Database Impedance Mismatches

Alex Popescu argues that document databases have an impedance mismatch with object-based software. He compares the situation to relational databases:

“One of the most often mentioned issues reported by software engineers working with relational databases from object-oriented languages is the object-relational impedance mismatch. Document databases adopters are saying that one benefit of document stores is that there is no impedance mismatch between the object and document worlds.

“I don’t think this is entirely true.”

Given that databases and in-memory representations of objects serve different purposes, I don’t think we’ll ever completely manage to do without mappers of some kind. (Otherwise we’d all be using Java Object Serialization as our database.)

However, to me at least it appears that of all database technologies, graph databases like InfoGrid have the smallest impedance mismatch: a graph of objects is fundamentally closer to what is happening in memory of an object-based application than any other representation (e.g. document-based / hierarchical / relational / key-value etc.)

Grade and return an project – desktop – school room facilitate

Educative practices are items or reasons which derive from observations and thinking. These hypotheses are actually attempted and proved by proponents mainly because the generic ideas that help to explain and calculate comprehension. A United States pedagogue recognised via the company name David Botkin displayed the definition of revolutionary instruction for the technological network 2 decades returning. Botkin acquired a number of these answers brimming with controversies since expression meant permanent and finished revision to the policies which traditional notions on instruction regarded as axiomatic, (Lee and Performed 2007, 194-204). Appearance
David Botkins resourceful teaching takes into account awareness less an end but as a technique, orienting with the kids style progression. His check out is in opposition to classic training which landscapes the foremost value of the entire process of training as know-how truly being transferred to the student. The useful schooling offer does not put emphasis on taking care of the procedure of knowledge, for this reason establishing scenarios the spot that the learner is at a best place to produce his very own aims and work at achieving them, changing themself and regulating the educational undertaking. The common variety of knowledge has a composition that is fewer stable and is not going to put into action the required evolves as time shifts. Insight accumulation earnings as traditional in subjects like literature and reputation, which might be broadening and growing gradually unlike science things like math, biochemistry and science that can be tricky to adjustment for quit some time.

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Botkin, during his research into the useful plan, gives you another differing final choice which implies that the device of education and learning is powerful characterised based on the altering composition that is definitely habitually undergoing regrouping and renewal with new educational curricula and disciplines truly being launched on a regular basis, (Botkin, Jim and Kaipa 2004, 409-423). (more…)

NetBeans7 and Tomcat6

InfoGrid trunk has been upgraded to NetBeans7, but for the time being, we remain with Tomcat6. Unfortunately the NetBeans guys have not exactly made it easy to remain compiling JSPs against the Tomcat6-supported specs instead of Glassfish.

In the relevant InfoGrid projects, we set the relevant properties in for Tomcat6. They are picked up when running the build from the command line.

If you find yourself with compilation errors when compiling from the IDE, the following trick might help:

  • Find your system-wide NetBeans 7.0 properties default file, e.g. ~/.netbeans/7.0/
  • In that file, find the properties that start with libs.jsp- such as libs.jsp-compiler.classpath.
  • Comment them all out!

Given the sequence in which NetBeans reads in those property files (system-wide, private project-specific, all project-specific), they might override the correct settings otherwise.