Application performance monitoring

Question

I need to get some information from an Oracle database using SQL queries, presumably from the v$ tables but I'm unfamiliar with them.
For the database, I would like to get
- # of Connections to the database
- # of transactions per minute (or total, can compute myself if needed)
- # of long running queries, currently
- # of sessions currently active
- # of locks/latchs active
I don't know if there is SQL that will get information for all of these values, but anything I can get would be of help.

Answer 1

- # of Connections to the databaseselect * from v$session where username is not null;
- # of transactions per minute (or total, can compute
myself if needed)
- # of long running queries, currentlyselect * from v$session s, v$session_longops sl where s.sid = sl.sid and s.serial# = sl.serial#
- # of sessions currently activeselect * from v$session s where status = 'ACTIVE' and username is not null
- # of locks/latchs activeSELECT DECODE(request,0,'Holder: ','Waiter: ')||sid sess,
id1, id2, lmode, request, type
FROM V$LOCK
WHERE (id1, id2, type) IN
(SELECT id1, id2, type FROM V$LOCK WHERE request>0)
ORDER BY id1, request;