Wt (web toolkit)#Code example

• Automatic graceful degradation and progressive enhancement
• Supports server-initiated events (Comet)
• A unified rendering API (SVG, the HTML5 canvas element, VML)
• Client- and server-side validation
• Contains various security features to avoid Cross-site scripting and Cross-site request forgery (CSRF) vulnerabilities
• Includes a compact C++ ORM-layer ("Wt::Dbo")
• Uses the WebSocket networking protocol, if available, for Client–server model of communication, with fallbacks to Ajax or plain web page rendering

For a more detailed overview, see the Features section of official website.

The "Hello, World!" program in Wt:

1. include
2. include
3. include
4. include
5. include
6. include

/*

* A simple hello world application class which demonstrates how to react

* to events, read input, and give feed-back.

*/

class HelloApplication : public Wt::WApplication

{

public:

HelloApplication(const Wt::WEnvironment& env);

private:

Wt::WLineEdit *nameEdit_;

Wt::WText *greeting_;

void greet();

};

/*

* The env argument contains information about the new session, and

* the initial request. It must be passed to the WApplication

* constructor so it is typically also an argument for your custom

* application constructor.

• /

HelloApplication::HelloApplication(const Wt::WEnvironment& env)

: WApplication(env)

{

setTitle("Hello world"); // application title

root()->addNew("Your name, please ? "); // show some text

nameEdit_ = root()->addNew(); // allow text input

nameEdit_->setFocus(); // give focus

auto button = root()->addNew("Greet me."); // create a button

button->setMargin(5, Wt::Side::Left); // add 5 pixels margin

root()->addNew(); // insert a line break

greeting_ = root()->addNew(); // empty text

/*

* Connect signals with slots

*

* - simple Wt-way: specify object and method

*/

button->clicked().connect(this, &HelloApplication::greet);

/*

* - using an arbitrary function object, e.g. useful to bind

* values with std::bind() to the resulting method call

*/

nameEdit_->enterPressed().connect(std::bind(&HelloApplication::greet, this));

/*

* - using a lambda:

*/

button->clicked().connect([=]() {

std::cerr << "Hello there, " << nameEdit_->text() << "\n";

});

}

void HelloApplication::greet()

{

/*

* Update the text, using text input into the nameEdit_ field.

*/

greeting_->setText("Hello there, " + nameEdit_->text());

}

int main(int argc, char **argv)

{

/*

* Your main method may set up some shared resources, but should then

* start the server application (FastCGI or httpd) that starts listening

* for requests, and handles all of the application life cycles.

*

* The last argument to WRun specifies the function that will instantiate

* new application objects. That function is executed when a new user surfs

* to the Wt application, and after the library has negotiated browser

* support. The function should return a newly instantiated application

* object.

*/

return Wt::WRun(argc, argv, [](const Wt::WEnvironment &env) {

/*

* You could read information from the environment to decide whether

* the user has permission to start a new application

*/

return std::make_unique(env);

});

}

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• Comparison of web-frameworks
• JWt (Java web toolkit), a native Java version of Wt
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