Welcome!

Adobe Flex Authors: Matthew Lobas, PR.com Newswire, Shelly Palmer, Kevin Benedict

Related Topics: Java IoT, SYS-CON MEDIA

Java IoT: Article

i-Technology Viewpoint: Is Model Driven Architecture Coming Into Its Own?

MDA has been with us for years; will the arrival of meta-data bring it closer to the mainstream?

JDJ's Bill Dudney (pictured) writes: With the popularity of Object Relational Mapping tools like Hibernate and Cayenne, developers are more often than other giving control of some of their code to models. Will this help raise MDA into the mainstream? Will MDA take its hoped-for place as the next level of abstraction for developers?

What about MDA

Model Driven Architecture, also known as MDA, started in late 2000 with a white paper. Basically the idea is that we define the software we want to build in sophisticated models that capture the detail of the application. Then from these abstract models a series of transformations is applied to turn that abstract model into a running application. The highest-level model is referred to as a Platform Independent Model (PIM). There is an even more abstract model called a Computational Independent Model but we won't discuss that model. The PIM is, as the name suggests, independent of the deployment platform (i.e. .NET Java EE 5 etc.) In this model the business is specified, classes that make up the domain are fleshed out and specified. This model is then transformed into one or more Platform Specific Models (PSM) that can be elaborated with more detail specific to the platform. From the PSM a running application can be generated.

Now of course there is a need to put in your own business logic. Most tools today provide a way for you to edit the 'business logic' apart from the fully generated code. For example AndroMDA (an open source MDA tool) will generate some files only once (where your business logic is written). Other tools like OptimalJ take a different approach giving you code you can edit and 'protected blocks' that are part of the generated code. I'm sure there are other approaches as well that are taken by other tools.

The Promise

  • Productivity - the ability to raise the level of abstraction so that developers can become more productive is one of the greatest promises of MDA. Just as Java raised the level of abstraction from C/C++ so MDA raises the level abstraction for Java EE / .NET.
  • Portability - greater ease of migration between various technologies (such as .NET to Java EE) or between different versions of the same technology (i.e. EJB 2.1 to EJB 3.0). Once developed your PIM is the repository of knowledge about your application, so moving to another underlying technology is 'easy'.
  • Consistency - greater consistency of application architectural principals. This feature is hard to ignore. Many enterprise level projects have divergent architectures on the same project. Maintenance is very difficult in these projects to be sure.

The Problems

At its core MDA is about using meta-data to drive program creation. The idea is that if we can develop a sophisticated enough model to express software then we can fully generate the actual running program from the model (or even create a virtual machine that could execute the model). The problem with taking this idea too far of course is that we end up with just another platform. Probably even worse though is that it's 'programming with pictures' which was already tried at least once in the late 80s and failed miserably. Few are willing to try programming with pictures again.

Many proponents of the MDA approach like to say that given a PIM with sufficient detail one would be free to move between .NET, Java EE or to something like Hibernate & Spring assuming that you had the proper set of transformations for these other PSMs. While this is a great marketing pitch for MDA and the PIM it is just not that straightforward. A PSM has too much platform-specific knowledge buried in it to simply move between different technologies. After all the PSM is where the business logic that makes the application unique actually resides. In order to make this move all that logic must be changed to fit into the new target technology.

Finally, and probably most significantly, MDA must overcome the grass roots resistance to the idea. Developers like to develop. They don't like to have control taken from them. There is a fundamental distrust of code generation and a resistance to this type of abstraction.

Sea-Change?

There are a couple of moves afoot that make me think we might be on the verge of a change in perception about MDA. The first is a more pragmatic approach being taken by vendors. Instead of expecting developers to program in pictures, many vendors are taking a more pragmatic approach. Developers are expected to build more familiar UML class diagrams and annotate them. Few are expecting a full blown executable model.

Second and more significantly is the emergence of meta-data as a normal part of every day life for Java developers. Several years ago the XDoclet project started bringing meta-data into the mainstream. The 'killer-app' for XDoclet was that EJBs only needed the bean class, the rest of the required files (remote/local interfaces, deployment descriptor entries, value objects etc.) were updated/generated automatically by XDoclet. Many developers embraced this approach because of the reduced tedious work that had to be done. With XDoclet, developers no longer have to mess with keeping the remote and local interfaces in-sync with the implementation methods. Instead XDoclet automatically generates the remote and local interfaces.

