Well, all good things come to an end, including this conference. I will use the spare time tomorrow to reflect upon what I liked and what could be improved about the sessions in TSSJS in Barcelona, which all in all was a pleasant experience, hola!
With MDA being totally out of the picture, Gregor Hophe (energetic and excellent speaker) and Erik Doemenburg is getting down to the point of what is really important point when it comes to modeling, not do create pictures that you can generate code from, but to generate a graphical presentation from an existing system and an existing codebase.
I write a blog entry called "Feeding the architect" that dealt with this topic. In that case using maven, dotuml and GrapViz to generate diagrams (static and dynamic) from an existing codebase. The main problem is to combine data from static code analysis and from a running system, exactly what Gregor and Erik is going into presenting.
Three different models are suggested:
OnnoKluyt is leading the panel with the following guys:
John Davies from C24 has been of of the profiles at this convention. I missed the keynote so I wanted to drop in at the banking and grid session to see what the fuzz was all about.
A lot of cases where we deal with applications we don't really need databases as we know them John claims. More than viewing the database as the central repository of all information you can view the grid as the repository of the information.
Typical cost is 1$ per CPU per hour. Interestingly when several of the banks that John is working for has as many as 10K CPUS. Utilizing these effectively is important with respect to ROI.
C24 want to avoid using XML though the wire when transferring information is not to use XML because it is not efficient enough, but use java databinding and efficient object serialization instead. They do this through something they call Integration Objects. The fact that John discourages the use of XML in the grid computing space is that is not efficient enough. This is also an important moment in the SOA space discussions.
How do you do this when you don't have any data stored in a central repository only in a grid where you don't have a query language.
John is referring to a case study where everything is stored and manipulated in a grid space in two different grid spaces, one that receives the feeds and organize them and one replicated feed that is optimized and used solely for querying.
The technology is based upon JavaSpaces and has some quite interesting attributes. One of them being that querying is done in javaspaces based on what kind of interface(s) that are implemented. Then some matching logic. The thing here is that the searching seems to be quite procedurally oriented, like searching for some course grained items and then doing a new query on that subset. I would prefer this to be more declaratively oriented, don't tell the system how to do it tell it what to get!. This is what has been working well with RDBMS'es for the last 15 (maybe even more) years. Maybe it just because I didn't understand the example?
Richard Öberg in the audience asks what are the maingoctchass. One of the gotchas with JavaSpaces and the way that C24 applies the technology is classloading, understanding the nature of the distribution and multithreading issues in grid environments.
What kind of knowledge will you need to implement this technology effectively. Knowledge of grid computing and products technologies that may have been around for a while without having to much momentum is definitely an issue. This might be a major challenge in implementing grid computing effectively.
Dr. Heinz Kabutz, author of the Java Specialist Newsletter is talking to us about coding productivity and about using the IDE ad your tools effectively. This is also something I have been thinking a lot about since I am often in a position where I do pair programming and coaching. Then you tend to notice how other people work, if they use keyboard shortcuts, how they navigate and so on.
being able to use the IDE effectively, especially using keyboard shortcuts is really a differentiating factor in productivity. How fast you type, and if you use touch or not may also be a factor, because we still think faster than we type.
Important to actually make sure that you know what code you actually need, which code gets executed in production. Important, since most money goes into maintenance and you don't want to maintain unused code.
Heinz also talks about how he has mate this doclet that finds this and that like unused methods fields and so on. I use IDEA to locate stuff like this intead of running a doclet.
More discussions on exception handling, increasing tghe use of private/protected scoping and so on. Many developers should read up about this, resonable scoping will make your class easier to use and less confusing and actually reduce the chance of anything being duplicated if the api uses a reasonable naming strategy and relevant javadoc where needed. Still Heninz has not told me anything that I am not allready aware of, except for for a couple of funny comments in the J2SE core awt code and how the actual enforcements access to final fields as changed back and forth from 1.1 to 1.6.
This is a really interesting topic, the topic of the discussion is development environments. IDEs has been one of the most important factors related to developer productivity and is often the starting points for religious debates amongst developers.
