Adobe ColdFusion Interview Questions and Answers

In computing, ColdFusion is the name of a commercial rapid application development platform invented by Jeremy and JJ Allaire in 1995. (The programming language used with that platform is also commonly called ColdFusion, though is more accurately known as CFML.) ColdFusion was originally designed to make it easier to connect simple HTML pages to a database, by version 2 (1996) it had become a full platform that included an IDE in addition to a “full” scripting language.

As of 2010, versions of ColdFusion (purchased by Adobe Systems in 2005) include advanced features for enterprise integration and development of rich Internet applications.

The advantages are much easier Installation and Migration, it is compatible with each operating system and database, it has simpler learning process and accelerated development, has permissions to each J2EE library and this part of Adobe family being compatible with Flash, Flex, PDF, etc.

The versions of Coldfusion older than 6 where developed with Microsoft Visual C++, version 6 is based on a Java type of construction. MX means Matrix, in this version the most important things implemented are: support for Linux and Mac, OOP, Verity Searches.

Application Time Out is the duration of the existence of an application, until it times out, if it is not accessed. Session Time Out is the duration of the existence protocols of a session until it times out, if it is not accessed.

Coldfusion component is a basic construction block for making structured, teared or scalable applications, it is made to process black boxes, for transactions and back­end integration.

CFCHART has over 200 various attributes; they can be modified and used for animation, colours and label control. The CFCHART engine can make graphs, sketches of charts that have great quality and are very useful in Business Analysis; very versatile presentations can also be made.

ColdFusion is like a Common Gateway Interface Application. This means it works like a mechanism that enables dynamic output to be received by web servers. Usually web servers use static data and now the dynamic data will be seen as static.

• when a request is transmitted by the browser to a web server for the purpose of getting a ColdFusion template the server will see the data sent by the browser as a CGI output request.
• in the case in which forms are used to initiate requests the data from the form will be stored by the server in a place where other programs may find it.To do this we often use STDOUT data streams. The form information will be written to the INI type of files by the WinCGI interface, it will become available for the CGI application for reading.
• the data is requested by the CGI program and returned in step.
• the data is formatted by the CGI program and return in step.
• the output is received by the server which makes the next server side processing that is required and then it is sent to the browser. Normally Coldfusion uses server API modules for server to server communication.

Stored procedures give the best performance when it comes to putting application logic to the database side. They have the disadvantage of slowing down the performance and the development if their code is weak.

When page directory of an application is not having an Application.cfm page, the ColdFusion directory tree is being verified for the existence of an Application.cfm page; if there are more than one in multiple directories, the first found will be used. If the permission are set, ColdFusion will include Application.cfm anyway. For every request only one Application.cfm will be processed.

The OnRequestEnd.cfm page is processed after every page in the application, in the same way like Application.cfm performing prior to the application page code. OnRequestEnd.cfm and Application.cfm pages have to exist in the same directory that is used by Coldfusion for the present page. Only that directory isbeing searched.

ColdFusion have the following main components:

• ColdFusion admin
• CFML (ColdFusion markup language)
• CF script
• Variety search

Presentation server (presentation layer), Application server, Web server and a database server. It has a J2ee web container that is the base of ColdFusion environment. And a ColdFusion runtime environment that will interprets the ColdFusion requests, and a database server.

ColdFusion has many benefits over other web languages. The very first thing we need to discuss is, ColdFusion is the first web languages that has been developed to build web application (dynamic). After ColdFusion, PHP, and Microsoft’s asp .net were in the market. PHP is free and so many small companies and individual entrepreneurs use it. So php is widely used compared to others because it is free. Microsoft’s asp .net is next to it for mid to big size organizations as it give good support and of course the brand name also does the magic. ColdFusion though it is the first language from the rest, because of lack of publicity and cost, it is still not widely used. But below are the main benefits of ColdFusion over others. It is very easy to install and very easy to migrate from older version to new version. It does support all operating systems. It is very easy to learn because of its self-explanatory code/tags.

Easy integration to other adobe products such as flex, adobe pdf, flash etc.. Good database support and works for all protocols.

New era started for ColdFusion from MX versions. such as Mac, Linux support, Flash remoting new Variety search functionalityand code and debug of flash components.

ColdFusion 9.0 has many benefits over older versions and to name few they are:

Coldfusion can be used as a service with out writing lines of code, we can get results by using:  CFChart, Cfdocument, CFImage, CFmail, CFPDF and cfpop etc. And also these services can be sandboxed in order to give more security. Adobe AIR database synchronization. New AJAX controls are added. Server manager is a new feature by which from one access point we can manage several admin tasks of various servers. Also ColdFusion 9 allows you to create coldfusion component as a portlet.

Application.cfm page will be used to define application level variables, for example instead of declaring dsn variable in every query you use, you can define the variable in application.cfm page once and can use that variable in every ColdFusion page you use queries to retrieve data from database. We can definitely use more than one application.cfm pages, however, only the first application.cfm page that the ColdFusion server finds, will be used. Application.cfm page is not mandatory.

Name, clientStorage, LoginStorage, ClientManagement, ApplicationTimeout, SetclientCcookies, SessionTimeout etc..

ClientManagement can be enabled and disabled as and when we need depending upon the requirement.

