Q: Does jTask work under Java2?
Yes. However it will only work with Swing 1.03 (included in the install).
Q: Does jTask work under UNIX?
Yes, there is a download available that has been tested under Red Hat Linux 6.1, using the Blackdown JDK 1.1.7_v3. There is a known bug with the File/Exit menu not working, and it has to be closed via the X at the top right. It is recommended that you use 1.1.7_v3 or higher, since the Preferences screen would not open when tested on JDK 1.1.6 There is also a download available for Solaris which has not been tested yet.
Q: Does jTask work under MacOS?
There is a MacOS download available, but has not been tested yet.
Q: Does jTask work under Windows 95/98? 2000?
The target OS for jTask is Windows NT 4 and Windows 2000. It has been tested on Windows 95/98 and will work on these platforms, but NT or 2000 is recommended.
Q: Does jTask run under the Microsoft Java Virtual Machine?
Not at this time, due to complications using Remote Method Invocation
(RMI) with the MS JVM.
Q: Does jTask support multiple users on a single machine?
By default, jTask runs as a Service under the System account. and is geared for one user per workstation. (the Administrator)
Q: I do not have Administrator privileges on the NT machine that I use, can I still use jTask?
To install jTask as an NT service onto the machine, you must have
System Administrator privileges. You could still run jTask as a background application (there is an icon in the Program Group for this). Please note however, that you will have to put the shortcut into the Startup folder. Also note that jTask won't start until you login, and to stop it you will have to use the Task Manager via Ctl-Alt-Del.
Q: Can I run the jTask Control Panel on a different machine the jTask service is running on?
This feature has been disabled until we can get the correct security
measures in place. For
the time being you will need to resort to a program like PCAnywhere to
manipulate jTask remotely.
Q: Are there any security implications associated with running jTask?
Since jTask uses sockets (RMI) for client/server communication, considerations have been taken to avoid any security problems. jTask uses a custom RMISecurityManager and only accepts connections from the local machine. By default, jTask accepts connections on port 1077, so you could make sure this port has been blocked by your company firewall for added security.
Q: Is it possible to set environment variables? Does jTask have an equivalent of java -Dkey=value?
Yes, this is done via the Parameters window.
Q: Can I easily move the data from one machine to another?
Yes, is possible to export scheduled tasks to a file and import them
on another machine running jTask.
Q: How come there is no calendar picker for entering dates?
This is something we will add in the next version. We are working
on speeding up the front-end interface before adding a calendar widget.
Q: Will it screw things up if I change my system clock?
No, each scheduled task checks the system time once per minute to see if it
should execute, if the clock is moved forward (for example) then obviously
the task will have missed those trigger times in between, but operations
will resume as if the clock had advanced normally.
Q: What if my system clock is wrong?
jTask will act according to your system clock. If you are concerned
about your system clock being accurate you should look into connecting
to an NTP server.
Q: Are there any performance issues?
Yes, with 50 tasks running every minute on a Pentium
II, jTask will produce a 50% spike in the CPU that lasts about 2 seconds, assuming the tasks themselves are doing very
little processing. At 250 tasks (running once per minute) the spike goes to 100% and widens out to about 15 seconds. At this point though, the main performance bottleneck will be in the front end (control panel), which will have very long startup times and slow response times. Work is underway to implement a paging mechanism in the JTable (front end), which should remove this bottleneck.
jTask was written for reliability at the expense of efficiency (see above). Most software in this area uses a single loop which cycles over all scheduled events and fires off the ones that are ready. jTask takes a different approach, and each scheduled task is actually an independent thread of execution, which makes it autonomous and independent, and for that reason makes the application itself fairly robust to error (but at the cost of efficiency, since each thread carries a relatively large amount of overhead). In the common approach, if the inner loop fails then everything fails. In jTask, if one scheduled event thread fails, the others will go on unaffected. To make jTask fail completely, theoretically the entire VM somehow has to crash, and this is a pretty rare thing to happen.
Q: Is there built-in logging capabilities? Will I be notified of errors?
Yes, both of these features are included. jTask will optionally log all System.out.println(), System.err.println() statements to separate files, as well as perform error notification via desktop notification or E-mail.
Q: Can I set dependencies between different tasks?
No, this is far beyond the scope of the current version of jTask.
Q: How is technical support handled?
Bug reports are welcome from anyone, but we will only commit to technical support to license holders. You will get (3 free incidents per year) X (num of machines licensed), and will be charged $25/incident after that (via E-mail only). We reserve
the right to refuse to provide support on problems related to using the java.lang.Runtime() class.
Upgrades to all future versions of jTask are provided free of charge.
Q: Can I run normal Windows EXE's?
Yes, jTask ships with a "wrapper" class which uses the java.lang.Runtime()
class to invoke EXE's much like as if they were invoked from the command
line. Source code is provided. (NOTE: this is traditionally
a painful area of Java programming, and we reserve the right to refuse
to provide technical support in this area) Please see Tips
and Tricks for examples.
Q: What restrictions are there on executed tasks?
jTask uses a custom RMISecurityManager object when executing tasks,
the only restriction being that calls to System.exit() are ignored, and that a new SecurityManager cannot be installed. Additionally, it is not currently possible to connect to other InstantDB databases from within invoked tasks. (more..)
Q: What about accessing network drives?
See Technical Q&A
Q: What tools were used to create jTask?
jTask was developed using the JDK from Sun Microsystems. InstantDB is the Java RDBMS used for Object Persistence. jTask also uses InstallAnywhere
Express from Zero G. TextPad was the editor of choice, the Anfy Team Graphics API was used to create the water effect on the home page, Leelou was used to create the demos, and the swarming bugs on the Technical Support page were created by Doctor Ozone.
Q: Is there an API? Can I embed jTask in my application?
jTask is strictly a desktop application, but you could check out JDring for this functionality.
A line in the Complex Plane across which a Multivalued Function is discontinuous. more....