BRoster

Derived from: none
Declared in:  be/app/Roster.h
Library: libbe.so
Summary:  more...

The BRoster object represents a service that keeps a roster of all applications currently running. It can provide information about any of those applications, activate one of them, add another application to the roster by launching it, or get information about an application to help you decide whether to launch it.

There's just one roster and it's shared by all applications. When an application starts up, a BRoster object is constructed and assigned to a global variable, be_roster. You always access the roster through this variable; you never have to instantiate a BRoster in application code.

The BRoster identifies applications in three ways:

• By entry_ref references to the executable files where they reside.

• By their signatures. The signature is a unique identifier for the application assigned as a file-system attribute or resource at compile time or by the BApplication constructor at run time. You can obtain signatures for the applications you develop by contacting Be's developer support staff. They can also tell you what the signatures of other applications are.

• At run time, by their team_ids. A team is a group of threads sharing an address space; every application is a team.

If an application is launched more than once, the roster will include one entry for each instance of the application that's running. These instances will have the same signature, but different team identifiers.

Constructor and Destructor

BRoster()

BRoster(void)

Sets up the object's connection to the roster service.

When an application constructs its BApplication object, the system constructs a BRoster object and assigns it to the be_roster global variable. A BRoster is therefore readily available from the time the application is initialized until the time it quits; you don't have to construct one. The constructor is public only to give programs that don't have BApplication objects access to the roster.

~BRoster()

~BRoster()

Does nothing.

Member Functions

ActivateApp()

status_t ActivateApp(team_id team) const

Activates the team application (by bringing one of its windows to the front and making it the active window). This function works only if the target application has a window on-screen. The newly activated application is notified with a B_APP_ACTIVATED message.

See also: BApplication::AppActivated()

AddToRecentDocuments() , GetRecentDocuments()

void AddToRecentDocuments(const entry_ref *document,       const char *appSig = NULL) const void GetRecentDocuments(BMessage *refList, int32 maxCount,       const char *ofType = NULL,       const char *openedByAppSig = NULL) const void GetRecentDocuments(BMessage *refList, int32 maxCount,       const char *ofTypeList[] = NULL, int32 ofTypeListCount,       const char *openedByAppSig = NULL) const

AddToRecentDocuments() adds the document file specified by document to the list of recent documents. If you wish to record that a specific application used the document, you can specify the signature of that application using the appSig argument; otherwise you can specify NULL.

GetRecentDocuments() returns a list of the most recent documents. The BMessage refList will be filled out with information about the maxCount most recently used documents. If you want to obtain a list of documents of a specific type, you can specify a pointer to that MIME type string in the ofType argument. Likewise, if you're only interested in files that want to be opened by a specific application, specify that application's signature in openedByAppSig; if you don't care, pass NULL.

If you want to get a list of files of multiple types, you can specify a pointer to an array of strings in ofTypeList, and the number of types in the list in ofTypeListCount.

Specifying NULL for ofType will fetch all files of all types.

The resulting refList will have a field, "refs", containing the entry_refs to the resulting list of files.

AddToRecentFolders() , GetRecentFolders()

void AddToRecentFolders(const entry_ref *folder,       const char *appSig = NULL) const void GetRecentFolders(BMessage *refList, int32 maxCount,       const char *openedByAppSig = NULL) const

AddToRecentFolders() adds the folder specified by folder to the list of recent folders. If you wish to record that a specific application used the folder, you can specify the signature of that application using the appSig argument; otherwise you can use NULL.

GetRecentFolders() returns a list of the most recently-accessed folders. The BMessage refList will be filled out with information about the maxCount most recently used folders. If you're only interested in folders that were used by a specific application, specify that application's signature in openedByAppSig; if you don't care, pass NULL.

The resulting refList will have a field, "refs", containing the entry_refs to the resulting list of folders.

Broadcast()

status_t Broadcast(BMessage *message) const status_t Broadcast(BMessage *message, BMessenger reply_to) const

Sends the message to every running application, except to those applications (B_ARGV_ONLY) that don't accept messages. The message is sent asynchronously with a timeout of 0. As is the case for other message-sending functions, the caller retains ownership of the message.

This function returns immediately after setting up the broadcast operation. It doesn't wait for the messages to be sent and doesn't report any errors encountered when they are. It returns an error only if it can't start the broadcast operation. If successful in getting the operation started, it returns B_OK.

Replies to the broadcasted message will be sent via the reply_to BMessenger, if specified. If reply_to is absent, the replies will be lost.

