Need for a Digital Interface

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Clement Lau HAVi Organization Sony
Electronics clement_at_arch.sel.sony.com
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- Event Manager

• a mechanism to signal a change of state of a
  software element or the network in general
• change is represented by an event
• work as subscription and notification model
• an event is either posted only to local host or
  globally to all IAV/FAV in the network
• fully transparent, no need to know the physical
  location of event poster or subscriber
• easy API for posting / receiving events anywhere
  in network

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Event Manager

• three types of events
• system event
• vendor specific event
• application specific event
• system events are defined by the HAVi
  organization and can only be posted by trusted
  software elements
• private events can be defined either by vendor or
  by application

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Event Manager Model (subscriber)

• a software element decides the list of events it
  wants to keep track of (the listen-to event
  list)
• subscribes to the listen-to event list by
  sending a registration request to the local Event
  Manager
• the registration request contains opcode of the
  function that the software element uses to
  process event notification
• when any of the subscribed event is posted
  (anywhere in the network), the local Event
  Manager sends an event notification message to
  the software element

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Event Manager Model (subscriber)

• an event notification message contains the posted
  event, the posters SEID, and is delivered to the
  receiving software elements message callback
  function
• the software element deciphers the event
  notification message, extracts the event handling
  function opcode, and invokes the function to
  perform actual processing of the event delivered

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Event Manager Model (subscriber)

• subscription service API
• EventManagerRegister
• EventManagerUnregister
• EventManagerReplace
• EventManagerAddEvent
• EventManagerRemoveEvent

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Event Manager Model (poster)

• software element wishing to post an event (event
  poster) first construct the event to be posted
• a request is sent to the local Event Manager to
  either post the event locally or globally to all
  remote Event Manager in the network
• each Event Manager finds the list of local
  software elements interested in the event
• for each interested software element, the Event
  Manager constructs an event notification message
  and sends it to the software element

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Event Manager Model (poster)

• if the event is to be posted globally, coordinate
  with all remote Event Managers to deliver the
  event to the remote nodes
• posting of a global event is totally transparent
  to the poster in the sense that
• it is not aware of the physical location of the
  notified software elements
• semantically, it can safely assume that all
  software elements interested in the event
  regardless where they physically reside will get
  the notification

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Event Manager Model (poster)

• HAVi defines the protocol for a local Event
  Manager to coordinate with remote Event Managers
  to deliver an event globally to all interested
  software element in the network
• event posting service API
• EventManagerPostEvent
• EventManagerForwardEvent (inter Event Manager
  only)

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- DCM Manager

• component responsible for installing and
  uninstalling DCM code units that act as agents
  for applications to access functionality/service
  provided by BAV/LAV (known as guest)
• DCM code units for FAV/IAV (if present) are self
  managed
• mandatory on FAV, optional on IAV (the FAV/IAV is
  known as host)
• automatic installation of a DCM code unit when a
  guest is connected, uninstallation of the guests
  DCM code unit when it is disconnected from the
  network

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DCM Manager

• LAV is either 1394 (but not HAVi compliant)
  device or non 1394 device
• non 1394 device
• e.g., VCR with NTSC analog signal and hard front
  panel controls
• 1394 device (non HAVi compliant)
• e.g., DV camcorder

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DCM Manager

control command
like proprietary protocol such as SLink
LAV device
like analog AV stream
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DCM Manager

control command
SDD DCM DDI
IEC 61883 FCP
BAV device
IEC 61883 CMP
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DCM Manager

Potential DCM hosts
SDD DCM FCM
Global DCM Manager decides on DCM host
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DCM Manager

• HAVi defines a default scheme to select a host
  whenever a new guest is found in the network,
  which will then install the DCM code unit for the
  guest
• a set of user modifiable preferences can be used
  to guide the selection of host and the DCM code
  unit of a guest
• four preferences
• PREFER_VENDOR_HOST
• PREFERRED_HOST
• PREFERRED_URL
• PREFERRED_URL_DEVICE

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DCM Manager

• a leader selection protocol is executed whenever
  there is a change of number of DCM Managers in
  network
• one of the DCM Managers is selected as the
  leader, the rest are called followers
• the leader inquires the followers for the state
  of DCM code units installed for all BAV/LAV found
  in network
• if any BAV/LAV does not have an installed DCM
  code unit, the leader coordinates with followers
  to select the most suitable host to install the
  DCM code unit
• host selection is either done by the default
  protocol or guided by preferences

