Saturday, March 21, 2015

Six Years as JBoss CTO

It's coming up to 6 years since Sacha asked me to take over from him as CTO. It was a privilege and it remains so today. Despite the facts that Arjuna was involved with JBoss for many years prior to my officially joining in 2005 and that my good friend/colleague Bob Bickel was a key member of JBoss, I didn't join JBoss officially until 2005. I found it to be a great company and a lot more than I ever expected! A decade on and now part of Red Hat, it remains an exciting place to work. I wake up each morning wondering what's in store for me as CTO and I still love it! Thanks Marc, Sacha and Bob!

Sunday, March 15, 2015

Restrospecting: Sun slowly setting

I remember writing this entry a few years back (2010), but it appears I forgot to hit submit. Therefore, in the interests in completeness I'm going to post it even though it's 5 years old!


So the deal is done and Sun Microsystems is no more and I'm filled with mixed emotions. Let's ignore my role within Red Hat/JBoss for now, as there are certainly some emotions tied up in that. It's sad to see Sun go and yet I'm pleased they haven't gone bust. I have a long history with Sun as a user and, through Arjuna, as a prospective partner. When I started my PhD back in the mid 1980's my first computer was a Whitechapel, the UK equivalent to the Sun 360 at the time. But within the Arjuna project the Sun workstation was king and to have one was certainly a status symbol. I remember each year when the new Sun catalogue came out or we had a new grant, we'd all look around for the next shiney new machine from Sun. We had 380s, Sparc, UltraSparc and others all the way through the 1990's (moving from SunOS through to the Solaris years). The Sun workstation and associated software was what you asipired to get, either directly or when someone left the project! In fact the Arjuna project was renowned within the Computing Department for always having the latest and greatest Sun kit.

The lustre started to dim in the 1990's when Linus put out the first Linux distribution and we got Pentium 133s for a research grant into distributed/parallel computing (what today people might call Grid or Cloud). When a P133 running Linux was faster than the latest Sun we knew the writing was on the wall. By the end of the decade most Sun equipment we had was at least 5 years old and there were no signs of it being replaced by more Sun machines.

Throughout those years we were also in touch with Sun around a variety of topics. For instance we talked with Jim Waldo about distributed systems and transactions, trying to persuade them not to develop their own transction implementation for Jini but to use ours. We also got the very first Spring operating system drop along with associated papers. We had invitations to speak at various Sun sites as well as the usual job offers. Once again, in those days Sun was the cool place to be seen and work.

But that all started to change as the hardware dominance waned. It was soon after Java came along, though I think that is coincidental. Although Solaris was still the best Unix variant around, Linux and NetBSD were good enough, at least in academia. Plus they were a heck of a lot cheaper and offered easier routes to do some interesting research and development, e.g., we started to look at reworking the Newcastle Connection in Linux, which would have been extremely difficult to do within Solaris.

Looking back I can safely say that I owe a lot to Sun. They were the best hardware and OS vendor in the late 1980's and early 1990's, providing me and others in our project with a great base on which to develop Arjuna and do our PhDs. In those days before Java came along they were already the de facto standard for academic research and develpment, at least with the international communities with which we worked. I came to X11, Interviews, network programming, C++ etc. all through Sun, and eventually Java of course. So as the Sun sinks slowly in the west I have to say a thanks to Sun for 20 years of pleasant memories.


I travel a lot and until a couple of years ago I lugged around a 17" laptop. It was heavy, but it was also the only machine I used and I don't use an external monitor at home, just the office, so I needed the desktop space. But it was heavy and almost unusable when on a plane, especially if the person in front decided to recline their seat! Try coding when you can't see the entire screen!

In the past I'd tried to have a second smaller laptop for travelling, but that didn't work for me. Essentially the problem was once of synchronisation: making sure my files (docs, source, email etc.) which mainly resided on my 17" (main) machine were copied across to the smaller (typically 13") machine and back again once I was home. Obviously it's possible to do - I did it for a couple of years. But it's a PITA, even when automated. So eventually I gave up and went back to having just one machine.

