class= calendar.jspCalendar  />

request

response

Day: <%=clock.getDayOfMonth() %>

Year: <%=clock.getYear() %>

An Example Using a Tag Library

FIGURE 1 2

 is another example of a JSP page. This page uses custom actions to create the 

server side object and then to produce the response data. In the example, a 

taglib

 directive 

first makes available into this page a tag library for data base queries. The directive indicates 

the tag library to use and provides a prefix to use locally in this page to name those actions.

Designing tag libraries is a delicate effort, analogous to that of designing a language; we are 

making no special effort here to define tags that are useful for any but pedagogical purposes. 

For the purposes of this example, we will assume that this fictitious tag library introduces 

four actions :

A 

queryBlock 

action introduces a data base connection; it can contain queryStatement 

actions and queryCreateRow actions. The connData attribute refers to connection specific 

data, like login and password, that are to be defined elsewhere; see Appendix 5.8.3 for 

suggestions on where to place the information.

A 

queryStatement 

action must be enclosed in a queryBlock. A queryStatement's body is a 

SQL statement; it will use the connection data defined in the enclosing queryBlock.

Chapter 1

Overview

20