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minutes-20001129b.txt
Minutes of meeting 29/11/00 @ 5pm
Location: UKC Computer Science Multimedia Lab then
Eliot College computer room.
Present: ajm4, tdb1
Absent: None
AJ and Tim met to discuss and work on the code tidying
issues. It was decided, afterwards, that the work should be
documented in the form of minutes, so that a record can be
made of what's happened.
Meeting start (MM Lab): 17:00
Break for dinner: 22:00
Resume (Eliot) : 22:30
Finish : 04:30
Firstly a new class was introduced to the system. This
class, called the ReferenceManager, was originally designed
to hold references to the various items that a system
component (ie. the filter) would require. This would cut
down on passing of references between classes.
However, as the was implemented it became clear that it
could infact handle the CORBA references as well, and then,
further to that, all the CORBA initialisation. In the end it
ended up handling all the CORBA code, and held references to
all the things required by a system component.
The class was designed as a singleton, again to cut down on
reference passing. Generally the class needs to be
initialised before use, and this will be done in the main
method of the component it's involved in. From then on a
reference can be obtained by any class within the component
using one simple method call.
This has significantly reduced the complexity of the main
methods of the system components, and allowed a clear line
to be drawn between the CORBA code and the rest of the code.
This has also meant that all the CORBA error handling is
focused in one place, and can therefore be more thoroughly
dealt with.
The next item to be dealt with was the packaging. This was a
major, but required, task and took some organising. The
whole system now resides below the following package,
uk.ac.ukc.iscream;
The currently list of subpackages are,
uk.ac.ukc.iscream.core;
uk.ac.ukc.iscream.core.loggers;
uk.ac.ukc.iscream.filter;
uk.ac.ukc.iscream.filtermanager;
uk.ac.ukc.iscream.rootfilter;
uk.ac.ukc.iscream.util;
The first five containing the existing components, but the
last has been created to house more general purpose classes.
Currently it has the xml parsing classes, and the
ReferenceManager. It will, in the future, hold a class to
deal with naming and generation of toString()'s.
The inclusion of these packages has made the directory
structure look a bit unwieldy, but as you'll see further
down makefile's have been written to make compilation
easier.
As a side note, the generated IDL classes reside in similar
packages, although they are in a separate location to avoid
confusion. Ultimately they will be merged.
Makefile's have been generated for the whole system. They
allow easy compilation of any component, or the whole thing.
They also allow for easy cleaning of compiled class files.
It is expected that they will in future support packaging of
the system into JAR files.
They work on a recursive structure, with a single root
Makefile. Each directory contains it's own Makefile for the
files it contains, with links to any subdirectories that
also contain Makefiles. This makes the system much more
manageable when adding, changing, and removing class files.
Ultimately only the root Makefile need be used, and it will
recursively execute all the others.
As a result of the above packaging, and the ReferenceManager
it became necessary to tidy large chunks of code. The main
two done were the Filter and RootFilter. Both now make use
of the ReferenceManager throughout, and have a nice common
theme through them - similar variable names, and class
structure. These classes are now much nearer the required
standards.
Also modified were the loggers in the core. They now reside
in a seperate subdirectory of the core, although this could
be moved. This layer of seperation makes life much easier
for managing and adding loggers.
That was about it for changes. A few bugs were fixed as
things progressed, but the functionality of the system (from
an external point of view) remained pretty much the same
throughout.
A short list of "nice features" to be added was prepared.
This list is in no certain order, and there is no gaurantee
they'll even be done in the near future.
- redesign the toString() methods. Modifying them, at
present requires changing every class. This is bad. A
new class in the util package could be created to
centralise this behaviour.
The toString() method is mainly used for logging
purposes.
- implement "remote logging" sessions. This would require
modifying the exist setup, but the majority of code is
in place to support it already. The idea of remote
logging is that a logging console could be fired up
independently on the server, and allow the user to
monitor the status of the system.
- improve error handling, and exception catching. Fatal
errors should be informative to the end user.
- the SimpleSwingLogger is broken. It will, after quite a
few thousand lines, run out of memory and crash. This
bug was identified previously, but the cause only found
during the course of this meet.
- allow hosts (and clients?) to log to the central logger
as well. This would require a "logger proxy" of sorts,
but it is suggested that this could be encapsulated in
the existing UDP packages - ie. generate a packet of
type "logmsg" that the UDP reading class will direct
straight into the system logger.
- sort of garbage collection issues, specifically with the
Configuration objects, although there may be other areas
that have yet to be found.
- the configuration system support dynamic updates, and
the host makes good use of this feature. However, it
would be nice if the server could implement this
internally where possible.
The semi-meeting was concluded at a rather late (or early)
hour after some very productive work.