Enter the tablet age. I decided to try to use a tablet for doing things when on a plane, but still just have a single machine and travel with it. That worked, but it was still limiting, not least because I don't like typing quickly on a touch screen - too many mistakes. Then I considered getting a keyboard for the tablet and suddenly thought about a Chromebook, which was fortunate because I happened to have one that was languishing unused on a shelf.

Originally I wasn't so convinced about the Chromebook. I'd lived through the JavaStation era and we had one in the office - one of the very first ever in the UK. Despite being heavy users of Java, the JavaStation idea was never appealing to me and it didn't take off despite a lot of marketing from Sun. There were a number of problems, not least of which were the lack of applications and the fact that the networks at the time really weren't up to the job. However, today things are very different - I use Google docs a lot from my main development machine as well as from my phone.

Therefore, although the idea of using a Chromebook hadn't appealed initially, it started to grown on me. What also helped push me over the tipping point was that I grew more and more disinterested in my tablet(s). I don't use them for playing games or social media; typically they are (were) used for email or editing documents, both of which I can do far better (for me at least) on a Chromebook.

So I decided that I could probably get away with a Chromebook on a plane, especially since it has offline capabilities - not many planes have wifi yet. But then I began to think that perhaps for short trips I could get away with it for everything, i.e., leave the main machine at home. Despite the fact I don't get a lot of time to spend coding, I still do it as much as I can. But for short trips (two or three days) I tend to only be working on documents or reading email. If I didn't take my main machine I wouldn't be able to code, but it wouldn't be such a problem. I also wouldn't need to sync code or email between the Chromebook and my main machine.

Therefore, I decided to give it a go earlier this year. I'd used the Chromebook at home quite extensively but never away from there. This meant there were a few teething problems, such as ensuring the work VPN worked smoothly and installing a few more applications that allowed for offline editing or video watching instead of real-time streaming. It wasn't a perfect first effort, but I think it was successful enough for me to give it another go next time I travel and know I won't need to code. I've also pretty much replaced my tablets with the Chromebook.

Saturday, March 07, 2015

More thoughts on container-less development

It's time to get back to the concept of container-less development. I gave an outline of my thinking a while back, but let's remember that I'm not talking about containers such as docker or rocket, though they do have an impact on the kinds of containers I am concerned about: those typically associated with application servers and specifically Java application servers. Over the years the Java community has come to associate containers with monolithic J2EE or Java EE application servers, providing some useful capabilities but often in a way which isn't natural for the majority of Java developers who just "want to get stuff done."

Now of course those kinds of containers did exist. Probably the first such container was what came out of implementing the J2EE standard and that itself evolved from CORBA, which despite some bad press, wasn't as bad as some people make out (though that's perhaps a topic for a different entry.) CORBA was based around the concept of services, but back then natural unit of concurrency was the operating system process because threading wasn't a typical aspect of programming languages. Early threading implementations such as using setjmp/longjmp or Sun's LWP package for SunOS/Solaris, were very much in their infancy. When Java came along with its native support for threads, CORBA was still the popular approach for enterprise middleware, so it was fairly natural to try to take that architecture and transplant it into Java. What resulted was the initial concept of a container of interacting services minus the distribution aspect to improve performance. (It's worth noting that the success of Java/J2EE, the inclusion of Java as a supported language for CORBA, and the increase in thread support for other languages resulted in a reverse imitation with the CORBA Component Model Architecture.)

Now of course there's a lot more to a container these days than the services (capabilities) it offers. But in the good 'ol days this approach to kickstarting the J2EE revolution around CORBA resulted in some inefficient implementations. However, as they say, hindsight is always 20/20. What exacerbated things though is that despite gaining more and more experience over the years, most J2EE application servers didn't really go back to basics and tackle the problem with a clean slate. Another problem, which frameworks such as Spring tried to address, was that CORBA didn't really have a programming model, but again that's for another entry.

Unfortunately this history of early implementations hasn't necessarily always had a positive impact on current implementations. Change can be painful and slow. And many people have used these initial poor experiences with Java containers as a reason to stay away from containers entirely. That is unfortunate because there is a lot of good that containers mask and which we take for granted (knowingly or unknowingly.) They include things such as connection pooling, classloader management, thread management, security etc. Of course as developers we were able to manage much of these things before containers came on the scene and to this day. CORBA programmers did the exact same thing (anyone remember dependency hell with shared libraries in C/C++?) But for complex applications, those (in a single address space) that grow in functionality and typically built by a team or from components built by different programmers, handling things yourself can become almost a full time job in itself. These aspects of the container are useful for developers.

