|By Bill Dudney||
|October 13, 2005 10:15 AM EDT||
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.
- 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.
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.
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.
|Joe Gaber 10/15/05 07:27:38 PM EDT|
Here are comments related to snippets of your article:
1. "Developers like to develop" - this is true; however, developers have developed using a wide variety of programming languages and OCL (instrumental to the fulfillment of MDA) is another programming language (in fact its similar to the much aclaimed language smalltalk), and in the same way that Java didn't become a big deal until Java 2, OCL and UML (now at 2.0) are likely to now gain the same acceptance. Also, see my blog for a way for developers and architects to work in pairs in a version of Agile Modeling that I am professing is the missing link between modeling and programming collaboration.
2. "There is a fundamental distrust of code generation and a resistance to this type of abstraction" - isn't any 3rd GL (i.e., Java) an abstraction, or two, from 0s and 1s?? And, doesn't the entire J2EE array of APIs provide even more abstraction from code writting?? And, doesn't every IDE on the market today provide all types of functionality that helps write and refactor code?? Conclusion: If it wasn't for increasing abstractions from the 0s and 1s a CPU uses, we would be producing the same amount of 0s and 1s today as 30 years ago. The fact that we (developers) produce vastly greater amounts of machine code through the "abstract" languages and tools of today then we did before is what produces "productivity". At the point productivity ceases to increase, programming (wirtting code) becomes a commodity given to the lowest bidder.
3. "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" - whether you write meta-data in the code or in a model it only matters from a business standpoint not an engineering standpoint. What I mean by this is that business models far outlive the applications that fulfill the business's objective. Modeling the business domain, its processes, and transforming that into code provides the business with a much longer lived artifact than code. You can use XDoclet, Java 5 annotation, or an external transformation/mapping file (as with MDA), it doesn't matter, the fact is you are still using the meta-data to generate specific code. Also, as far as the idea of a "visual modeling paradigm", once you add the rich semantics into the visual elements of the model, you know have much more than pictures. You have a programmically rich artifact with much more power than just written code.
4. "Another thing that developers typically don't like about the MDA approach is the feeling of lack of control over what is generated" - in the case of a MDA tool like the open-source Andromda, what is generated is exactly what you specify in the templates, metafades, and specific cartridge descripter files used. All of which is under the complete control of whoever the busines decides, including developers. I am currently writting a cartridge for Andromda to generate specific applications using the Sprng Framework, including Spring's MVC implementation as well as to include DWR(AJAX) integrated with Spring. There is no restrictions to the way I decide for the code to be generated as I am the one creating the templates that produce the code.
The arguements about how MDA, CASE tools, CORBA, Meta-data, etc have not been embraced in the past is an indication of the future of MDA is, IMO, absurd. In order for MDA to succeed, there has had to be, and continues to be, numerous different technologies and methodologies to converge. MDA is in its infancy in terms of being a practical approach to software development. The fact is that MDA is highly dependent upon tools, and quite frankly, no tool of the past has had the power, functionality, vision, etc to truly meet the needs of MDA. That is changing as we speak, with virtually every major tool vendor, and the two leading OS IDEs (Eclipse and Netbeans), introducing new products, or projects, which include UML modeling, OCL, BPM, and MDA functionality all wrapped up into a compete high productivity tool.
Major trends and emerging technologies – from virtual reality and IoT, to Big Data and algorithms – are helping organizations innovate in the digital era. However, to create real business value, IT must think beyond the ‘what’ of digital transformation to the ‘how’ to harness emerging trends, innovation and disruption. Architecture is the key that underpins and ties all these efforts together. In the digital age, it’s important to invest in architecture, extend the enterprise footprint to the cl...
Sep. 26, 2016 05:15 PM EDT Reads: 232
Vidyo, Inc., has joined the Alliance for Open Media. The Alliance for Open Media is a non-profit organization working to define and develop media technologies that address the need for an open standard for video compression and delivery over the web. As a member of the Alliance, Vidyo will collaborate with industry leaders in pursuit of an open and royalty-free AOMedia Video codec, AV1. Vidyo’s contributions to the organization will bring to bear its long history of expertise in codec technolo...
Sep. 26, 2016 05:15 PM EDT Reads: 2,571
SYS-CON Events announced today that Bsquare has been named “Silver Sponsor” of SYS-CON's @ThingsExpo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. For more than two decades, Bsquare has helped its customers extract business value from a broad array of physical assets by making them intelligent, connecting them, and using the data they generate to optimize business processes.
Sep. 26, 2016 05:00 PM EDT Reads: 2,714
If you’re responsible for an application that depends on the data or functionality of various IoT endpoints – either sensors or devices – your brand reputation depends on the security, reliability, and compliance of its many integrated parts. If your application fails to deliver the expected business results, your customers and partners won't care if that failure stems from the code you developed or from a component that you integrated. What can you do to ensure that the endpoints work as expect...
Sep. 26, 2016 04:30 PM EDT Reads: 1,614
In his keynote at 18th Cloud Expo, Andrew Keys, Co-Founder of ConsenSys Enterprise, provided an overview of the evolution of the Internet and the Database and the future of their combination – the Blockchain. Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life sett...
Sep. 26, 2016 04:30 PM EDT Reads: 3,344
The Transparent Cloud-computing Consortium (abbreviation: T-Cloud Consortium) will conduct research activities into changes in the computing model as a result of collaboration between "device" and "cloud" and the creation of new value and markets through organic data processing High speed and high quality networks, and dramatic improvements in computer processing capabilities, have greatly changed the nature of applications and made the storing and processing of data on the network commonplace.
