docs/develop: reorganize app_server documentation
Separate the "interface specification" into multiple individual, shorter pages. Also update some outdated parts and replace references to OpenBeOS with Haiku. Change-Id: I86baa9a78c5f7a8a3c4c7aa3ac2992714afecae6 Reviewed-on: https://review.haiku-os.org/c/haiku/+/6084 Tested-by: Automation <automation@haiku-os.org> Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>
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App Server Interface Specification v0.3
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#######################################
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Purpose:
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========
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The app_server provides services to the OpenBeOS by managing processes,
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filtering and dispatching input from the Input Server to the appropriate
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applications, and managing all graphics-related tasks.
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Tasks:
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======
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The tasks performed by the app_server are grouped in relation to its
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purpose.
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- Receives and redirects (dispatches) messages from the input server
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- Responds to messages from apps
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- Receives and consolidates requests from BView, BWindow, BBitmap, and others to draw stuff (draw bitmap, etc)
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- Utilizes ports to communicate with child processes
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- Handles drag & drop messaging
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- Manages the system clipboard
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- Loads and Kills processes
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- Detects absence of Input Server and restarts when not running
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- Aids in system shutdown
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- Dynamically loads accelerant portion of graphics driver
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- Creates a connection with BBitmaps requiring a child view
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- Draws the blue desktop screen
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- Provides workspace support
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- Provides functionality to the BeAPI for drawing primitives, such as rectangles, ellipses, and beziers
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- Provides a means for BViews to draw on BBitmaps
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- Manages window behavior with respect to redraw (move to front, minimize, etc)
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- Returns a frame buffer to direct-access classes
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- Caches fonts for screen and printer use
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- Draws text and provides other font API support for the BeAPI classes
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Graphics:
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=========
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Desktop Initialization
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-----------------------
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The graphics hardware is abstracted from the rest of the app_server.
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When started, the server creates the desktop, which is little more than
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a collection of workspaces. The desktop actually creates a DisplayDriver
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and then calls the driver's method Inititialize() before calling a few
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high-level routines for setup. Below is the process by which the
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HWDriver class, which is used to access the primary graphics card in the
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system, followed by the steps taken to set up the desktop.
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Load Accelerant
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...............
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The app_server looks in three paths when scanning for an accelerant:
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- /fd/beos/system/add-ons/app_server
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- /boot/home/config/add-ons/app_server
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- /boot/beos/system/add-ons/app_server
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When the app_server searches a path, it simply prints to the debug
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stream on the serial port a message akin "Attempting to load accelerant
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so-and-so" when loading the accelerant. Following this, it is loads the
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accelerant via load_add_on(), obtains the hook function
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control_graphics_card is via get_image_symbol, and
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control_graphics_card(OPEN_GRAPHICS_CARD) is called. If this returns an
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error, the image is unloaded after a
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control_graphics_card(CLOSE_GRAPHICS_CARD) is called and the server
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spits out a message like "So-and-so is not an acceptable driver" to the
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serial port. Assuming that the OPEN call succeeds, the app_server serial
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prints "Using so-and-so as accelerant." Hook functions are then acquired
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through control_graphics_card(B_GET_GRAPHICS_CARD_HOOKS). At this point,
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it is a good idea to have a palette generated for 8-bit mode (just in
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case we're going to use it), so the server generates the system palette.
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The palette on the graphics card is then set through many calls to
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control_graphics_card(B_SET_INDEXED_COLOR).
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Set up workspaces
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.................
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Workspace preferences are read in from disk. If they exist, they are
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used; otherwise the default of 3 workspace, each with the settings
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640x480x256@59.9Hz, is used. Each workspace is initialized to the proper
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information (preferences or default). Additionally, all settings are
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checked and possibly "clipped" by information gained through the driver
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class. With the desktop having been given the proper settings, the
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default workspace, 0, is activated.
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Display
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.......
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Provided that everything has gone well so far, the screen is filled to
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the user-set workspace color or RGB(51,102,160) Also, the global
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clipboard is created, which is nothing more than a BClipboard object.
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The Input Server will notify the app_server of its existence, at which
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point the cursor will be set to B_HAND_CURSOR and shown on the screen.
