For example, you may call GET to request your user profile:

    http://www.domyinvoice.com/resources/[username]/profile

Using CURL the request:

curl -X GET -u joebloggs:password http://www.domyinvoice.com/resources/joebloggs/profile

…will return something like…

<profile>
    <username>joebloggs</username>
	<email_address>joe@bloggs.com</email_address>
	<first_name>Joe</first_name>
	<last_name>Bloggs</last_name>
</profile>

Resources in DMI are self-describing, thus with the addition of a single parameter, you can view the documentation for that resource. Thus the url…

http://www.domyinvoice.com/resources/joebloggs/profile?help

…returns a list of the HTTP verbs accepted by the resource, basic description and more detailed information about each verb. If you don’t have an account (it’s free for the first month, by the way), you can see a static version of this help information here.

Another example, is the clients resource. You can GET a list of clients:

curl -X GET -u joebloggs:password http://www.domyinvoice.com/resources/joebloggs/clients

<clients>
	<client id="76">
		<client-name>test company</client-name>
		<address1>address line 1</address1>
		<address2>address line 2</address2>
		<city>London</city>
		<postcode>sa1 sa2</postcode>
		<country>United Kingdom</country>
	</client>
</clients>

A client can be added with the use of an HTTP PUT:

curl -X PUT -u joebloggs:password http://www.domyinvoice.com/resources/joebloggs/clients/test+company+2 -d @-

address_1=23+Wrights+Lane&address_2=Kensington&city=London&postcode=W8+6TA&country=GB&currency_symbol=£&currency_format=1&sales_tax_label=VAT&sales_tax=0.175

Which also returns the created client (assuming nothing went wrong):

<clients>
	<client id="80">
		<client-name>test+company+2</client-name>
		<address1>23 Wrights Lane</address1>
		<address2>Kensington</address2>
		<city>London</city>
		<postcode>W8 6TA</postcode>
		<country>United Kingdom</country>
	</client>
</clients>

Said client could then be deleted with the use of the DELETE verb:

curl -X DELETE -u joebloggs:password http://www.domyinvoice.com/resources/joebloggs/clients/test+company+2

The obvious advantage of using RESTful resources internally is that I’m effectively providing an external API for free — in other words, without requiring any additional development effort.

To be honest, I really have no argument with Orcon otherwise. It just seems like false advertising to call something “Zero Shock”, when I find myself damn shocked at how slow it is.

The other ISP I have experience with is IHUG, who, if they reduce their prices for some reason, will keep quiet about it… “it’s your responsibility to check our website”. I’ve experienced this and so, more recently, has my father. Seems you should focus on keeping your current customers happy, rather than just attracting new ones.

That’s two of NZ’s larger ISPs, and I know the largest (Xtra) has had problems in the past.

I wonder if the issue is industry wide?

When my daughter was about 2 and a half years old, we got a long piece of string, poked it through holes in a pair of yogurt containers, pulled the string tight and used it as a telephone. It was difficult to get the concept across to a 2 year old; of talking into the container, then listening for the response. It was also difficult keep the string taut enough, so that sound waves were transmitted properly.

Somehow, Orcon have managed not only to keep a piece of string tight over thousands of kilometres, they have also managed to connect the yogurt container to the local internet loop. An extremely impressive piece of engineering. Even if it does mean my international traffic is slower than a 28K modem. Just think of the science!

So it’s now almost a month since I first noticed the problem, and over 3 weeks since I reported it — and there is still no resolution in sight. At least a couple of emails have gone unanswered in the last few weeks, although the initial response from their support department (instructions on how to provide all the data their technicians would need) was positive. Last night I finally gave up waiting and decided to sit on hold for 10 minutes or so. Their helpdesk, while nice enough (and local), were unable to shed any light and would need to pass on the details to technicians. But…

“…we have had reports from other customers of similar problems… it may have something to do with the traffic shaping…”

Yes. I’m blimmin’ well aware that it’s traffic shaping. I could’ve told you that a month ago.

“…a quick fix might be to upgrade your plan…”

Where’s the sound of screeching tyres when you want it?

Upgrade my plan?

I must remember that if I ever get a complaint about software I’ve developed…

“I’m sorry you’re having problems sir. Other people have also experienced problems with that version of our software. I invite you to upgrade to a more expensive version, in which we have fixed that issue.”