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DCM Manager

• highlights of default host selection protocol
• if the guest is a BAV, an eligible FAV capable of
  uploading its Java DCM code unit is selected
• if the guest is a LAV or there isnt any node
  capable of uploading a BAV Java DCM code unit,
  any FAV/IAV capable of installing a proprietary
  embedded DCM code unit for the guest is selected
• all conditions being equal, a host with the
  lowest number of installed DCM code unit is
  selected
• for BAV, the URL stored in its SDD takes
  precedence over its built-in DCM code unit

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DCM Manager

• highlights of preference guided host selection
  (note if any step succeeds, the remaining steps
  are skipped)
• if PREFERRED_HOST is specified and the host is a
  valid node in network, it is selected
• if PREFERRED_VENDOR_HOST is TRUE, a host of the
  same vendor as the guest that is capable of
  hosting its DCM code unit is selected
• any FAV capable of hosting the guest DCM code
  unit is selected
• any IAV capable of hosting the guest DCM code
  unit is selected

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DCM Manager

• highlights of preference guided DCM code unit
  selection (note if any step succeeds, the
  remaining steps are skipped)
• if PREFERRED_URL is specified and the selected
  host is a FAV, the Java DCM code unit stored in
  the specified URL is installed
• for a BAV guest and if the selected host is a
  FAV, the Java DCM code unit stored in the
  location specified by the URL in its SDD is
  installed
• for a BAV guest and if the selected host is a
  FAV, the built-in Java DCM code unit stored in
  its SDD is installed
• a proprietary embedded DCM code unit is installed
  by the selected host

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DCM Manager

• the event DcmInstallIndication is posted at the
  end of the process indicating the status of the
  DCM code unit installation attempt
• an application should subscribe to this event if
  it wants to know the result of a guest DCM code
  unit installation

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DCM Manager

• when a guest disappears from the network, each
  DCM Manager gets a Network Reset event
  notification
• check if the node currently hosts the guest DCM
  code unit and automatically uninstall the code
  unit if it does
• there is no need to involve the leader in this
  process, each DCM Manager performs this task
  autonomously
• the event DcmUninstallIndication is posted at the
  end of the process indicating the status of the
  DCM code unit uninstallation attempt
• an application should subscribe to this event if
  it wants to know the result of the guest code
  unit uninstallation

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DCM Manager

• DCM Manager service API
• DcmManagerSetPreference
• DcmManagerGetPreference
• DcmManagerInstallDCM
• DcmManagerUninstallDCM

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Self Describing Device data (SDD)

• data in a HAVi compliant device configuration ROM
  containing
• descriptive information about the device (e.g.
  device class)
• device capabilities (e.g. support level 2 GUI)
• DCM code unit
• data to construct DDI user interface graphical
  elements
• proprietary vendor specific data
• configuration ROM based on IEEE 1212r
  specification
• DCM Manager reads SDD to determine if it is
  capable of hosting a DCM code unit (Java or
  embedded) of the device

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Self Describing Device data (SDD)

• HAVi Unit Directory in the configuration ROM
  contains actual SDD data
• mandatory fields in HAVi Unit Directory
• Specifier_ID (0x00A02D assigned to 1394 TA by
  IEEE)
• Version (0x010008 assigned by HAVi)
• HAVi Message Version (0x000100 assigned by HAVi)
• HAVi_Device_Profile (24 bit immediate value)
• HAVi_User_Preferred_Name (24 bit leaf offset)
• HAVi_DCM (24 bit leaf offset)
• HAVi_DCM_Profile (24 bit leaf offset)
• HAVi_DCM_Reference (24 bit leaf offset)
• HAVi_Device_Icon_Bitmap (24 bit leaf offset)

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Self Describing Device data (SDD)

• each leaf offset is the pointer to a 1212 leaf
  structure containing actual data for that field
• for example, the HAVi_DCM_Profile field contains
  the offset to a leaf structure which in turn
  contains information about the DCM code unit such
  as its total size in bytes, required memory size
  of code segment, required memory size of data
  segment etc
• non HAVi device do not have SDD and proprietary
  mechanism can be used by vendors to determine
  what these devices are (e.g. use AVC protocols)