A Sip From The Firehose: Friday, March 20, 1998

Friday, March 20, 1998
Hanover Germany

C++ Programmers - Two Faces, One Language

Building a Web Server Application

I am at the annual CeBit computer show in Hanover Germany. This show lasts for seven days and has over 850,000 attendees (and I thought Comdex Las Vegas was big). I am on another one of my 10 countries in 10 days trips to Europe showing C++Builder 3 and previewing JBuilder 2 to customers, press and partners. In my visits with developers I have been impressed with the quality of the projects they are working on and the questions they ask. One example in Italy is a multi-tier Delphi/Interbase/As400 application for a major clothing manufacturer. The application lets employees in the store order clothes direct from the factory when stocks are low.

As I travel I am often asked if developers are different around the world. I am also asked where the best developers are. My answer to both questions are that there are great developers everywhere. No country has a lock on the best programmers. We all have access to the best tools, the latest information, and the future operation system and hardware interfaces. Programmers around the world are trying to solve the same business problems.

To get a finger on the pulse of C++ developers, last fall we placed a survey on Borland Online (there is a survey now available for Delphi programmers too). The survey asked what types of applications were they building, what problems were they facing, and what were their future application development requirements. From the survey two distinct types of C++ programmers and their needs emerged - Systems Developers and Applications Developers.

C++ Developer Web Survey Results

More than 8,000 C++ developers responded to the survey. The survey showed that they are unhappy with the current tools they are using especially in the areas of creating visual applications, debugging, and project management. Their future requirements include the ability to easily create database, Internet, and visual applications all within the same environment. C++ developers told us that they did not want to have to use one visual tool for the user interface, and another tool for database and systems programming. They also told us that the critical issues facing every C++ developer are programmer productivity, application performance, and support for industry standards.

Developers were also asked what type of applications they were building, what were the application characteristics, what debugging support they required, and the type of project build environment they needed.

C++ Systems Programmers

Systems programmers focus on performance generally building console applications, NT Services, device drivers, ActiveX controls, embedded and real-time systems. The applications they build are usually characterized as being non-visual, high-performance, low-level, object oriented, and built with object frameworks. The debugging support required includes a native code generated assembly language view, complex conditional breakpoints, and ability to view application events. Their build/make project environment needs to be very modular and flexible, and has to support the building of many targets. The bottom line for C++ Systems Programmers is an ANSI/ISO C++ compiler, strong debugging, and support for system API's and object frameworks.

C++ Application Programmers

Application programmers focus on productivity using C++ to build database, Internet, multi-tier, and game applications. Their applications are characterized by being very visual, high-performance, component oriented, and event driven. Debugging of applications requires local variable inspection, conditional breakpoints, and the ability to step into, out of, and over functions. Their project management environment needs to support building of forms, DLLs, resources, and multiple targets. The bottom line for C++ Application Programmers is support for database programming, Internet standards and assembling applications using components.

Solution: C++Builder 3!

Borland C++Builder 3 is the solution for both the systems developer and the application developer. It delivers the productivity and performance that you expect and demand when building any Windows applications. C++Builder 3 delivers the advanced Project Manager for handling complex applications requiring multiple target types, six new powerful debugging capabilities, over 15 new compiler options for smaller and more efficient code, seamless client/server database development and three new integrated internet development technologies. Exclusive to C++Builder 3 are technology solutions for decision support with the Decision Cube multi-dimensional cross-tab components, MIDAS (Multi-Tier distributed application services) development kit for building business critical applications with DCOM, and the new Adaptive Compiler Technologies for unbelievable performance.

Building a C++Builder3 Web Server Application - A Different Type of Survey

Which category of C++ programmer are you? Systems or Applications programmer? In a smaller development department you might be both. Are there other critical factors that affect your development efforts? I have included my own short survey below to find out more about C++ programmer issues. If you are interested in taking part in the David I survey, click here.

With C++Builder3 Client/Server Suite you can build your own web server applications. C++Builder3 includes new components (WebModule, PageProducer, QueryTableProducer, and DataSetTableProducer) that let C++ programmers build CGI (Common Gateway Interface), WinCGI (Windows CGI), ISAPI (Microsoft Internet Information Web Server API), and NSAPI(Netscape Web Server API) web server applications. The WebBroker technology included with C++Builder3 Client/Server Suite lets you build one set of web server application logic and use it to build all four types of server applications. In my case I've built an ISAPI DLL web server application that creates a HTML survey form and uses InterBase to store the responses. The source code for the survey is included in a zip file.