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Window management
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-----------------
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Window management is a complicated issue, requiring the cooperation of a
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number of different types of elements. Each BApplication, BWindow, and
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BView has a counterpart in the app_server which has a role to play.
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These objects are Decorators, ServerApps, ServerWindows, Layers, and
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WindowBorders.
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ServerApps
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..........
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ServerApp objects are created when a BApplication notifies the
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app_server of its presence. In acknowledging the BApplication's
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existence, the server creates a ServerApp which will handle future
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server-app communications and notifies the BApplication of the port to
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which it must send future messages.
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ServerApps are each an independent thread which has a function similar
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to that of a BLooper, but with additional tasks. When a BWindow is
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created, it spawns a ServerWindow object to handle the new window. The
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same applies to when a window is destroyed. Cursor commands and all
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other BApplication functions which require server interaction are also
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handled. B_QUIT_REQUESTED messages are received and passed along to the
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main thread in order for the ServerApp object to be destroyed. The
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server's Picasso thread also utilizes ServerApp::PingTarget in order to
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determine whether the counterpart BApplication is still alive and
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running.
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ServerWindows
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.............
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ServerWindow objects' purpose is to take care of the needs of BWindows.
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This includes all calls which require a trip to the server, such as
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BView graphics calls and sending messages to invoke hook functions
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within a window.
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Layers
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......
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Layers are shadowed BViews and are used to handle much BView
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functionality and also determine invalid screen regions. Hierarchal
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functions, such as AddChild, are mirrored. Invalid regions are tracked
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and generate Draw requests which are sent to the application for a
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specific BView to update its part of the screen.
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WindowBorders
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.............
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WindowBorders are a special kind of Layer with no BView counterpart,
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designed to handle window management issues, such as click tests, resize
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and move events, and ensuring that its decorator updates the screen
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appropriately.
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Decorators
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..........
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Decorators are addons which are intended to do one thing: draw the
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window frame. The Decorator API and development information is described
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in the Decorator Development Reference. They are essentially the means
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by which WindowBorders draw to the screen.
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How It All Works
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................
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The app_server is one large, complex beast because of all the tasks it
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performs. It also utilizes the various objects to accomplish them. Input
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messages are received from the Input Server and all messages not
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specific to the server (such as Ctrl-Alt-Shift-Backspace) are passed to
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the active application, if any. Mouse clicks are passed to the
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ServerWindow class for hit testing. These hit tests can result in window
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tabs and buttons being clicked, or mouse click messages being passed to
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a specific view in a window.
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These input messages which are passed to a running application will
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sometimes cause things to happen inside it, such as button presses,
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window closings/openings, etc. which will cause messages to be sent to
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the server. These messages are sent either from a BWindow to a
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ServerWindow or a BApplication to a ServerApp. When such messages are
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sent, then the corresponding app_server object performs an appropriate
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action.
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Screen Updates
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--------------
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Screen updates are done entirely through the BView class or some
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subclass thereof, hereafter referred to as a view. A view's drawing
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commands will cause its window to store draw command messages in a
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message packet. At some point Flush() will be called and the command
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packet will be sent to the window's ServerWindow object inside the
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server.
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The ServerWindow will receive the packet, check to ensure that its size
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is correct, and begin retrieving each command from the packet and
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dispatching it, taking the appropriate actions. Actual drawing commands,
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such as StrokeRect, will involve the ServerWindow object calling the
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appropriate command in the graphics module for the Layer corresponding
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to the view which sent the command.
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Cursor Management
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-----------------
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The app_server handles all messiness to do with the cursor. The cursor
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commands which are members of the BApplication class will send a message
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to its ServerApp, which will then call the DisplayDriver's appropriate
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function. The DisplayDriver used will actually handle the drawing of the
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cursor and whether or not to do so at any given time.
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OpenBeOS R1 will also include the advent of an extension of the API:
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SetCursor(BBitmap \*), which will accept a BBitmap of color space
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RGB(A)32, RGBA16, CMAP8, GRAY8, or GRAY1. Thus, color cursors and
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cursors which are not 16x16 are now supported.
