Services API enhancements in Firebird v2.
-----------------------------------------

1) Services API extension for new shutdown modes.
(Alex Peshkov, peshkoff@mail.ru, 2008)

New DB shutdown modes can now be set using services. A number of new 
isc_spb_prp_* constants should be used for it.

isc_spb_prp_shutdown_mode and isc_spb_prp_online_mode are used to perform
database shutdown/online operation. They have a single byte parameter, 
setting new shutdown mode: isc_spb_prp_sm_normal, isc_spb_prp_sm_multi,
isc_spb_prp_sm_single and isc_spb_prp_sm_full. They exactly match gfix's
shutdown modes. When performing shutdown operation, you must specify
also type of shutdown: one of isc_spb_prp_force_shutdown, 
isc_spb_prp_attachments_shutdown or isc_spb_prp_transactions_shutdown. 
They have single int (4-byte) parameter, specifying timeout for desired
operation.
Please note that old-styled parameters are also supported and should be
used to enter default shutdown (currently 'multi') and online ('normal') 
modes.

Samples of use of new parameters in fbsvcmgr utility (supposing login and 
password are set using some other method):
 Shutdown database to single-user maintenance mode:
  fbsvcmgr service_mgr action_properties dbname employee prp_shutdown_mode prp_sm_single prp_force_shutdown 0
 After it enable multi-user maintenance:
  fbsvcmgr service_mgr action_properties dbname employee prp_online_mode prp_sm_multi
 After it go to full shutdown mode, disabling new attachments during 60 seconds:
  fbsvcmgr service_mgr action_properties dbname employee prp_shutdown_mode prp_sm_full prp_attachments_shutdown 60
 Return to normal state:
  fbsvcmgr service_mgr action_properties dbname employee prp_online_mode prp_sm_normal

2) Services API extension - nbackup support.
(Alex Peshkov, peshkoff@mail.ru, 2008)

Nbackup performs two logical groups of operations - locking/unlocking database 
and backup/restore it. It doesn't make sense duplicating locking/unlocking in 
services, cause that functionality is present remotely in much better (from any 
point of view) in SQL language interface (ALTER DATABASE). But backup and restore 
must be run on localhost and the only way to access them is nbackup utility.
Therefore expanding services API with this functionalty is very useful.

The following actions were added:
isc_action_svc_nbak - incremental nbackup,
isc_action_svc_nrest - incremental database restore.
The following parameters were added:
isc_spb_nbk_level - backup level (integer),
isc_spb_nbk_file - backup file name (string),
isc_spb_nbk_no_triggers - do not run DB triggers (option).

Samples of use of new parameters in fbsvcmgr utility (supposing login and
password are set using some other method):
 Create backup level 0:
  fbsvcmgr service_mgr action_nbak dbname employee nbk_file e.nb0 nbk_level 0
 Create backup level 1:
  fbsvcmgr service_mgr action_nbak dbname employee nbk_file e.nb1 nbk_level 1
 Restore database from this files:
  fbsvcmgr service_mgr action_nrest dbname e.fdb nbk_file e.nb0 nbk_file e.nb1


3) Services API extension - trace support.
(Khorsun Vlad, hvlad@users.sourceforge.net, 2009)

	There are five new services and corresponding actions to manage by user
trace sessions :

Start user trace session :
	action
		isc_action_svc_trace_start    

	parameter(s)
		isc_spb_trc_name : trace session name, string, optional
		isc_spb_trc_cfg  : trace session configuration, string, mandatory

	output
		text message with status of operation :
			- Trace session ID NNN started
			- Can not start trace session. There are no trace plugins loaded
		contents of trace session in text format


Stop trace session
	action
		isc_action_svc_trace_stop     

	parameter(s)
		isc_spb_trc_id : trace session ID, integer, mandatory

	output
		text message with status of operation :
			- Trace session ID NNN stopped
			- No permissions to stop other user trace session
			- Trace session ID NNN not found


Suspend trace session
	action
		isc_action_svc_trace_suspend  

	parameter(s)
		isc_spb_trc_id : trace session ID, integer, mandatory

	output
		text message with status of operation :
			- Trace session ID NNN paused
			- No permissions to change other user trace session
			- Trace session ID NNN not found

Resume trace session
	action
		isc_action_svc_trace_resume   

	parameter(s)
		isc_spb_trc_id : trace session ID, integer, mandatory

	output
		text message with status of operation :
			- Trace session ID NNN resumed
			- No permissions to change other user trace session
			- Trace session ID NNN not found

List of existing trace sessions
	action
		isc_action_svc_trace_list     

	parameter(s)
		none

	output
		text messages with list and state of trace sessions
			- Session ID: <number>
			-   name:  <string>
			-   user:  <string>
			-   date:  YYYY-MM-DD HH:NN:SS
			-   flags: <string>

		"name" is trace session name and not printed if empty.
		"user" is creator user name
		"date" is session start date and time
		"flags" is comma delimited set of
			session's run state : "active" or "suspend"
			if creator user is administrator : "admin"
			if the session was created by the engine itself : "system"
			kind of session : "audit" or "trace"
			if user session log file is full : "log full"


	Output of every service is obtained as usually using isc_service_query call
with isc_info_svc_line or isc_info_svc_to_eof information items.

See also README.trace_services


4) Services API extension - running gbak at server side with .fbk at the client.
(Alex Peshkov, peshkoff@mail.ru, 2011-2012)

This way of doing backups is specially efficient when one needs to perform
backup/restore operation for database, located on a server accessed using
internet, due to the great performance advantage.

The simplest way to use this feature is fbsvcmgr. To backup database run
approximately the following:
fbsvcmgr remotehost:service_mgr -user sysdba -password XXX \
	action_backup -dbname some.fdb -bkp_file stdout >some.fbk

and to restore it:
fbsvcmgr remotehost:service_mgr -user sysdba -password XXX \
	action_restore -dbname some.fdb -bkp_file stdin <some.fbk

Please notice - you can't use "verbose" switch when performing backup because
data channel from server to client is used to deliver blocks of fbk files. You
will get appropriate error message if you try to do it. When restoring database
verbose mode may be used without limitations.

If you want to perform backup/restore from your own program, you should use
services API for it. Backup is very simple - just pass "stdout" as backup file
name to server and use isc_info_svc_to_eof in isc_service_query() call. Data,
returned by repeating calls to isc_service_query() (certainly with
isc_info_svc_to_eof tag) is a stream, representing image of backup file. Restore
is a bit more tricky. Client sends new spb parameter isc_info_svc_stdin to server
in isc_service_query(). If service needs some data in stdin, it returns
isc_info_svc_stdin in query results, followed by 4-bytes value - number of bytes
server is ready to accept from client. (0 value means no more data is needed right
now.) The main trick is that client should NOT send more data than requested by
server - this causes an error "Size of data is more than requested". The data is
sent in next isc_service_query() call in the send_items block, using
isc_info_svc_line tag in tradition form: isc_info_svc_line, 2 bytes length, data.
When server needs next portion, it once more returns non-zero isc_info_svc_stdin
value from isc_service_query().

A sample of how services API should be used for remote backup and restore can be
found in source code of fbsvcmgr.


5) Services API extension - using services with non-default security database.
(Alex Peshkov, peshkoff@mail.ru, 2013)

If one wants to use services API to access database which is configured to use
non-default security database, new SPB item isc_spb_expected_db should be used
when attaching to services manager. Value of this item is a database which is
expected to be accessed.

Formally this does not raise backward incompatibility - as long as one does not
use new FB3 feature (multiple security databases) he has no problems with old
programs using services API. In a case when one has really big need to use old
program for a database with non-default configuration there is a workaround:
setting environment variable FB_EXPECTED_DB which will be added to SPB
automatically.

Example. Imagine we have the following lines in databases.conf:
employee = $(dir_sampledb)/employee.fdb
{
  SecurityDatabase = employee
}
i.e. employee database is configured as security database for itself.

To access it using fbsvcmgr one should use the following command line:
fbsvcmgr host:service_mgr user sysdba password xxx expected_db employee action_db_stats dbname employee sts_data_pages

or in advance set FB_EXPECTED_DB:
export FB_EXPECTED_DB=employee
fbsvcmgr host:service_mgr user sysdba password xxx action_db_stats dbname employee sts_data_pages

Certainly any other database action can be used here.


6) Services API extension - using services to temporary turn off linger for database.
(Alex Peshkov, peshkoff@mail.ru, 2013)

Linger is used to optimize performance in some cases (see also sql.extensions/README.linger).
If you want to turn off linger temporary (for next database close) you may use gfix utility or
services. New tag isc_spb_prp_nolinger is added for it (option). Setting isc_spb_prp_nolinger
option turns off linger for the next database close operation and may be used to force closing
database in linger state.

Example:
fbsvcmgr host:service_mgr user sysdba password xxx action_properties dbname employee prp_nolinger


7) Services API extension - passing SQL role to services manager.
(Alex Peshkov, peshkoff@mail.ru, 2014)

Just a few actions (user-management related) were capable to pass SQL role to server in pre-3
releases. With flexible access control in FB3 passing role to the services manager is sometimes
useful and therefore possible. Services manager now accepts SPB item isc_spb_sql_role_name in
start() call and passes it to invoked utilities.

Example (assumimg user "leg" is granted admin rights):
fbsvcmgr host:service_mgr user leg password leg action_restore dbname target.fdb bkp_file some.fbk
   (fails with "no permission for CREATE access to DATABASE" error)
fbsvcmgr host:service_mgr user leg password leg role 'rdb$admin' action_restore dbname target.fdb bkp_file some.fbk
   (works as expected)

