how can i write demo version of my JavaApplication

[jack jack_3747]

i want to know that how can i write demo version of my JavaApplication which
should be applicable only for 7 days from the date of installation of software.After
7 day it should disable the startup and display order information for acquiring
a full version.

[Jo Desmet]

Interesting problem isn't it?
Because the date of installation should be remembered and persistant, you
will probably need to write out the date into a file. If however you write
this out to a file, then it can easely be changed to a later date. The next
option is to have encryption. If however you use a simple and well known
method, it will probably not take long before somebody has cracked the
encryption. Yet another option again is to sign the file containing the
installation date, making each change visible.

Licensing tools (like flexlm) go much further into this, you have per user
licenses, licenses counted by number of users, limitted time licenses,
licenses floating over your corporate network, failover ... But you will
have to pay for those nice features!

<jack jack_3747> wrote in message news:399120db$1@news.devx.com...
>
> i want to know that how can i write demo version of my JavaApplication
which
> should be applicable only for 7 days from the date of installation of
software.After
> 7 day it should disable the startup and display order information for
acquiring
> a full version.

[Ruchi Dhar]

I have a different idea in my mind we can use java's Externalization for writing
the date of installatio along with custom class loading. One can have their
own custom class loading mechanism i.e class is nothing but some bytes of
data along with the class file we can add some more bytes of data which contains
the installation date. When we create any object out of the class we can
use our own custom class loader to strip of extra bytes what we wrote and
create the object. I am not sure how well this idea works I never tried
my self.

WARRANTY: Not responisble for not working.


"Jo Desmet" <jo_desmet@yahoo.com> wrote:
>Interesting problem isn't it?
>Because the date of installation should be remembered and persistant, you
>will probably need to write out the date into a file. If however you write
>this out to a file, then it can easely be changed to a later date. The next
>option is to have encryption. If however you use a simple and well known
>method, it will probably not take long before somebody has cracked the
>encryption. Yet another option again is to sign the file containing the
>installation date, making each change visible.
>
>Licensing tools (like flexlm) go much further into this, you have per user
>licenses, licenses counted by number of users, limitted time licenses,
>licenses floating over your corporate network, failover ... But you will
>have to pay for those nice features!
>
><jack jack_3747> wrote in message news:399120db$1@news.devx.com...
>>
>> i want to know that how can i write demo version of my JavaApplication
>which
>> should be applicable only for 7 days from the date of installation of
>software.After
>> 7 day it should disable the startup and display order information for
>acquiring
>> a full version.
>
>