Steps to Build the Web Survey ISAPI DLL Server Application

This section lists the steps required to build and test the web server DLL. To test the DLL you will need either the Microsoft Internet Information server running under Windows NT, or the Microsoft Personal Web server running under Windows 95. If you decide to build a CGI or WinCGI executable you can also use the O'Reilley & Associates Web Server as well. You can build web server applications either as CGI/WinCGI executables (.exe) or ISAPI/NSAPI DLLs (.dll) files. Executables are loaded as separate processes and are automatically unloaded from memory when the web request is finished. To debug a web server executables you use the old fashion text file output method, dumping messages and values to an external file. DLLs are loaded into the same process space as the web server and stay in memory for all subsequent requests. With C++Builder3's new DLL debugging capabilities you can easily use the development environment to step through your logic. One downside with using web DLLs is that you have to stop your web server to kick the DLL out of memory so that you can copy newer versions of the DLL into your web applications folder.

Step 1 - Build the InterBase database

Build an InterBase database to hold the survey results. The meta data for the database is very simple.

CREATE DATABASE "C:Survey.gdb" PAGE_SIZE 1024;

CREATE TABLE SURVEY (SURVEYKEY INTEGER NOT NULL,
  SURVEYNAME VARCHAR(20) NOT NULL,
  QUESTIONNUMBER INTEGER NOT NULL,
  QUESTIONKEYWORD VARCHAR(20) NOT NULL,
  USERANSWER VARCHAR(40),
PRIMARY KEY (SURVEYKEY));

CREATE GENERATOR SURVEY_GEN;

CREATE TRIGGER CREATE_SURVEYKEY FOR SURVEY                          
ACTIVE BEFORE INSERT POSITION 0 
AS BEGIN
  NEW.SURVEYKEY = GEN_ID(SURVEY_GEN, 1); 
END;

Step 2 - Create the BDE Alias

The alias name for the InterBase database needs to be SURVEY. Set the database type to InterBase. Set the directory path to where you put your Survey.gdb file.

Step 3 - Start C++Builder3 and Create a Web Server Application

Start up C++Builder 3. From the main menu chose File|New. Select the Web Server Application from the object repository. This will bring up the Web Server Application wizard. Chose the radio button for ISAPI/NSAPI to create the DLL project and the main application source file and the Web Module. You can also chose to build a CGI or WinCGI application.

Step 4 - Add a Database component to the Web Module

From the Data Access component palette drop a Database component into the Web Module. This will allow you to connect to the InterBase database, login to the database and stay connected between sessions. Set the Name property to SurveyDatabase. Set the AliasName property to the Survey alias created in Step 2. Set the DatabaseName property to any text string. Set the Params property to the folling strings:

  USER NAME=SYSDBA
  PASSWORD=masterkey

Set the LoginPrompt property to false (the Params property will contain the needed username and password). Set the HandleShared property to True. Set the Connected property to true to turn on the connection to the InterBase database.

Step 5 - Add a Table component to the Web Module

From the Data Access component palette drop a Table component into the Web Module. Set the Name property to SurveyTable. Set the DatabaseName property to the string you set in the Database component. Set the TableName property to the SURVEY table in the InterBase database. Set the Active property to True.

Step 6 - Add a PageProducer component to the Web Module

The first page producer will be used to generate the survey questions HTML page. Set the Name property to SurveyPageProducer. Set the HTMLFile property to the Survey.HTM html file included in the source code zip file. You could also use the HTMLDoc property to embed the HTML strings into the executable. There are two notes included in the C++Builder3 help file that are important when using the PageProducer.

Note: Setting HTMLFile clears the HTMLDoc property.
Note: When distributing applications that contain page producers which use the HTMLFile property, be sure to distribute the file along with the application. Also, be sure that the value of HTMLFile does not include a hard-coded path name that will not be available on the users disk.

I placed the Survey.HTM file in the same directory as my web server application DLL.

The HTMLFile text is too long to list in this column so I will just show you the HTML file with one of the survey questions.

<HTML>
<HEAD>
<TITLE>David I's Survey January 1998</TITLE>
</HEAD>
<BODY BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#006666" 
     ALINK="#009999" VLINK="#666666">
<h2>David I's January 1998 Survey</h2>
<form method=POST action="/scripts/websurvy.dll/survey">
<h3>1) What do you eat while you are programming?</h3>
<UL>
<table cellpadding="2" cellspacing="2">
<td><INPUT TYPE="radio" NAME="food" VALUE="Pizza">Pizza</td>
<td><INPUT TYPE="radio" NAME="food" VALUE="Sushi">Sushi</td>
<tr>
<td><INPUT TYPE="radio" NAME="food" VALUE="Pasta">Pasta</td>
<td><INPUT TYPE="radio" NAME="food" VALUE="Cookies">Cookies</td>
<tr>
<td><INPUT TYPE="radio" NAME="food" VALUE="Chips and
      Salsa">Chips and Salsa</td>
<td><INPUT TYPE="radio" NAME="food" VALUE="Candy">Candy</td>
<tr>
<td><INPUT TYPE="radio" NAME="food" VALUE="Popcorn">Popcorn</td>
<td><INPUT TYPE="radio" NAME="food" VALUE="Trail Mix">Trail Mix</td>
<tr>
<td><INPUT TYPE="radio" NAME="food" VALUE="Burgers and
      Fries">Burger and Fries</td>
<td><INPUT TYPE="radio" NAME="food" VALUE="Chinese">Chinese</td>
<tr>
<td><INPUT TYPE="radio" NAME="food" VALUE="Crackers and
      Cheese">Crackers and Cheese</td>
<td><INPUT TYPE="radio" NAME="food" VALUE="Programming is food"
      CHECKED>Programming is the food of life</td>
</table>
</UL>
<INPUT TYPE="submit" VALUE="Send">
<INPUT TYPE="reset" VALUE="Reset">
</form>
</body>
</html>

