Tandem Java library or for getting Timestamp.

[sumit lall]

Hi All,


We need get Tandem Timestamp in our Java servers Please suggest which Tandem Java library or class we can use and how we can use.

Thanks in advance,
Sumit Lall.

[Keith Dick]

I am not much of a Java programmer, but I can help a little.

I have a collection of documentation in html. It is identified as NonStop Server for Java 7.0 API and the document number is 710328-001. I don't remember where I got it, but it seems not to be findable currently via http://www.hp.com/go/nonstop-docs so I'm not sure where you can get it. Maybe it gets installed on the NonStop system when Java is installed. It came in a .zip file.

In that set of html documentation, there is a class named com.tandem.util.NSKTime which contains one field and one method. It appears to me that neither returns just the 64-bit value that JULIANTIMESTAMP procedure returns, but returns something that you can compute that value from. Seems a little weird to me. I don't see anything that corresponds to the ability to get the timestamp converted to LCT or LST, but maybe Java has something that already can do that.

If this is not suitable for your needs, I think it would not be hard to use the Java Native Interface to create your own custom class that calls a one-line C function to return the JULIANTIMESTAMP value. There are instructions in the NonStop Server for Java 7.0 Programmer's Reference for creating a class using JNI. I've never done it, so I don't know how easy it is, but for something as simple as getting the JULIANTIMESTAMP value, I imagine it would not be very hard.

In case you cannot find the API document, either, I'll copy here what I think is the minimum you need to know how to use the NSKTime class. Note there is an example program for the NSKTime.currentSQLTimestamp() method, which might tell you all you need:


The NSKTime class contains a class field and a method that help in getting time information for an HP NonStop Kernel Operating System. The class cannot be instantiated.

The field represents the POSIX Epoch of Jan 1, 1970 00:00:00 GMT as measured in microseconds since the Julian Epoch Jan 1, 4713 B.C. to help quickly convert between a POSIX Epoch and a Julian Epoch. The method returns a java Timestamp object with microsecond granularity.

Field EPOCHTIMESTAMP

public static final long EPOCHTIMESTAMP

EPOCHTIMESTAMP represents the POSIX Epoch of Jan 1, 1970 00:00:00 GMT as measured in microseconds since the Julian Epoch Jan 1, 4713 B.C. This value can be used to convert between time in POSIX Epoch and Julian Epoch.
..
//Calculate the number of microseconds since the Julian Epoch
long julianMicros = (ts.getTime()/1000) * 1000000 + ts.getNanos()/1000
+ com.tandem.util.NSKTime.EPOCHTIMESTAMP;
..
// Calculate number of microseconds since the POSIX Epoch
long micros = julianMicros - com.tandem.util.NSKTime.EPOCHTIMESTAMP;
..


Method currentSQLTimestamp

public static java.sql.Timestamp currentSQLTimestamp()

currentSQLTimestamp() returns a java.sql.Timestamp object, which represents time with microsecond granularity. The returned value would have to be modified by the user to get the corresponding microsecond value from the Timestamp object. The getTime() method of the Java.sql.Timestamp object can be used to get the millisecond value, this value also includes the milliseconds which are accounted for in the Timestamps' nanos field separately. The user needs to ensure that the millisecond value is not used twice.

The example code below shows how the user can use the Timestamp object to get the microseconds since the POSIX Epoch and the Julian Epoch.

Using java.sql.Timestamp to get microseconds since the POSIX Epoch:

import com.tandem.util.NSKTime;
..
..
java.sql.Timestamp ts = NSKTime.currentSQLTimestamp();
..
// Calculate number of microseconds since the POSIX Epoch
long micros = (ts.getTime()/1000) * 1000000 + ts.getNanos()/1000;
...
//Calculate the number of microseconds since the Julian Epoch
long julianMicros = (ts.getTime()/1000) * 1000000 + ts.getNanos()/1000
+ com.tandem.util.NSKTime.EPOCHTIMESTAMP;
..
..

[sumit lall]

Hi Keith,

Big thanks to you ,we do solved our problem with your help.

Thanks & regards,
Sumit Lall.