It's important to understand that some containers have changed for the better over the years. They've become more streamlined, fit for purpose and looking at the problem domain from a whole new perspective. The results are lightweight containers that do a few core things that all (majority) developers will always need really well and anything else is an add-on that is made available to the developer or application on an as-needed basis. The idea is that typically any of these additional capabilities are selected (dynamically or statically) with the understanding of the trade-offs they may represent, e.g., overhead versus functionality, so the selection to enable them is made as an informed choice rather than imposed by the container developers. Very much like the micro-kernels that we saw developing from the old monolithic operating systems back in the 1980's. So even if you're not
a Java EE fan or don't believe you need all of the services that often come out of the box such as transactions, messaging and security, the container's probably doing some goodness for you that you'd rather not want to handle manually.

Apart from the complexity and overhead that containers may provide (or are assumed to provide), there's the ability to dynamically update the running instance. For instance, adding a new service that wasn't available (or needed) at the time the container booted up. Or migrating a business object from one container to another which may require some dependent services to be migrated to the destination container. Or patching. Or simply adding a more up-to-date version of a service whilst retaining the old service for existing clients. Not all containers support this dynamism, but many do and it's a complexity that does not come without cost, even for the most efficient implementations.

Whether or not you agree with it, it should be apparent by now why there's a growing movement away from containers. Some people have experienced the overhead some containers impose for very little value. Some people haven't, but trust the opinions of their colleagues and friends. Still others have never been keen on containers in the first place. Whatever the reasons, the movement does exist. And then along come the new generation of (different) containers, such as docker and rocket which some in the container-less movement believe obviate the need for old-style containers entirely. The argument goes something like this (I'll use docker as an example simply because if I use the term container here it will become even more confusing!): docker produces immutable images and is very easy to use, so rather than worry about creating dynamically updateable containers within it, the old style "flat classpath"/container-less development strategies make more sense. In other words, work with the technology to get the best out of what it provides, rather than try to do more that really doesn't make sense and give you any real benefit.

This is a good argument and one that is not wrong. Docker images are certainly immutable and fairly easy to use. But that doesn't mean they obviate the need for Java containers. You've got to write your application somehow. That application may be complex, built by a team or built from components created by developers from different organisations over a period of years. And the immutability aspect of docker images is only true between instantiations of the image, i.e., the state of a running image can be changed, it's just that once it shuts down all changes are lost and any new instance starts from scratch with the original state. But docker instances may run for a long time. If they're part of a high-availability instance, with each image a replica of the others, then the replica group could be running indefinitely and the fact that changes occur to the state of one means that they are applied to the others (new replicas would have their state brought up to date as they join the group). Therefore, whilst immutability is a limitation it's no different than only having an in-memory database, for example, which has no persistent backing store: it can be architected around and could be a performance benefit.

If you believe that the mutability of a running docker instance is something that makes sense for your application or service, then long running instances are immediately part of your design philosophy. As a result, the dynamic update aspect of containers that we touched on earlier immediately becomes a useful thing to have. You may want to run multiple different instances of the "same" service. You may need to patch a running instance(s) whilst a pre-patched image is deployed into the application or replica group (eventually the pre-patched docker instances will replace the in-memory patches versions by natural attrition.)

And then we have microservices. I've said enough about them so won't go into specific details. However, with microservices we're seeing developers starting to consider SOA-like deployments for core capabilities (e.g., messaging) or business logic, outside the same address space of other capabilities which would normally be co-located within the Java container. This is very much like the original CORBA architecture and it has its merits - it is definitely a deployment architecture that continues to make sense decades after it was first put into production. But microservices don't remove the need for containers, even if they're using docker containers, which is becoming a popular implementation choice. As I said in my original article on this topic, in some ways the operating system becomes your container in this deployment approach. But within these docker instance, for example, containers are still useful.

