Wednesday, 5 November 2008

Ramaze - first impressions

I've spent the past couple of days evaluating Ramaze. I started with the tutorial To-Do-List example and tried to move beyond that to something resembling a real web application backed with a proper database (MySQL). In general, I feel that this framework is more intuitive to use and therefore gets results faster than e.g. Ruby on Rails, if you're having to learn both from scratch. I also found it very easy to refactor the code, because it encourages a fairly aspect-oriented style and all changes are loaded immediately without having to re-start the server. Last but not least, the designers of Ramaze have considered enterprise-level deployment requirements from the very start, so your Ramaze application can run on anything from a shared virtual host rented for a few dollars per year to an enterprise server farm or on-demand compute-cloud configurations.

Ramaze also leverages the power of Ruby in very elegant ways. For example, here's a description of a basic content-management system based on Ramaze in just a single page of code.

I'm going to walk you through the to-do list tutorial, which dates back to 31st January 2008. Ramaze has evolved a fair bit since then and I have had to find out what the changes are to adapt the tutorial to the current version. Hopefully my observations will be incorporated in a future version of the tutorial. All of my work was done on Windows XP (blame my employer, not me :-) so the installation instructions etc. are related to that.

First of all, if you don't yet have Ruby and Ramaze installed, here's how you do it:
  • Grab the latest Ruby installer
  • Install with default options
  • Open a command shell and make sure that your Ruby bin directory is on the PATH
  • gem install ramaze
You may find yourself being asked to approve the installation of various dependencies. Just agree to each one. If gem offers you options (ruby, java, mswin32 etc.), choose "ruby" or "mswin32" (assuming you're on a Windows 32-bit machine).

My next big problem came with Eclipse. I wanted to use Eclipse as my IDE for Ruby and Ramaze. Trying to use the Help -> Software Updates feature to install Ruby support, I discovered by much trial and error that it was possible to do so, provided you configure the update site and select "Uncategorized -> Ruby Development Tools" and nothing else. Using this plug-in, you get a language-sensitive editor and the ability to launch Ruby applications, not much else, but it's a whole lot better than using just a text editor. The first time you try to open the Ruby perspective, the Hierarchy pane displays an error message ("Could not create the view: org/eclipse/search/internal/ui/text/ResourceTransferDragAdapter"). Just close it and use the Navigator pane instead. I'd be interested to know if there is a better Ruby plug-in for Eclipse.

While I was about it, I also installed the Web Page Editor from one of the Eclipse update sites. This came in useful when I was working on template pages later.

Then I started working my way through the tutorial. The first discrepancy came in chapter 3 - the View. Ramaze has evolved so that you supply just partial pages under the view folder. So the view/index.xhtml file in the tutorial should contain only the part of the page that will be supplied to the main page template in the variable @content. It looks like this:
TodoList.each do |title, value|
status = value[:done] ? 'done' : 'not done'
<li>#{title}: #{status}</li>
<?r end ?>
Of course, at this stage you won't have assigned a value to @title, so your page will be rendered without a page title or first heading.

Also on this page, ignore the instruction to "run ramaze" from the command line. That won't work under Windows. Instead, Eclipse comes to the rescue. Just right-click the start.rb file in the Navigator pane and select "Run As... -> Ruby Application". When you want to terminate the server, click the red stop button in the console pane. Subsequently you can re-run the server by selecting start.rb from the pull-down menu under Eclipse's green Run button.

In chapter 4 of the tutorial, again please omit the HTML scaffolding and just write
  <?r if @tasks.empty? ?>
No Tasks
<?r else ?>
<?r @tasks.each do |title, status| ?>
<li>#{title}: #{status}</li>
<?r end ?>
<?r end ?>
Now add the following line at the very top of the index method:
  @title = ["To-Do List"]
The standard page template inserts this value both in the page title and the top-level heading. You may have noticed that the MainController contains the line
  layout '/page'
This indicates that the file view/page.xhtml will be used as the template, not src/element/page.rb as described in the tutorial.

In chapter 5 of the tutorial, obviously you should not add the level-one heading as shown. Just put the link at the very top of the file view/index.xhtml.

Next, the new file view/new.xhtml is also much simplified:
  <a href="/">Back to TodoList</a>
<form method="POST" action="create">
Task: <input type="text" name="title" /><br />
<input type="submit" />
Before creating an action for create, as described in the tutorial, you will also need an action for new. This is the only way that I have found to generate a title for the new.xhtml page. Insert the following in main.rb:
def new
@title = ["Create a new To-Do List item"]
# See view/new.xhtml
Chapter 6 of the tutorial remains pretty much unchanged. Just remember not to delete the @title initialisation at the very top of the index method.

In chapter 7 of the tutorial, I found that I was able to add and delete tasks to my heart's content until I tried deleting a task such as "Lunch with Bob?". Ramaze has a very simple mapping scheme from URL path to action argument, which stops parsing the path_info as soon as it encounters a "?" or ";". I spent a considerable amount of time trying to think of ways to circumvent this and pass the offending characters as url-encoded escape sequences, but in the end it was all to no avail. The lesson is that you would be well advised to never use user-supplied values as keys into your data. Instead, treat the user-supplied string as a data field and generate your own system ID for each item. By the way, this lesson applies equally well in other frameworks. Following my completion of the tutorial I will show how I refactored the code to achieve greater robustness. For now, just avoid using metacharacters in your task titles!

The solution to the problem of stuck tasks was of course to edit the YAML database file to delete the offending characters.

Chapter 8 of the tutorial seems to me now to be more or less redundant. All I had to do was to modify the file view/page.xhtml slightly to incorporate the error message from the flash object. Here's the resulting body section:
<div id="error">
<div id="content">
Note that there is no need for any logic to decide whether an error message is present. If it's there, it gets rendered as part of the page. Otherwise the renderer omits that element.

The prettification step in chapter 9 of the tutorial still applies as it stands, except that the stylesheet entries are inserted into the file view/page.xhtml instead of the Page element. I also added a style for the error message, where present. The resulting HTML header now contains the following entries:
   <style type="text/css">
body { margin: 2em; font-family:Verdana }
#content { margin-left: 2em; }
#error { margin-left: 2em; color:red; }
<style type="text/css">
table { width: 80%; }
tr { background: #efe; width:100%; }
tr:hover { background: #dfd; }
td.title { font-weight: bold; width: 60%; }
td.status { margin: 1em; }
a { color: #3a3; }
I had real fun in chapter 10 of the tutorial. Firstly, I had to install the mongrel adapter:
gem install mongrel
For both mongrel itself and its fastthread dependency, I chose the "ruby" option.
When I tried to start Ramaze again, it complained that some other process was already listening on port 80. After some detective work with process explorer, I discovered that this was a little peer-to-peer application called kservice from Kontiki Inc. I had probably unwittingly installed it with some Internet media player. After following the uninstall instructions kindly blogged by "Geoff" I was finally able to start my server on port 80.

(to be continued)

1 comment:

Anonymous said...

Thanks for trying Ramaze, and for sticking with it even though it may not have been so smooth. We're sorry for the tutorial being out of date. Within the next month or so, we are planning to have the website revamped, and along with that, updated wiki content and such. Feel free to join us in the IRC channel to chat about Ramaze.