandler(ctx: *httpx.router.Context) anyerror!httpx.router.Response {
    var out = std.ArrayList(u8).empty;
    var writer = httpx.sse.Event.Writer.init(ctx.allocator);
    try writer.writeEvent(&out, &[_][]const u8{"Connected to SSE live stream"}, "status", 1, 5000);
    try writer.writeEvent(&out, &[_][]const u8{"First data packet"}, "message", 2, null);

    return .{
        .status = 200,
        .body = out.items,
        .contentType = "text/event-stream; charset=utf-8",
        .headers = try ctx.allocator.dupe(httpx.router.Header, &[_]httpx.router.Header{
            .{ .name = "Cache-Control", .value = "no-cache" },
            .{ .name = "Connection", .value = "keep-alive" },
        }),
    };
}

Expected Output

SSE server running on http://127.0.0.1:41237
GET /events -> status=200, body=retry:5000
id:1
event:status
data:Connected to SSE live stream

id:2
event:message
data:First data packet

SSE server verification completed successfully.

Statuses, event payloads, ids, retry intervals, URLs, and ports vary with the handler logic and the ephemeral port selected at runtime.

How to Run

zig build run-sse-server

Related

• Getting Started
• All Examples