Panelists
We had a discussion during lunch here related to web frameworks, how many there are, how they compare and how web development in the Java space is actually quite difficult. Creating a nice looking web interface with good interaction capabilities with dynamic content is difficult and costly, and I am not particularly happy with what I have seen so far. I have done some work using spring MVC and JSP 2.0 and JSTL lately, and it works fairly well, but for the presentation part there is still a lot missing. Spring 2.0 will have a new set of tags that will make life easier, but anyway. Wicket seems appealing.
The underlying component model and the fact that you may are able to work with the page itself as a first class object, and being able to have a simple databinding approach.
Patrick Lindksey is giving his talk "The good bad and the ugly" related to EJB 3.0 persistence. Interesting to get a more detailed picture of the JPA specification. I really find it more interesting today compared to last year. One of the reasons is that we have more or less nothing else but runtime dependencies and some wrapper code around a generic repository implementation in my current project. This may make it feasible to actually swich persistence providers as long as we have several good open source ones available already. The only thing that will require some work is getting rid of the implementations we have related to searching that uses the Hibernate Criteria API. Maybe JQL will do the job? I don't know I have never been using this part of the API.
One thing Patrick went into depths explaining related to POJO based persistence is really interesting. It really hides some subtleties related to designing API's and access to fields and properties. This applies to most mapping frameworks including Hibernate and is relevant when it comes to discussing domain models and where to put the actual business logic.
Consider the following code fragment representing the setter for the age property in the Customer class:
public void setAge(int age) {
if (age < 18) {
throw new JuvenileException("We dont accept young customers");
}
this.age = age;
}
Who is interested in Geronimo? Obviously a lot of people, I don't know too many people actually using it apart from using it as maven dependencies for the J2EE API's.
I attended Bruce Snyders presentation on ServiceMix and found that one interesting because I have been reading up on Mule a little bit so I attended to get a comparison. I am currently also working on a project where we are on a good way to actually implement small parts of an ESB so the topic is really interesting. With that said, I am not necessarily an advocate of adding a dependency to a third party library just because it contains an out of the box implementation of something I can do with 10 lines of javacode.
Managing 100 different and possible incompatibilities might be just much of a nightmare as writing the 1000 lines of code that those frameworks help me to replace.
The panel lineup of the Geronimo Panel Discussion are:
Rod starts the presentation with saying that the final 2.0 release will probably be scheduled at the 5'th of July this year. This is good because enable a lot of projects, during the summer to conclude the upgrade to Spring 2.0. A lot of development environments enforces summer freeze periods which makes the summer an attractive period for experimenting with such things. Currently I am busy with getting thins production ready for a big client so I will have to do this on my spare time when I am not hanging out with the guys at PhatMC.com
There are a lot of nice new features that are of particular interest to me as we are using spring at the project I am currently working on. Especially the support for Asynch Messaging without MDBS's with is really good. By trying to replace the message activation infrastructure we are currently using by POJO based messaging we will probably be able to
A guy from Sun responsible for Suns managing http://www.sunsource.net/ and participating in developing Suns Open Source strategy is here to explain to us different strategies and approaches for dealing with open source. He starts explaining to us the shift from to the consumer age to the participation age. The key is to understand that certain events changes the way we think about stuff. I think the point he is getting to is the way that Open Source has changed the way we think about software. Various patent models and how large corporations think regarding licensing and patents is also interesting.
Simon Phipps also believes that we will stop paying for using software in advance, and shift towards paying when it adds value. It would be interesting to see how such policies might be enforced. As a consultant I play a role in providing business value through adapting and creating software, not through the software itself, so this is an interesting thing.
Open source communities is based on a casual allignment of interests Phipps concludes.
Would be interesting to discuss further how it is possible to actually charge for software when it adds value and beyond simple scenarios like the number of customers or the number of employees in the company that bought the software. Neither of these marketing models are sufficient to define market value.
Looking through the agenda briefly, regarding Web Application frameworks, there are only two presentations on webframeworks this year, Wicket and RIFE. Not to many people had even heard of those last year. The proliferation of frameworks in the web space really says something about the maturity or lack of such in this space. Rife has continuations which enables a really interesting programming model the reaches far beyond being able to support using the back button in the browser.
