Standard Page Buttons To Run Apex Class (not a webservice class)

How do you solve the following requirement, there are lot of ways to do it but we feel this is best for our case.

The Requirement: When user clicks on "Close All Cases" custom button on Account Detail Page, It should update status of all the child case records.

Fortunately we already have a class that updates the case status to "Closed". all we need to so is call that class.

Our Solution: Have a custom field, a small trigger to call that class.

Step1: Create a custom checkbox "closecases".

Step 2:  Create a custom detail page button "Close All The Cases" and show it on the page layout
 with the following code:
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{!REQUIRESCRIPT("/soap/ajax/19.0/connection.js")}  

var a = new sforce.SObject("Account");
a.id = "{!Account.Id}";
a.closecases__c=true;
var result = sforce.connection.update([a]);
// alert(result);
window.location.reload();
================================================


Step 3: Create a simple trigger when the value changes from false to true (only).

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trigger triggeredfrombuttonclosecases on Account (after update) {
string oldbox;
string newbox;

// get the old box value
      for(account old: trigger.old){
       oldbox= old.closecases__c;
      }
//get the updated value
      for(account newt: trigger.new){
       newbox= newt.closecases__c;
      }
// when both are not equal call the method in the class. so that it wont be triggered all the time.    
    if(oldbox!=newbox && newbox==true){
    bulkcases.updateAll(trigger.new[0].id)  
    }
}
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Step 4. Create a WFR on case, when the new case is created update the parent field closecases__c to false.

So its complete without having to expose the existing functional class as a webservice class or create a new webservice class. pretty resourceful isnt it?

This solution can also be used to invoke classes like approvalprocesses, or so...

Please notice that this is 4 step process compared to "sforce.connection.execute", a single line.

As an alternative; you could create a webservice class instead of trigger to call the apex class, but I prefer to keep it in the same box instead of increasing the calls count unnecessarily.

HTH
Prabhan.