Commit ef2a9ff6 authored by Stephanie Gawroriski's avatar Stephanie Gawroriski
Browse files

Write stuff into the readme.

parent 1c21f95b
......@@ -5,17 +5,31 @@
* Copyright (C) 2013-2016 Multi-Phasic Applications
<http://multiphasicapps.net>
SquirrelJME is intended to be a JavaME 8 compatible environment for strange and
many other devices.
**SquirrelJME** is intended to be a Java ME 8 compatible environment for
strange and many other devices.
Licenses:
## Licenses
* [GNU Affero General Public License, Version 3 or later](license.mkd)
Links:
## Links
* [Online repository](http://multiphasicapps.net:8080/squirreljme)
## Goals
* _To be self-hosting_ - it can build itself while running on itself, provided
there is a filesystem.
* _To be small_ - Smaller programs are easier to maintain and are usually
simpler.
* _To be fast_ - With the potential of AOT/JIT, systems that do not normally
have a port of an existing virtual machine will usually only have an
interpreter.
* _To be compatible_ - So that existing Java ME 8 applications can run on this
virtual machine.
## Donations
You may donate to SquirrelJME to help keep the author alive:
* BitCoin (**BTC/XBT**): [`1HNRD44krsCFUzUvVWaXr5jqvuyZDZy71M`](
......@@ -25,3 +39,60 @@ You may donate to SquirrelJME to help keep the author alive:
* DogeCoin (**DOGE**): [`DPsW21MV8RMuXhA3GoN8VPjkmQEugrEn8h`](
dogecoin:DPsW21MV8RMuXhA3GoN8VPjkmQEugrEn8h)
# Supported Operating Systems and Freestanding Hardware
## Hosted
## Freestanding
# Differences Between Java SE and Java ME
Java ME is a much lighter Java platform and here are the things which are
missing along with a reason as to why this may be a good thing:
* No finalizers (the `finalize()` method).
* Finalizers are very integrated with how the garbage collector works.
* It is never known when they will actually be called (if ever).
* Timing attacks could be performed when finalizers are called between
garbage collection runs.
* No serialization.
* Not all objects are `Serializable`.
* Serialization uses virtual machine magic to access internal details.
* The `transient` keyword should never appear.
* Simplifies implementation.
* No reflection.
* There is `Class.forName()` and `Class.newInstance()`, however they are
trivial to support.
* More secure because access checks do not have to be performed at run-time
to determine if it is permissable to access an object.
* Random object fields (and finals) can be cached because their reference
or primitive values will never change.
* More secure because for example changing `Boolean.TRUE` to be `false` may
cause security exploits with code that relies on it being `true`.
* No `invokedynamic` instruction.
* Simplifies virtual machine operation, at the cost of lambdas (which could
be smartly wrapped in anonymous classes by a compiler).
However, given these differences there are advantages:
* Faster
* Due to the lack of reflection, optimization is safer because finals are
truly final. This means no exceptions are required to allow for this
change.
* Lighter
* The main library is much smaller which means it will load faster and
use less memory. Less memory means it can run on smaller systems such as
calculators.
There are also disadvantages however:
* Without reflection, one cannot include plugins dynamically from the program.
* However, Java ME 3 (or so) added LIBlets which may be optional and provide
a slight alternative to plugins. These however are fixed to the JAR/JAD
which means that the difficulty is increased.
* Alternatively, Java ME 8 has `ServiceLoader` which enables JARs to
potentially be merged to provide services. Also using `Class.forName()`
and `Class.newInstance()`, plugins using a common interface can be
initialized when they are not directly known.
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment