Wt

Here is my experience with installing Wt on a Debian Squeeze LAMP machine. It was an involved process. I've worked on large, complex code bases before, so I knew about the question, "How does one eat an elephant?" The answer is "One bite at a time." Meaning, I had to decompose the issue down to manageable chunks and nibble away at the smaller problems.

1) I downloaded a LAMP appliance from TurnKey Linux. I ran it on the free VMware player. It's how I've developed PHP, MySQL and JavaScript projects.

2) I looked at what was required to install WT: http://www.webtoolkit.eu/wt/doc/reference/html/InstallationUnix.html

3) Okay - requirements. I had no idea about CGI, as I'd not used it before. I had to learn about CGI which I did, by going here: http://httpd.apache.org/mod_fcgid/mod/mod_fcgid.html and here: http://httpd.apache.org/docs/2.2/howto/cgi.html . I realized I wanted to start with FCGI, because if I were ever going to deploy, that's what I was going to use. Why? Apache is a well-known and reliable web server. Also, there's a difference between FCGI and FastCGI which is quite significant. FastCGI is encumbered with licensing and/or patent issues while FCGI is not.

4) So I installed the libapache2-mod-fcgid for Debian Squeeze. I had to learn about dpkg, dpkg-query and apt-get. And the sources.list file. I'd used apt-get before but I just knew what it did and few other details.

5) I needed to test whether FCGI was working. The LAMP machine had a test.cgi file in its cgi-bin directory. That worked. I created a directory called fcgi-bin. I copied test.cgi into it. No joy. As it turned out, the cgi-bin directory was set up to allow .cgi file execution in the Apache configuration files via the ScriptAlias directive. I had to add a handler to handle cgi scripts outside of that directory with AddHandler cgi-script .cgi. The CGI scripts now worked in fcgi-bin. But that's just CGI. What about FCGI? I needed a simple test script.

6) So, I had installed the FCGI package (libapache2-mod-fcgid). It loaded a module in Apache called mod_fcgid.c. The handler for FCGI is called fcgid-script, which was set to handle file types of .fcgi. That was in the fcgid.conf file by default. I set the Options +ExecCGI for the fcgi-bin directory in Apache via a directive. And I added the file type .pl (for Perl) to the fcgid-script handler entry in the IfModule directive within the fcgid.conf file.

7) The perl file was still not working when I tried to run it via the browser. Finally, I discovered that in the perl script file, one need to use "Use FCGI" not "Use CGI::Fast". And I found a simple two line script that would work under FCGI. CGI and FCGI perl scripts are quite different. Then, from looking at the Apache error log, I determined I needed to install the perl FCGI package, libfcgi-perl. The perl script finally worked with FCGI. Finally I knew FCGI was working.

8) Next, I went to install Wt. But before that, I had to install package 'build-essential' for the c compilers and make. Then I had to install CMake.

9) Finally, I installed packages witty and witty-dev.

10) I compiled the hello.c example with g -o hello hello.c -lwtfcgi -lwt. Turns out the library libwtfcgi isn't on my machine. So, based on reading the forums, it seemed like the best way to get the most current installation of Wt with the required libraries, I should compile and install Wt myself. It wasn't installed as part of the witty packages I installed earlier.

11) So I had to read up on CMake, which is a utility which manages and generates makefiles. I went through the CMakeLists.txt files. I made a few minor changes. In the main CMakeLists.txt file, I set it to use the FCGI connector, not the built-in webserver one. I changed where the examples should go. The directions in the INSTALL.html file were spot on - perfect for building the project.

12) Recommendation: READ the main CMakeLists.txt file. It'll take 20 minutes, but it's 20 minutes well spent. Also, read up on CMake.

13) Warning: The CMake program wants to chown /var/run/wt directory to apache:apache. On my machine, it should be www-data:www-data. There's no user apache.

14) Read your wt_config.xml file. Might have to set num-threads to '2'. I did. It's working. Don't know if it's important.

15) Then, I had to make the examples. Per the instructions, I did a make -C examples from the build directory I created to compile the Wt project. That worked. I saw that I had a hello.wt file in the examples/hello directory. The directions said to run ./deploy.sh. But there was no suitable deploy.sh. I copied deploy.sh from the root directory of the Wt-3.1.2 directory to the hello directory. Ran it. It choked. I looked at the deploy.sh file and I could sort of follow along with what it was doing. Copying in a resources directory with images and such. I don't know from where the variables in deploy.sh were supposed to be set.

16) The /var/www/wt directory had to have Options +ExecCGI set. The fcgid-script handler was set to handle .wt files. Both of these items are set in the Apache config files.

17) Okay, next. I copied in hello.wt to my /var/www/wt directory. Tried to run it from a browser. No dice. Internal server error. In the Apache error log, I saw the same old error 104: mod_fcgid: error reading from fast cgi server, premature end of script headers. Sh-t. However, I recalled that someone on the forums said one could run the wt executable on the command line and it should run. I went to do that, ./hel- hit tab to autocomplete the name and nothing. A ha! It wasn't set to execute. So I chmod 755 hello.wt, ran it on the command line, then it worked! Then I ran it from the browser and it worked! HALLELUJAH!

18) I tried the treeview example, as I'm fond of treeviews. I ran it, and it ran, but it looked awfully sparse. Well, the deploy.sh talked about a resources directory. I noticed that FireBug, my web page inspector, was reporting several missing icons. So I created symbolic links to the resources directory on my server, in the same directory as the treeviewexample.wt (/var/www/wt), as well as to the icons directory. Everything then displayed correctly.

Next steps:

1) Install Eclipse on the VM I'm working on.

2) Set up x-forwarding so that the Eclipse display on the machine will display on my Windows machine.

3) Then, I can actually start learning how to develop with WT.

Recommendations to Wt developers:

It took me about a solid week to get from downloading the intro PDFs to the point where hello.wt was working on my server. It was quite a job, a lot of fiddling around. I had to learn about CGI, FCGI, CMake, dpkg, dpkg-query, apt-get, perl, Apache configuration, linking libraries. It was worthwhile. HOWEVER, when I started with PHP, I downloaded a fully functioning virtual machine with the foundations installed and configured, so I could immediately start working with LAMP development without having to deal with setup. So - I would strongly suggest that the Wt project also look into creating virtual machines with FCGI and Apache (as they are very common) that people can download and immediately start testing the examples and developing with Wt. Installing Wt really was eating the elephant. Again, I learned a lot but I'm not so sure most people will be so tenacious.

The process itself wasn't quite as clean as I've listed above. I actually installed build-essentials, then witty, and then started fighting with FCGI and perl.