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Display Drivers
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---------------
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Unlike the BeOS R5 app_server, OpenBeOS' server will have a special
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feature: a modular graphics driver access class. The class is not
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actually the graphics driver, but, rather, a generalized interface which
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is implemented to interact with various destinations for graphics
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output. This allows the server to draw to a BWindow/BView combination, a
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BDirectWindow, or the actual frame buffer of a particular graphics card.
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All that the rest of the server needs to do is call whichever graphics
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function that is needed.
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Process Management
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==================
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BApplication execution
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-----------------------
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Applications will come in two types: those which communicate with the
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app_server and take advantage of its services, and those which do not.
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To access the app_server, an application must be derived from
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BApplication.
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When a BApplication (referred to hereafter as a BApp) is executed, the
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app constructor creates its BLooper message port with the name
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AppLooperPort. This port's id, by means of BLooper, registers its
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port_id with the app_server so that the two can communicate with each
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other most easily.
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When the app_server receives notification that an app has been created,
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the server creates an AppMonitor (with accompanying thread) in its own
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team to handle messages sent to it and sends a reply with the port_id of
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the AppMonitor, to which all future messages are sent. These AppMonitor
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objects are stored in a global BList created for the storage of such
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things.
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non-BApplication execution
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--------------------------
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Other applications do not communicate with the app_server. These
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applications have no access to app services and do not generally pass
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BMessages. This includes, but is not limited to, UNIX apps. The
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app_server ignores such applications except when asked to kill them.
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While, technically, these are not limited to being non-GUI applications,
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in practice these applications are command-line-only, for the
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application would be required to (1) render the app_server unable to
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access video hardware and (2) reinvent existing graphics code to load
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and use accelerants and draw onto the video buffer. This is extremely
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bad style and programming practice, not to mention more work than it is
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worth except in one case: the OpenBeOS app_server can coexist with the
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BeOS R5 app_server with some degree of peace because it can utilize
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extra video cards which the BeOS app_server does not use.
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Killing/Exiting Applications
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----------------------------
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While the input server handles the Team Monitor window, the app_server
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actually takes care of shutting down teams, peacefully or not. Exiting
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an app is done simply by sending a B_QUIT_REQUESTED message to
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particular app. Killing an app is done via kill_team, but all the messy
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details are handled by the kernel itself through this call. When the
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user requests a team die via the Team Monitor, the Input Server sends a
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message to the app_server to kill the team, attaching the team_id. The
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app_server responds by happily nuking the respective team and notifies
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the registrar of its forcible removal from the roster.
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System Shutdown
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---------------
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Although the server maintains an internal list of running GUI
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applications, when a request to shut down the system is received by the
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app_server, it will pass the request on to the registrar, which will, in
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turn, increment its way through the app roster and request each app
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quit. When each quit request is sent, a timer is started and after
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timeout, the registrar will ask the server to kill the particular team
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and continue iterating through the application list.
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Input Processing
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================
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Input Server messages
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---------------------
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The Input Server collects information about keyboard and mouse events
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and forwards them to the app_server via messages. They are sent to port
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specifically for such messages, and the port is monitored by a thread
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whose task is to monitor, process, and dispatch them to the appropriate
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recipients. The Input Server is a regular BApplication, and unlike other
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applications, it requests a port to which it can send input messages.
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Mouse
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-----
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Mouse events consist of button changes, mouse movements, and the mouse
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wheel. The message will consist of the time of the event and attachments
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appropriate for each message listed below:
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B_MOUSE_DOWN
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............
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- when
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- location of the cursor
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- button number
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- modifiers
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- clicks
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B_MOUSE_UP
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..........
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- time
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- buttons' status // not implemented for R5 but included for future expansion
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- location of the cursor
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- modifiers
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B_MOUSE_MOVED
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.............
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- time
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- location of the cursor
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- buttons' status
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B_MOUSE_WHEEL_CHANGED
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.....................
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- time
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- location of the cursor
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- transit - in or out
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- x delta
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- y delta
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Keyboard
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--------
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Keyboard events consist of notification when a key is pressed or
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released. Any keypress or release will evoke a message, regardless of
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whether or not the key is mapped. The message will consist of the
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appropriate code and attachments listed below:
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B_KEY_DOWN
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..........
