Content Based Routing on Microsoft Platform

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Use case

McKeever Technologies is a medium-sized business, which manufactures latex products. They have recently grown in size through a series of small acquisitions of competitor companies. As a result, the organization has a mix of both home-grown applications and packaged line-of-business systems. They have not standardized their order management software and still rely on multiple systems, each of which houses details about a specific set of products. Their developers are primarily oriented towards .NET, but there are some parts of the organization that have deep Java expertise.

Up until now, orders placed with McKeever Technologies were faxed to a call center and manually entered into the order system associated with the particular product. Also, when customers want to discover the state of their submitted order, they are forced to contact McKeever Technologies’ call center and ask an agent to look up their order. The company realizes that in order to increase efficiency, reduce data entry error, and improve customer service they must introduce some automation to their order intake and query processes.

McKeever Technologies receives less than one thousand orders per day and does not expect this number to increase exponentially in the coming years. Their current order management systems have either Oracle or SQL Server database backends and some of them offer SOAP service interfaces for basic operations. These systems do not all maintain identical service-level agreements; so the solution must be capable of handling expected or unexpected downtime of the target system gracefully.

The company is looking to stand up a solution in less than four months while not introducing too much additional management overhead to an already over-worked IT maintenance organization. The solution is expected to live in production for quite some time and may only be revisited once a long-term order management consolidation strategy can be agreed upon.

Key requirements

The following are key requirements for a new software solution:

  • Accept inbound purchase requests and determine which system to add them to based on which product has been ordered
  • Support a moderate transaction volume and reliable delivery to target systems
  • Enable communication with diverse systems through either web or database protocols.

Additional facts

The technology team has acquired the following additional facts that will shape their proposed solution:

  • The number of order management systems may change over time as consolidation occurs and new acquisitions are made.
  • A single customer may have orders on multiple systems. For example, a paint manufacturer may need different types of latex for different products. The customers will want a single view of all orders notwithstanding which order entry system they reside on.
  • The lag between entry of an order and its appearance on a customer-facing website should be minimal (less than one hour).
  • All order entry systems are on the same network. There are no occasionally connected systems (for example, remote locations that may potentially lose their network connectivity).
  • Strategic direction is to convert Oracle systems to Microsoft SQL Server and Java to C#.
  • The new order tracking system does not need to integrate with order fulfillment or other systems at launch.
  • There are priorities for orders (for example, “I need it tomorrow” requires immediate processing and overnight shipment versus “I need it next week”).
  • Legacy SQL Servers are SQL Server 2005 or 2008. No SQL Server 2000 systems.

Pattern description

The organization is trying to streamline data entry into multiple systems that perform similar functions. They wish to take in the same data (an order), but depending on attributes of the order, it should be loaded into one system or another. This looks like a content-based routing scenario.

What is content-based routing? In essence, it is distributing data based on the values it contains. You would typically use this sort of pattern when you have a single capability (for example, ADD ORDER, LOOKUP EMPLOYEE, DELETE RESERVATION) spread across multiple systems. Unlike a publish/subscribe pattern where multiple downstream systems may all want the same message (that is, one-to-many), a content-based routing solution typically helps you steer a message to the system that can best handle the request.

What is an alternative to implementing this routing pattern? You could define distinct channels for each downstream system and force the caller to pick the service they wish to consume. That is, for McKeever Technologies, the customer would call one service if they were ordering products A, B, or C, and use another service for products D, E, or F. This clearly fails the SOA rules of abstraction or encapsulation and forces the clients to maintain knowledge of the backend processing.

The biggest remaining question is what is the best way to implement this pattern. We would want to make sure that the routing rules were easily maintained and could be modified without expensive redeployments or refactoring. Our routing criteria should be rich enough so that we can make decisions based on the content itself, header information, or metadata about the transmission.

Candidate architectures

A team of technologists have reviewed the use case and drafted three candidate solutions. Each candidate has its own strengths and weaknesses, but one of them will prove to be the best choice.

Candidate architecture #1–BizTalk Server

A BizTalk Server-based solution seems to be a good fit for this customer scenario. McKeever Technologies is primarily looking to automate existing processes and communicate with existing systems, which are both things that BizTalk does well.

