Client Session

Table of contents

RUI library requires developers to specify an address and port on which to listen for client connections. Clients can be either a browser or a WebView. To be able to listen for incoming connections using a public interface, we can use the rui.GetLocalIP() function:

Go

rui.StartApp(rui.GetLocalIP() + ":80", …

Every time a new client opens a page with our application, RUI library creates a Session that holds all resources dedicated to this client as well as its capabilities. The session also implements interaction between the client and the server, so it acts as a bridge between these two. The lifetime of a session is limited by the lifetime of the browser page. The process of creating a session is hidden by the library.

Session is represented as an interface. See the Session reference documentation for more details.

Let's briefly look at some methods provided by the session interface, which can be divided into the following groups.

Client parameters

  • DarkTheme() bool - query client's current theme mode. By default RUI library support both light and dark theme for all its UI controls.

  • TouchScreen() bool - query whether the client has a sensitive touch screen.

  • PixelRatio() float64 - query the client's screen logical pixel ratio, as an example for the iPhone device it could be 2.0 or 3.0.

  • TextDirection() int - query the default text direction on a client side.

  • UserAgent() string - query the user agent string of the client.

  • RemoteAddr() string - query the remote client address.

Internationalization settings

  • SetLanguage(lang string) - sets the language of the application for the current session. By default, RUI library follows the language setting of the client. This method can be used to overwrite this behavior. It is useful when the application provides a language selection option for the end user. Language can be set at any time. Text translations generally prepared in resource files and library automatically use the right translation for the session.

  • Language() string - query the client's language setting. The language is usually returned in the form: "en", "en-US", "de" and so on.

  • GetString(tag string) (string, bool) - query for a text translation of the current language. This method may be useful when constructing complex strings on the fly from multiple pieces of localized text.

Theme settings

  • Constant(tag string) (string, bool) - query the value of a constant in the current application theme.

  • Color(tag string) (Color, bool) - query for the color constant's value from the current application theme.

  • ImageConstant(tag string) (string, bool) - query for the image constant's value from the current application theme.

  • SetCustomTheme(name string) bool - set a custom theme by its name. This is useful when the application provides a theme selection option for the end user.

Browser tab settings

  • SetTitle(title string) - change the title of the browser's tab.

  • SetTitleColor(color Color) - changes the background color of the browser tab's title. This function has an effect only in some browsers, such as Safari and Chrome for Android.

As a rule of thumb use the rui.StartApp() function which sets these values during application startup.

Client actions

  • DownloadFile(path string) - initiate a download file action on the client side where path is the location of the existing file on the server side.

  • DownloadFileData(filename string, data []byte) - initiate a download file action on the client side where filename is the preferred file name and data is the content of the file. This method is useful when application prepare some file on the fly(in memory) and want the end user to save it.

  • OpenURL(url string) - force the browser to open a specific URL in a separate window or tab.

UI controls settings

  • RootView() View - query for top most UI control of the session.

  • Get(viewID, tag PropertyName) any - query for property value of the UI control based on UI control ID and property name. Library will search for an UI control starting from the root view of the session. This can be equivalent to this call:

Go

rui.Get(session.RootView(), viewID, tag)
  • Set(viewID, tag PropertyName, value any) bool - change some property value of the UI control. The library will search for the UI control starting from the root view of the session. This can be equivalent to this call:

Go

rui.Set(session.RootView(), viewID, tag, value)

Example

To demonstrate client session, let's create a simple application that logs the settings of any connected client.

Go

package main

import (
    "fmt"
    "log"

    "github.com/anoshenko/rui"
)

// Port on which listen for incoming connections
const port = ":8080"

type appSession struct {
}

// CreateRooView will create an empty root view
func (app appSession) CreateRootView(session rui.Session) rui.View {

    // Log session data
    logSession(session)

    // Create an empty view
    return rui.NewView(session, rui.Params{})
}

// createSession creates an instance of our implementation of rui.SessionContent
func createSession(session rui.Session) rui.SessionContent {
    return new(appSession)
}

// logSession will log basic session information
func logSession(session rui.Session) {
    darkThemeStr := fmt.Sprintf("%t", session.DarkTheme())
    touchScreenStr := fmt.Sprintf("%t", session.TouchScreen())
    pixelRatioStr := fmt.Sprintf("%.1f", session.PixelRatio())

    log.Println("User agent: " + session.UserAgent())
    log.Println("Language: " + session.Language())
    log.Println("Remote: " + session.RemoteAddr())
    log.Println("Dark theme: " + darkThemeStr)
    log.Println("Pixel ratio: " + pixelRatioStr)
    log.Println("Touch screen: " + touchScreenStr)
}

// main entry point
func main() {
    // Prepare address to listen on
    addr := "localhost" + port

    // Open browser window locally for convenience
    rui.OpenBrowser("http://" + addr)

    // Initialize RUI library and wait for incoming connections
    rui.StartApp(addr, createSession, rui.AppParams{
        Title: "Session example",
    })
}

The main function starts the application by defining the address where it will listen for incoming connections. It also opens a browser window at that address for convenience. The RUI library is initialized with a callback function createSession() which creates an instance of our implementation of the rui.SessionContent interface. When the browser window requests our application page the CreateRootView() function will be called, where we'll log session information.

Depending on your system configuration, the output of the application may differ:

2024/10/02 10:49:51 User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.1 Safari/605.1.15
2024/10/02 10:49:51 Language: en-GB
2024/10/02 10:49:51 Remote: 127.0.0.1:54806
2024/10/02 10:49:51 Dark theme: false
2024/10/02 10:49:51 Pixel ratio: 2.0
2024/10/02 10:49:51 Touch screen: false

© Alxanosoft inc.