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- time
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- key code
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- repeat count
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- modifiers
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- states
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- UTF-8 code
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- string generated
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- modifier-independent ASCII code
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B_KEY_UP
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........
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- time
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- key code
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- modifiers
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- states
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- UTF-8 code
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- string generated
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- modifier-independent ASCII code
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B_UNMAPPED_KEY_DOWN
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...................
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- time
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- key code
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- modifiers
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- states
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B_UNMAPPED_KEY_UP
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.................
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- time
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- key code
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- modifiers
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- states
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B_MODIFIERS_CHANGED
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...................
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sent when a modifier key changes
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- time
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- modifier states
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- previous modifier states
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- states
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Nearly all keypresses received by the app_server are passed onto the
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appropriate application. Control-Tab, when held, is sent to the Deskbar
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for app switching. Command+F?? is intercepted and a workspace is
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switched. Left Control + Alt + Delete is not even intercepted by the
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app_server. The Input Server receives it and shows the Team Monitor
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window.
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Messaging
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=========
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Inter-Application Messaging
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---------------------------
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The details of messaging are depicted under Process
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Management::BApplication.
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Drag-and-drop
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-------------
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Methods
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-------
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Messaging with the app_server is not done using BMessages because of the
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overhead required to send them costs time and speed. Instead, ports are
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utilized indirectly by means of the PortLink class, which simply makes
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attaching data to a port message easier, but requires very little
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overhead.
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172
docs/develop/servers/app_server/graphics.rst
Normal file
172
docs/develop/servers/app_server/graphics.rst
Normal file
@ -0,0 +1,172 @@
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Graphics
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=========
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Desktop Initialization
|
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-----------------------
|
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|
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The graphics hardware is abstracted from the rest of the app_server.
|
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When started, the server creates the desktop, which is little more than
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a collection of workspaces. The desktop actually creates a DisplayDriver
|
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and then calls the driver's method Inititialize() before calling a few
|
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high-level routines for setup. Below is the process by which the
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HWDriver class, which is used to access the primary graphics card in the
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system, followed by the steps taken to set up the desktop.
|
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|
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Load Accelerant
|
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...............
|
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|
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First of all, the available video cards are scanned by enumerating the contents of /dev/graphics.
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For each device, the B_GET_ACCELERANT_SIGNATURE ioctl is used to find the corresponding accelerant
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name.
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The app_server looks for an accelerant matching that name in the "accelerants" subdirectory of each
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add-on directory (enumerated using BPathFinder). The first matching accelerant is loaded
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using load_add_on(). Then the get_accelerant_hook() function is obtained through get_image_symbol.
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This is the only needed entry point for the accelerant, and can be used to call all the other
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needed code, starting with B_INIT_ACCELERANT.
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For more information about the accelerant hooks, see `Writing video card drivers <https://www.haiku-os.org/legacy-docs/writing-video-card-drivers/04-accelerant>`_.
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|
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Set up workspaces
|
||||
.................
|
||||
|
||||
Workspace preferences are read in from disk. If they exist, they are
|
||||
used; otherwise the default of 3 workspace, each with the settings
|
||||
640x480x256@59.9Hz, is used. Each workspace is initialized to the proper
|
||||
information (preferences or default). Additionally, all settings are
|
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checked and possibly "clipped" by information gained through the driver
|
||||
class. With the desktop having been given the proper settings, the
|
||||
default workspace, 0, is activated.
|
||||
|
||||
Display
|
||||
.......
|
||||
|
||||
Provided that everything has gone well so far, the screen is filled to
|
||||
the user-set workspace color or RGB(51,102,160) Also, the global
|
||||
clipboard is created, which is nothing more than a BClipboard object.
|
||||
|
||||
The Input Server will notify the app_server of its own existence, at which
|
||||
point the cursor will be set to B_HAND_CURSOR and shown on the screen.
|
||||
|
||||
Window management
|
||||
-----------------
|
||||
|
||||
Window management is a complicated issue, requiring the cooperation of a
|
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number of different types of elements. Each BApplication, BWindow, and
|
||||
BView has a counterpart in the app_server which has a role to play.
