As you may know, VoiceObjects 7.4 has been released and is available for download on this developer portal.

Now, I wanted to see what’s in VoiceObjects 7.4 for developers. In particular, I was interested in exploring some of the new expression functions – there is large number of new functions in the realm of date and time handling, string operations, regular expressions and more, plus some other more VoiceObjects-specific functions. My plan was to adapt our Prime Telecom demo application to leverage some of the new VoiceObjects 7.4 functionality. Of course, the existing “legacy” Prime Telecom application works fine in VoiceObjects 7.4, but then … at the end of the day it’s a demo application, so I thought it should stay up-to-date, best-practice-wise.

I started reviewing the existing Connector and Script objects in Prime Telecom, assuming that these presented the lowest hanging fruits: If I could replace some of them by mere Expression objects, using the new functionality, the gains in application maintainability and scalability would be obvious. And indeed, I did find a few objects that had become obsolete:

• Three Connector objects that had called custom Java code to validate the format of email addresses, credit card numbers, and expiration dates, could be replaced by simple Expression objects using the new MATCHESREGEXP function. This function checks whether a value matches a given regular expression. No more Java code to maintain here! Check out, for example, the new Expression object Is Email Address Valid in the new version of Prime Telecom to see how it’s done.
• The Script object First Day Next Month had contained some JavaScript logic to calculate, well, the first day of the next month (relative to the system date). With the new expression functions LASTDAYINMONTH, ADDDATE and CONVERTDATE, this Script object could be easily replaced by Expression objects. There are quite a few more date and time related expressions, like NEXTWEEKDAY or TIMEBETWEEN that should help you implement most conceivable tasks in date and time arithmetics.
• The Script object Monthly Rate for All Active Addons contained JavaScript code that iterated over the prices of all tariff add-ons currently subscribed to by the caller. Whenever the caller subscribes to a new add-on, the total monthly rate has to be re-calculated, so this Script object had to be re-executed. Now, with the new Expression function ITERATE, it was easy to replace this script by a few expressions: First, a Collection object is initialized with all prices of the current add-ons (Expression object Assign List of subscribed Add-On Prices). Then, after resetting the “total monthly rate” variable , another expression simply iterates over all rows in this collection and sums up the prices (Expression object Sum up Prices of all Active Add-Ons).

After getting rid of a few Connectors and Scripts, I reviewed the existing Expression objects in Prime Telecom. I found some implementation details that looked a bit cumbersome in the light of the new possibilities. Hence, I tried to replace them with new expressions, lowering the total number of objects used and trying to make the code more maintainable at the same time.

• First, I investigated the new string operations. For a start, using the new functions RIGHT and LEFT instead of MID where appropriate helps keep the number of objects down.
• The new function COUNTOCCURRENCES made several other expressions in Prime Telecom obsolete. It counts how often a certain substring appears in another string. In combination with the XPATH expression, it helped implement a very efficient way to count available tariff add-ons: Inspect, for example, the Expression object Add-On Row Counter.
• Note, by the way, that the XPATH expression now takes a third argument returnAsCollection: This allows returning a list of XML nodes not only as a variable containing blank-separated strings (returnAsCollection=false), but alternatively as a handy Collection object (returnAsCollection=true). This makes the result of an XML query much easier to handle, as you can see when you inspect the Calculate Subscribed Add-Ons Sequence object.
• In the same sequence, I found the new ITERATE function to be useful. I use it in the Iterate over remaining Add-Ons Expression object to create a comma-separated list of the names of subscribed tariff add-ons. ITERATE can make the (much more powerful) Loop object obsolete in cases when you just need to iterate over an expression to perform some simple logic.
• The new VALUESUBSTITUTION function was instrumental in minimizing the number of expressions in the context of managing the headlines in the web and text channel. This function extracts a piece of functionality that was previously only available in the context of the Formatting object’s Value substitution field: It searches a variable in a Collection object and returns a lookup value – which can differ per language. This comes in very handy in multi-language applications. Check out the expression Headline to see how the (language-dependent) headlines in Prime Telecom’s web and text channel are implemented. 

There are many more new expressions to explore; some of the most powerful ones, like APPLYCONFIGURATION, deserve dedicated blog entries just to explore their capabilities.

Let me conclude with two more nice catches that have an impact on the Prime Telecom implementation:

• The Channel filter is now also available on the Menu Items in Menu objects and on the Correction Mappings in the Confirmation object. This makes it much easier than before to create multi-channel applications with different sets of menu items across the different channels. For example, you might want to offer an “Address Change” self-service in the text-based channels, but not in the voice channel. For an example in Prime Telecom, check out the Confirm Credit Card Confirmation object: The “Correct both” (both the credit card number and the expiration date, that is) Correction Item is available only in the voice channel.
• In the web channel, fields in web forms are now automatically pre-populated with the according variable values. This works for text fields, radio buttons, and lists. Note how the Prime Telecom web forms no longer “forget” your input when correcting, for example, credit card details.

If you want to reproduce my findings, I suggest you download your copy of the new version of the Prime Telecom demo application, install it in your VoiceObjects 7.4 Developer edition and inspect it in detail.

Tags: Prime Telecom, VoiceObjects 7.4

This entry was posted on Tuesday, January 6th, 2009 at 9:57 pm and is filed under Best Practices. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.