Solution design aspects

We are dealing with a fairly low volume of data (1000 orders per day, and at most, 5000 queries of order status) and small individual message size. A particular order or status query should be no larger than 5KB in size, meaning that this falls right into the sweet spot of BizTalk data processing.

This proposed system is responsible for accepting and processing new orders, which means that reliable delivery is critical. BizTalk can provide built-in quality of service, guaranteed through its store-and-forward engine, which only discards a message after it has successfully reached its target endpoint. Our solution also needs to be able to communicate with multiple line-of-business systems through a mix of web service and database interfaces. BizTalk Server offers a wide range of database adapters and natively communicates with SOAP-based endpoints. We are building a new solution which automates a formerly manual process, so we should be able to design a single external interface for publishing new orders and querying order status. But, in the case that we have to support multiple external-facing contracts, BizTalk Server makes it very easy to transform data to canonical messages at the point of entry into the BizTalk engine. This means that the internal processing of BizTalk can be built to support a single data format, while we can still enable slight variations of the message format to be transmitted by clients. Similarly, each target system will have a distinct data format that its interface accepts. Our solution will apply all of its business logic on the canonical data format and transform the data to the target system format at the last possible moment. This will make it easier to add new downstream systems without unsettling the existing endpoints and business logic.

From a security standpoint, BizTalk allows us to secure the inbound transport channel and message payload on its way into the BizTalk engine. If transport security is adequate for this customer, then an SSL channel can be set up on the external facing interface.

To assuage any fears of the customer that system or data errors can cause messages to get lost or “stuck”, it is critical to include a proactive exception handling aspect. BizTalk Server surfaces exceptions through an administrator console. However, this does not provide a business-friendly way to discover and act upon errors. Fortunately for us, BizTalk enables us to listen for error messages and either re-route those messages or spin up an error-specific business process. For this customer, we could recommend either logging errors to a database where business users leverage a website interface to view exceptions, or, we can publish messages to a SharePoint site and build a process around fixing and resubmitting any bad orders. For errors that require immediate attention, we can also leverage BizTalk’s native capability to send e-mail messages.

We know that McKeever Technologies will eventually move to a single order processing system, so this solution will undergo changes at some point in the future. Besides this avenue of change, we could also experience changes to the inbound interfaces, existing downstream systems, or even the contents of the messages themselves. BizTalk has a strong “versioning” history that allows us to build our solution in a modular fashion and isolate points of change.

Solution delivery aspects

McKeever Technologies is not currently a BizTalk shop, so they will need to both acquire and train resources to effectively build their upcoming solution. Their existing developers, who are already familiar with Microsoft’s .NET Framework, can learn how to construct BizTalk solutions in a fairly short amount of time. The tools to build BizTalk artifacts are hosted within Visual Studio.NET and BizTalk projects can reside alongside other .NET project types.

Because the BizTalk-based messaging solution has a design paradigm (for example, publish/subscribe, distributed components to chain together) different from that of a typical custom .NET solution, understanding the toolset alone will not ensure delivery success. If McKeever Technologies decides to bring in a product like BizTalk Server, it will be vital for them to engage an outside expert to act as a solution architect and leverage their existing BizTalk experience when building this solution.

Solution operation aspects

Operationally, BizTalk Server provides a mature, rich interface for monitoring solution health and configuring runtime behavior. There is also a strong underlying set of APIs that can be leveraged using scripting technologies so that automation of routine tasks can be performed.

While BizTalk Server has tools that will feel familiar to a Windows Administrator, the BizTalk architecture is unique in the Microsoft ecosystem and will require explicit staff training.

Organizational aspects

BizTalk Server would be a new technology for McKeever technologies so definitely there is risk involved. It becomes necessary to purchase licenses, provision environments, train users, and hire experts. While these are all responsible things to do when new technology is introduced, this does mean a fairly high startup cost to implement this solution.

That said, McKeever technologies will need a long term integration solution as they attempt to modernize their IT landscape and be in better shape to absorb new organizations and quickly integrate with new systems. An investment in an enterprise service bus like BizTalk Server will pay long term dividends even if initial costs are high.

Solution evaluation

Content Based Routing on Microsoft Platform

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