3.1 Introduction

The servlet interface is designed to make creating Web applications an easy and intuitive process. This chapter explains the process of creating a servlet and presents the code for a simple servlet.

The HydraExpress servlet container instantiates the servlet when it starts, then calls the init() method on the servlet. Each time a client request arrives, the servlet container calls a handler method on the servlet. Before the container shuts down, it calls the destroy() method on the servlet. This chapter covers the steps required to define, implement, compile, and deploy a complete servlet. Although the servlet described is simple, the example presents all the basic tasks necessary to write a servlet.

The servlet described in this section is included in the files HelloWorldExample.h and HelloWorldExample.cpp in the tutorials\servlet directory of the HydraExpress installation. The servlet itself is available at http://localhost:8090/examples/HelloWorldExample on a system running HydraExpress.

Creating and deploying a servlet involves the following steps:

• Create a class that inherits from rwsf::HttpServlet. This class provides the basic framework for a C++ servlet (Section 3.2)

• Define the servlet by using the RWSF_DEFINE_SERVLET macro within a single source file (Section 3.3)

• Implement the request handlers (Section 3.4)

• Compile the servlet into a shared library (Section 3.5)

• Copy the shared library into the path that the system uses to load shared libraries (Section 3.6)

• Add the servlet deployment descriptor to the web.xml file in the servlet context (Section 3.7)

• If the servlet resides in a new context, configure any external Web servers to forward requests to the new context. Section 4.12 describes the process of reconfiguring the Web server.

• Stop and restart the HydraExpress Agent (Section 3.8).

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