Enabling productivity, effective development environments and a component based model like JSF, maybe where everything is expressed in java will be the way to go I beleive. I have been doing a bit of JSP programming and JSTL 2.0 lately. In combination with clever use of CSS like Maxdesign makes webdevelopment much more simple, event not as simple as I would like to.
I attended Gregor Hophes session on SOA in Las Vegas I little over a year ago and liked it. I wanted to drop into his session in Barcelona to see if the presentation has been updated.
Gregor now works for Google, let us see if that has changed his attitude and presentation form.
Gregor gives the following definition of a service:
Hey, we have to pay for WIFI here at Fira Palace. I stay at Vincci Arena nearby where WIFI is free. I miss free WIFI, well, but to feed the community with information I am more than happy to pay 17 Euros for 24 hour access.
We didnt get coffe when we arrived, I would like to get coffe when I want and as musch as I want.
Anyway the conference is actually quite intimate. 250 Participants, 275 with speakers.
My current session crasshed with Gavin King's session about Seam, so I went to listen to Jonas Boner instead.
Jonas Boner is talking about clustering in spring, a topic of interest since I am currently developing applications that are deployed into a clustered envrionment, and I want the fact thta applications are deployed into a clustered environment to be transparent. It should be possible to deploy applications that are clusterable also in to non clustered environments such as an embedded Jetty container because that facilitates effective unit testing.
Jonas comes up with a problem definition, scaling and that we need to share data throughout multiple JVM's. I think that in most cases, this should not be neccessary. In stateless applications you might just as well keep multiple copies of reference data (which constitutes what Martin Fowler refers to as the knowledege tier), which is most likely read-only anyway.
Jonas starts go into an example, a Store domain class that is subject to crud operations, and how to replicate state changes across a cluster. Hmmmm, this sounds more like how to replicate state across a cluster, well before you do that, ask the question do you need to? If you want to store the data, put it in the database, you will have to put it there eventually anyway.
Now he continues to discuss aspects related to track changes, well, I have been using Hibernate for that some time, so this is for the most just problems from an OR mapping perspective.
Now some stuff that actually relates to the spring clustering stuff and Teracotta of course, which is the product you will need to support directly what Jonas is referring to. Hani has some viewpoints on this.
In my perception try to design your application so that you have uniform access to data, either read mostly/only reference data and operational data. By designing a data layer effectively I see no reason whatsoever to associate spring with clustering throuch teracotta. If clustering relates to sharing data in a cluster, use isolate this in the data layer. You will most probably be using an OR-mapping tool anyway. Seems as Jonas is taking areas related to data synchronization from the data layer and moving it higher up in the application tiers where tehy do not belong. Synchronizing data using the database is probably the most effective solution anyway.
Ive just been relaxing in the back on a session with Geert Bevin, the founder of the RIFE framework and he has been explaining to us about continuations and how it is beeing used in RIFE, a webframework that uses continuations heavily.
I was missing some informations related to how continuations may be used decoupled from RIFE by apart from that it is a very powerfult concept. I am not really sure how it will affect the programming model that I am currently using on my projects since all the classes that may contain state in continuations must be cloneable, but I will have to dig into that.
Just been browsning through the agenda and preparing myself for the Barcelona trip. Been planning the agenda online as well using the online agenda planner available at http://javasymposium-europe.techtarget.com/ . The slots available in the online tool are not the same as in the online agenda. It does not present the slots side by side when they are overlapping either. Guess I will stick to a printed version and just put circles (with a pen) around the slots I want to join.
The agenda is not overly impressive. I counted 43 sessions plus some keynotes and some bofs. But given the lineup, I will not have any problems attending something interesting.
Compared to what we are planning for JavaZone 2006 the venue in Barcelona is small compared to the +80 session programme we are currently concluding, with an even more impressive lineup.
After the hacker havok at svitjod.rymdweb.com, we never got our b2evolution installation up again. A pity, but thats life. I might as well find somewhere else. I am soon heading for TSSJS In Barcelona as welll, and I want to get ready for some hardcore blogging from the conference, so get ready, at least I am (will?)