haiku/docs/develop/servers/registrar/Protocols

Protocols
=========

Standard Replies
----------------

standard success reply message

reply:		B_REG_SUCCESS
			[ <additional fields> ]

fields:
- <additional fields>: Request-specific fields.

-----------------------------------------------------------------------

standard error reply message

reply:		B_REG_ERROR
			"error": B_INT32_TYPE
			[ "error_description": B_STRING_TYPE ]
			[ <additional fields> ]

fields:
- "error": The error code (a status_t).
- "error_description": Optional human readable description.
- <additional fields>: Request-specific fields.

-----------------------------------------------------------------------

standard general result reply message

reply:		B_REG_RESULT
			"result": B_INT32_TYPE
			[ "result_description": B_STRING_TYPE ]
			[ <additional fields> ]
			  
fields:
- "result": The result value (a status_t).
- "result_description": Optional human readable description.
- <additional fields>: Request-specific fields.
 
-----------------------------------------------------------------------


General Requests
----------------

getting the messengers for MIME, clipboard and disk device management
respectively

target:		registrar app looper (preferred handler)
message:	B_REG_GET_MIME_MESSENGER/B_REG_GET_CLIPBOARD_MESSENGER
			/B_REG_GET_DISK_DEVICE_MESSENGER
reply:		standard success
			"messenger": B_MESSENGER_TYPE
on error:	- B_NO_REPLY (fatal)
			- standard error (fatal)

reply fields:
- "messenger": The requested messenger.

-----------------------------------------------------------------------

shut down

target:		registrar app looper (preferred handler)
message:	B_REG_SHUT_DOWN
			"reboot":			B_BOOL_TYPE
			"confirm":			B_BOOL_TYPE
			"synchronously":	B_BOOL_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error (fatal)

message fields:
- "reboot": If true, the system reboots instead of turning the power off.
- "confirm": If true, the user will be asked to confirm to shut down the system.
- "synchronously": If true, the request sender gets a reply only, if the
				   shutdown process fails. Otherwise the reply will be sent
				   right before asking the user for confirmation (if desired).

-----------------------------------------------------------------------


Roster Requests
---------------

app registration (BRoster::AddApplication())

target:		roster
message:	B_REG_ADD_APP
			"signature":			B_MIME_STRING_TYPE
			"ref":					B_REF_TYPE
			"flags":				B_UINT32_TYPE
			"team":					B_INT32_TYPE
			"thread":				B_INT32_TYPE
			"port":					B_INT32_TYPE
			"full_registration":	B_BOOL_TYPE
reply:		standard success
			[ "token":				B_INT32_TYPE ]
			[ "other_team":			B_INT32_TYPE ]
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "signature": The application signature.
- "ref": An entry_ref to the application executable.
- "flags": The application flags.
- "team": The application team (team_id).
- "port": The app looper port (port_id).
- "full_registration": Whether full or pre-registration is requested.

reply fields:
- "token": If pre-registration was requested (uint32). Unique token to be
  passed to BRoster::SetThreadAndTeam().
- "other_team": For single/exclusive launch applications that are launched
  the second time. The team ID of the already running instance (team_id).

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_ENTRY_NOT_FOUND: The entry_ref doesn't refer to a file.
  - B_ALREADY_RUNNING: For single/exclusive launch applications
    that are launched the second time.
  - B_REG_ALREADY_REGISTERED: The team is already registered.
  - ...

-----------------------------------------------------------------------

app registration (BRoster::CompleteRegistration())

target:		roster
message:	B_REG_COMPLETE_REGISTRATION
			"team":		B_INT32_TYPE
			"thread":	B_INT32_TYPE
			"port":		B_INT32_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "team": The application team (team_id).
- "thread": The application looper thread (thread_id).
- "port": The app looper port (port_id).

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_REG_APP_NOT_PRE_REGISTERED: The team is unknown to the roster or the
    application is already fully registered.
  - ...

-----------------------------------------------------------------------

app pre-registration check (BRoster::IsAppPreRegistered())

target:		roster
message:	B_REG_IS_APP_PRE_REGISTERED
			"ref":	B_REF_TYPE
			"team":	B_INT32_TYPE
reply:		standard success
			"pre-registered":	B_BOOL_TYPE
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "ref": An entry_ref to the application executable.
- "team": The application team (team_id).

reply fields:
- "pre-registered": true, if the app is pre-registered, false otherwise.

