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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.
100 lines
3.3 KiB
Markdown
100 lines
3.3 KiB
Markdown
---
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title: "E04. SSEをクライアントで受信する"
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order: 51
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status: "draft"
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---
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cpp-httplibには`sse::SSEClient`という専用のクラスが用意されています。自動再接続、イベント名別のハンドラ、`Last-Event-ID`の管理まで面倒を見てくれるので、SSEを受信するときはこれを使うのが一番ラクです。
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## 基本の使い方
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```cpp
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#include <httplib.h>
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httplib::Client cli("http://localhost:8080");
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httplib::sse::SSEClient sse(cli, "/events");
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sse.on_message([](const httplib::sse::SSEMessage &msg) {
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std::cout << "data: " << msg.data << std::endl;
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});
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sse.start(); // ブロッキング
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```
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`Client`と接続先パスを渡して`SSEClient`を作り、`on_message()`でコールバックを登録します。`start()`を呼ぶとイベントループが走り、接続が切れると自動で再接続を試みます。
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## イベント名で分岐する
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サーバー側で`event:`を付けて送られてくる場合は、`on_event()`で名前ごとにハンドラを登録できます。
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```cpp
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sse.on_event("message", [](const auto &msg) {
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std::cout << "chat: " << msg.data << std::endl;
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});
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sse.on_event("join", [](const auto &msg) {
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std::cout << msg.data << " joined" << std::endl;
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});
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sse.on_event("leave", [](const auto &msg) {
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std::cout << msg.data << " left" << std::endl;
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});
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```
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`on_message()`は、名前なし（デフォルトの`message`イベント）を受け取る汎用ハンドラとして使えます。
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## 接続イベントとエラーハンドリング
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```cpp
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sse.on_open([] {
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std::cout << "connected" << std::endl;
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});
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sse.on_error([](httplib::Error err) {
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std::cerr << "error: " << httplib::to_string(err) << std::endl;
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});
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```
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接続確立時やエラー発生時にもフックを挟めます。エラーハンドラが呼ばれても、`SSEClient`は内部で再接続を試みます。
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## 非同期で動かす
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メインスレッドを塞ぎたくない場合は`start_async()`を使います。
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```cpp
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sse.start_async();
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// メインスレッドは別の仕事を続ける
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do_other_work();
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// 終わったら止める
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sse.stop();
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```
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`start_async()`は裏でスレッドを立ち上げてイベントループを回します。`stop()`でクリーンに止められます。
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## 再接続の設定
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再接続間隔や最大試行回数を調整できます。
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```cpp
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sse.set_reconnect_interval(5000); // 5秒
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sse.set_max_reconnect_attempts(10); // 10回まで（0=無制限）
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```
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サーバー側で`retry:`フィールドを送っていると、そちらが優先されます。
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## Last-Event-IDの自動管理
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`SSEClient`は受信したイベントの`id`を内部で保持していて、再接続時に`Last-Event-ID`ヘッダーとして送ってくれます。この挙動はサーバー側で`id:`付きイベントを送っていれば自動で有効になります。
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```cpp
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std::cout << "last id: " << sse.last_event_id() << std::endl;
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```
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現在のIDは`last_event_id()`で参照できます。
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> **Note:** SSEClientの`start()`はブロッキングなので、単発のツールならそのまま使えますが、GUIアプリやサーバーに組み込むときは`start_async()` + `stop()`の組み合わせが基本です。
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> サーバー側の実装は[E01. SSEサーバーを実装する](../e01-sse-server)を参照してください。
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