|
||||
These objects are Decorators, ServerApps, ServerWindows, Layers, and
|
||||
WindowBorders.
|
||||
|
||||
ServerApps
|
||||
..........
|
||||
|
||||
ServerApp objects are created when a BApplication notifies the
|
||||
app_server of its presence. In acknowledging the BApplication's
|
||||
existence, the server creates a ServerApp which will handle future
|
||||
server-app communications and notifies the BApplication of the port to
|
||||
which it must send future messages.
|
||||
|
||||
ServerApps are each an independent thread which has a function similar
|
||||
to that of a BLooper, but with additional tasks. When a BWindow is
|
||||
created, it spawns a ServerWindow object to handle the new window. The
|
||||
same applies to when a window is destroyed. Cursor commands and all
|
||||
other BApplication functions which require server interaction are also
|
||||
handled. B_QUIT_REQUESTED messages are received and passed along to the
|
||||
main thread in order for the ServerApp object to be destroyed. The
|
||||
server's Picasso thread also utilizes ServerApp::PingTarget in order to
|
||||
determine whether the counterpart BApplication is still alive and
|
||||
running.
|
||||
|
||||
ServerWindows
|
||||
.............
|
||||
|
||||
ServerWindow objects' purpose is to take care of the needs of BWindows.
|
||||
This includes all calls which require a trip to the server, such as
|
||||
BView graphics calls and sending messages to invoke hook functions
|
||||
within a window.
|
||||
|
||||
Layers
|
||||
......
|
||||
|
||||
Layers are shadowed BViews and are used to handle much BView
|
||||
functionality and also determine invalid screen regions. Hierarchal
|
||||
functions, such as AddChild, are mirrored. Invalid regions are tracked
|
||||
and generate Draw requests which are sent to the application for a
|
||||
specific BView to update its part of the screen.
|
||||
|
||||
WindowBorders
|
||||
.............
|
||||
|
||||
WindowBorders are a special kind of Layer with no BView counterpart,
|
||||
designed to handle window management issues, such as click tests, resize
|
||||
and move events, and ensuring that its decorator updates the screen
|
||||
appropriately.
|
||||
|
||||
Decorators
|
||||
..........
|
||||
|
||||
Decorators are addons which are intended to do one thing: draw the
|
||||
window frame. The Decorator API and development information is described
|
||||
in the Decorator Development Reference. They are essentially the means
|
||||
by which WindowBorders draw to the screen.
|
||||
|
||||
How It All Works
|
||||
................
|
||||
|
||||
The app_server is one large, complex beast because of all the tasks it
|
||||
performs. It also utilizes the various objects to accomplish them. Input
|
||||
messages are received from the Input Server and all messages not
|
||||
specific to the server (such as Ctrl-Alt-Shift-Backspace) are passed to
|
||||
the active application, if any. Mouse clicks are passed to the
|
||||
ServerWindow class for hit testing. These hit tests can result in window
|
||||
tabs and buttons being clicked, or mouse click messages being passed to
|
||||
a specific view in a window.
|
||||
|
||||
These input messages which are passed to a running application will
|
||||
sometimes cause things to happen inside it, such as button presses,
|
||||
window closings/openings, etc. which will cause messages to be sent to
|
||||
the server. These messages are sent either from a BWindow to a
|
||||
ServerWindow or a BApplication to a ServerApp. When such messages are
|
||||
sent, then the corresponding app_server object performs an appropriate
|
||||
action.
|
||||
|
||||
Screen Updates
|
||||
--------------
|
||||
|
||||
Screen updates are done entirely through the BView class or some
|
||||
subclass thereof, hereafter referred to as a view. A view's drawing
|
||||
commands will cause its window to store draw command messages in a
|
||||
message packet. At some point Flush() will be called and the command
|
||||
packet will be sent to the window's ServerWindow object inside the
|
||||
server.
|
||||
|
||||
The ServerWindow will receive the packet, check to ensure that its size
|
||||
is correct, and begin retrieving each command from the packet and
|
||||
dispatching it, taking the appropriate actions. Actual drawing commands,
|
||||
such as StrokeRect, will involve the ServerWindow object calling the
|
||||
appropriate command in the graphics module for the Layer corresponding
|
||||
to the view which sent the command.