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_ENTRY_NOT_FOUND: The entry_ref doesn't refer to a file.
  - ...

-----------------------------------------------------------------------

pre-registrated app unregistration (BRoster::RemovePreRegApp())

target:		roster
message:	B_REG_REMOVE_PRE_REGISTERED_APP
			"token":	B_INT32_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "token": The token BRoster::AddApplication() returned (uint32).

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_REG_APP_NOT_PRE_REGISTERED: The token does not identify a pre-registered
    application.
  - ...

-----------------------------------------------------------------------

app unregistration (BRoster::RemoveApp())

target:		roster
message:	B_REG_REMOVE_APP
			"team":	B_INT32_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "team": The application team (team_id).

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_REG_APP_NOT_REGISTERED: The team is unknown to the roster.
  - ...

-----------------------------------------------------------------------

app pre-registration, set thread/team (BRoster::SetThreadAndTeam())

target:		roster
message:	B_REG_SET_THREAD_AND_TEAM
			"token":	B_INT32_TYPE
			"team":		B_INT32_TYPE
			"thread":	B_INT32_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "token": The token BRoster::AddApplication() returned (uint32).
- "team": The application team (team_id).
- "thread": The application looper thread (thread_id).

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_REG_APP_NOT_PRE_REGISTERED: The token does not identify a pre-registered
    application.
  - ...

-----------------------------------------------------------------------

app registration, change app signature (BRoster::SetSignature())

target:		roster
message:	B_REG_SET_SIGNATURE
			"team":			B_INT32_TYPE
			"signature":	B_STRING_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "team": The application team (team_id).
- "signature": The application's new signature.

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_REG_APP_NOT_REGISTERED: The team does not identify a registered
    application.
  - ...

-----------------------------------------------------------------------

get an app info (BRoster::Get{Running,Active,}AppInfo())

target:		roster
message:	B_REG_GET_APP_INFO
			[ "team":			B_INT32_TYPE
			  | "ref":			B_REF_TYPE
			  | "signature":	B_STRING_TYPE ]
reply:		standard success
			"app_info":	B_REG_APP_INFO_TYPE
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "team": The application team (team_id).
- "ref": An entry_ref to the application executable.
- "signature": The application signature.
- If both are omitted the active application is referred to.

reply fields:
- "app_info": The requested app_info (flat_app_info).

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_BAD_TEAM_ID: The supplied team ID does not identify a registered
    application.
  - B_ERROR:
    - An entry_ref or a signature has been supplied and no such application
      is currently running.
    - No team ID has been supplied and currently there is no active
      application.
  - ...

-----------------------------------------------------------------------

get an app list (BRoster::GetAppList())

target:		roster
message:	B_REG_GET_APP_LIST
			[ "signature":	B_STRING_TYPE ]
reply:		standard success
			"teams":	B_INT32_TYPE[]
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "signature": The application signature.

reply fields:
- "teams": The requested list of team IDs (team_id).

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - ...

-----------------------------------------------------------------------

activate an app (BRoster::ActivateApp())

target:		roster
message:	B_REG_ACTIVATE_APP
			"team":	B_INT32_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "team": The application team (team_id).

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_BAD_TEAM_ID: The supplied team ID does not identify a registered
    application.
  - ...

-----------------------------------------------------------------------

broadcast a message (BRoster::Broadcast())

target:		roster
message:	B_REG_BROADCAST
			"team":			B_INT32_TYPE
			"message":		B_MESSAGE_TYPE
			"reply_target":	B_MESSENGER_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "team": The requesting team (team_id).
- "message": The message to be broadcast.
- "reply_target": The reply target for the message.

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - ...

-----------------------------------------------------------------------

start roster watching (BRoster::StartWatching())

target:		roster
message:	B_REG_START_WATCHING
			"target":	B_MESSENGER_TYPE
			"events":	B_INT32_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "target": The target the event messages shall be sent to.
- "events": Specifies the events the caller is interested in (uint32).

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - ...

-----------------------------------------------------------------------

stop roster watching (BRoster::StopWatching())

target:		roster
message:	B_REG_STOP_WATCHING
			"target":	B_MESSENGER_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "target": The target that shall not longer receive any event messages.

