What is preverification ?

Answers were Sorted based on User's Feedback

Answer / b.chandra sai mohan

After the compilation process, we will get a class file.
Before installing the class file in the device, JVM verifies
whether the class file is structurally or conceptually
correct according to J2me specification.If the class file
fails this check it is rejectd.This is "PREVERIFY" step.This
is performed by very small tiny JVM in mobile also.So,
verifying a classfile in a mobile is a risky job becoz of
memory and resource constriants. So, we have to do
preverification off the device. We will have a preverify.exe
file which we will keep in bin folder of WTK22. If we .class
file input to this tool we will get preverified class file.
Some extra information is added to class file specifying
that is preverfied. When we install it in device the device
sees this information and the proceeds. Otherwise it
rejects. In this we can reduce overhead on device by
preverifying our class file off device.

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Answer / guest

Due to memory and processing power available on a device,
the verification process of classes are split into two
processes. The first process is the preverification which is
off-device and done using the preverify tool. The second
process is verification which is done on-device.

Is This Answer Correct ?    12 Yes 3 No

Answer / mathhoang

in generally, because of the memory and resources
constraints of mobile-device so we should have "preverify"
step to check whether our class is suitable or not for

we have 2 steps to check: preverification(off-device) and
run-time verification(on-device)

Is This Answer Correct ?    4 Yes 2 No

Answer / guest

Preverification is a new phase in the development and
deployment cycle for Java applications designed to run on
the J2ME CLDC.

Preverification performs certain checks on the Java
bytecodes ahead of runtime. If this first verification pass
is ok, the preverifier annotates the classfiles (using
standard Java bytecode "attributes", so that these are still
plain old Java bytecodes and will be executable in VMs not
aware of the benefits of preverification), and then saves
the annotated class files or passes them along to the next
tool in the compile chain.

When the KVM attempts to run execute a J2ME CLDC-based
application, it checks the Java class files for these
preverification annotations. Proper annotations in the class
files guarantee that certain compile-time checks were made,
and so the KVM can pass through its own verfication and
security checks much faster and start executing the
application more quickly.

Sun's CLDC reference implementation SDK includes the
'preverify' tool. You use the tool after compiling your code
via javac (or your favorite Java compiler). More information
on preverify is included in the CLDC specification and in
the developer docs included with the CLDC SDK.

Is This Answer Correct ?    2 Yes 0 No

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