|
||||
|
||||
Cursor Management
|
||||
-----------------
|
||||
|
||||
The app_server handles all messiness to do with the cursor. The cursor
|
||||
commands which are members of the BApplication class will send a message
|
||||
to its ServerApp, which will then call the DisplayDriver's appropriate
|
||||
function. The DisplayDriver used will actually handle the drawing of the
|
||||
cursor and whether or not to do so at any given time.
|
||||
|
||||
In addition to the 1 bit per pixel cursors used in BeOS, Haiku also allows to create a BCursor
|
||||
object from a BBitmap in any colorspace. This allows color cursors and also larger cursor sizes.
|
||||
The default cursors also use greyscale and alpha channel for antialiasing.
|
||||
|
||||
Display Drivers
|
||||
---------------
|
||||
|
||||
Unlike the BeOS R5 app_server, Haiku' server has an extra abstraction layer between the graphic
|
||||
driver and the main drawing functions. This allows to generalize the interface and redirect the
|
||||
drawing commands in various ways. For example, drawing commands can be redirected to another
|
||||
machine for the remote_app_server, or drawing for a specific window can be granted direct access
|
||||
to the framebuffer on a specific display and video card, while other applications go through the
|
||||
normal process of drawing only to their currently exposed region only.
|
||||
|
||||
118
docs/develop/servers/app_server/input.rst
Normal file
118
docs/develop/servers/app_server/input.rst
Normal file
@ -0,0 +1,118 @@
|
||||
Input Processing
|
||||
================
|
||||
|
||||
Input Server messages
|
||||
---------------------
|
||||
|
||||
The Input Server collects information about keyboard and mouse events
|
||||
and forwards them to the app_server via messages. They are sent to port
|
||||
specifically for such messages, and the port is monitored by a thread
|
||||
whose task is to monitor, process, and dispatch them to the appropriate
|
||||
recipients. The Input Server is a regular BApplication, and unlike other
|
||||
applications, it requests a port to which it can send input messages.
|
||||
|
||||
Mouse
|
||||
-----
|
||||
|
||||
Mouse events consist of button changes, mouse movements, and the mouse
|
||||
wheel. The message will consist of the time of the event and attachments
|
||||
appropriate for each message listed below:
|
||||
|
||||
B_MOUSE_DOWN
|
||||
............
|
||||
|
||||
- when
|
||||
- buttons' status
|
||||
- location of the cursor
|
||||
- modifiers
|
||||
- clicks
|
||||
|
||||
B_MOUSE_UP
|
||||
..........
|
||||
|
||||
- time
|
||||
- buttons' status
|
||||
- location of the cursor
|
||||
- modifiers
|
||||
|
||||
B_MOUSE_MOVED
|
||||
.............
|
||||
|
||||
- time
|
||||
- location of the cursor
|
||||
- buttons' status
|
||||
|
||||
B_MOUSE_WHEEL_CHANGED
|
||||
.....................
|
||||
|
||||
- time
|
||||
- location of the cursor
|
||||
- transit - in or out
|
||||
- x delta
|
||||
- y delta
|
||||
|
||||
Keyboard
|
||||
--------
|
||||
|
||||
Keyboard events consist of notification when a key is pressed or
|
||||
released. Any keypress or release will evoke a message, regardless of
|
||||
whether or not the key is mapped. The message will consist of the
|
||||
appropriate code and attachments listed below:
|
||||
|
||||
B_KEY_DOWN
|
||||
..........
|
||||
|
||||
- time
|
||||
- key code
|
||||
- repeat count
|
||||
- modifiers
|
||||
- states
|
||||
- UTF-8 code
|
||||
- string generated
|
||||
- modifier-independent ASCII code
|
||||
|
||||
B_KEY_UP
|
||||
........
|
||||
|
||||
- time
|
||||
- key code
|
||||
- modifiers
|
||||
- states
|
||||
- UTF-8 code
|
||||
- string generated
|
||||
- modifier-independent ASCII code
|
||||
|
||||
B_UNMAPPED_KEY_DOWN
|
||||
...................