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - ...

-----------------------------------------------------------------------


MIME Database Requests
----------------------

install a mime type (BMimeType::Install())

target:		mime manager (BRoster::fMimeMess) 
message:	B_REG_MIME_INSTALL
			"type": B_STRING_TYPE
reply:		standard general result

message fields:
- "type": The mime type

reply fields:
- "result":
  - B_OK: success
  - B_FILE_EXISTS: the type is already installed
  - ...			

-----------------------------------------------------------------------

remove a mime type (BMimeType::Delete())

target:		mime manager (BRoster::fMimeMess)
message:	B_REG_MIME_DELETE
			"type": B_STRING_TYPE
reply:		standard general result

message fields:
- "type": The mime type

reply fields:
- "result":
  - B_OK: success
  - B_ENTRY_NOT_FOUND: the type was not found
  - (other error code): failure			

-----------------------------------------------------------------------

set a specific attribute of a mime type (BMimeType::Set*()),
installing if necessary

target:		mime manager (BRoster::fMimeMess) 
message:	B_REG_MIME_SET_PARAM
			"type": B_STRING_TYPE
			"which": B_INT32_TYPE
			[ additional fields depending upon the "which" field (see below) ]
			
reply:		standard general result

message fields:
- "type": The mime type
- "which": Which attribute to set. May be one of the following:

    "which"                     additional message fields       field comments
    -------------------------   ----------------------------    --------------------------
	B_REG_MIME_ICON:			"icon data": B_RAW_TYPE,        B_CMAP8 bitmap data only
								"icon size": B_INT32_TYPE       B_{MINI,LARGE}_ICON
	B_REG_MIME_PREFERRED_APP:	"signature": B_STRING_TYPE,
								"app verb": B_INT32_TYPE
	B_REG_MIME_ATTR_INFO:		"attr info": B_MESSAGE_TYPE
	B_REG_MIME_FILE_EXTENSIONS:	"extensions": B_MESSAGE_TYPE
	B_REG_MIME_DESCRIPTION:		"long": B_BOOL_TYPE,
								"description": B_STRING_TYPE
	B_REG_MIME_SNIFFER_RULE:	"sniffer rule": B_STRING_TYPE
	B_REG_MIME_APP_HINT:		"app hint": B_REF_TYPE
	B_REG_MIME_ICON_FOR_TYPE	"file type": B_STRING_TYPE,
								"icon data": B_RAW_TYPE,
								"icon size": B_INT32_TYPE
	B_REG_MIME_SUPPORTED_TYPES:	"types": B_MESSAGE_TYPE
	
reply fields:
- "result":
  - B_OK: success
  - (error code): failure			

-----------------------------------------------------------------------

delete a specific attribute of a mime type (BMimeType::Delete*()),

target:		mime manager (BRoster::fMimeMess) 
message:	B_REG_MIME_DELETE_PARAM
			"type": B_STRING_TYPE
			"which": B_INT32_TYPE
			[ additional fields depending upon the "which" field (see below) ]
			
reply:		standard general result

message fields:
- "type": The mime type
- "which": Which attribute to delete. May be one of the following:

    "which"                     additional message fields       field comments
    -------------------------   ----------------------------    --------------------------
	B_REG_MIME_ICON:			"icon size": B_INT32_TYPE       B_{MINI,LARGE}_ICON
	B_REG_MIME_PREFERRED_APP:	"app verb": B_INT32_TYPE
	B_REG_MIME_ATTR_INFO:			
	B_REG_MIME_FILE_EXTENSIONS:	
	B_REG_MIME_DESCRIPTION:		"long": B_BOOL_TYPE,
	B_REG_MIME_SNIFFER_RULE:		
	B_REG_MIME_APP_HINT:			
	B_REG_MIME_ICON_FOR_TYPE	"file type": B_STRING_TYPE,
								"icon size": B_INT32_TYPE
	B_REG_MIME_SUPPORTED_TYPES:	
	
reply fields:
- "result":
  - B_OK: success
  - B_ENTRY_NOT_FOUND: no such attribute exists, or the type is not installed
  - (other error code): failure			

