Added an intermediate base class for the CPP-HTTPLIB-based REST services

src/http/CMakeLists.txt

@@ -3,6 +3,7 @@ add_library(http SHARED)
 target_sources(http PRIVATE
     AsyncReq.cc
     BinaryEncoding.cc
+    ChttpModule.cc
     Client.cc
     ClientConnPool.cc
     ClientConfig.cc
@@ -25,6 +26,7 @@ target_link_libraries(http PUBLIC
     Boost::filesystem
     Boost::regex
     Boost::system
+    cpp-httplib
 )
 
 install(TARGETS http)

src/http/ChttpModule.cc

@@ -0,0 +1,69 @@
+/*
+ * LSST Data Management System
+ *
+ * This product includes software developed by the
+ * LSST Project (http://www.lsst.org/).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the LSST License Statement and
+ * the GNU General Public License along with this program.  If not,
+ * see <http://www.lsstcorp.org/LegalNotices/>.
+ */
+
+// Class header
+#include "http/ChttpModule.h"
+
+// System headers
+#include <iterator>
+
+// Third-party headers
+#include <httplib.h>
+
+// Qserv headers
+#include "http/RequestQuery.h"
+
+using namespace std;
+
+namespace lsst::qserv::http {
+
+ChttpModule::ChttpModule(string const& authKey, string const& adminAuthKey, httplib::Request const& req,
+                         httplib::Response& resp)
+        : Module(authKey, adminAuthKey), _req(req), _resp(resp) {}
+
+string ChttpModule::method() const { return _req.method; }
+
+unordered_map<string, string> ChttpModule::params() const { return _req.path_params; }
+
+RequestQuery ChttpModule::query() const {
+    // TODO: The query parameters in CPP-HTTPLIB are stored in the std::multimap
+    // container to allow accumulating values of non-unique keys. For now we need
+    // to convert the multimap to the std::unordered_map container. This may result
+    // in losing some query parameters if they have the same key but different values.
+    // Though, the correct solution is to fix the QHTTP library to support
+    // the std::multimap container for query parameters.
+    unordered_map<string, string> queryParams;
+    for (auto const& [key, value] : _req.params) queryParams[key] = value;
+    return RequestQuery(queryParams);
+}
+
+void ChttpModule::getRequestBody(string& content, string const& requiredContentType) {
+    auto itr = _req.headers.find("Content-Type");
+    if (itr != _req.headers.end() && itr->second == requiredContentType) {
+        content = _req.body;
+    }
+}
+
+void ChttpModule::sendResponse(string const& content, string const& contentType) {
+    _resp.set_content(content, contentType);
+}
+
+}  // namespace lsst::qserv::http

src/http/ChttpModule.h

@@ -0,0 +1,85 @@
+
+/*
+ * LSST Data Management System
+ *
+ * This product includes software developed by the
+ * LSST Project (http://www.lsst.org/).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the LSST License Statement and
+ * the GNU General Public License along with this program.  If not,
+ * see <http://www.lsstcorp.org/LegalNotices/>.
+ */
+#ifndef LSST_QSERV_HTTP_CHTTPMODULE_H
+#define LSST_QSERV_HTTP_CHTTPMODULE_H
+
+// System headers
+#include <string>
+#include <unordered_map>
+
+// Qserv headers
+#include "http/Module.h"
+
+// Forward declarations
+
+namespace httplib {
+class Request;
+class Response;
+}  // namespace httplib
+
+namespace lsst::qserv::http {
+class RequestBodyJSON;
+class RequestQuery;
+}  // namespace lsst::qserv::http
+
+// This header declarations
+namespace lsst::qserv::http {
+
+/**
+ * Class ChttpModule is an extended base class specialized for constructing
+ * the CPP-HTTPLIB request processing modules.
+ */
+class ChttpModule : public Module {
+public:
+    ChttpModule() = delete;
+    ChttpModule(ChttpModule const&) = delete;
+    ChttpModule& operator=(ChttpModule const&) = delete;
+
+    virtual ~ChttpModule() = default;
+
+protected:
+    /**
+     * @param authKey  An authorization key for operations which require extra security.
+     * @param adminAuthKey  An administrator-level authorization key.
+     * @param req  The HTTP request.
+     * @param resp  The HTTP response channel.
+     */
+    ChttpModule(std::string const& authKey, std::string const& adminAuthKey, httplib::Request const& req,
+                httplib::Response& resp);
+
+    httplib::Request const& req() { return _req; }
+    httplib::Response& resp() { return _resp; }
+
+    virtual std::string method() const;
+    virtual std::unordered_map<std::string, std::string> params() const;
+    virtual RequestQuery query() const;
+    virtual void getRequestBody(std::string& content, std::string const& requiredContentType);
+    virtual void sendResponse(std::string const& content, std::string const& contentType);
+
+private:
+    httplib::Request const& _req;
+    httplib::Response& _resp;
+};
+
+}  // namespace lsst::qserv::http
+
+#endif  // LSST_QSERV_HTTP_CHTTPMODULE_H