Re: flexfax: Design for a portable Java hylafax clients: i want your opinions, please!

[Ulrich Eckhardt <Ulrich.Eckhardt@transcom.de>]

Bernd Proissl wrote:

> > > am thinking about, maybe you can give me your opinions:
> > >
> > > 1. is java 2 widely availabe on your (client) platforms?
> > >    or is it supposed to become availbe in the near future?
> >
> > Hi,
> >
> > i think if it's worth then everyone will install java 2
> if nobody has created a java 2 VM then you will not be able to install it
> :-(

Hi,

ok, this is a good reason, do you know  if a VM for linux exists ?
 
> > > 2. What is your prefered procedure for sending a fax?
> > >
> > >    a1. redmon: capture the printout of an application on the client side
> > >        and let the hylafax client process it: e.g. ask user for fax.nr.
> > >        and the hand it to the hylafax server directly.
> >
> > you should handle this so, that it runs on every platform. So
> > redmon will work only on Windows.
> yes.
> of course there must be a redmon replacement on other platforms.
> > Probably create a java
> > application which reads files from the commandline and create
> > OS-specific wrapper scripts.
> yes.
> i think about a sendfax.java with or without GUI

I think creat here a GUI but with the options to read a filename
from command line and and option that this file will be deleted
after submitting to the HylaFAX server.

On Windows : change redmon, that he writes the output to a file
             (trivial). But now there are problems to call your 
             Java Programm directly. So one solution would be    
             to write a small ole server which then invokes 
             your Java Programm. And Implement the needed ole
             call to redmon and pass there the created filename.
	     Since some users are quick with prining, the filenames
             must be unique.

		
On Unix  :   Create a small shellscript, which reads from STDIN
             and creates a temporary file with a unique name and
             then call your java client.
           
             Put this script into the printcap and the faxprinter
             for Unix is done. 

On Mac : I don't know

  
> > It's not that bad, if you don't forget to implement passive connections.
> > HylaFAX supports it (and WHFC somewhere in the future).
> currently i am not sure how to do this in java.
> can you give me a pointer on how to configure it in hylafax?

You don't need to configure anything on hylafax. Passive
is only a special Transfer mode of ftp. Here are some excerpts
from RFC 959 

--------------
  3.3.  DATA CONNECTION MANAGEMENT

      Default Data Connection Ports:  All FTP implementations must
      support use of the default data connection ports, and only the
      User-PI may initiate the use of non-default ports.

      Negotiating Non-Default Data Ports:   The User-PI may specify a
      non-default user side data port with the PORT command.  The
      User-PI may request the server side to identify a non-default
      server side data port with the PASV command.  Since a connection
      is defined by the pair of addresses, either of these actions is
      enough to get a different data connection, still it is permitted
      to do both commands to use new ports on both ends of the data
      connection.

      Reuse of the Data Connection:  When using the stream mode of data
      transfer the end of the file must be indicated by closing the
      connection.  This causes a problem if multiple files are to be
      transfered in the session, due to need for TCP to hold the
      connection record for a time out period to guarantee the reliable
      communication.  Thus the connection can not be reopened at once. 
[..SNIP..]
  PASSIVE (PASV)

            This command requests the server-DTP to "listen" on a data
            port (which is not its default data port) and to wait for a
            connection rather than initiate one upon receipt of a
            transfer command.  The response to this command includes the
            host and port address this server is listening on.
---------
> currently i have problems accessing hfaxd over subnets (see your FAQ!)
> AFAIK the rounting on the server is not setup correctly to handle this.
> did not have time to dig into this.

I don't know exactly the JAVA API but you have the possibility
to specify an ipaddress (and so the network card) on Class
ServerSocket to which the socket should be bound.

> what are the advantages of active ftp  (is it called active?, is it
> necessary for
> masquerading?)
> 
> > Probably here we should do it on the HylaFAX side, so that HylaFAX
> > stores all as tiff. This would help on other Clients like WHFC too.
> yes, good idea.
> but i do not know how and if this can be done!
> Dmitry, please, can you give me a hint?
> I am pretty shure you know this :-)))

Would be cool for WHFC also :-)

> > Also have a look on the phonebook. Probably a phonebook
> > which can be extended by plugins, so that it will later
> > be possible to use JDBC, LDAP and some sort of text
> > phonebooks.
> yes, true.
> i think exactly about this, java supports dynamic class loading
> (seee JDBC Manager, JNDI, ...)
> also XML as a text file phonebook looks very interesting.

Sounds good.

Happy Weekend
Uli
-- 
Ulrich Eckhardt                         Tr@nscom  
http://www.uli-eckhardt.de              http://www.transcom.de
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