PS. Unsurprisingly, still no response from technical support.

For example, the following code shows the onload in action:

img = new Image();

var onloadFunc = function() {
    alert("got here... you really should do something now");
};

img.onload = onloadFunc;
img.src = url;
if (img.complete) {
    onloadFunc();
}

That works in most situations, but I’ve just discovered IE6 is seriously buggy (so what’s new?) in its onload event handling. The specific problem is preloading an image from the body’s onload event (or any other method that fires after the page has loaded, such as a script at the bottom of the page, etc).

A morning of googling failed to find a solution, so for future-me’s reference, basically the best way to ensure images are preloaded at the end of a pageload is something like the following:

var timer = null;
var images = new Array(); 

// trigger this from the body's onload
function onPageLoad() {
	images[0] = new Image();
	images[0].src = 'url to some image';
	images[1] = new Image();
	images[1].src = 'url to another image';
	timer = window.setInterval("onPageCheck()", 250);
} 

function onPageCheck() {
	for(var i = 0; i < images.length; i++) {
		if (!images[i].complete) {
			return;
		}
	}

	window.clearInterval(timer);
	images = null;

	// now use the images
	...
}

Basically, create an array of images (where the .src property triggers the preload), then use a timeout to check if the load is completed.

This appears to get around the problem. Note that the onload seems to work fine when triggered outside of the page onload (a button click and so on).

I’ve just added logproxy.py to my projects page, after updating it to handle virtual hosts (in other words, when using Apache to serve more than one domain).

This is not quite as impressive a change as it might sound. It basically means correctly setting the Host HTTP header, rather than defaulting to localhost…

Anyway, a few people appear to have found it useful, judging from my access logs, so this update might help someone else (it certainly helped me figure out why my wsgi app was failing to properly handle multipart form content).

A bit of googling finds the following…

http://www.eweek.com/article2/0%2C1895%2C1500432%2C00.asp
http://www.extremetech.com/article2/0,1697,20373,00.asp

…making me think that I’m basically stuffed, despite the fact that I followed the RFC. Excellent work Microsoft! (Sarcasm alert!)

Should’ve done some reading first I think.

So now a decision. Persevere with digest auth and upgrade (irreversibly?) to IE7 in the vain hope that it works, or roll back to Basic auth which will obviously support more browsers.

Much as I’d like to stick with digest (and see if my implementation works in IE7), I think Basic auth is the safer option (at least coupled with SSL), particularly when you look at browser market share.

I’m sure pure CSS popup menus are all well and good, but it’s painful picking out the useful bits.

So, more for my own future reference, a simple CSS popup can be accomplished using the following CSS:

a span {
	display: none;
	text-decoration: none;
}

a:hover {
/** fix for IE6 popup bug.  nice one Microsoft! */
	overflow: hidden;
	text-decoration: none;
}

a:hover span {
	display: inline;
	border: 1px solid black;
	position: absolute;
	background-color: white;
	padding: 5px;
	margin-left: 5px;
	overflow: hidden;
}

The first reference hides the popup, the second redisplays, using margin-left to move the popup a little to the right of the href it’s linked from.

Then create HTML as follows:

<p>this is a test this is a test this is a test this is a test this is a test this is a test this is a test
this is a test this is a test this is a test this is a test this is a test this is a test this is a test
<a href="#">popup<span>test message 1<br />test message 2</span></a>
this is a test this is a test this is a test this is a test this is a test this is a test this is a test this is a test
this is a test this is a test this is a test this is a test this is a test this is a test this is a test this is a test
this is a test this is a test this is a test this is a test this is a test this is a test </p>

Check this link for an example.

It doesn’t help that I tend to put experimental code in my apache www dir on occasion — and forget to back it up — so that after a system reinstall, I then have to dredge the dim, dark recesses of my memory to remember how to do simple stuff.