• In the Application.cfc initialization code This.clientmanagement=”True” / “false”

          This.clientStorage=”[Ur_datasource_name]” / “registry” / “cookie”

• In appliation.cfm using tag attributes clientManagement=”yes” / “no”

           clientStorage=”[Ur_datasource_name]” / “registry” / “cookie”

[Ur_datasource_name] ­ Stored in ODBC or native data source.You must create storage repository in the Administrator. registry ­ Stored in the system registry.cookie ­ Stored on client computer in a cookie. Scalable. If client disables cookies in the browser, client variables do not work.

By using cffile tag, we can upload a file to the server.

A typical cffile syntax is:

<cffile action=”upload”

fileField=”fileUpload”

 destination=”C:docs”>

Coldfusion has a beautiful feature called Query of Queries which is mainly used for improving performance of the application. Query of Queries is the result of an existing database query result.This will be done by using coldfusion “cfquery” tag and need to

specify dbtype = ‘query’.

Eg:

select *

from NameOfAnotherQuery

where ColumnName = ‘SomeValue’

Coldfusion provides us many debugging options in order to trouble shoot a coldfusion program.

The important are:

CFDUMP, eg: <cfdump var=”#abcd#”>

CFABORT, eg: <cfabort>

On the debugging settings in coldfusion administrator. (you will see the lengthy debugging information at the bottom of the coldfusion result).

While debugging is mainly used to debug the code and to see run time values. Especially for trouble shooting. However, once the programs are in production server, we cannot debug, but to avoide users seeing all the error messages when a program unexpectedly failed and throwing errors, we can use error handling methods. TRY and CATCH is the best among them to handle any database related errors.

<cftry>

Here is your actual code…of coldfusion….

</cfcatch>

Write your message to the user in case of any error.

</cfcatch>

</cftry>

A server that exposes business logic to client applications through various protocols including HTTP, HTTPS, IIOS/SSL.

Eg: Sun Java Application server, weblogic server It takes care of important issues like Transaction Management, Security, Database Connection Pooling, Clustering, Scalability,session management,load balancing,thread management and Messaging etc. A web server cannot provide these.

A computer that delivers (serves up) Web pages. Every Web server has an IP address and possibly a domain name. For example, if you enter the URL http://www.domainname.com/index.html in your browser, this sends a request to the server whose domain name is domainname.com. The server then fetches the page named index.html and sends it to your browser. Any computer can be turned into a Web server by installing server software and connecting the machine to the Internet. There are many Web server software applications, including public domain software from NCSA and Apache, and commercial packages from Microsoft, Netscape and others.

ColdFusion is implemented on the J2EE. J2EE is a standard, it is not a programming language. J2EE is an implementation of the Java programming language, but includes a number of Application Programming Interfaces (APIs) for connecting to databases, queuing messages, connecting to registries and naming and directory services. All of these APIs are used by coldfusion for many of its base services and other runtime services.

ColdFusion consists of following components:

• cf script
• CFML
• ColdFusion Administrator
• Verity Search Server

To Flush cached queries <cfobjectcache action=”clear”>

To Flush cached pages <cfcache action=”flush”>

ApplicationTimeout : The time span an application will exist before it times out (if the application is not accessed in any way). This defaults to the value set in the ColdFusion administrator.

SessionTimeout : The time span a session will exist before it times out (if the application is not access in any way by that session’s user). This defaults to the value set in the ColdFusion administrator.

It defines the scope of a ColdFusion application; enables and disables storage of Client variables; specifies the Client variable storage mechanism; enables Session variables; and sets Application variable time­outs.

Yes. If the application page directory does not have an Application.cfm page, ColdFusion searches up the directory tree until it finds an Application.cfm page. If several directories in the directory tree have an Application.cfm page, ColdFusion uses the first page it finds. If the Application.cfm page is present in the directory tree (and has the required permissions set), you cannot prevent ColdFusion from including it.

ColdFusion processes only one Application.cfm page for each request. If a ColdFusion page has a cfinclude tag pointing to an additional ColdFusion page, ColdFusion does not search for an Application.cfm page when it includes the additional page.

Absolute is from the absolute 0,0 position in the top left corner of the browser window. Relative is relative from the positioning of where the div is declared within the html body.

Yes. If the application page directory does not have an Application.cfm page, ColdFusion searches up the directory tree until it finds an Application.cfm page. If several directories in the directory tree have an Application.cfm page, ColdFusion uses the first page it finds. If the Application.cfm page is present in the directory tree (and has the required permissions set), you cannot prevent ColdFusion from including it. ColdFusion processes only one Application.cfm page for each request. If a ColdFusion page has a cfinclude tag pointing to an additional ColdFusion page, ColdFusion does not search for an Application.cfm page when it includes the additional page.

When ColdFusion receives a request for an application page, it searches the page’s directory for a file named Application.cfm. If one exists, the Application.cfm code is logically included at the beginning of that application page. If your application runs on a UNIX platform, which is casesensitive, you must spell Application.cfm with an initial capital letter.

• Simplified Installation and Migration
• All Operating System (OS) Support All Database support
• Faster Development & Easy to Learn
• Improved & support for all Protocols
• access to all the J2EE libraries
• Integration with Other adobe Products (Flex, Flash, PDF..)