What is services-oriented architecture (SOA), what impact will it have in control industry?

The ICT industry in general is buzzing with SOA being positioned as the next big thing. SOA is enjoying similar hype to that which surrounded any number of other "cure-all" solutions, such as CRM, business intelligence and countless other technologies or concepts that were perceived as the answer to technology problems.

As with all new technological fashions, SOA promises to deliver better, faster, cheaper IT support than was possible before it arrived.

However, all this hype seems to have resulted in a great deal of confusion around just what SOA is, and what it isn't. In this article, we take a look at what SOA really is, how it will benefit you and your business, what its impact will be and what you should look out for when you begin with the roll-out of SOA.

The general goal of both business and vendors is to try and get to "real-time business". At the shop-floor and control room level, we are used to the real-time world but, in general, as soon as you move above the SCADA/HMI (Supervisory Control and Data Acquisition/Human Machine Interface) level the IT world moves into the transactional world of databases.

MES/LIMS/ERP (Manufacturing Execution Systems/Laboratory Information Management Systems/Enterprise Resource Planning) are all essentially in this domain. The challenge business has always faced is: how do you build a real-time business out of the transactional world so managers can make timeous and informed decisions "in real-time" as opposed to making decisions based on historical reports and data that looks backwards?

It is also important to try and understand the concept of "The real-time enterprise". As instrumentation and control engineers - the real-time world is in seconds or better. To a production manager, the concept of real-time - on say a batching plant - may be at best the duration of the batch or production run, or a shift.

Think of calculations like OEE (overall equipment effectiveness), and downtime per shift - which may be the best and most sensible metrics available. To an operations manager dealing with a number of lines in a factory, his/her "real-time" is probably moved back to a daily basis. The financial director on the top end is probably used to make decisions on a monthly or, at best, weekly basis given the accounting cycle.

The concept of the real-time enterprise is an attempt to compress and reduce "reporting cycles" and to make data from all systems available for exposing KPI's (Key Performance Indicators) and define metrics to decision-makers across an organisation, with a view to exposing problems earlier. This, in turn, will lead to improved operational efficiency through quicker corrective actions and decisions.

How has technology evolved to support this concept?

In the I&C (Instrumentation & Control) world, OPC (OLE for Process Control) made its way onto the scene in the late 90s as a way of allowing interoperability between systems.

If you have an OPC server then any OPC client would be able to access your data and have it available to them. Hence OPC was a standard way of both exposing and accessing data between different software products.

Why not OPC? OPC was designed with the process control markets needs in mind. Single pieces of real-time data are exposed in a defined way so different applications can inter-operate and exchange data reliably and seamlessly.

Web services was "invented" as a way of similarly allowing systems to expose data in "loosely coupled" object oriented way, and offer a standard way of interfacing to and "consuming" the service or data from the application.

The concept of Web services was borne out of Web-based applications enabling others who want to use the service supplied - without having to either embed code or "tightly" bind themselves to that provider of information.

An example of this would be a company based in South Africa, which supplies an advanced control piece of software. Firstly, due to the complex nature of such software it would be fairly limited in the geographical area in which it can work and offer its software.

All this software may need to assist in optimising the process, which for example, is five variables every 20 minutes, taking 10 minutes to calculate a new set point for the next hour.

The traditional way of implementing the solution would be to purchase the software, install it on site, get trained and use the product. New versions require upgrading the software on site - probably at great cost.

Using Web services instead - it would be possible for the supplier to offer or expose its "advanced control algorithm service" to the entire world. It would host the main application at its offices, and write code to expose the variables needed to run the algorithm via a Web service.

In order for any user to employ the software, it would require them to develop very simple code. The code would connect to the Web service - which is fully-described in clear English text using XML (extensible mark-up language) and then to take the necessary variables from their plant and put them in the algorithm. The results would follow, which, in turn, would allow them to change the necessary set-points in the process. They would then close the connection and run it for the next hour, repeating the process then.

The advantage of this is the vendor only ever upgrades and optimises the software at their site, using their own staff to work on the code - remotely or on-site.

The users are generally not concerned about what versions are being used, as long as it works - and all they need is an Internet connection. If it does not work - they are not locked-in and could simply go to another vendor of a similar service who happens to work out of China, for example.

The advantage is that anyone, anywhere in the world, can now start to use these "services". They may be pay-per-use or subscription based - but the maintenance headaches are removed.

If you have got your head around the basic principals of software as a service and Web services - SOA is really just an IT architectural approach to extending thinking on a general basis.

What SOA offers is a way of structuring software components to get additional benefits in a standardised way - without necessarily providing anything unique or additional. It is simply one approach of software design that does not negate other approaches.

Dave Wibberley, managing director of Adroit Technologies, says: "Organisations start with application silo architecture, which are mostly individual applications. They then move through standardised architecture, involving more standardisation and centralisation. They end up with a rationalised data architecture that includes the standardisation of data and processes with a view to ultimately ending up with a services-oriented architecture."

In other words, SOA is to have all the necessary applications used within an organisation implementing Web service interfaces, or to use product offerings such as .Net visualisation platform, VIZNET, and TIBCO (integration server software for enterprises) to create an SOA layer.

This allows developers to build and achieve the business tools that require dashboards and allow collaboration between applications, using standard interfaces and services.

"People need to realise that SOA will not magically solve integration issues or suddenly allow companies to re-use components of software, there are numerous underlying design decisions and imperatives that have to first be considered," says Wibberley.

The general feeling among IT practitioners is that although the return on investments is difficult to quantify - companies that implement SOA will generally see the returns after the second or third project.

Adroit Technologies' technical director, Mike Lamusse, points out: "We have already implemented a Web service interface to Adroit and VIZNET. It is architected on an SOA approach so we, as vendors, are 'SOA ready'".

"In addition, our VIZNET product is ideally suited to building a composite portal around a company's SOA. This is because it can auto-discover Web services and integrates into other disparate and legacy systems through standards such as OLEDB (object linking and embedding database) and OPC, making it a very complementary application," concludes Lamusse.