See also: BMessenger::SendMessage()

FindApp()

status_t FindApp(const char *type, entry_ref *app) const status_t FindApp(entry_ref *file, entry_ref *app) const

Finds the application associated with the MIME data type or with the specified file, and modifies the app entry_ref structure so that it refers to the executable file for that application. If the type is an application signature, this function finds the application that has that signature. Otherwise, it finds the preferred application for the type. If the file is an application executable, FindApp() merely copies the file reference to the app argument. Otherwise, it finds the preferred application for the file type.

In other words, this function goes about finding an application in the same way that Launch() finds the application it will launch.

If it can translate the type or file into a reference to an application executable, FindApp() returns B_OK. If not, it returns an error code, typically one describing a file system error.

See also: Launch()

GetAppInfo() , GetRunningAppInfo() , GetActiveAppInfo()

status_t GetAppInfo(const char *signature, app_info *appInfo) const status_t GetAppInfo(entry_ref *executable, app_info *appInfo) const status_t GetRunningAppInfo(team_id team, app_info *appInfo) const status_t GetActiveAppInfo(app_info *appInfo) const

These functions return (in appInfo) information about a specific application. In all cases, the application must be running.

• GetAppInfo() finds an app that has the given signature, or that was launched from the executable file. If there's more than one such app, the function chooses one at random.

• GetRunningAppInfo() reports on the app that corresponds to the given team identifier.

• GetActiveAppInfo() reports on the currently active app.

If they're able to fill in the app_info structure with meaningful values, these functions return B_OK. GetActiveAppInfo() returns B_ERROR if there's no active application. GetRunningAppInfo() returns B_BAD_TEAM_ID if team isn't a valid team identifier for a running application. GetAppInfo() returns B_ERROR if the application isn't running.

The app_info structure contains the following fields:

thread_id thread
   The identifier for the application's main thread of execution, or –1 if the application isn't running. (The main thread is the thread in which the application is launched and in which its main() function runs.)

team_id team
   The identifier for the application's team, or –1 if the application isn't running. (This will be the same as the team passed to GetRunningAppInfo().)

port_id port
   The port where the application's main thread receives messages, or –1 if the application isn't running.

uint32 flags
   A bitfield that contains information about the behavior of the application.

entry_ref ref
   A reference to the file that was, or could be, executed to run the application. (This will be the same as the executable passed to GetAppInfo().)

char signature []
   The signature of the application. (This will be the same as the signature passed to GetAppInfo().)

The flags bitfield can be tested (with the bitwise & operator) against these two constants:

• B_BACKGROUND_APP. The application won't appear in the Deskbar's application list.

• B_ARGV_ONLY. The application can't receive messages. Information can be passed to it at launch only, in an array of argument strings (as on the command line).

flags also contains a value that explains the application's launch behavior. This value is retrieved by masking flags with the B_LAUNCH_MASK constant. For example:

unit32 behavior = theInfo.flags & B_LAUNCH_MASK;

The result will match one of these three modes:

• B_EXCLUSIVE_LAUNCH. The application can be launched only if an application with the same signature isn't already running.

• B_SINGLE_LAUNCH. The application can be launched only once from the same executable file. However, an application with the same signature might be launched from a different executable. For example, if the user copies an executable file to another directory, a separate instance of the application can be launched from each copy.

• B_MULTIPLE_LAUNCH. There are no restrictions. The application can be launched any number of times from the same executable file.

These modes affect BRoster's Launch() function. Launch() can always start up a B_MULTIPLE_LAUNCH application. However, it can't launch a B_SINGLE_LAUNCH application if a running application was already launched from the same executable file. It can't launch a B_EXCLUSIVE_LAUNCH application if an application with the same signature is already running.

See also: Launch(), BApplication::GetAppInfo()

GetAppList()

void GetAppList(BList *teams) const void GetAppList(const char *signature, BList *teams) const

Fills in the teams BList with team identifiers for applications in the roster. Each item in the list will be of type team_id. It must be cast to that type when retrieving it from the list, as follows:

BList *teams = new BList; be_roster->GetAppList(teams); team_id who = (team_id)teams->ItemAt(someIndex);

The list will contain one item for each instance of an application that's running. For example, if the same application has been launched three times, the list will include the team_ids for all three running instances of that application.

If a signature is passed, the list identifies only applications running under that signature. If a signature isn't specified, the list identifies all running applications.

See also: TeamFor(), the BMessenger constructor

GetRecentApps()

void GetRecentApps(BMessage *refList, int32 maxCount) const

GetRecentApps() returns a list of the most recently-launched applications. The BMessage refList will be filled out with information about the maxCount most recently-launched applications.

The resulting refList will have a field, "refs", containing the entry_refs to the resulting applications.