You'll find the complete HTML I used in the source code zip file both in the Web Module form file and in a separate survey.txt file.

Step 7 - Add another PageProducer component to the Web Module

The second page producer will be used to generate a response HTML page thanking survey respondents for taking part in the survey. Set the Name property to SurveyResponsePageProducer. Set the HTMLFile property to the Response.HTM file. The Response.HTM file contains the following HTML strings.

<html>
<title>Thank You!</title>
<body>
<CENTER>
<h3>Thank You</h3>
<h3>for completing the</h3>
<h3>January 1998</h3>
<h3>David I</h3>
<h3>web survey</h3>
<img src="/images/davidi1.gif">
<p>
<img src="/images/davidsig.gif">
</CENTER>
</body>
</html>

I placed the Response.HTM html file in the same directory as my web server application DLL.

Step 8 - Bring up the Web Module Action Editor

Right mouse click in the Web Module window. Select the Action Editor menu item from the pop-up menu.

Step 9 - Add the Survey Form default action item

In the Action Editor click the Add button. This will create a web action in the Web Module Actions array. In the Inspector, set the Name property to WebSurveyDefaultAction. Set the Default property true - this will mean that any execution of this web server application DLL will use this actions event handler for processing unless a pathinfo string is found to match a user request (see the next step). Switch to the events tab in the inspector. Double click in the OnAction event to create an event handler. Inside the event handler code put the following line of code that will use the Page Producer to create the main survey form HTML page.

Response->Content = SurveyPageProducer->Content();

Step 10 - Add the Survey Response action item

Go back to the Editing WebSurveyModule->Actions window to create another action handler. This action handler will be used to accept the data from the HTML form and store the data in the InterBase database. In the Editing Actions window, click the Add button. In the Inspector, set the Name property to WebSurveyPostInfo. Set the MethodType property to mtPost - this means this action handler will only accept HTTP post messages. Set the PathInfo property (also called the URI in web circles) to the string /survey. In the events tab of the Inspector, double click in the OnAction event to create an event handler for this web action. When the user clicks the submit button on the HTML form, the form action will issue a HTTP post message with the name of the DLL followed by the /survey string. The DLL will see this PathInfo string and know that it is to fire the SurveyResponse action event handler. The code for the event handler will save the data and use a Page Producer to send a thank you response to the browser.

// write out results of survey form to interbase database
for (int i=0 ; i < Request->ContentFields->Count ; i++) {
  SurveyTable->Insert();
  SurveyTableSURVEYNAME->AsString = "9801Survey";
  SurveyTableQUESTIONNUMBER->AsInteger = i+1;
  SurveyTableQUESTIONKEYWORD->AsString = Request->ContentFields->Names[i];
  SurveyTableUSERANSWER->AsString = 
Request->ContentFields->Values[Request->ContentFields->Names[i]];
  SurveyTable->Post();
}
Response->Content = SurveyResponsePageProducer->Content();

Step 11 - Build the Web Server Application DLL

While in the environment, save the project and do a build of the web server application. This will create the .DLL file in your project folder. Copy the generated DLL to your web server applications folder, usually the SCRIPTS folder (or wherever you put your web applications). If you have previously tried a build of your web server DLL you will need to shut down the web server in order to unload the DLL from memory (if you don't you will get a sharing violation error, the DLL file is currently in use).

Step 12 - Use your browser to try the Web Server application

Using your web browser type in the URL to your web server application DLL. You will key in something like http://ww5.borland.com/scripts/websurvy.dll. This will cause your web server to load the DLL into the same process space and activate the default action event for your web application. Since the default activation event will generate an HTML form for the survey, you should see the HTML form appear in your web browser. Select your choice of radion button answers to the questions and click the submit button. The post action for this form will re-enter the DLL using the /survey PathInfo string. The action event handler for the survey form will cause the code to execute to save the survey form results into the InterBase database. You will see the survey response HTML page in respond to a successful session with your web server application. If you have not set up the database alias for the InterBase survey table, you will get error messages in your browser.

Good Luck Building Your Own Web Server Applications

We appreciate all those who filled out the C++ developer survey. Your continued feedback will help us build the right products that fit all developer's current and future needs.

davidi@inprise.com