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* Add Server::CustomRoute() for HTTP methods outside the built-in set parse_request_line validates the request method against a fixed whitelist and rejects anything else with 400 before routing runs. That blocks WebDAV, where PROPFIND, PROPPATCH, MKCOL, COPY, MOVE, LOCK and UNLOCK are ordinary methods defined by RFC 4918, and it blocks extension methods such as UPnP's SUBSCRIBE. The need has been open since #847. Registering a handler is now what makes the server accept a method: svr.CustomRoute("PROPFIND", "/dav/:id", handler); Because custom methods go through the normal dispatch path, patterns work the way they do for Get() and friends, and the request body is available in req.body. Serving these methods through set_pre_routing_handler was never enough: the body has not been read at that point, so PROPPATCH and LOCK, which require one, could not be implemented at all. A HandlerWithContentReader overload is available too. The content reader gate in routing() also fires when a custom method carries no body, matching what expect_content() does unconditionally for POST/PUT/PATCH/DELETE, so a body-less PROPFIND (RFC 4918 treats one as allprop) reaches its handler instead of falling through to 404. Method names are validated as RFC 9110 tokens, and the ten built-in methods are refused. Seven of them are dispatched by the if/else chain in routing() before the custom tables are consulted, so a route registered for one could never fire; CONNECT, TRACE and PRI carry protocol-level meaning this library does not route. A refused registration makes is_valid() return false, so listen() fails rather than starting a server holding a handler that would never run. This is also why SSLServer::is_valid() now chains to Server::is_valid() instead of only checking ctx_. Servers that never call CustomRoute() keep the previous per-request cost: the built-in method set is checked first and short-circuits, and the custom lookup returns early on an empty map. * Add cookbook recipe for custom HTTP methods The CustomRoute() docs were a section inside S01, which pushed that page to 90 lines, the longest in the cookbook, and mixed a separate feature into a page about registering GET/POST/PUT/DELETE handlers. Move the section into its own recipe and give it room for the part that was missing: the OPTIONS handler returning DAV: and Allow, which WebDAV clients probe for before anything else. S01 goes back to 68 lines and keeps a pointer to the new page. The recipe is titled after the API rather than after WebDAV, and says outright that generating the 207 Multi-Status XML, interpreting Depth and managing locks are the reader's job. Routing the method is all the library does. S23 takes order 42, so the TLS, SSE and WebSocket recipes shift to 43-57. That only moves the sort key. Filenames, the T01/E01/W01 labels, the published URLs and every cross-reference are untouched.
2.9 KiB
title, order, status
| title | order | status |
|---|---|---|
| E02. Use Named Events in SSE | 49 | draft |
SSE lets you send multiple kinds of events over the same stream. Give each one a name with the event: field, and the client can dispatch to a different handler per type. Great for things like "new message", "user joined", "user left" in a chat app.
Send events with names
auto send_event = [](httplib::DataSink &sink,
const std::string &event,
const std::string &data) {
std::string msg = "event: " + event + "\n"
+ "data: " + data + "\n\n";
sink.write(msg.data(), msg.size());
};
svr.Get("/chat/stream", [&](const httplib::Request &req, httplib::Response &res) {
res.set_chunked_content_provider(
"text/event-stream",
[&, send_event](size_t offset, httplib::DataSink &sink) {
send_event(sink, "message", "Hello!");
std::this_thread::sleep_for(std::chrono::seconds(2));
send_event(sink, "join", "alice");
std::this_thread::sleep_for(std::chrono::seconds(2));
send_event(sink, "leave", "bob");
std::this_thread::sleep_for(std::chrono::seconds(2));
return true;
});
});
A message is event: → data: → blank line. If you omit event:, the client treats it as a default "message" event.
Attach IDs for reconnect
When you include an id: field, the client automatically sends it back as Last-Event-ID on reconnect, telling the server "here's how far I got."
auto send_event = [](httplib::DataSink &sink,
const std::string &event,
const std::string &data,
const std::string &id) {
std::string msg = "id: " + id + "\n"
+ "event: " + event + "\n"
+ "data: " + data + "\n\n";
sink.write(msg.data(), msg.size());
};
send_event(sink, "message", "Hello!", "42");
The ID format is up to you. Monotonic counters or UUIDs both work — just pick something unique and orderable on the server side. See E03. Handle SSE reconnection for details.
JSON payloads in data
For structured data, the usual move is to put JSON in data:.
nlohmann::json payload = {
{"user", "alice"},
{"text", "Hello!"},
};
send_event(sink, "message", payload.dump(), "42");
On the client, parse the incoming data as JSON to get the original object back.
Data with newlines
If the data value contains newlines, split it across multiple data: lines.
std::string msg = "data: line1\n"
"data: line2\n"
"data: line3\n\n";
sink.write(msg.data(), msg.size());
On the client side, these come back as a single data string with newlines.
Note: Using
event:makes client-side dispatch cleaner, but it also helps in the browser DevTools — events are easier to filter by type. That matters more than you'd expect while debugging.