TAILIEUCHUNG - Oracle XSQL- P26

Oracle XSQL- P26Welcome to the exciting world of eXtended Structured Query Language (XSQL) development! What’s so exciting? Efficiency and ease of use. XSQL isn’t some razzle-dazzle technology to wow your users. It also isn’t the latest X standard du jour that no one can stop talking about until you ask, “But what does it do for me today?” The problem with all of the great stuff out there is that no one technology does it all. | 480 Chapter 18 development. They are both similar in a lot of ways yet have some important differences. Hopefully this discussion will solidify your understanding of the basic art and science of action handler development. The last section discusses how to debug action handlers. Hello Action Handler On any journey there is a first step. The first step here is to create a working action handler. The goal of the action handler is simple It is to add an empty element named hello to the datagram. As you read this discussion you ll see how to write the code deploy the class and invoke the action handler. The best place to start is on familiar ground. The following is the XSQL page that will invoke the action handler. When the XSQL page processor sees the xsql action action it loads the class specified by the handler attribute. xml version encoding UTF-8 page xmlns xsql urn oracle-xsql xsql action handler HelloActionHandler page The name must be the fully qualified class name. For these simple examples the classes aren t in a package. If your classes are in packages you will need to specify the fully qualified name as follows xml version encoding UTF-8 page xmlns xsql urn oracle-xsql xsql action handler page In this particular example there are no parameters and the xsql action element has no children. This particular action handler doesn t need them. If there were any present they would be ignored. But the xsql action element can have parameters and values. You ll see later in this chapter how to manipulate them from inside the action handler. Before moving on to the action handler code itself it s worth noting that the xsql action element doesn t have to be a child element. It can be a top-level element just as any of the other actions can as shown in the following code. You may have also noticed that there is no database connection specified. For the simple examples given in this chapter you won t need a database .

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