So for my own future reference…

1. a WSGI handler (wsgi_handler.py) for mod_python can be found here
2. the handler needs to be accessible on the python path, so copying it to /usr/lib/python2.4/site-packages means it’s accessible (there’s a better way, but it momentarily escapes me)
3. the apache config required is:

   <Directory /var/www/test>
   PythonHandler wsgi_handler
   PythonOption WSGI.Application hello::simple_app
   AddHandler python-program .py
   </Directory>
   

   Where:

   • /var/www/test is an absolute path to a directory I’m serving on the web
   • hello is a python script (hello.py — see below)
   • simple_app is a function in the script

   In the case of my kubuntu laptop, I just created a mod_python.conf file containing the above in /etc/apache2/mods-enabled

4. hello.py, a simple WSGI app, looks like this (snaffled from the python PEP for WSGI):

   def simple_app(environ, start_response):
       status = '200 OK'
       response_headers = [('Content-type','text/plain')]
       start_response(status, response_headers)
       return ['Hello world!\n']
   

5. restart apache, and hopefully we’re away…

I’ve also added an extension to make wsgi_handler slightly more useful for my purposes; the ability to serve more than one ‘app’ from the same script. The extended version can be found here.

The apache configuration can then be modified to:

<Directory /var/www/test>
PythonHandler wsgi_handler
PythonOption WSGI.Application hello
AddHandler python-program .py
</Directory>

And hello.py now looks like this:

def simple_app(environ, start_response):
    status = '200 OK'
    print str(environ)
    response_headers = [('Content-type','text/plain')]
    start_response(status, response_headers)
    return ['Hello WSGI world!\n']

def test(environ, start_response):
    status = '200 OK'
    response_headers = [('Content-Type','text/plain')]
    start_response(status, response_headers)
    return ['test test test\n']

Meaning that you can now point your browser to:

http://localhost/test/test.py/simple_app

or:

http://localhost/test/test.py/test

Which is useful for experimentation.

Continuing from the code started here, I’ve added data for the central section of the page; which uses the dom from an imported template. The engine has been changed slightly to re-calculate the ID attributes of imports so that they remain unique in the page. This is something that the user/developer would need to be aware of, but not necessarily the template designer.

template['main:top-content'] = engine.load('multi-col-content.html')
template['main:top-content:heading'] = 'Treat Yourself'

template['main:top-content:img'] = [ template2.get(None, src='amazon_fp_files/1887521003.jpg', alt='some title text'),
                                     template2.get(None, src='amazon_fp_files/1887521003.jpg', alt='some other title text'),
                                     template2.get(None, src='amazon_fp_files/0316015849.jpg', alt='some title text') ]

template['main:top-content:title']  = [ 'Some title text', 'Some other title text', 'More title text' ]
template['main:top-content:author'] = [ 'by Someone', 'by Another Person', 'by Yet Another Person' ]
template['main:top-content:price']  = [ ' ', '$10.99', '$15.25' ]
template['main:top-content:link']   = template2.hidden()

template['main:repeated-content'] = [ engine.load('multi-col-content.html'),
                                      engine.load('multi-col-content.html') ]

template['main:repeated-content:1:heading'] = 'Up to 50% Off Bostonian Shoes'
template['main:repeated-content:1:img']     = [ template2.get(None, src='amazon_fp_files/B0007MCQCQ.jpg', alt='shoe1'),
                                                template2.get(None, src='amazon_fp_files/B0007MCQR6.jpg', alt='shoe2'),
                                                template2.get(None, src='amazon_fp_files/B000BYIBA6.jpg', alt='shoe3') ]
template['main:repeated-content:1:title']   = template2.hidden()
template['main:repeated-content:1:author']  = template2.hidden()
template['main:repeated-content:1:price']   = template2.hidden()
template['main:repeated-content:1:link']    = [ template2.get('link1 text', href='http://localhost/amazon/somelink1'),
                                               template2.get('link2 text', href='http://localhost/amazon/somelink2'),
                                               template2.get('link3 text', href='http://localhost/amazon/somelink3') ]

template['main:repeated-content:2:heading'] = 'Free Shipping on the New Samsung DLP HDTVs'
template['main:repeated-content:2:img']     = [ template2.get(None, src='amazon_fp_files/B000F2N7D0.jpg', alt='tv1'),
                                                template2.get(None, src='amazon_fp_files/B000F2P300.jpg', alt='tv2'),
                                                template2.get(None, src='amazon_fp_files/B000F2PHDI.jpg', alt='tv3') ]
template['main:repeated-content:2:title']   = template2.hidden()
template['main:repeated-content:2:author']  = template2.hidden()
template['main:repeated-content:2:price']   = template2.hidden()
template['main:repeated-content:2:link']    = [ template2.get('link1 text', href='http://localhost/amazon/somelink1'),
                                                template2.get('link2 text', href='http://localhost/amazon/somelink2'),
                                                template2.get('link3 text', href='http://localhost/amazon/somelink3') ]

