Marcus' notes

Generics Gotcha: Intransitive Inheritance from self-referential types

2010-01-17T16:24:00.004+01:00

The setupI was used to the assumption that type inheritance in Java is transitive, that is B extends A and C extends B implies that C is a subtype of A as well as of B. As long as A,B and C denote straight classes, this is true to the best of my knowledge. But as I, admittedly only recently, learned, once generic type expressions come into play it gets a bit more interesting:Let's make A a

Spring AOP: Excessive startup time for "perTarget" advice

2009-11-14T13:20:00.002+01:00

Well over 300,000 Class.forName calls during context-initialisation were the result of setting up a simple "perTarget" advice for a 400-something beans application. With the standard "per class" instantiation model, the overhead went back to "normal", returning the Hibernate SessionFactory to the top of the list of startup resource-consumers. From a quick look at the profiler output, AspectJ's

Powerbook survived HD-ectomy

2008-02-23T20:36:00.002+01:00

My beloved "old" (3.5 years) powerbook (G4, 15", 1.5 GHz) started to make humming noises, especially when tilted. A couple of weeks later there were sudden hangups, it would only restart after given some cooling time. That it finally survived my amateur-surgery - albeit somewhat battered - let me immediately regret my fancying a new macbook. Some notes: I followed this guide I did need to poke

Tapestry Components in Scala

2007-06-04T21:42:00.000+02:00

Recently, I became interested in Scala: Multiple inheritance, good support for functional programming, a nice syntax, to mention the greatest highlights.As a first exercise, I tried to write some Tapestry-4 components in Scala to gain some real-world experience, and to see whether Tapestry's pretty extensive use of bytecode-generation would somehow break Scala's Java-compatibility. I was pretty

Clean and Flexible Authorisation for Tapestry Applications

2007-05-12T12:27:00.000+02:00

Currently we'r working on an application that will be used by 4 different departments. And I can already anticipate people dropping in to casually remark someting like "Oh, by the way, we've hired this guy who needs Access to module X of the invoicing system, but of course he mustn't be allowed to press button Y, and he needs to be able to change the comment-field. And don't hurry, he'll not

Subversive beats Subclipse as SVN Plugin for Eclipse

2007-04-25T20:29:00.001+02:00

I've switched from subclipse to subversive recently. The former used to annoy me by its inability to handle directory moves/copies. I had to go and delete .svn dirs manuallyThe annoying need to do manual updates after each commitSubversive mostly works in any of these cases. And when it doesn't want to keep track of me moving some directory around, it politely asks me to commit before continuing.

Maven2: creating JavaDoc links behind a firewall

2007-03-08T10:42:00.000+01:00

I just spent the better part of the morning trying to make javadoc links work. In short: configuring the proxy did not work - We have to cope with offline package-lists, not a big problem really. Of course, to configure the maven-javadoc-plugin to do this, reading the source was the quickest way to go. So put something like this in your pom.xml:

XFire newbie gotcha: use the correct ServiceFactory

2007-02-15T13:10:00.000+01:00

If you use the jaxb binding (the default with the Maven-plugin) to generate you client proxies, to actually use your service, you have to instantiate a org.codehaus.xfire.jaxb2.JaxbServiceFactory instead of an org.codehaus.xfire.service.binding.ObjectServiceFactory. Otherwise the parameter names (wsdl:part@name) will be replaced with "in0"-elements by XFire - and the server will complain about an

Quality of Maven integration becomes decisive for OSS adoption - good bye Axis

2007-02-15T12:54:00.000+01:00

Today I realised, how important it became for any open-source project to play nicely with the Maven repository and to get its dependencies right in its pom's . When I had to whip up a web-service client yesterday, I started out trying Axis-2 since I knew the server impl was bases on Axis. Quickly I had to decide to either start debugging their maven-plugins dependencies (obviously wsdl4j was lost

New Version 1.0.2 of hivedoc-plugin for HiveMind /Maven2

2007-02-11T17:56:00.000+01:00

Finally, I got around to enhancing the hivedoc-plugin with: Support for sub-modules Removal of empty columns in the module-summary table.The new version 1.0.2 should be on the central repo as soon as MAVENUPLOAD-1377 is resolved.

