Last week I came up with a small side project. It was basically a simple web chat, working pretty much like the comments on a blog. I decided to build this as a classic Domino application, not using Xpages. I started development Wednesday mid-afternoon, and the application needed be done Thursday evening, and I of course had my regular job to do. So I could not justify spending the time I needed to learn doing it in Xpages, and then try to write CSS to get it to look like I wanted it. So there you have the reason for why I did not use Xpages.
I decided to take a look at YUI, the framework developed by Yahoo. The latest version is version 3, and it is really nice and powerful. I looked into in, and realized that I could do things very quickly, getting the same functionality as using Xpages (partial refresh or page, etc) in just a few lines of code.
So what did I need for my application? I started with a blank Notes database. I created a page, which is where all the action would take place. On the page I created a header section (logo), a content section (where the messages/chat would be displayed) and a form section where I put a few fields for the users to fill out. The fields were name/handle, email, (optional) website and lastly the message to send. I also put two images there, one to use as a submit button, and one to refresh the chat content without having to submit a text.
I added some javascript at the top of the page, loading YUI3 (hosted by Yahoo, I did not even have to download anything):
<script src="http://yui.yahooapis.com/3.5.1/build/yui/yui-min.js"></script>
The next step was to add some code for the actual logic on the page. YUI works by binding functions to events on elements on the page. I wanted to bind function functions to the onClick event of the two buttons, "submit" and "refresh". To avoid this blog entry to be too long, I will just show the code behind the refresh button:
Y.one('#refresh').on('click', function(e) { e.preventDefault(); var contentcell = Y.one("#contentCell"); if (contentcell) { var currentTime = new Date(); Y.one('#refresh').set('src','webchat.nsf/ajax-loader-150.gif'); var args = &refresh=true&datetime=" + currentTime.getTime(); contentcell.load("webchat.nsf/SendText?OpenAgent" + args,"", function() { Y.one('#refresh').set('src','webchat.nsf/refresh.png'); } ); } });
This code gets a reference to the first element with the id "refresh" using Y.one(), then bind a function to the "click" event. The function is defined right there, and it will do a couple of things. First it get a reference to the element (in this case a DIV) with the id "contentCall". I check if it was found, and if so I get the current time (get a unique number). I then change the image of the refresh element to a spinning "loading" icon.
The next line is the coolest one. In one line of code I perform an Ajax call to an agent on the Domino server, and put the returned data into the contentcell element. Finally, after the server returns teh data, another function is called, which restored the refresh button to the original image.
The agent is written in Lotusscript, and it just read the existing chat entries from a database and output it using the print statement as HTML. I add the times in seconds as a second argument, just to get each call to be unique. Otherwise the returned data might be cached on the server and the user would not get the latest data.
The submit action is similar, the difference is that it read the values from the different fields on the form and submit them to the same agent as name-value pairs. The agent will detect that data is being passed to it, and will store the values in a new Notes document, then return HTML for all entries just like the refresh.
As you can see, a complete Ajax call (calling the server, waiting for data, gettingthe data back, replacing the content of an element on a page to perform a partial refresh and triggering additional code when the data has been returned) is just one line of code. Could not be much easier!
The actual application got more functionality, I check for certain required fields already in the web client, using javascript, I load up the content when the page is first opened (so the user does not have to press refresh to see anything), etc. The webchat is also just open specific times, when it is closed a message is displayed about when it will be open next, etc. The open/close is set by a Notes configuration document. Note: Do not use profile documents to store items for a web application, they get cached on the server and you will probably not get the latest data…
I am impressed with how easy and quick it was to build this application, using a compbiantion of classic Notes and a powerful javascript framework.