The template itself, at this point is remarkably uncomplicated, meaning that most of the complexity stays in the code (something I don’t personally have a problem with):

<div id="main">
    <div>
        <h2>Main Column</h2>
        <span id="main:top-content">
        top content pane here
        </span>
    </div>

    <div>
        todo: replace this with 'specials' section
    </div>    

    <div id="main:repeated-content">
        repeated content here
    </div>
</div>

The imported template is also simple. The cell contents are defined once, then repeated in code using a list of imported templates (engine.load(...) statements), and finally content is applied to those imported elements; and in some cases removed, using the template2.hidden() statement.

<div>
    <h4 id="heading">heading here</h4>
    <table class="multicol">
        <tr>
            <td id="img"><img src="" alt="" /></td>
        </tr>
        <tr>
            <td id="title">title text here</td>
        </tr>
        <tr>
            <td id="author">author text here</td>
        </tr>
        <tr>
            <td id="price">$0.00</td>
        </tr>
        <tr>
            <td id="link"><a href="">link text</a></td>
        </tr>
    </table>
</div>

Resources:

• Main template
• Imported template
• Template engine
• Script to create amazon html
• Current output

So, to recap my prior thoughts:

1. I don’t like the complexity, and general inelegance, of the templates required to produce dynamic content with facelets & JSF. Faces on its own is bad enough; facelets (while admittedly helping to fix a lot of the nastiness inherent in JSF) adds its own ugliness factor.
2. I don’t think it would be hard to design something better. Actually, let me rephrase that:

   An electric charge applied to a few single-celled organisms contained in a small bucket of slime could design something better.

My intention is, therefore, to hack together a quick prototype — hopefully coming up with something a little more elegant in the process. And since (I hope) I have a few brain cells to rub together, I might just provide reasonable competition to the bucket of slime.

For demo purposes, I’ve come up with a basic template copying the main sections of the Amazon front page:

I’m gradually adding dynamic elements and enhancing the templating as I go. At the moment, the template looks like this. Note I’m not bothering to include style and images from the Amazon site — focussing, rather, on the content and basic layout.

Below you can see an example of the code used to inject dynamic content. Basically, I’ve defined 2 classes: Localiser - a component to localise the text in an element, and ValueLocaliser - a preset value that will be localised and replace the text in an element. The dummy ‘localise’ function merely converts the text to upper case; just to prove it has processed the text. Once the template is loaded, dynamic content is added using the xhtml element ID as the reference.
For example a template with:

<p id="someid">default value</p>

would be injected with dynamic content using the code:

template['someid'] = 'somevalue'

Similarly, a template with:

<a id="myanchor" href="">link text</p>

Could be repeated in the output by applying:

template["myanchor"] = [ template2.get('Amazon', href='http://www.amazon.com'),
template2.get('Google', value='http://www.google.com') ]

It’s worth emphasising that all I’m talking about here is templating; not lifecycle, event handling and other guff that goes into your average web ‘framework’. Thus the code below is all about applying the content of a model (albeit just dummy data) to a view. The advantage of this approaching to templating xhtml content is that you can view the template in-browser — what-you-see-is-what-you-get (well almost).

The (unfinished) result of running the code against the aforementioned template can be found here. You can hopefully see that the ‘localiser’ has converted text to uppercase where specified. The template ‘engine’, as it currently stands, is here.

More to come…

#! /usr/bin/python

import template2

# dummy localiser function
# just returns upper value of string to prove it has
# processed
def localise(val):
    return val.upper()

class Localiser(template2.PluginAttributes):
    '''
    a subclass of a template plugin that 'localises' the content
    of an element (nodeValue) and any children.  Note that the
    localise is just a dummy function that capitalises the value
    '''

    def process(self, dom, node):
        template2.PluginAttributes.process(self, dom, node)

        if node.nodeValue:
            node.nodeValue = localise(node.nodeValue)

        if node.hasChildNodes():
            for n in node.childNodes:
                self.process(dom, n)

class ValueLocaliser(template2.PluginAttributes):
    '''
    a subclass of a template plugin which 'localises' a preset
    value
    '''

    def __init__(self, content, **kwargs):
        template2.PluginAttributes.__init__(self, **kwargs)
        self.content = content

    def process(self, dom, node):
        template2.PluginAttributes.process(self, dom, node)
        if node.firstChild:
            node.firstChild.nodeValue = localise(self.content)
        else:
            node.nodeValue = localise(self.content)