Half a Year of Maven 2: An experience of the awkward kind

2007-01-08T16:33:00.000+01:00

We're using Maven 2 now for all new projects. At the highest level I can summarize our experience as:The concepts behind Maven are sound and amazingly useful.The implementation is just about usable - no show-stoppers anymore, but lots and lots of little, annoying bugs and surprising gotchasThe documentation is sloppy.The really funny thing is, how point 1. still by far outweighs the shortcomings

New Version of hivedoc-plugin for HiveMind

2007-01-05T08:49:00.000+01:00

Since some people seem to use it, I've updated my hivedoc-plugin to version 1.0.1 . Notable changes are:Support for custom resource root directoriesBackport to Java 1.4proper plugin-docsThe new version should show up on the central Maven 2 repo soon. If you need it before that, here's the repo-bundle.

hivedoc-plugin generates Maven 2 docs for HiveMind descriptors

2007-01-02T10:42:00.000+01:00

If you're using HiveMind and Maven 2, generating docs for your HiveMind descriptors is now really quick and simple.Find the docs under http://marcus-schulte.ch/hivedoc-plugin/.

Honeycomb now comes with a Maven2 archetype for Tapestry/Hibernate based web-apps.

2006-09-15T21:26:00.000+02:00

Version 0.3.3 of Honeycomb is released.Honeycomb provides an easy integration for Tapestry and Hibernate. Its distinguishing key feature is session-per-conversation support.The main changes in this release are:re-structuring into 4 libraries replaced the templates for the Core/Webapp projects with maven archetypes. Maven users get started without manual downloads.Fixed rollback on

The Return of the Database - who needs more "middleware"?

2006-08-26T21:15:00.000+02:00

Maybe it's just my organization's policy of giving its developers relatively free access to db's while, at the same time, putting lots of administrative hurdles and hurdle-like administrators between them and the app-server. But it's really amazing how little there is that you can't get done nicely with a sturdy db and a decent servlet-container (at most).Example: For some time I thought a nice

KickStart is now Honeycomb, release 0.3 out

2006-02-27T07:35:00.000+01:00

Kickstart has moved from SourceForge to JavaForge, and it's changed its name to Honeycomb (alluding to the central role that HiveMind plays in it). Honeycomb integrates Tapestry with Hibernate for painless full-stack web-dev-support.New features comprise A hibernate DataSqueezer Pluggable Audit-Trail via hibernate interceptor Support for session per request pattern via simple config

With Kickstart 0.2 Tapestry supports the hibernate session-per-conversation pattern out of the box

2006-01-15T18:58:00.000+01:00

I've uploaded a new release of KickStart. Improvements are: Full support for the hibernate-session-per-conversation pattern. See hibernate.org for more. fixed wrong unsaved-value-mapping

KickStart integrates Tapestry with Hibernate for painless full-stack web-dev-support

2006-01-07T19:55:00.000+01:00

While Web-Development with Java is supported by a variety of great frameworks it is still not easy (even tedious) to, firstly, choose the right ones for a given problem and, secondly, make them work together. (needless to refer to all the envious appraisals of RoR and, yes, even Visual-Studio by Java-developers). I've set up a Sourceforge project, called KickStart, (first download available right

Finally no more clob-clipping: Oracle 10g supports standard JDBC CLOB-handling

2005-10-23T15:46:00.000+02:00

The new enhancements in Oracle JDBC 10g promises to simplify the insertion and retrieval techniques for the CLOBs using the standard APIs. Handling Clobs in Oracle 10g Just discovered the above link after trying to use Oracle's thin JDBC-Driver with Hibernate to save CLOB-data ... This automatically and silently nullifies the CLOB-field when you try to save more then 4k to it which you are

Apache DBCP - never forget maxWait

2005-10-19T19:00:00.000+02:00

Had some not so cozy hours debugging a productive app on Tomcat. The thing would spontaneously hang about once a day (The whole of Tomcat, apart from JMX was completely hung). It hung in an infinite wait in the Database-Pool. Funnily the default of the maxWait-Param is "-1", i.e. infinitely. Now, after I fixed this it runs nicely.But it's still not clear to me, where the total deadlock came from.

The Scattered State-Machine - An Antipattern for Web-Controllers

2005-10-05T16:56:00.000+02:00

Like a lot of popular anti-patterns the scattered controller stems from the naive implementation of a seemingly obvious abstraction. The reasoning goes like this: Web-Apps show some html-page, each user event (http-request) triggers an action which, in turn, results in an event determining the next state which is either an action or a an html-page transferred back to the user's browser. So, use

Now on the hivemind-wiki: Hivemind support for Hibernate Long-Session-Pattern

2005-09-27T18:27:00.000+02:00

Handling Hibernate-Sessions is a recurrent topic on the Tapestry users mailing list. Still, long sessions seem to be surprisingly unknown, once one considers the fact that Gavin King advocates its use in "Hibernate in Action".So, I've posted some code implementing the Long-Session-Pattern in Hivemind on the Hivemind-Wiki.I'd be curious to hear whether it worked for anyone (or why it didn't) ...

