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Lic. Jorge Guerra Guerra

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A text-based documents capable of

returning dynamic content to a client

browser.Contains HTML, XML, programming

code, and JSP tags(HTML and XML

tags) allowing access to components

such as JavaBeans.

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Content and display logic are separated.

Simplify development with JSP, java beans

and custom tags.

Supports software reuse through the use ofcomponents.

Recompile automatically when changes are

made to the source file.

Easier to author.

Platform-independent.

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Declarations: define variables and methods.

Scriptlets JSP code fragments.

Expressions: results of evaluating the expression are converted toa string.

Destination:

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Used to define variables, methods.Examples:

Variable declaration:

x Results in member variables within the compiled servlet.

Method declaration:x

The scope of the declaration is in a JSP file. If the JSP file includes other files within the includedirective, the scope expands to cover the includedfiles as well.

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Programming code fragments that

perform tasks beyond the capabilities

of markup languages (HTML).

Everything defined in scriptlet goes to

service() method in JSP servlet.

Variables declared in scriptlets are localvariables in service() method.

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Expressions evaluated during thegeneration of a response. The result is converted into a string, also called the

output stream. Inserted into the servlet's output. i.e.Results in

something like out.println(expressions)Syntax

Semi-colons are not allowed for expressions.

Expressions are evaluated in a left-to-right order.

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Directives are messages to the JSP containerand do not produce output into the currentoutput stream.

They have a syntax as follows:

Important directives: page: Communicate page dependent attributes and

communicate these to the JSP container.x

include:Used to include text and or code at JSP pagetranslation-time.x

Taglib: Indicates a tag library that the JSP containershould interpret.

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Give high-level information about theservlet that results from the JSP page.

Control

Which classes are improted.x What MIME type is generated.x

How multithreading is handled.x x

What page handles unexpected errors.x

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A JSP page has access to certainimplicit objects that are alwaysavailable, without being declared first.

They are the following: request(HttpServletRequest)

response(HttpServletRepsonse).

session(HttpSession)

application(ServletContext).

pageContext, out(of type JspWriter)

config(ServletConfig), page, exception.

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Forwards request to HTML page, JSP, or servlet

Includes output or response from another file

into this current JSP page.

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