Now of course I'm not suggesting that Java containers are the answer to all use cases. There are many examples of successful applications that don't use these containers and probably wouldn't have benefited much from them. Maybe some microservices implementations won't need them. But I do believe that others will. And of course the definition of the container depends upon where you look - just because it's not as obvious as the traditional Java container doesn't mean there's not a container somewhere, e.g., your operating system. However they're implemented, containers are useful and going container-less is really not an option.

Saturday, February 28, 2015

The Undiscovered Country

I grew up in the 60's and 70's with Star Trek. In those days you didn't have hundreds of TV channels or many options of things to watch and Star Trek stood out for good reasons. I continue to be a fan today, but the original series is my favourite. So it was with great sadness that I heard of the death of Leonard Nimoy. I watched him in Mission Impossible back then too, but it was as Spock that I'll remember him the most. I thought about how I'd want to put my thoughts down but realised that someone else said it a lot better than I could many years ago.

"We are assembled here today to pay final respects to our honored dead. And yet it should be noted that in the midst of our sorrow, this death takes place in the shadow of new life, the sunrise of a new world; a world that our beloved comrade gave his life to protect and nourish. He did not feel this sacrifice a vain or empty one, and we will not debate his profound wisdom at these proceedings. Of my friend, I can only say this: of all the souls I have encountered in my travels, his was the most... human."

Saturday, February 21, 2015


I've been meaning to write up some thoughts I've had on microservices for quite a while but never really had the time (or made the time). However, when I was asked if I'd like to do an interview on the subject for InfoQ I figured it would be a forcing function. I think the interview was great and hopefully it helped to make it clear where I stand on the topic: whatever it's called, whether it's services-based, SOA, or microservices, the core principles have remained the same throughout the last 4 decades. What worries me about microservices, though, is the headlong rush by some to adopt something without understanding fully those principles. Yes there are some really interesting technologies around today that make it easier to develop good SOA implementations, such as Docker, Vert.x and Fabric8, but building and deploying individual services is the least of your worries when you embark on the service/SOA road.

Of course identifying the services you need is an important piece of any service-oriented architecture. How "big" they should be is implicitly part of that problem, though most successful implementations I've come across over the years rarely consider size in terms of lines of code (LOC) but rather business function(s). The emphasis on size in terms of LOC is one of the things I don't really like in microservices - unlike in the scientific world, micro here is not well defined and one persons "micro" could easily be another's "macro".

This brings us to the concept of service composition. Not all applications will be built from atomic (indivisible) services. Some services may be composed of other services. Of course there are different ways of approaching that from an implememtation perspective. For instance, a composite service could just be an intelligent endpoint (service) which acts as a coordinator for remote interactions on the other (constituent) services, such that a client never gets to interact with them directly. Another implementation could be to co-locate the consituent services in the same address space as the coordinator. Of course a good service-based implementation would not allow these implementation choices to be exposed by the composite service API to the client so that implementations could be changed without requiring changes to users.

Some other factors that must be taken into account when considering the "size" of a service or how the constituent services relate to a composite service include:

(i) performance - remote invocations, whether using a binary protocol such as AMQP, and especially text based protocols such as HTTP, are significantly slower than intra-process communication. Therefore, if performance is important and there will be many cross-service interactions, it may make sense to either consider merging services or deploying them within the same address space so that intra-process communication can be used instead. A service does not have to reside in its own distinct operating system process.

(ii) fault tolerance - despite the fact that you may be able to replicate a specific service to try to obtain high availability, there's always going to be a finite probability that your service will become unavailable - catastrophic failures do happen (entropy always increases!) And remember that it may not be possible, or at least easy, to replica some services, e.g., active replication of a service requires the business logic to be deterministic otherwise you need to use a passive replication protocol, which may adversely impact performance to the point of making it unrealistic to replicate in the first place. Therefore, if the failure of a service causes other services to be unusable (no Plan B), it may make more sense to co-locate these services into a unit of failure, such that if one is going to fail (crash) they all fail anyway.

Of course there are a number of other considerations when building applications from services and again we've been addressing them over the years in SOA deployments or earlier with services-based applications. One of the most critical is service (or task) orchestration - rarely is an application constructed from just one service and even if it were, that service may itself be using other services to perform its work. As such, applications are really the flow of control between different services and rarely is this some static a priori determination; the failure of a service may cause the application logic to determine that the next action is to invoke an operation on some other (compensation?) service. But again, as I said earlier, this is something we really should be taking for granted as understood, at least at a fundamental level. Whether or not the microservices community likes standards such as BPMN, the aims behind them or their bespoke implementations, remain and we would be ill advised to ignore. At least if you're going to build a new wheel it's a good idea to understand why the current wheel isn't good enough!