At this point many MDA vendors and proponents should be saying to themselves, hey that is exactly what we have been doing for years! And it is, the difference is no visual model. The developers write the meta-data that would normally be in stereotypes and/or tagged values right into their code. For many this bridges a semantic gap that is missing in the visual modeling paradigm.

Back to the meta-data being more 'normal'. The other major change that has recently happened that brings meta-data front and center is the addition of Annotations to the Java SE 5 platform and especially the use of this meta-data in Java EE 5. Developers will be using meta-data on a daily basis.

Another thing that developers typically don't like about the MDA approach is the feeling of lack of control over what is generated. I have often heard the assertion that the developer could do better than the code generator and other such comments. While it is probably true that a hand-crafted piece of code would be 'better' in many respects, it is also true that the generated code can be done in a fraction of the time and is 'good enough'.

An area where developers have been resistant to adopt a meta-data driven approach in the past has been persistence. The same argument of 'I could do better' was used quite often. More recently though it seems that Object Relational Mapping frameworks like Hibernate and/or Cayenne have been gaining momentum. On the surface you might be thinking that I'm nuts to draw a comparison between R/O Mapping and MDA but the comparison is not that far off. Most MDA tools rely on code generation instead of a framework but basically it's the same kind of thing. Hibernate has a framework but could just as well generate code at run time (or imagine aspects being attached to your POJOs). Either way (framework or code generation) meta-data is driving the way objects are mapped to rows in tables.

With the current set of R/O mapping tools a lot of control is removed from the developer; what exact SQL is executed is no longer in the developers direct control. However many are willing to give up this control for the increased productivity gain allowed by using something like Hibernate. Who really wants to write all that JDBC code anyway?

So where does this leave us? Will MDA take its hoped -for place as the next level of abstraction for developers? Will MDA become the next best thing that is relegated to the dustbin of history? Hard to say for sure, one thing is for certain though, meta-data is becoming more a part of developers everyday lives.

More Stories By Bill Dudney

Bill Dudney is Editor-in-Chief of Eclipse Developer's Journal and serves too as JDJ's Eclipse editor. He is a Practice Leader with Virtuas Solutions and has been doing Java development since late 1996 after he downloaded his first copy of the JDK. Prior to Virtuas, Bill worked for InLine Software on the UML bridge that tied UML Models in Rational Rose and later XMI to the InLine suite of tools. Prior to getting hooked on Java he built software on NeXTStep (precursor to Apple's OSX). He has roughly 15 years of distributed software development experience starting at NASA building software to manage the mass properties of the Space Shuttle.

