How does master page functionality work

a) Create a master page
You need a master page (i.e. the template) with global layout of your web application, there can be multiple templates if you want different look and feel for different section or can have just one global master page for the entire web app, part of the template you will have to also put in placeholder that can be updated by the developer that will be creating functionality for individual pages.

b) Create content page
Content page is the actual page that gets shown to the user; it’s the combination of template + the content relevant to that page. In this page the developer fills in the master page placeholder with page relevant content and there for have full control over what gets rendered to the end user.

Why is master page required in ColdFusion application?

Before I even answer this question, lets walk through the scenario of how page template are created in most of the ColdFusion application, normally the header and footer or other section gets broken into separate file like Header.cfm, footer.cfm etc etc, and the individual content page like index.cfm will include header.cfm on top and then add some html code for the page and finally include footer.cfm something like this.

<cfinclude template="header.cfm"/>
Some content,  static, via db or other means.
<cfinclude template="footer.cfm"/>

So what’s the big deal?

Normally this is not a problem when you start with the project, but slowly and slowly as the number of pages for the site increases you start to realize that header and footer has to change on page by page basis, and you start introducing variables and start having conditional logic in your header and footer pages, or another situation can be that for some special pages you need to add css or javascript because those pages are doing special ajax stuff, but you don’t want to add that to header, because it will get included for all pages and that will slow down the site, so basically start adding the css and javascript withing the content page and after some time your page looks like javascript and css all over the place, plus your header and footer files have ton’s of conditional logic.
Check out http://www.sys-con.com/ and perform view source, scroll through the html and see how css and javascript is pretty much all over the page, and not consolidated in header section, where it should be right?
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So what is Strategy Design Pattern?
Wikipedia : “In computer programming, the strategy pattern (also known as the policy pattern) is a particular software design pattern, whereby algorithms can be selected at runtime.”
Gang of four : “Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.”

So from the various descriptions it’s clear that this pattern can be used in the situation where there is possibility of having difference/multiple calculation and the application has to choose the right one on the fly.

I am going to use a scenario to build the case on why and how this pattern should be used.

Scenario:

Let’s say there is a web application which has multiple developers working on it, or have multiple teams working on independent section of the application, in such sort of application its fundamental to have core set of components that the developer use and there is also a possibility that they may be used across multiple applications. In such sort of scenario its inherent that core component be stable and least amount of changes should be done on the core components (i.e. cfc’s ) to avoid large scale impacts to other modules/developers.

So let’s say one of the core components that we have is the Customer.cfc it has some properties and also methods which get used by the appropriate section of the web applications

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(read about the pattern @ http://en.wikipedia.org/wiki/Observer_pattern )

This post will demonstrate the usage of this pattern in ColdFusion

In the example I am creating a user list and the list if being watched by a logging observers that prints the message out to the browser anytime the new user gets added
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• A Real estate side notifying the user that property matching their criteria just got listed
• A job side notifying user that a new job matches there keywords
• Application server error alert send to administrator
• Notifying that stock prices went down or up

I can think of hundreds of different situation where notification functionality can be use, today’s most of the notification either happens though email or by the fact that user will come to certain section of site to get the updated information, not trying to downplay the fact that there are tools like nagios etc that can pull data from SNMP traps and send notification but that’s require you to implement SNMP protocol in your application which is not a trivial task.

With the every growing popularity of Instant messaging where millions of users are now actively using IM as means of communication both in office and personal environment bring a very promising platform for application development that can provide the notification mechanism that once thought was tough to implement.

Though instant messaging application like MSN, Yahoo Messenger, AOL Instant Messenger, Google Talk etc have implemented their own protocol and don’t cross communicate but there is light at the end of the tunnel. Google Talk uses XMPP protocol for messaging and looks like yahoo and AOL may follow the suite in future.
http://florianjensen.com/2008/01/17/aol-adopting-xmpp-aka-jabber/
http://www.process-one.net/en/blogs/article/after_aol_yahoo_is_also_experimenting_with_xmpp/

XMPP (Extensible Messaging and Presence Protocol) aka Jabber, is a light weight XML based messaging protocol for which various libraries exists and can be used for application development. If all the IM application start supporting XMPP the application development for IM platform will become super simple, but that not the case yet and I think it’s going to be a while before something like this will happen. (more…)

The issue started with the changes that backend/services team implemented in development environment, where they were throwing axis fault in error situation so that the calling application can trap that information and perform appropriate action, It was a little different then how it used to be down before. The main issue for the coldfusion developer was that they were not getting the AxisFault object back, instead in the exception object the fault data was back as a string which they parse and search for the error code and description.

After having the discussion with both the group it was clear that services team wanted to keep the functionality but for frontend/coldfusion team it was additional burden for parsing string and looking for information.

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There are various steps that can be taken for application optimization and to have uninterruptible application availability, but for the moment I am just going to focus on database side. This wont be the first time you are hearing about database/query optimization for having a healthy application, and assuming you have the best optimization done there are still times when unthinkable happens i.e. network connection to database is slow, database transaction log is full, query is running without using a index etc. The point being unforeseen issue can happen with database and it can bring your site to its knees, and your customers have to suffer.

Many of the large scale application uses stored procedure instead of inline SQL queries in CF code and therefore CFStoreproc tag is the ideal choice for running Stored procedure. But one of the biggest disadvantages of using CFStoredproce is the missing timeout attribute, which can lead to slow sites and complete crapping out of server. For whatever reason if the stored procedure executing time goes up then normal expectancy its going to slow down the page processing and eventually result in request queuing for high traffic site and the unavailable server crash.

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I set out tonight to determine if the Prototype design pattern would be useful in object factories in ColdFusion 8. The Prototype pattern, in a nutshell, is to create a new instance of an object by copying an existing object instantiation. The object to copy is an object instantiated once and then used as a blueprint for future objects of the same type. The thought is that copying an object holds a lesser cost than instantiating a new object.

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Data Access Object and Gateways are the names given to ColdFusion components that access information from a database or other external data source. Within the ColdFusion community DAOs and Gateways have pretty much taken on the meaning as follows

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For those of you new to this concept, an object factory is nothing but a component whose sole job is to create components. An object factory is quite simple and small. Its main role is to collect the information necessary to create an instance of the intended object’s class and then to invoke that class’s constructor

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The tutorial is simple in its presentation but gets the job done and includes a full working application putting everything to good use. You’ll be creating a home automation Remote Control for the appliances in your house. My remote has simple on/off buttons and and undo button but the tutorial will teach you to do more

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