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327 lines
9.1 KiB
Markdown
327 lines
9.1 KiB
Markdown
# webcc
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[同学们,【中文版】在这里!](README_zh_CN.md)
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Lightweight C++ HTTP client and server library based on [Boost Asio](https://www.boost.org/doc/libs/release/libs/asio/).
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Please turn to our [Wiki](https://github.com/sprinfall/webcc/wiki) for more tutorials and guides.
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Wondering how to build Webcc? Check [Build Instructions](https://github.com/sprinfall/webcc/wiki/Build-Instructions).
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Git repo: https://github.com/sprinfall/webcc. Please check this one instead of the forked for the latest features.
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**Features**
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- Cross-platform: Windows, Linux and MacOS
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- Easy-to-use client API inspired by Python [requests](https://2.python-requests.org//en/master/)
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- SSL/HTTPS support with OpenSSL (optional)
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- GZip compression support with Zlib (optional)
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- Persistent (Keep-Alive) connections
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- Data streaming
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- for uploading and downloading large files on client
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- for serving and receiving large files on server
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- Basic & Token authorization
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- Timeout control
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- Source code follows [Google C++ Style](https://google.github.io/styleguide/cppguide.html)
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- Automation tests and unit tests included
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- No memory leak detected by [VLD](https://kinddragon.github.io/vld/)
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## Client API
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Let's start from a complete client example:
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```cpp
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#include <iostream>
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#include "webcc/client_session.h"
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#include "webcc/logger.h"
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int main() {
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// Configure logger to print only to console.
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WEBCC_LOG_INIT("", webcc::LOG_CONSOLE);
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// Session provides convenient request APIs, stores request configurations
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// and manages persistent connenctions.
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webcc::ClientSession session;
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// Catch exceptions for error handling.
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try {
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// Send a HTTP GET request.
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auto r = session.Send(webcc::RequestBuilder{}.
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Get("http://httpbin.org/get")
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());
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// Print the response data.
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std::cout << r->data() << std::endl;
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} catch (const webcc::Error& error) {
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std::cerr << error << std::endl;
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}
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return 0;
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}
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```
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As you can see, a helper class named `RequestBuilder` is used to chain the parameters and finally build a request object. Please pay attention to the `()` operator.
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URL query parameters can be easily added through `Query()` method:
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```cpp
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session.Send(webcc::RequestBuilder{}.
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Get("http://httpbin.org/get").
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Query("key1", "value1").Query("key2", "value2")
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());
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```
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Adding additional headers is also easy:
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```cpp
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session.Send(webcc::RequestBuilder{}.
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Get("http://httpbin.org/get").
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Header("Accept", "application/json")
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());
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```
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Accessing HTTPS has no difference from HTTP:
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```cpp
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session.Send(webcc::RequestBuilder{}.Get("https://httpbin.org/get")());
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```
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*NOTE: The HTTPS/SSL support requires the build option `WEBCC_ENABLE_SSL` to be enabled.*
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Listing GitHub public events is not a big deal:
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```cpp
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auto r = session.Send(webcc::RequestBuilder{}.
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Get("https://api.github.com/events")
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());
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```
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You can then parse `r->data()` to JSON object with your favorite JSON library. My choice for the examples is [jsoncpp](https://github.com/open-source-parsers/jsoncpp). But Webcc itself doesn't understand JSON nor require one. It's up to you to choose the most appropriate JSON library.
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`RequestBuilder` provides a lot of functions for you to customize the request. Let's see more examples.
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In order to list the followers of an authorized GitHub user, you need either **Basic Authorization**:
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```cpp
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session.Send(webcc::RequestBuilder{}.
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Get("https://api.github.com/user/followers").
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AuthBasic(login, password) // Should be replaced by valid login and passwords
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());
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```
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Or **Token Authorization**:
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```cpp
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session.Send(webcc::RequestBuilder{}.
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Get("https://api.github.com/user/followers").
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AuthToken(token) // Should be replaced by a valid token
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());
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```
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Though **Keep-Alive** (i.e., persistent connection) is a good feature and enabled by default, you can turn it off:
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```cpp
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auto r = session.Send(webcc::RequestBuilder{}.
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Get("http://httpbin.org/get").
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KeepAlive(false) // No Keep-Alive
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());
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```
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The API for other HTTP requests is no different from GET.
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POST request needs a body which is normally a JSON string for REST API. Let's post a small UTF-8 encoded JSON string:
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```cpp
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session.Send(webcc::RequestBuilder{}.
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Post("http://httpbin.org/post").
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Body("{'name'='Adam', 'age'=20}").Json().Utf8()
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());
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```
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Webcc has the ability to stream large response data to a file. This is especially useful when downloading files.
