The client (the Web user) uses a browser to access the site.
The browser sends a request to the server that is hosting the requested site. In this request, it indicates the page that must be displayed and different parameters allowing the server to build the corresponding page.
The server receives this request, processes it and returns the corresponding "HTML" page. HTML (HyperText Markup Language) is the language used by all browsers to display the Web pages.

Therefore, there are two types of events:

Events run at browser level, on the Web user's computer.
Events run at server level.

The code run at browser level is called JavaScript code. The browsers can only run JavaScript code.

And in WEBDEV?

With WEBDEV, everything is developed:

in WYSIWYG ("What You See Is What You Get") in the editor: your pages are visually identical when being created and at runtime.
in WLanguage for the programming side.

WEBDEV converts your page created in the editor into HTML page that can be read by the browsers.

The server code is run in WLanguage.

The browser code is converted into JavaScript.

To create a site with WEBDEV, a single language is required: WLanguage.

However, two types of code are available: server code and browser code.

Why this distinction between server/browser? For performance reasons. Indeed, between the browser and the server stands Internet, with its response time, latency, ... Some simple operations can be performed on the browser directly, without having to go back to the server.

Server/Browser operation of a WEBDEV site

Practical example

To better understand the difference between server and browser events, we have prepared a simple example:

Start WEBDEV 25 (if necessary). Display the WEBDEV home page if necessary: press Ctrl + <.

Open the "WEBDEV concepts" project. To do so, in the home page, click "Tutorial" and select the project named "WEBDEV concepts (Exercise)".


	Remark	If the UAC is enabled in Windows, a specific window may be displayed. This window indicates that the WD250Admin.exe program will be run on the current computer. Grant the authorization. This program corresponds to the local WEBDEV administrator that is used to run the test of sites developed with WEBDEV. Its features will be presented later in this tutorial.

Open the "PAGE_Registration" page in the editor: double-click its name in the "Project explorer" pane.


	Remark	The "Project explorer" pane allows you to display in the environment a list of all the elements found in the project. These elements are grouped by theme: Pages, Procedures, ... To display the "Project explorer" pane: On the "Home" pane, in the "Environment" group, expand "Panes". In the list of panes that is displayed, select "Project explorer".

This page contains edit controls and a "REGISTER" Button control. The "REGISTER" Button control must do two things:
1. Check that all controls have been filled.
2. Save the values of controls in the database.

Let's see the WLanguage code associated with the Button control:
1. Select the "Register" Button control.
2. Display the popup menu of the control (right click) and select "Code".
3. The code editor is displayed with the different events linked to the Button control. To see all the events associated with the Button control, press the Page Up key.


	Remark	The code editor allows you to write the WLanguage code of your processes. The code editor presents the events associated with each control, which means the events on which a specific process can be run. Remark: Events are displayed in the order in which they will be run. For example, the events associated with the Button control are: Initialization. Browser click. Server click.

Let's study the WLanguage code displayed: the server code and the browser code are identified by different colors:
- The browser code, that will be run on the computer of Web user, is displayed in green.
- The server code, that will be run on the server, is displayed in yellow.

In our example, all input checks are performed in browser code (green code). For example, the EDT_LastName control must not be empty. The corresponding code is as follows:

// Check whether the "EDT_LastName" control is equal to empty string
// (excluding spaces and punctuation)
IF EDT_LastName ~= "" THEN
// The control is empty, display an error message to
 // the user
Error("Type your last name")
// Return in edit into the "EDT_LastName" control (without running
// the rest of code)
ReturnToCapture(EDT_LastName)
END

This check is performed in browser code because there is no need to go back to the server to check that the controls are filled.

This is used to avoid useless round trips and to reduce the wait for the Web user: the navigation is more fluid.

Once the browser code was run, the page sends the values typed to the server. Then, the server runs the server code. In the server code, you have the ability to process the information received.

In our example, the information received is added into the database via the following code:

// Reset the customer structure
HReset(Customer)
 
// Get the values of controls in
// the customer structure
ScreenToFile()
 
// Add the customer into the database
HAdd(Customer)

This operation cannot be performed in browser code because the database is common to all site users and therefore it is located on the server.

Close the code window (click the cross in the top right corner).

Close the page displayed in the editor (click the cross in the top right corner).

Intranet/Extranet/Internet

Principle

An Intranet or Extranet site is often considered as being a management application in Web mode, which means an application run in a browser.

This Web application can present:

business features intended for specific users,
processes that must be secured: not everyone should be able to access the application.

The Web application can be accessed:

from a company network only, in which case we talk of Intranet site.
from Internet, in which case we talk of Extranet site.

In both cases, the Web application is secured by managing logins, passwords, rights, etc.

An Internet site is a site meant for "public" consumption (business users or regular users). An Internet site must be easily found on the Web. Some examples: presentation site, e-commerce site, ...

To bring more Web users to your site, the site must be referenced by the search engines. In order for the search engines to reference each page properly, an additional constraint appears: the site pages must be accessible at any time. But this constraint is also a guarantee of simplicity for the Web user: he can easily copy/paste a link from a page and re-use this link whenever required.

And in WEBDEV? (Session/AWP, PHP, Static)

In WEBDEV, to develop an Intranet or Extranet site, the "Session" mode is more suitable because it includes the following features: integrated security, automatic contexts. Indeed, the Session mode includes automatic sessions. The session identifier is included in the URL. The address for the pages depends on this identifier which changes for each connection.
Drawback: The search engines cannot index this site.

In WEBDEV, to develop an Internet site, you can choose one of the following modes:

The AWP mode (Active WEBDEV Page).
The PHP generation mode.
The static mode if your site contains preset pages only (no database).

Páginas

sábado, 5 de setembro de 2020

DICAS 3068 -WEBDEV TUTORIAL 1-Licao 1.2-14-09-2020 15hrs-Web development and WEBDEV - PARTE A

https://youtu.be/26FmrkPtIxs

Esse Ao Vivo vai estrear as 15:00 do dia 14/09/2020

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