-----------------------------------------------------------------------

subscribe a BMessenger to the MIME monitor service (BMimeType::StartWatching())

target:		mime manager (BRoster::fMimeMess)
message:	B_REG_MIME_START_WATCHING
			"target": B_MESSENGER_TYPE
reply:		standard general result

message fields:
- "target": The BMessenger subscribing to the monitor service

reply fields:
- "result":
  - B_OK: success
  - (error code): failure			

-----------------------------------------------------------------------

unsubscribe a BMessenger from the MIME monitor service (BMimeType::StopWatching())

target:		mime manager (BRoster::fMimeMess)
message:	B_REG_MIME_STOP_WATCHING
			"target": B_MESSENGER_TYPE
reply:		standard general result

message fields:
- "target": The BMessenger unsubscribing from the monitor service

reply fields:
- "result":
  - B_OK: success
  - B_ENTRY_NOT_FOUND: the given BMessenger was not subscribed to the service
  - (other error code): failure			

-----------------------------------------------------------------------

perform an update_mime_info() call

target:		mime manager (BRoster::fMimeMess)
message:	B_REG_MIME_UPDATE_MIME_INFO
			"entry": B_REF_TYPE
			"recursive": B_BOOLEAN_TYPE
			"synchronous": B_BOOLEAN_TYPE
			"force": B_INT32_TYPE
reply:		standard general result

message fields:
- "entry": The base entry to update.
- "recursive": If true and "entry" is a directory, update all entries
  below "entry" in the hierarchy.
- "synchronous": If true, the call will block until the operation is
  completed. If false, the call will return immediately and the operation
  will run asynchronously in another thread.                 
- "force": Specifies how to handle entries for which a BEOS:TYPE attribute
  already exists. Valid values are 
  B_UPDATE_MIME_INFO_{NO_FORCE, FORCE_KEEP_TYPE, FORCE_UPDATE_ALL}.

reply fields:
- "result":
  - B_OK: The asynchronous update_mime_info() call has been successfully
          started (and may still be running).
  - (error code): failure

-----------------------------------------------------------------------

perform a create_app_meta_mime() call 

target:		mime manager (BRoster::fMimeMess)
message:	B_REG_MIME_CREATE_APP_META_MIME
			"entry": B_REF_TYPE
			"recursive": B_BOOLEAN_TYPE
			"synchronous": B_BOOLEAN_TYPE
			"force": B_INT32_TYPE
reply:		standard general result

message fields:
- "entry": The base entry to update.
- "recursive": If true and "entry" is a directory, update all entries
  below "entry" in the hierarchy.
- "synchronous": If true, the call will block until the operation is
  completed. If false, the call will return immediately and the operation
  will run asynchronously in another thread.                 
- "force": If != 0, also update entries for which meta app information
  already exists.

reply fields:
- "result":
  - B_OK: The asynchronous update_mime_info() call has been successfully
          started (and may still be running).
  - (error code): failure

-----------------------------------------------------------------------

notify the thread manager to perform a clean up run

target:		thread manager/mime manager (MIMEManager::fThreadManager/BRoster::fMimeMess)
message:	B_REG_MIME_UPDATE_THREAD_FINISHED
reply:		none (message should be sent asynchronously)

-----------------------------------------------------------------------


Message Runner Requests
-----------------------

message runner registration (BMessageRunner::InitData())

target:		roster
message:	B_REG_REGISTER_MESSAGE_RUNNER
			"team":					B_INT32_TYPE
			"target":				B_MESSENGER_TYPE
			"message":				B_MESSAGE_TYPE
			"interval":				B_INT64_TYPE
			"count":				B_INT32_TYPE
			"reply_target":			B_MESSENGER_TYPE
reply:		standard success
			"token":				B_INT32_TYPE
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "team": ID of the team owning the BMessageRunner (team_id).
- "target": The message target.
- "message": The message to be sent to the target.
- "interval": Period of time before the first message is sent and between
			  messages (if more than one shall be sent) in microseconds.
- "count": Specifies how many times the message shall be sent.
		   A value less than 0 for an unlimited number of repetitions.
- "reply_target": Target replies to the delivered message(s) shall be sent to.

reply fields:
- "token": Unique token identifying the message runner.

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - ...

-----------------------------------------------------------------------

message runner unregistration (BMessageRunner::~BMessageRunner())

target:		roster
message:	B_REG_UNREGISTER_MESSAGE_RUNNER
			"token":				B_INT32_TYPE
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "token": Unique token identifying the message runner. Returned by the
		   B_REG_REGISTER_MESSAGE_RUNNER request.