	GetRecentDocuments()  see AddToRecentDocuments()
	GetRecentFolders()  see AddToRecentFolders()
	IsRunning()  see TeamFor()

Launch()

status_t Launch(const char *type,       BMessage *message = NULL,       team_id *team = NULL) const status_t Launch(const char *type,       BList *messages,       team_id *team = NULL) const status_t Launch(const char *type,       int argc,        char **argv,       team_id *team = NULL) const status_t Launch(const entry_ref *file,       const BMessage *message = NULL,       team_id *team = NULL) const status_t Launch(const entry_ref *file,       const BList *messages,       team_id *team = NULL) const status_t Launch(const entry_ref *file,       int argc,       const char * const char *argv,       team_id *team = NULL) const

Launches the application associated with a MIME type or with a particular file. If the MIME type is an application signature, this function launches the application with that signature. Otherwise, it launches the preferred application for the type. If the file is an application executable, it launches that application. Otherwise, it launches the preferred application for the file type and passes the file reference to the application in a B_REFS_RECEIVED message. In other words, Launch() finds the application to launch just as FindApp() finds the application for a particular type or file.

If a message is specified, it will be sent to the application on-launch where it will be received and responded to before the application is notified that it's ready to run. Similarly, if a list of messages is specified, each one will be delivered on-launch. The caller retains ownership of the BMessage objects (and the container BList); they won't be deleted for you.

Sending an on-launch message is appropriate if it helps the launched application configure itself before it starts getting other messages. To launch an application and send it an ordinary message, call Launch() to get it running, then set up a BMessenger object for the application and call BMessenger's SendMessage() function.

If the target application is already running, Launch() won't launch it again, unless it permits multiple instances to run concurrently (it doesn't wait for the messages to be sent or report errors encountered when they are). It fails for B_SINGLE_LAUNCH and B_EXCLUSIVE_LAUNCH applications that have already been launched. Nevertheless, it assumes that you want the messages to get to the application and so delivers them to the currently running instance.

Instead of messages, you can launch an application with an array of argument strings that will be passed to its main() function. argv contains the array and argc counts the number of strings. If the application accepts messages, this information will also be packaged in a B_ARGV_RECEIVED message that the application will receive on-launch.

If successful, Launch() places the identifier for the newly launched application in the variable referred to by team and returns B_OK. If unsuccessful, it sets the team variable to –1 and returns an error code, typically one of the following:

• B_BAD_VALUE. The type or file is not valid, or an attempt is being made to send an on-launch message to an application that doesn't accept messages (that is, to a B_ARGV_ONLY application).

• B_ALREADY_RUNNING.,The application is already running and can't be launched again (it's a B_SINGLE_LAUNCH or B_EXCLUSIVE_LAUNCH application).

• B_LAUNCH_FAILED.,The attempt to launch the application failed for some other reason, such as insufficient memory.

• A file system error. The file or type can't be matched to an application.

See also: the BMessenger class, GetAppInfo(), FindApp()

StartWatching() , StopWatching()

status_t StartWatching(BMessenger target, uint32 events = B_REQUEST_LAUNCHED | B_REQUEST_QUIT) const status_t StopWatching(BMessenger target) const

StartWatching() initiates the application event monitor, which is used for keeping track of events such as application launches. The caller specifies the events to monitor through the events argument; target is the BMessenger to which the corresponding notification messages are sent. The events flags and the corresponding messages are listed below:

Flag	Message
B_REQUEST_LAUNCHED	B_SOME_APP_LAUNCHED
B_REQUEST_QUIT	B_SOME_APP_QUIT
B_REQUEST_ACTIVATED	B_SOME_APP_ACTIVATED

The fields in a notification message describe the application that was launched, quit, or activated:

Field	Type	Description
"mime_sig"	B_STRING_TYPE	MIME signature
"team"	B_INT32_TYPE	team_id
"thread"	B_INT32_TYPE	thread_id
"flags"	B_INT32_TYPE	application flags
"ref"	B_REF_TYPE	executable's entry_ref

StopWatching() terminates the application monitor previously initiated for a given BMessenger.

StartWatching()

TeamFor() , IsRunning()

team_id TeamFor(const char *signature) const team_id TeamFor(entry_ref *executable) const bool IsRunning(const char *signature) const bool IsRunning(entry_ref *executable) const

Both these functions query whether the application identified by its signature or by a reference to its executable file is running. TeamFor()StartWatching() returns its team identifier if it is, and B_ERROR if it's not. IsRunning() returns true if it is, and false if it's not.

If the application is running, you probably will want its team identifier (to set up a BMessenger, for example). Therefore, it's most economical to simply call TeamFor() and forego IsRunning().

If more than one instance of the signature application is running, or if more than one instance was launched from the same executable file, TeamFor() arbitrarily picks one of the instances and returns its team_id.

See also: GetAppList()