# create an instance of the template engine, then load
# a template
engine = template2.Engine()
template = engine.load('amazon_template.html')

# create a localiser
localiser = Localiser()

# inject banner1 content
template['b1:home'] = template2.get(href='http://www.amazon.com')
template['b1:user-store'] = template2.get('Jason\'s Store', href='http://localhost/amazon/store/jason')
template['b1:categories'] = template2.get(href='http://localhost/amazon/categories')
template['b1:account'] = template2.get(href='http://localhost/amazon/account/jason')
template['b1:cart'] = template2.get(href='http://localhost/amazon/cart/jason')
template['b1:help'] = Localiser(href='http://localhost/amazon/help')
template['b1:wish-list'] = template2.get(href='http://localhost/amazon/wish-list/jason')

# inject banner 2 content
template['b2:specials'] = [ ValueLocaliser('Gift Ideas', href='http://localhost/amazon/gifts'),
                            ValueLocaliser('International', href='http://localhost/amazon/international'),
                            ValueLocaliser('New Releases', href='http://localhost/amazon/new-releases'),
                            ValueLocaliser('Top Sellers', href='http://localhost/amazon/top-sellers'),
                            ValueLocaliser('Today\'s Deals', href='http://localhost/amazon/todays-deals'),
                            ValueLocaliser('Sell your stuff', href='http://localhost/amazon/sell') ]

template['b2:searchlabel'] = Localiser()
template['b2:searchwhat'] = [ template2.get('Amazon.com', value='amazon'),
                              template2.get('Books', value='books'),
                              template2.get('Popular Music', value='popular-music'),
                              template2.get('Music Downloads', value='music-downloads') ]
template['b2:searchtext'] = template2.get(None, value='some search term I entered last')

# inject banner 3 content
template['b3:welcome1'] = localiser
template['b3:user'] = 'Jason R Briggs'
template['b3:welcome2'] = localiser
template['b3:recommendations'] = template2.get(None, href='http://localhost/amazon/recommendations/jason')

# inject subnav content
template['subnav:browse-heading'] = localiser
template['subnav:favourites-heading'] = localiser
template['subnav:favourites'] = [ ValueLocaliser('Books', href='http://localhost/amazon/favourites/books/jason'),
                                  ValueLocaliser('Music', href='http://localhost/amazon/favourites/music/jason') ]

template['subnav:stores-heading'] = localiser
template['subnav:stores'] = [ ValueLocaliser('Apparel & Accessories', href='http://localhost/amazon/stores/apparel'),
                              ValueLocaliser('Beauty', href='http://localhost/amazon/stores/beauty'),
                              ValueLocaliser('DVD\'s TV Central', href='http://localhost/amazon/stores/dvd'),
                              ValueLocaliser('Electronics', href='http://localhost/amazon/stores/electronics'),
                              ValueLocaliser('Gourmet Food', href='http://localhost/amazon/stores/food') ]

# inject content for the books/music/dvd subsection
template['subnav:bmd'] = [ ValueLocaliser('Books', href='http://localhost/amazon/bmd/books'),
                           ValueLocaliser('DVD', href='http://localhost/amazon/bmd/dvd'),
                           ValueLocaliser('Magazine Subscriptions', href='http://localhost/amazon/bmd/subscriptions'),
                           ValueLocaliser('Music', href='http://localhost/amazon/bmd/music'),
                           ValueLocaliser('Video', href='http://localhost/amazon/bmd/video'),
                           ValueLocaliser('Amazon Shorts', href='http://localhost/amazon/bmd/shorts'),
                           ValueLocaliser('Textbooks', href='http://localhost/amazon/bmd/textbooks') ]

# print out the result
print str(template)

I have hit one minor snag already. I’ve used rparsexml.py in my hacked together template engine (a piece of python code that will admittedly never win any code-elegance competitions), only to discover (RTFM) it dumps html comment blocks — which is perhaps only a pain if you happen to wrap your embedded styles in comments. So I haven’t entirely convinced myself that it’s not worth going back and revisiting the code with a better xml parser, motivation being in general short supply at the moment…