Sep. 26, 2016 04:15 PM EDT Reads: 1,019
SYS-CON Events announced today that ReadyTalk, a leading provider of online conferencing and webinar services, has been named Vendor Presentation Sponsor at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. ReadyTalk delivers audio and web conferencing services that inspire collaboration and enable the Future of Work for today’s increasingly digital and mobile workforce. By combining intuitive, innovative tec...
Sep. 26, 2016 04:00 PM EDT Reads: 2,836
Cognitive Computing is becoming the foundation for a new generation of solutions that have the potential to transform business. Unlike traditional approaches to building solutions, a cognitive computing approach allows the data to help determine the way applications are designed. This contrasts with conventional software development that begins with defining logic based on the current way a business operates. In her session at 18th Cloud Expo, Judith S. Hurwitz, President and CEO of Hurwitz & ...
Sep. 26, 2016 03:45 PM EDT Reads: 2,902
The vision of a connected smart home is becoming reality with the application of integrated wireless technologies in devices and appliances. The use of standardized and TCP/IP networked wireless technologies in line-powered and battery operated sensors and controls has led to the adoption of radios in the 2.4GHz band, including Wi-Fi, BT/BLE and 802.15.4 applied ZigBee and Thread. This is driving the need for robust wireless coexistence for multiple radios to ensure throughput performance and th...
Sep. 26, 2016 03:30 PM EDT Reads: 1,555
Enterprise IT has been in the era of Hybrid Cloud for some time now. But it seems most conversations about Hybrid are focused on integrating AWS, Microsoft Azure, or Google ECM into existing on-premises systems. Where is all the Private Cloud? What do technology providers need to do to make their offerings more compelling? How should enterprise IT executives and buyers define their focus, needs, and roadmap, and communicate that clearly to the providers?
Sep. 26, 2016 03:00 PM EDT Reads: 1,552
SYS-CON Events announced today that Commvault, a global leader in enterprise data protection and information management, has been named “Bronze Sponsor” of SYS-CON's 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Commvault is a leading provider of data protection and information management solutions, helping companies worldwide activate their data to drive more value and business insight and to transform moder...
Sep. 26, 2016 02:45 PM EDT Reads: 2,612
Fifty billion connected devices and still no winning protocols standards. HTTP, WebSockets, MQTT, and CoAP seem to be leading in the IoT protocol race at the moment but many more protocols are getting introduced on a regular basis. Each protocol has its pros and cons depending on the nature of the communications. Does there really need to be only one protocol to rule them all? Of course not. In his session at @ThingsExpo, Chris Matthieu, co-founder and CTO of Octoblu, walk you through how Oct...
Sep. 26, 2016 02:15 PM EDT Reads: 2,108
The Internet of Things can drive efficiency for airlines and airports. In their session at @ThingsExpo, Shyam Varan Nath, Principal Architect with GE, and Sudip Majumder, senior director of development at Oracle, will discuss the technical details of the connected airline baggage and related social media solutions. These IoT applications will enhance travelers' journey experience and drive efficiency for the airlines and the airports. The session will include a working demo and a technical d...
Sep. 26, 2016 02:00 PM EDT Reads: 1,716
There is little doubt that Big Data solutions will have an increasing role in the Enterprise IT mainstream over time. Big Data at Cloud Expo - to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA - has announced its Call for Papers is open. Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is...
Sep. 26, 2016 01:45 PM EDT Reads: 2,573
Digital innovation is the next big wave of business transformation based on digital technologies of which IoT and Big Data are key components, For example: Business boundary innovation is a challenge to excavate third-party business value using IoT and BigData, like Nest Business structure innovation may propose re-building business structure from scratch, as Uber does in the taxicab industry The social model innovation is also a big challenge to the new social architecture with the design fr...
Sep. 26, 2016 01:30 PM EDT Reads: 1,172
The many IoT deployments around the world are busy integrating smart devices and sensors into their enterprise IT infrastructures. Yet all of this technology – and there are an amazing number of choices – is of no use without the software to gather, communicate, and analyze the new data flows. Without software, there is no IT. In this power panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists will look at the protocols that communicate data and the emerging data analy...
Sep. 26, 2016 01:00 PM EDT Reads: 1,631
DevOps at Cloud Expo, taking place Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long dev...
Sep. 26, 2016 12:45 PM EDT Reads: 3,427
SYS-CON Events announced today that China Unicom will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. China United Network Communications Group Co. Ltd ("China Unicom") was officially established in 2009 on the basis of the merger of former China Netcom and former China Unicom. China Unicom mainly operates a full range of telecommunications services including mobile broadband (GSM, WCDMA, LTE F...
Sep. 26, 2016 12:45 PM EDT Reads: 1,743
Data is an unusual currency; it is not restricted by the same transactional limitations as money or people. In fact, the more that you leverage your data across multiple business use cases, the more valuable it becomes to the organization. And the same can be said about the organization’s analytics. In his session at 19th Cloud Expo, Bill Schmarzo, CTO for the Big Data Practice at EMC, will introduce a methodology for capturing, enriching and sharing data (and analytics) across the organizati...
Sep. 26, 2016 12:15 PM EDT Reads: 1,677
SYS-CON Events announced today the Enterprise IoT Bootcamp, being held November 1-2, 2016, in conjunction with 19th Cloud Expo | @ThingsExpo at the Santa Clara Convention Center in Santa Clara, CA. Combined with real-world scenarios and use cases, the Enterprise IoT Bootcamp is not just based on presentations but with hands-on demos and detailed walkthroughs. We will introduce you to a variety of real world use cases prototyped using Arduino, Raspberry Pi, BeagleBone, Spark, and Intel Edison. Y...
Sep. 26, 2016 11:15 AM EDT Reads: 2,881