|
||||
|
||||
- time
|
||||
- key code
|
||||
- modifiers
|
||||
- states
|
||||
|
||||
B_UNMAPPED_KEY_UP
|
||||
.................
|
||||
|
||||
- time
|
||||
- key code
|
||||
- modifiers
|
||||
- states
|
||||
|
||||
B_MODIFIERS_CHANGED
|
||||
...................
|
||||
|
||||
sent when a modifier key changes
|
||||
|
||||
- time
|
||||
- modifier states
|
||||
- previous modifier states
|
||||
- states
|
||||
|
||||
Nearly all keypresses received by the app_server are passed onto the
|
||||
appropriate application. Control-Tab, when held, is sent to the Deskbar
|
||||
for app switching. Command+F?? is intercepted and a workspace is
|
||||
switched. Left Control + Alt + Delete is not even intercepted by the
|
||||
app_server. The Input Server receives it and shows the Team Monitor
|
||||
window.
|
||||
|
||||
|
||||
22
docs/develop/servers/app_server/messaging.rst
Normal file
22
docs/develop/servers/app_server/messaging.rst
Normal file
@ -0,0 +1,22 @@
|
||||
Messaging
|
||||
=========
|
||||
|
||||
Inter-Application Messaging
|
||||
---------------------------
|
||||
|
||||
The details of messaging are depicted under Process
|
||||
Management::BApplication.
|
||||
|
||||
Drag-and-drop
|
||||
-------------
|
||||
|
||||
Methods
|
||||
-------
|
||||
|
||||
Messaging with the app_server is not done using BMessages because of the
|
||||
overhead required to send them costs time and speed. Instead, ports are
|
||||
utilized indirectly by means of the PortLink class, which simply makes
|
||||
attaching data to a port message easier, but requires very little
|
||||
overhead.
|
||||
|
||||
|
||||
75
docs/develop/servers/app_server/process_management.rst
Normal file
75
docs/develop/servers/app_server/process_management.rst
Normal file
@ -0,0 +1,75 @@
|
||||
Process Management
|
||||
==================
|
||||
|
||||
BApplication execution
|
||||
-----------------------
|
||||
|
||||
Applications will come in two types: those which communicate with the
|
||||
app_server and take advantage of its services, and those which do not.
|
||||
To access the app_server, an application must be derived from
|
||||
BApplication.
|
||||
|
||||
When a BApplication (referred to hereafter as a BApp) is executed, the
|
||||
app constructor creates its BLooper message port with the name
|
||||
AppLooperPort. This port's id, by means of BLooper, registers its
|
||||
port_id with the app_server so that the two can communicate with each
|
||||
other most easily.
|
||||
|
||||
When the app_server receives notification that an app has been created,
|
||||
the server creates an AppMonitor (with accompanying thread) in its own
|
||||
team to handle messages sent to it and sends a reply with the port_id of
|
||||
the AppMonitor, to which all future messages are sent. These AppMonitor
|
||||
objects are stored in a global BList created for the storage of such
|
||||
things.
|
||||
|
||||
This setup normally requires that there is a single app_server instance running, and all
|
||||
BApplications establish contact with it. There are however several exceptions to this:
|
||||
|
||||
- Multi-user and multi-sessions setups are possible, for example with the use of remote_app_server.
|
||||
In this case, each user session (corresponding to UNIX 'login' sessions) can have its own
|
||||
app_server.
|
||||
- The test_app_server is a test tool that allows to run most of app_server code in its own BWindow,
|
||||
displayed inside the main app_server (mainly for debugging app_server code). In this case, the
|
||||
applications are compiled with specific code to connect specifically with the test_app_server.
|
||||
|
||||
non-BApplication execution
|
||||
--------------------------
|
||||
|
||||
Other applications do not communicate with the app_server. These
|
||||
applications have no access to app services and do not generally pass
|
||||
BMessages. This includes, but is not limited to, UNIX apps. The
|
||||
app_server ignores such applications except when asked to kill them.
