Case studies in SOA using an ESB backbone…DigiPen TollCollect System

by David A. Chappell

The DigiPen application
In all three cities during last week’s European leg of the SOA Architect Forum series we did a walkthrough and discussion of a very innovative use of a SOA using bleeding edge technologies in a business application--the DigiPen and the ESB.

A Sonic customer, Bendit Innovative Interfaces, did a live demonstration of their application that was built for performing real time toll collection for 1.2 million registered truck drivers in Germany. This is a SOA based application, built using an ESB, that connects, mediates, and controls the end-to-end processes between a simple device that every truck driver has, and the backend toll collection systems that are located in a datacenter somewhere in Germany. At a high level, here’s how it works:

Each truck driver is equipped with a kit which includes a DigiPen, a pad containing special forms, and a cell phone.

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Now there are some special things I should mention about the things in this kit. Digipen has a builtin optical reader, which knows how to recognize and record pen strokes on the special paper form. The paper form has a special dot pattern that is barely visible to the naked eye. This dot pattern acts kind of like a bar code in that it is unique for every position within every field on the form, and also unique for every form in the stack. In fact I’m told the dot pattern is completely unique for an area the size of Europe. Using the DigiPen, the truck drivers simply fill in the form with information about the routes that they take. image

The DigiPen also has a Bluetooth interface, which is then used to send the form data to the Bluetooth enabled cell phone that is also part of the kit. The cell phone sends an SMS message to an SMS gateway that is the “onramp” onto the ESB. The following figure shows some of the deployment characteristics of the ESB -

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Part of the reason that it is depicted using the messaging layer components is to highlite the importance of continuous availability. The circles labeled “P” and “S” represent the primary and secondary message brokers that are used in the Continuous Availability Architecture (CAA).

The following illustration shows the high level steps involved in the processing of the toll collection form, once it arrives “on the bus”.

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Here is the “SOA view” of that same high level process. This represents that actual services implemented in the ESB, and the ESB process that coordinates their interaction. What’s more interesting about this SOA view is that some of these steps represent composites of other sub-processes, which can be further broken down into their individual services.

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In fact, the whole processing tree can get pretty complex, as hinted at by the following illustration. I think I’ll save that explanation for a more full-feature article when I have some more time to get back to writing.

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ROI of the DigiPen application



Alternative approaches to this were considered. An internet login was considered, but deemed to be too costly and impractical for the truck drivers to become proficient at using. Then they considered using dedicated kiosks for toll collection. They installed 1200 kiosks around Germany to support a population of 1.2 million truck drivers. You can imagine how well that worked out. Additionally, a solution based on a dedicated on-board unit consisting of a GPS system and a GSM device. The following figure shows a relative comparison of the costs per truck driver for each approach.

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In summary, these are the benefits of the toll collection system that is based on DigiPen,SOA, and ESB –
- No wait time at terminals
- No installation and maintenance cost
- Spontanuous, flexible route planning
- Independent from GPS
- Registration number authorizes trip
- Optional copy of form via eMail
- Real-time monitoring of toll costs

In the end, the DigiPen solution was the most cost effective and easiest to learn and use….Just write!

Dave