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - ...

-----------------------------------------------------------------------

set message runner parameters (BMessageRunner::SetParams())

target:		roster
message:	B_REG_SET_MESSAGE_RUNNER_PARAMS
			"token":				B_INT32_TYPE
			[ "interval":			B_INT64_TYPE ]
			[ "count":				B_INT32_TYPE ]
reply:		standard success
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "token": Unique token identifying the message runner. Returned by the
		   B_REG_REGISTER_MESSAGE_RUNNER request.
- "interval": Period of time before the first message is sent and between
			  messages (if more than one shall be sent) in microseconds.
- "count": Specifies how many times the message shall be sent.
		   A value less than 0 for an unlimited number of repetitions.

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - ...

-----------------------------------------------------------------------

get message runner info (BMessageRunner::InitData())

target:		roster
message:	B_REG_GET_MESSAGE_RUNNER_INFO
			"token":				B_INT32_TYPE
reply:		standard success
			"interval":				B_INT64_TYPE
			"count":				B_INT32_TYPE
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "token": Unique token identifying the message runner. Returned by the
		   B_REG_REGISTER_MESSAGE_RUNNER request.

reply fields:
- "interval": Period of time before the first message is sent and between
			  messages (if more than one shall be sent) in microseconds.
- "count": Specifies how many times the message still has to be sent.
		   A value less than 0 for an unlimited number of repetitions.

error reply fields:
- "error":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - ...

-----------------------------------------------------------------------


Clipboard Handler Requests
--------------------------

add new clipboard to system (BClipboard::BClipboard())

target:		clipboard handler
message:	B_REG_ADD_CLIPBOARD
			"name":					B_STRING_TYPE
reply:		standard general result

message fields:
- "name": Name used to identify the particular clipboard to add

reply fields:
- "result":
  - B_OK: B
  - B_BAD_VALUE: name field was not specified in message

-----------------------------------------------------------------------

get clipboard write count (BClipboard::GetSystemCount())

target:		clipboard handler
message:	B_REG_GET_CLIPBOARD_COUNT
			"name":					B_STRING_TYPE
reply:		standard general result
			"count":				B_INT32_TYPE

message fields:
- "name": Name used to identify the particular clipboard

reply fields:
- "result":
  - B_OK: success
  - B_BAD_VALUE: no name / no valid name specified in message
- "count":
  - number of times this clipboard has been written to

-----------------------------------------------------------------------

start watching clipboard (BClipboard::StartWatching())

target:		clipboard handler
message:	B_REG_CLIPBOARD_START_WATCHING
			"name":					B_STRING_TYPE
			"target":				B_MESSENGER_TYPE
reply:		standard general result

message fields:
- "name": Name used to identify the particular clipboard
- "target": Messenger pointing to the target to notify

reply fields:
- "result":
  - B_OK: success
  - B_BAD_VALUE: no name / no valid name specified in message
  		 no target specified

-----------------------------------------------------------------------

stop watching clipboard (BClipboard::StopWatching())

target:		clipboard handler
message:	B_REG_CLIPBOARD_STOP_WATCHING
			"name":					B_STRING_TYPE
			"target":				B_MESSENGER_TYPE
reply:		standard general result

message fields:
- "name": Name used to identify the particular clipboard
- "target": Messenger pointing to the target to remove from the notify list

reply fields:
- "result":
  - B_OK: success
  - B_BAD_VALUE: no name / no valid name specified in message
  		 no target specified

-----------------------------------------------------------------------

download clipboard data (BClipboard::DownloadFromSystem())

target:		clipboard handler
message:	B_REG_DOWNLOAD_CLIPBOARD
			"name":					B_STRING_TYPE
reply:		standard general result
			"data":					B_MESSAGE_TYPE
			"data source":				B_MESSENGER_TYPE
			"count":				B_INT32_TYPE

message fields:
- "name": Name used to identify the particular clipboard

reply fields:
- "result":
  - B_OK: success
  - B_BAD_VALUE: no name / no valid name specified in message
  		 no target specified
- "data":
  - message with Data fields containing the contents of the clipboard
- "data source":
  - messenger to the be_app_messenger of the application which last wrote data
- "count":
  - number of times this clipboard has been written to