For a long time I wrote about and considered the necessity for SOA governance. In fact even before the term SOA was coined, governance has been a crucial component of any distributed system. Unfortunately it's also one of the most overlooked aspects. As we moved to a more service-oriented approach, runtime and design time governance became more and more important. How do you know the service you're about to use actually offers the right business capabilities as well as the right non-functional capabilities, e.g., can respond within the desired time, is secure, offers transactions etc? Of course there are a number of ways in which these questions can be answered, but essentially you need a contract between the client and the service. Part of the contract will inevitably have to include the service API, whether defined in WSDL, WADL, IDL or something else entirely. These days that part of (SOA) governance is not subsumed within the new term API Management. No less important, just a different categorisation. And microservices needs exactly the same thing because it really doesn't matter the size of a service - it'll have an API and hence need to be managed or governed.

Despite what I've heard about microservices, I really do believe that the existing SOA community had a lot to offer their microservices cousins; we've got to build on the experiences of the past decades and deliver better solutions to our communities rather than think that starting from scratch is the right approach.

Saturday, February 07, 2015

Container-less development

In the Java world been hearing a lot lately about container-less development. (Note, I'm not talking about containers such as docker.) Whether it's to help build microservices, to reduce complexity for Java EE developers, or some other reasons, moving away from containers seems to be the theme of the day. One of the core aims behind the movement away from containers appears to be simplifying the lives of application developers and that's definitely a good thing.

 In general anything we can do to improve the development experience is always a good thing. However, I worry that the idea of moving away from containers is not necessarily going to make the lives of developers easier in the long term. Let's spend a moment to look at some of the things we've heard as complaints for container-driven development. I'll paraphrase, but ... "They make it too complex to do easy things." Or "Containers are just too bloated and get in the way of agile development." Or "The notion of containers is an anti-pattern from the 20th century." Or even "Testing code in containers is just too hard."

Now before we try to address these concerns, let's look at something I said to Markus in a recent interview. "Any container, whether it's something like docker, the JVM or even a Java EE application server, shouldn't really get in your way as a developer but should also offer you the capabilities you need for building and running your applications in a way that is easy to use, understand and manage. If you think about it, your laptop is a container. The operating system is a container. We take these for granted because over the years we've gotten really really good at building them to be unobtrusive. Yet if you look under the covers at your typical operating system, it's doing a lot of hard work for you and offering you capabilities such as process forking and scheduling, that you don't know you need but you do need them."

It's easy to make blanket statements like "containers are bad for agile development" or "containers are not fit for modern web apps", but the reality is somewhat different. Of course there may be specific examples of containers where these statements are correct, but let's try and remain objective here! As I mentioned to Markus, we're using containers in our daily development lives and not even aware of them most of the time. A good container, whether an operating system or a Java EE application server, shouldn't get in your way but should be there when you need it. When you don't need it, it's sitting in the background consuming limited memory and processor time, perhaps still ensuring that certain bad things don't happen to your application while it's running and which you didn't even consider initially, e.g., how often do you consider that your operating system is providing red zone protection for the individual processes?

As I said, a good container shouldn't get in your way. However, that doesn't mean it isn't needed. Many applications start out a lot simpler than they end up. You may not consider security initially, for instance, but if your application/service is going to be used by more than you and especially if it's going to be available globally, then it's something you're going to need eventually and a good container should be able to either take care of that for you opaquely or offer a simple to use interface. In essence, a good (ideal?) container should be like your favourite operating system - doing things in the background that you need but don't want to really understand, and offering easy to use APIs for those services you do need.

For enterprise users (and I include Web developers in that category) those services would include security, data management (RDBMS, NoSQL), messaging (not everything will communicate using HTTP) and transactions (yes, some people may not like them but they're essential for many types of application to ensure consistency in a local and distributed case). I'm not going to suggest that there's any such thing as the ideal/perfect container in the Java world today. There are definitely some implementations that would want you to consider seriously looking at container-less solutions! However, there are several implementations that have made significant strides in improving the developer experience and pushing themselves into the background, becoming part of the substrate. And a number of developer tools have sprung up to help developers further, such as Forge and Arquillian.

