Describe the main practical principles of working…

JSP (JavaServer Pages) is a web development technology that allows embedding Java code into HTML pages. The main practical principles include:

Using JSP tags:
- Directives: Define general page settings (e.g., encoding, class imports).
```
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
```
- Scriptlets: Insert blocks of Java code (preferably minimize their use).
```
<%
    String name = "World";
    out.println("Hello, " + name + "!");
%>
```
- Expressions: Output values of Java variables or expressions.
```
<%= new java.util.Date() %>
```
- Action tags: Predefined tags for standard tasks (e.g., <jsp:include>, <jsp:forward>).
```
<jsp:include page="header.jsp" />
```
Model-View-Controller (MVC) principle: JSP is typically used for the View in the MVC pattern. Business logic should reside in servlets (Controller) or separate Java classes (Model), not in JSP.
JSP Standard Tag Library (JSTL): A set of standard tags for common operations (iteration, conditional operators, formatting). Preferable over scriptlets.
```
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<c:forEach items="${myList}" var="item">
    <p>${item}</p>
</c:forEach>
```
Expression Language (EL): Simplifies access to data stored in various scopes (page, request, session, application). Used with JSTL.
```
<p>User: ${sessionScope.currentUser.name}</p>
```
Error handling: Using the errorPage directive or configuring web.xml to redirect to an error page.
```
<%@ page errorPage="error.jsp" %>
```
Using JavaBeans: Storing data in JavaBeans and accessing them via EL or tags <jsp:useBean>, <jsp:getProperty>, <jsp:setProperty>.
Commenting: Using JSP comments (<%-- --%>) for comments that do not appear in the generated HTML.
Avoid code duplication: Using <jsp:include> or tag files for reusable fragments.
Security: Sanitizing user input to prevent XSS attacks. It's hard to do this effectively directly in JSP; better to use frameworks or libraries.
Testing: View testing (JSP) is usually conducted indirectly through controller testing and integration tests.
Performance: Excessive Java code in scriptlets can reduce performance. Use JSTL and EL.

Following these principles helps create more readable, maintainable, and secure JSP code.

Describe the main practical principles of working with JSP.