-----------------------------------------------------------------------

upload clipboard data (BClipboard::UploadToSystem())

target:		clipboard handler
message:	B_REG_UPLOAD_CLIPBOARD
			"name":					B_STRING_TYPE
			"data":					B_MESSAGE_TYPE
			"data source":				B_MESSENGER_TYPE
reply:		standard general result
			"count":				B_INT32_TYPE

message fields:
- "name": Name used to identify the particular clipboard
- "data":
  - message with Data fields containing the contents of the clipboard
- "data source":
  - messenger to the be_app_messenger of the application which last wrote data

reply fields:
- "result":
  - B_OK: success
  - B_BAD_VALUE: no name / no valid name specified in message
  		 no target specified
- "count":
  - number of times this clipboard has been written to

-----------------------------------------------------------------------


Disk Device Requests
--------------------

get next disk device

target:		disk device manager
message:	B_REG_NEXT_DISK_DEVICE
			"cookie":				B_INT32_TYPE
reply:		standard general result
			"device":				B_MESSAGE_TYPE
			"cookie":				B_INT32_TYPE

message fields:
- "cookie": An iteration cookie. Initially 0.

reply fields:
- "device": Archived BDiskDevice info.
- "cookie": Next value for the iteration cookie.
- "result":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_ENTRY_NOT_FOUND: Iteration finished.
  - ...

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get disk device

target:		disk device manager
message:	B_REG_GET_DISK_DEVICE
			"device_id":			B_INT32_TYPE
			| "session_id":			B_INT32_TYPE
			| "partition_id":		B_INT32_TYPE
reply:		standard general result
			"device":				B_MESSAGE_TYPE

message fields:
- "device_id": ID of the device to be retrieved.
- "session_id": ID of session whose device shall be retrieved.
- "partition_id": ID of partition whose device shall be retrieved.

reply fields:
- "device": Archived BDiskDevice info.
- "result":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_ENTRY_NOT_FOUND: A device/session/partition with that ID could not
  	be found.
  - ...

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update disk device

target:		disk device manager
message:	B_REG_UPDATE_DISK_DEVICE
			"device_id":			B_INT32_TYPE
			| "session_id":			B_INT32_TYPE
			| "partition_id":		B_INT32_TYPE
			"change_counter":		B_INT32_TYPE
			"update_policy":		B_INT32_TYPE
reply:		standard general result
			"up_to_date":			B_BOOLEAN_TYPE
			[ "device":				B_MESSAGE_TYPE ]

message fields:
- "device_id": ID of the device to be retrieved.
- "session_id": ID of session whose device shall be retrieved.
- "partition_id": ID of partition whose device shall be retrieved.
- "change_counter": Change counter of the object (or device in case of
					B_REG_DEVICE_UPDATE_DEVICE_CHANGED update policy) in
					question.
- "update_policy": (uint32)
  B_REG_DEVICE_UPDATE_CHECK: Check only, if the object is up to date.
  B_REG_DEVICE_UPDATE_CHANGED: Update only, if the object has changed.
  B_REG_DEVICE_UPDATE_DEVICE_CHANGED: Update, if the device has changed, even
									  if the partition/session has not.
  The latter two have the same semantics, if the object is a device.

reply fields:
- "up_to_date": true, if the object (and for
  B_REG_DEVICE_UPDATE_DEVICE_CHANGED also the device) is already up to date,
  false otherwise.
- "device": Archived BDiskDevice info.
- "result":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - B_ENTRY_NOT_FOUND: A device/session/partition with that ID could not
  	be found.
  - ...

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start disk device watching

target:		disk device manager
message:	B_REG_DEVICE_START_WATCHING
			"target":	B_MESSENGER_TYPE
			"events":	B_INT32_TYPE
reply:		standard general result
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "target": The target the event messages shall be sent to.
- "events": Specifies the events the caller is interested in (uint32).
- "result":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - ...

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stop disk device watching

target:		disk device manager
message:	B_REG_DEVICE_STOP_WATCHING
			"target":	B_MESSENGER_TYPE
reply:		standard general result
on error:	- B_NO_REPLY (fatal)
			- standard error

message fields:
- "target": The target that shall not longer receive any event messages.
- "result":
  - B_BAD_VALUE: A request message field is missing or contains an
    invalid value.
  - ...

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