Creating an HTTP Response

HydraExpress Servlet Development Guide
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8.4 Creating an HTTP Response

The servlet container provides several ways to use a rwsf::HttpServletResponse object to return a response to a client.

8.4.1 Using Java-Like Output Functions

Each response object contains an output object that supports a set of overloaded print() and println() functions described in the Servlet Specification. These functions are convenient for programmers accustomed to Java servlet programming. The sample below shows a doGet function that creates a simple HTML response with the Java-like functions:

void myServlet::doGet (rwsf::HttpServletRequest& request,
                       rwsf::HttpServletResponse& response)
{
  response.setContentType("text/html");                          // 1

  rwsf::ServletOutputStream& out = response.getOutputStream();   // 2

  out.println("<html>");                                         // 3
  out.println("<head><title>Simple Response</title></head>");
  out.println("<body bgcolor=\"white\">");
  out.println("<h1>Simple Response</h1>");
  out.println("A simple HTML response.");
  out.println("</body></html>");
}

`//1`	Sets the `Content-Type` of the response to `text/html`. A client may use the `Content-Type` to determine the kind of document in the response. Without this line, some clients interpret the response as plain text.
`//2`	Gets the output stream from the response.
`//3`	Prints a line of the response to the client. In this version, the servlet prints the string to the client using the Java-like function `println()`.

8.4.2 Setting the Response from a String

An rwsf::ServletResponse also provides a setPayload() function. The function sets the body of the response directly, from a single string. Setting the payload directly is generally more efficient than using the rwsf::ServletOutputStream class to write the response. The doGet() function below constructs a string, then uses the setPayload() function to create the response.

void myServlet::doGet (rwsf::HttpServletRequest& request,
                       rwsf::HttpServletResponse& response)
{
  response.setContentType("text/html");                        // 1

  std::string output("<html>\n"
    "<head><title>Simple Response</title></head>\n"
    "<body bgcolor=\"white\">\n"
    "<h1>Simple Response</h1>\n"
    "A simple HTML response.\n"
    "</body></html>\n");                                       // 2
 
   response.setPayload(output);                                // 3
}

`//1`	Sets the `Content-Type` of the response to `text/html`. A client may use the `Content-Type` to determine the kind of document in the response. Without this line, some clients interpret the response as plain text rather than HTML.
`//2`	Creates an *string* containing the response.
`//3`	Sets the content of the response to `output`. In this version, the servlet sets the entire response in a single operation.

The related function appendPayload() appends a string to the current contents of the response.

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