Comments (1)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
What sort of WebRTC based applications can we expect to see over the next year and beyond? One way to predict development trends is to see what sorts of applications startups are building. In his session at @ThingsExpo, Arin Sime, founder of WebRTC.ventures, discussed the current and likely future trends in WebRTC application development based on real requests for custom applications from real customers, as well as other public sources of information.
SYS-CON Events announced today that Massive Networks will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Massive Networks mission is simple. To help your business operate seamlessly with fast, reliable, and secure internet and network solutions. Improve your customer's experience with outstanding connections to your cloud.
"The Striim platform is a full end-to-end streaming integration and analytics platform that is middleware that covers a lot of different use cases," explained Steve Wilkes, Founder and CTO at Striim, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
SYS-CON Events announced today that Calligo, an innovative cloud service provider offering mid-sized companies the highest levels of data privacy and security, has been named "Bronze Sponsor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Calligo offers unparalleled application performance guarantees, commercial flexibility and a personalised support service from its globally located cloud plat...
IoT is at the core or many Digital Transformation initiatives with the goal of re-inventing a company's business model. We all agree that collecting relevant IoT data will result in massive amounts of data needing to be stored. However, with the rapid development of IoT devices and ongoing business model transformation, we are not able to predict the volume and growth of IoT data. And with the lack of IoT history, traditional methods of IT and infrastructure planning based on the past do not app...
SYS-CON Events announced today that DXWorldExpo has been named “Global Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Digital Transformation is the key issue driving the global enterprise IT business. Digital Transformation is most prominent among Global 2000 enterprises and government institutions.
SYS-CON Events announced today that Datera, that offers a radically new data management architecture, has been named "Exhibitor" of SYS-CON's 21st International Cloud Expo ®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Datera is transforming the traditional datacenter model through modern cloud simplicity. The technology industry is at another major inflection point. The rise of mobile, the Internet of Things, data storage and Big...
With tough new regulations coming to Europe on data privacy in May 2018, Calligo will explain why in reality the effect is global and transforms how you consider critical data. EU GDPR fundamentally rewrites the rules for cloud, Big Data and IoT. In his session at 21st Cloud Expo, Adam Ryan, Vice President and General Manager EMEA at Calligo, will examine the regulations and provide insight on how it affects technology, challenges the established rules and will usher in new levels of diligence...
In his session at @ThingsExpo, Sudarshan Krishnamurthi, a Senior Manager, Business Strategy, at Cisco Systems, discussed how IT and operational technology (OT) work together, as opposed to being in separate siloes as once was traditional. Attendees learned how to fully leverage the power of IoT in their organization by bringing the two sides together and bridging the communication gap. He also looked at what good leadership must entail in order to accomplish this, and how IT managers can be the ...
DX World EXPO, LLC., a Lighthouse Point, Florida-based startup trade show producer and the creator of "DXWorldEXPO® - Digital Transformation Conference & Expo" has announced its executive management team. The team is headed by Levent Selamoglu, who has been named CEO. "Now is the time for a truly global DX event, to bring together the leading minds from the technology world in a conversation about Digital Transformation," he said in making the announcement.
Everything run by electricity will eventually be connected to the Internet. Get ahead of the Internet of Things revolution and join Akvelon expert and IoT industry leader, Sergey Grebnov, in his session at @ThingsExpo, for an educational dive into the world of managing your home, workplace and all the devices they contain with the power of machine-based AI and intelligent Bot services for a completely streamlined experience.
In the enterprise today, connected IoT devices are everywhere – both inside and outside corporate environments. The need to identify, manage, control and secure a quickly growing web of connections and outside devices is making the already challenging task of security even more important, and onerous. In his session at @ThingsExpo, Rich Boyer, CISO and Chief Architect for Security at NTT i3, discussed new ways of thinking and the approaches needed to address the emerging challenges of security i...
While the focus and objectives of IoT initiatives are many and diverse, they all share a few common attributes, and one of those is the network. Commonly, that network includes the Internet, over which there isn't any real control for performance and availability. Or is there? The current state of the art for Big Data analytics, as applied to network telemetry, offers new opportunities for improving and assuring operational integrity. In his session at @ThingsExpo, Jim Frey, Vice President of S...
"DX encompasses the continuing technology revolution, and is addressing society's most important issues throughout the entire $78 trillion 21st-century global economy," said Roger Strukhoff, Conference Chair. "DX World Expo has organized these issues along 10 tracks with more than 150 of the world's top speakers coming to Istanbul to help change the world."
"We provide IoT solutions. We provide the most compatible solutions for many applications. Our solutions are industry agnostic and also protocol agnostic," explained Richard Han, Head of Sales and Marketing and Engineering at Systena America, in this SYS-CON.tv interview at @ThingsExpo, held June 6-8, 2017, at the Javits Center in New York City, NY.
"We are focused on SAP running in the clouds, to make this super easy because we believe in the tremendous value of those powerful worlds - SAP and the cloud," explained Frank Stienhans, CTO of Ocean9, Inc., in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
"We've been engaging with a lot of customers including Panasonic, we've been involved with Cisco and now we're working with the U.S. government - the Department of Homeland Security," explained Peter Jung, Chief Product Officer at Pulzze Systems, in this SYS-CON.tv interview at @ThingsExpo, held June 6-8, 2017, at the Javits Center in New York City, NY.
The financial services market is one of the most data-driven industries in the world, yet it’s bogged down by legacy CPU technologies that simply can’t keep up with the task of querying and visualizing billions of records. In his session at 20th Cloud Expo, Karthik Lalithraj, a Principal Solutions Architect at Kinetica, discussed how the advent of advanced in-database analytics on the GPU makes it possible to run sophisticated data science workloads on the same database that is housing the rich...
Internet of @ThingsExpo, taking place October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 21st Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devic...
"MobiDev is a Ukraine-based software development company. We do mobile development, and we're specialists in that. But we do full stack software development for entrepreneurs, for emerging companies, and for enterprise ventures," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.