no appender could be found for logger

simple case study:

u put log4j.jar into tomcat’s ROOT\WEB-INF\lib, u will get this error.

Looks like when system loads this jar it may complain because no log4j config file is present.


challenge#1 in Perl-module architecture

Pretend to be Larry Wall before he designed the module AR. Larry was pondering how to seamlessly integrate a module and its “client”.

Looks like Larry’s very first challenge was namespace sharing between the module and its client. A module, being a library, defines utility subrutines, to be called within client’s namespace.

This first challenge introduces us to, “polluting”, packages, sybol tables ..

portableremote.narrow() unable to cast between objects loaded by 2 class loaders


mscope.jar should not include com/titan/**/*.class, so
AdaptiveClassLoader [1] won’t load them.

Which classloader will load these classes? By default, classes mentioned on
the classpath are loaded by the default classpath classloader.

[1] This is a custom class loader to load from mscope.jar. It’s a descendant of the classpath classloader.

soa AR 4 q&&A

A: corba and dcom. seems like “dist obj” architecture”

A: Traditionally, connections between applications have been tightly coupled, as with CORBA (Common Object Request Broker Architecture). For example, flipping a wall switch to turn on a light is a tightly coupled system. However, making a telephone call to order a book is a loosely coupled system.

A: provider, consumer and a broker, just like JMS. Broker can also be a registry.
provider would PUBLISH its list of services to the registry

A: a Web service is little more than an SOA. However, an SOA doesn’t require the use of Web services as we understand them, and some types of Web services can be deployed without an SOA.

Simple SOA block diagram

Q: 3 basic roles (processes) for an SOA interaction?

Q: relation to web corba?

Q: relation to web services?

Q: similiar ideas to SOA?

eclipse time savers

— addiction to car, which may break down?

— mem intensive? lg2 in the future

—- ecl time-savers
line number? needed.
run tester without creating ant task?
1 key to run? n2h
multiple windows within a big window? n2h
click a java error message to jump to THE source? nice2have
click a var of type “mscope” to view its class source? nice to hav