|
||||
|
||||
While, technically, these are not limited to being non-GUI applications,
|
||||
in practice these applications are command-line-only, for the
|
||||
application would be required to (1) render the app_server unable to
|
||||
access video hardware and (2) reinvent existing graphics code to load
|
||||
and use accelerants and draw onto the video buffer. This is extremely
|
||||
bad style and programming practice, not to mention more work than it is
|
||||
worth.
|
||||
|
||||
Killing/Exiting Applications
|
||||
----------------------------
|
||||
|
||||
While the input server handles the Team Monitor window, the app_server
|
||||
actually takes care of shutting down teams, peacefully or not. Exiting
|
||||
an app is done simply by sending a B_QUIT_REQUESTED message to
|
||||
particular app. Killing an app is done via kill_team, but all the messy
|
||||
details are handled by the kernel itself through this call. When the
|
||||
user requests a team die via the Team Monitor, the Input Server sends a
|
||||
message to the app_server to kill the team, attaching the team_id. The
|
||||
app_server responds by happily nuking the respective team and notifies
|
||||
the registrar of its forcible removal from the roster.
|
||||
|
||||
System Shutdown
|
||||
---------------
|
||||
|
||||
Although the server maintains an internal list of running GUI
|
||||
applications, when a request to shut down the system is received by the
|
||||
app_server, it will pass the request on to the registrar, which will, in
|
||||
turn, increment its way through the app roster and request each app
|
||||
quit. When each quit request is sent, a timer is started and after
|
||||
timeout, the registrar will ask the server to kill the particular team
|
||||
and continue iterating through the application list.
|
||||
|
||||
|
||||
@ -1,6 +1,50 @@
|
||||
Application Server
|
||||
============================================
|
||||
|
||||
Purpose
|
||||
~~~~~~~
|
||||
|
||||
The app_server provides services to the Haiku by managing processes,
|
||||
filtering and dispatching input from the Input Server to the appropriate
|
||||
applications, and managing all graphics-related tasks.
|
||||
|
||||
Tasks performed by app_server
|
||||
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
The tasks performed by the app_server are grouped in relation to its purpose.
|
||||
|
||||
- Receives and redirects (dispatches) messages from the input server
|
||||
- Responds to messages from apps
|
||||
- Receives and consolidates requests from BView, BWindow, BBitmap, and others to draw stuff (draw bitmap, etc)
|
||||
- Utilizes ports to communicate with child processes
|
||||
- Handles drag & drop messaging
|
||||
- Manages the system clipboard
|
||||
- Loads and Kills processes
|
||||
- Detects absence of Input Server and restarts when not running
|
||||
- Aids in system shutdown
|
||||
- Dynamically loads accelerant portion of graphics driver
|
||||
- Creates a connection with BBitmaps requiring a child view
|
||||
- Draws the blue desktop screen
|
||||
- Provides workspace support
|
||||
- Provides functionality to the BeAPI for drawing primitives, such as rectangles, ellipses, and beziers
|
||||
- Provides a means for BViews to draw on BBitmaps
|
||||
- Manages window behavior with respect to redraw (move to front, minimize, etc)
|
||||
- Returns a frame buffer to direct-access classes
|
||||
- Caches fonts for screen and printer use
|
||||
- Draws text and provides other font API support for the BeAPI classes
|
||||
|
||||
App server components
|
||||
~~~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
.. toctree::
|
||||
|
||||
/servers/app_server/graphics
|
||||
/servers/app_server/process_management
|
||||
/servers/app_server/input
|
||||
/servers/app_server/messaging
|
||||
|
||||
- `Multiple Monitor Support Spec <MultiMonitor.htm>`__
|
||||
|
||||
Class Descriptions
|
||||
~~~~~~~~~~~~~~~~~~
|
||||
|
||||
@ -39,11 +83,3 @@ Font Infrastructure
|
||||
/servers/app_server/FontServer
|
||||
/servers/app_server/FontFamily
|
||||
|
||||
Other Documents
|
||||
~~~~~~~~~~~~~~~
|
||||
|
||||
.. toctree::
|
||||
|
||||
/servers/app_server/asis
|
||||
|
||||
- `Multiple Monitor Support Spec <MultiMonitor.htm>`__
|
||||
|
||||
Loading…
Reference in New Issue
Block a user