[Tutor] python and java report writers

[Oxymoron]

On Tue, Aug 18, 2009 at 8:50 AM, John<jfabiani at yolo.com> wrote:
> I don't know enough about jython to understand what has to be done.  Let's say
> I can write the code to retrieve the data in cPython.  And I can write a
> module in jython that will accept the data passing it on to the report
> writer.  How can I call the jython program?  It can't be called from the
> cPython program - right?  So the jython runs stand alone - right?

Yes Jython runs standalone (via the Java interpreter) in this
scenario. If you supply the data, chances are you need to either look
if there's a Datasource implementation readily available for the data
format you intend to supply - CSV, XML, etc. - or you would need to
create one (on the Jython side), essentially it reads in your
datafile/stream and passes it to the reporting engine appropriately.


> IPC = Inter-process communication - right?  Does that mean I need to write
> some sort of server?

Yep I meant interprocess communication. Using a server is one way of
doing it, but probably a bit much for simple requirements. Look at the
subprocess module and exec family (there have been a few posts
regarding these - I personally haven't used them as such so will only
refer you to docs and more able posts!), essentially you just need to
invoke the jython process, hook up the stdin and stdout between the
processes as necessary, e.g. let the jython program take command line
params for any operation modifiers/options if you need it to, and read
in your data via stdin. This way there's no server, just a simple
protocol that the reader process reads from stdin, and an end of file
indicates that there's no more data to read, and it can go and do it's
stuff. The jython process should also eventually do a System.exit(0)
for success, or System.exit(1) for failure (java.lang.System) for easy
error handling by CPython; you need to decide how to handle the report
output: have jython write it to a file in some predefined location, or
send it back your CPython invoker (which makes the IPC a bit more
involved).

Just depends on your needs, and the time you have available for the task!


Regards
Kamal

-- 
There is more to life than increasing its speed.
 -- Mahatma Gandhi