If you consider what lead to the rise of containers, it wasn't because someone somewhere thought "Oh wouldn't it be good if I threw everything and the kitchen sink into a deployment environment". Believe it or not there was a time before containers. Back then we didn't have multi-threaded languages. Everything was interconnected individual services, communicating using bespoke protocols. Your application was probably one or more services and clients, again communicating to get things done. If all of these services ran on the same machine (entirely possible) then once again you could consider the operating system as your application deployment container.

These services were there for a reason though: applications needed them! The development of containers as we know them today was therefore a natural evolution given improvements in language capabilities and hardware performance (reduce the interprocess communication at the very least). Granted we may not have focussed enough on making the development of applications with containers a seamless and natural thing. But that doesn't obviate the need.

Consider the container-less approach. For some applications this may be the right approach, just as we've never said that container-based development (or Java EE) was right for all applications. But as the complexity of the application or individual service grows and there's a need for more functionality (e.g., caching or security) then application developers shouldn't have to worry about which caching implementation is the best for their environment, or which version works well with the other functional components they're relying upon. Eventually container-less frameworks will start to address these concerns and add the "missing" features, whether as interconnected individual (micro?) services in their own address spaces or co-located with the application code/business logic but (hopefully) in an opaque manner that doesn't get in the way of the developer. Once we start down that road we're heading towards something that looks very similar to a container.

Rather than throw away the inherent benefits of containers, I think we should be working to make them even easier to use. Maybe this requires changes in standards, where those containers are based upon them. Maybe it's giving feedback to the container developers on what's getting in the way. Maybe it's working with the container-less efforts to build next generation containers that fit into their development and deployment experience seamlessly. There are a number of ways this can go, but none of them are really container-less.

Monday, October 27, 2014

Time to reflect

I don't use my blog as much as I used to due to lack of time and something to say that I don't say through other avenues. But something happened today that made me stop and think that perhaps I could use this blog for a more personal posting than usual.

I've always thought that life is precious and yet we often take it for granted, typically until the last moment. We make a big show of people being born because whatever your faith or beliefs, seeing a new life born into the world is a wonderful thing! Death is often more dour and a more personal thing. Typically unless someone we knew died, we all only hear about the deaths of celebrities, many of whom probably had little or no impact on our own lives.

Death is a sad enough occasion at the best of times. Again depending upon your faith or belief system it probably is the last time that unique individual will set foot on this planet and mingle with people here. Some aspects of what made them human, such as the raw materials, will eventually find their way back into the environment and, just as we're all made of "star stuff", back into other people in one way or another. But their uniqueness, their individuality, is gone forever - as best we can tell. That is sad. At it's rawest, this is a loss of information that can never be retrieved. A loss of memories, experiences etc. that helped to make the person who they were.

We often hear statements like "they're not dead as long as we remember them". Thinking about the sentiment behind these kinds of statements it makes sense. And we can all probably know someone who died, family or celebrity, that we remember fondly. But what of those people who have no one? That's the biggest loss of all: there's no one to remember them, to remember what made them unique within the 7 billion people on the planet. Maybe they weren't celebrities. Maybe they weren't world leaders or people who went down in the history books. But they were people nonetheless and to not be remembered is like them falling into a black hole, where no trace remains.

If you've gotten this far then you may be wondering why I'm writing this. I live with my family in an area of the country that means we have only 2 neighbouring houses. Both houses have people in them who have lived there for over 7 decades (we've been here for 14 years). Today one of those people, John Hudspith, died. He was 80 and a kind, quietly spoken gentleman; a man of his era. But he was alone. No family left alive. Few friends, other than ourselves and the other neighbours; none really close. Even then he was a private person. And it struck me that in his death he would be forgotten because he lacked celebrity status or family or history-worthiness. Well this is my small attempt to give him a little immortality, because if you've read here then you've paused for a moment to wonder about this John Hudspith, who he was and why I would want to remember him. Thank you.