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```cpp
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auto r = session.Send(webcc::RequestBuilder{}.
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Get("http://httpbin.org/image/jpeg")
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(), true); // stream = true
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// Move the streamed file to your destination.
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r->file_body()->Move("./wolf.jpeg");
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```
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Streaming is also available for uploading:
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```cpp
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auto r = session.Send(webcc::RequestBuilder{}.
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Post("http://httpbin.org/post").
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File(path) // Should be replaced by a valid file path
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());
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```
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The file will not be loaded into the memory all at once, instead, it will be read and sent piece by piece.
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Please note that `Content-Length` header will still be set to the true size of the file, this is different from the handling of chunked data (`Transfer-Encoding: chunked`).
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Please check the [examples](https://github.com/sprinfall/webcc/tree/master/examples/) for more information.
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## Server API
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### Hello, World!
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```cpp
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class HelloView : public webcc::View {
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public:
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webcc::ResponsePtr Handle(webcc::RequestPtr request) override {
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if (request->method() == "GET") {
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return webcc::ResponseBuilder{}.OK().Body("Hello, World!")();
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}
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return {};
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}
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};
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int main() {
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try {
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webcc::Server server(8080);
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server.Route("/", std::make_shared<HelloView>());
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server.Run();
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} catch (const std::exception&) {
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return 1;
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}
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return 0;
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}
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```
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### Book Store
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Suppose you want to create a book server and provide the following operations with RESTful API:
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- Query books based on some criterias.
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- Add a new book.
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- Get the detailed information of a book.
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- Update the information of a book.
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- Delete a book.
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The first two operations are implemented by `BookListView` deriving from `webcc::View`:
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```cpp
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class BookListView : public webcc::View {
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public:
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webcc::ResponsePtr Handle(webcc::RequestPtr request) override {
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if (request->method() == "GET") {
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return Get(request);
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}
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if (request->method() == "POST") {
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return Post(request);
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}
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return {};
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}
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private:
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// Get a list of books based on query parameters.
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webcc::ResponsePtr Get(webcc::RequestPtr request);
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// Create a new book.
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// The new book's data is attached as request data in JSON format.
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webcc::ResponsePtr Post(webcc::RequestPtr request);
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};
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```
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Other operations are implemented by `BookDetailView`:
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```cpp
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// The URL is like '/books/{BookID}', and the 'args' parameter contains
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// the matched book ID.
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class BookDetailView : public webcc::View {
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public:
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webcc::ResponsePtr Handle(webcc::RequestPtr request) override {
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if (request->method() == "GET") {
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return Get(request);
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}
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if (request->method() == "PUT") {
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return Put(request);
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}
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if (request->method() == "DELETE") {
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return Delete(request);
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}
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return {};
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}
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protected:
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// Get the detailed information of a book.
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webcc::ResponsePtr Get(webcc::RequestPtr request);
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// Update a book.
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webcc::ResponsePtr Put(webcc::RequestPtr request);
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// Delete a book.
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webcc::ResponsePtr Delete(webcc::RequestPtr request);
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};
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```
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The detailed implementation is out of the scope of this README, but here is an example:
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```cpp
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webcc::ResponsePtr BookDetailView::Get(webcc::RequestPtr request) {
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if (request->args().size() != 1) {
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// NotFound means the resource specified by the URL cannot be found.
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// BadRequest could be another choice.
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return webcc::ResponseBuilder{}.NotFound()();
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}
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const std::string& book_id = request->args()[0];
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// Get the book by ID from, e.g., the database.
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// ...
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if (<NotFound>) {
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// There's no such book with the given ID.
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return webcc::ResponseBuilder{}.NotFound()();
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}
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// Convert the book to JSON string and set as response data.
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return webcc::ResponseBuilder{}.OK().Data(<JsonStringOfTheBook>).
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Json().Utf8()();
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}
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```
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Last step, route URLs to the proper views and run the server:
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```cpp
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int main(int argc, char* argv[]) {
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// ...
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try {
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webcc::Server server(8080);
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server.Route("/books",
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std::make_shared<BookListView>(),
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{ "GET", "POST" });
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server.Route(webcc::R("/books/(\\d+)"),
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std::make_shared<BookDetailView>(),
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{ "GET", "PUT", "DELETE" });
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server.Run();
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} catch (const std::exception& e) {
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std::cerr << e.what() << std::endl;
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return 1;
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}
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return 0;
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```
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Please see [examples/rest_book_server.cc](https://github.com/sprinfall/webcc/tree/master/examples/rest_book_server.cc) for more details.
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