Bye, bye BEA: From Weblogic/EJB/CMP to Tomcat/Hivemind/Hibernate

2005-09-09T20:05:00.000+02:00

... and loosing some 1700 loc on the way (counting only Java, disregarding evil xml-deployment-descriptors). Our first non-trivial App on Hivemind/Hibernate is now productive for 5 weeks. No technical problems so far, just the usual buggies associated with cleaning up only part of a design-mess. The whole thing was never really performance-critical (only some 2000 transactions per workday), but

Java AWK - parsing csv-files in Java can be fun

2005-07-29T19:07:00.000+02:00

Ever parsed text-files, writing loops and calling indexOf / substr just to get some boring job done? I confess, I did. Today, instead, I sat back and browsed the jdk-JavaDocs. Thinking what it would take to bring some of the simplicity of AWK to Java - and it'really simple - just a few lines of code and you can write things like this:public class JawkSample extends JawkProgram { protected void

Unified service lifecyle-interface for different service-models

2005-07-28T18:07:00.000+02:00

Hivemind sports a bunch of service-models (singleton, pooled, threaded). After adding "client-session" for my request-spanning, hibernate-sessions, I realised that it's rather unfortunate that each of the service models comes with its own lifecycle-interface (Discardable, PoolManageable,...). So if you want to be able to switch service-models via configuration in one place, your service has to

nifty toy = Tomcat + MX4J + hivemind.management + mc4j

2005-07-28T17:59:00.000+02:00

Just brought up a managed version of Tomcat 5.5 on j2se 1.4 using mx4j and the hivemind.management module . There are just a few gotchas put mx4j.jar and mx4j-remote.jar on tomcat's system classpath, along with bootstrap.jar don't contribute services with performance interceptor to hivemind.management.MBeans Everything else works cleanly out of the box. It's fun to watch your services

Hivemind support for Hibernate Long-Session-Pattern

2005-06-03T20:26:00.000+02:00

Finally I got around to dig into HiveMind's concept of service-models. Not much digging, actually it's amazingly simple and intuitive. I've implemented a new service-model called "stateful" which attaches service instances to a User-Session. "Stateful" actually is a bit of a misnomer since threaded and pooled services also hold state for the duration of one request.Basically all one needs is a

Bugfix for Tapestry FCKeditor Component

2005-05-31T10:12:00.000+02:00

There were bugs in tapfckconfig.js (absolute URL) and the Readme (missing servlet-mapping in web.xml) which prevented the filebrowser from working. The new version is (again) available here

Tapestry FCKeditor component

2005-05-27T21:25:00.000+02:00

I've posted an FCKeditor component. It's a preliminary version - error handling support for File-Upload is still missing.It consists of a custom config-file tapfckconfig.js the editor-component itself a custom engine implementation mapping the filebrowser url's to the filebrowser service. a filebrowser service which makes use of an ... ... extension implementing the FileBrowser

Stateful services in IoC Containers

2005-04-28T19:28:00.000+02:00

Do HiveMind & Co. provide stateful services? I don't think so. Should they? As I'm growing increasingly fond of the Hibernate long-session-pattern, I do think so. You'd probably need some means of attaching/detaching some client-id to a thread (a servlet-filter, typically), so, after that the container could maintain same (service-id, client-id) to service-implementation map. In the servlet-case

Intercepting Exceptions in Tapestry Listeners

2005-04-26T15:15:00.000+02:00

While I'm growing increasingly fond of Tapestry, there's one tiny advantage to Struts-like Action-classes over listener-methods. Namely, taking care of (non-technical) user exceptions by converting them to friendly messages. A common base-class for all pages overriding AbstractComponent's getListeners() method does the trick. I made it return a sub-class of the standard ListenerMap, which, in

If you can't hide it below, hide it above

2005-04-20T15:44:00.000+02:00

In one of the last projects, I was involved in, a Web-Controller accessed business logic through a service facade implemented as a Spring-bean hiding a hibernate-pesisted domain model. Transactions (and hibernate sessions) were controlled declaratively at the service facade. Sounds so nice and clean - nice layers not allowed to know certain things about fellow layers. Only, it didn't work out

Web Services with Axis

2005-02-18T19:20:00.000+01:00

I'm currently thinking about using Web Services as a more robust (i.e. more tolerant to changes, compared to RMI) protocol for widely re-used services. Two days of fiddling with Axis 1.2 RC2 make me doubt whether that's a good idea. At least the jax-rpc stuff seems still quite brittle, especially on the client-side. Maybe, using WSDL2Java to generate stubs is not a good idea at all. One more

captatio benvolentiae

2005-02-16T10:34:00.000+01:00

So now I'm starting my random notes with a completely pointless one, just to test it. Hoping, of course, that some of the seemingly interesting thoughts that made me start this thing might come back later.