I thought I could write a tutorial for creating a basic coldfusion web service illustrating the possibilities of using reusable component rather than having lots of queries retrieving (in most of the cases) the same data.

Let's say there are 5 articles in a B&O database, each time the article is visited, a DB field visited is increased by 1 (obviously only once for 1 unique IP address). For instance the article Multiple Files Upload has been visited 290 times, Easy and secure way to retrieve data from a database (340) and Creating a newsfeed generator was visited 95 times.

We may create a coldfusion reusable component to get the most popular link along with some different stuff such as total number of vists etc:

//articles.cfc

<cfcomponent displayname="Web Service CFC Example">



//get a total_visits value for every article in a database

<cfquery name="get_visits" datasource="#DSN#">

SELECT article_title, total_visits FROM articles

</cfquery>



<cfproperty name="name" type="string">

<cfset this.name="Web Service CFC Example">



<cffunction name="totalVisits" access="public" returntype="numeric">

  <cfset total="0">

  <cfloop query="get_visits">

    <cfset total = total + #visits#>

  </cfloop>



  <cfreturn total>

</cffunction>



//check, which article is the most popular

<cffunction name="winningArticle" access="public" returntype="string">

  <cfset maximum = 0>

  <cfset winner = "unknown">



  <cfloop query="get_visits">

  <cfif #visits# gt maximum>

    <cfset maximum = #visits#>

    <cfset winner = #article_title#>

</cfif>

  </cfloop>



<cfreturn winner>



</cfcomponent>

It's worth to mention, that I might add an additional function in above component that returns the results as a structure (preferable way), in such case you would need to incorporate following code. I am going to write an additional tutorial explaining in detail how to use CFC structures.

<cffunction name="allResults" access="public" returntype="struct">

  <cfset all = structNew()>

  <cfloop query="get_visits">

    <cfset result = structInsert(all,#article_title#,#visits#)

</cfloop>

  <cfreturn all>

</cffunction>

The structure is basically a collection of data which is a bit more complex than a simple string or number.

Now, as the component is created, here's a way to call it and retire the result.

//links.cfm



Total visits:

<cfinvoke component="articles.cfc" method="totalVisits"

returnvariable="total">



<cfoutput>#total#</cfoutput>

The most popular article:



<cfinvoke component="articles.cfc" method="winningArticle"

returnvariable="winner">



<cfoutput>#winner#</cfoutput>

Tagged: coldfusion  web service