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MTP Daemon - DBus Interface Requirements

mtp (3) dbus (1) requirements (2)
Philipp Schmidt

DBus Interface Specifications

1. General

The exact interface specification including elaborate comments can be found in the "org.libmtp.mtpd.xml" file which is located in the "daemon/dbus" directory.

  1. The DBus interface shall provide the following APIs:
    • device management
    • file management
    • folder management
    • object management
  2. The following APIs shall be optional in a first version, but be implemented afterwards. They are therefore not detailed in the initial version of this document.
    • track management
    • playlist management
    • album management
  3. The APIs shall be modelled as close as possible to the LIBMTP APIs
  4. If something cannot be modelled using DBus or a significantly better alternative exists another approach should be used
    • For example callbacks are not possible: use DBus signals
    • Filetypes should be matched and presented as mime-types and not MTP-internal filetypes
  5. If an operation cannot be executed due to another long-running operation all waiting programs shall be notified
    • Client programs can then notify their users like this: "There is currently another operation active on the device. Please be patient!"
  6. Information about the daemon shall be made available as properties
    • e.g. API version
  7. Optional information that is not part of the specification shall be made available, but marked as such
    • e.g. If the daemon does internal caching the status can be exported as a property

2. Device Management

  1. The device access shall be neartly completely rewritten in contrast to the LIBMTP device management API to ensure useful usage of it
    • As the daemon abstracts all device handling for the client the direct access API is not necessary
  2. The following interfaces shall be available
    • listDevices
      List all devices currently connected
    • renameDevice
      Set the friendlyName of the device to something else
    • listStorages
      List all storages for a device
    • getMetadataforDevice
    • getMetadataforStorage
    • formatStorage
  3. The following interfaces for accessing device properties shall be modelled closely to the existing API
    • LIBMTP_Get_String_From_Object
    • LIBMTP_Get_u64_From_Object
    • LIBMTP_Get_u32_From_Object
    • LIBMTP_Get_u16_From_Object
    • LIBMTP_Get_u8_From_Object
    • LIBMTP_Set_Object_String
    • LIBMTP_Set_Object_u32
    • LIBMTP_Set_Object_u16
    • LIBMTP_Set_Object_u8
    • LIBMTP_Get_Property_Description
    • LIBMTP_Is_Property_Supported
    • LIBMTP_Get_Allowed_Property_Values
  4. The following interfaces still need to be discussed
    • LIBMTP_Get_Syncpartner
    • LIBMTP_Set_Syncpartner

3. File Management

  1. The following interfaces shall be adapted as closely as possible
    • LIBMTP_Get_Files_And_Folders
      Return type shall be a list
    • LIBMTP_Get_Filelisting
      Return type shall be a list
    • LIBMTP_Get_Filemetadata
    • LIBMTP_Set_File_Name
    • LIBMTP_Get_Thumbnail
  2. The following interfaces shall be altered for easier access or usage of DBus simplifications
    • LIBMTP_Get_File_To_File_Descriptor
      Progress function shall be implemented as a signal. The get-function itself shall return a transaction-id that will be included in the progress signal. It shall be the applications responsibility to filter for transactions issued by it.
    • LIBMTP_Send_File_From_File_Descriptor
      Progress function shall be implemented as a signal. The send-function itself shall return a transaction-id that will be included in the progress signal. It shall be the applications responsibility to filter for transactions issued by it.
  3. The following interfaces shall not be implemented
    • LIBMTP_new_file_t
    • LIBMTP_destroy_file_t
    • LIBMTP_Get_File_To_File
    • LIBMTP_Send_File_From_File
    • LIBMTP_new_filesampledata_t
    • LIBMTP_destroy_filesampledata_t
    • LIBMTP_Get_Filetype_Description
    • LIBMTP_Get_Filelisting_With_Callback
  4. The following interfaces still need to be discussed
    • LIBMTP_Get_File_To_Handler
    • LIBMTP_Send_File_From_Handler
    • LIBMTP_Get_Representative_Sample_Format
    • LIBMTP_Send_Representative_Sample
    • LIBMTP_Get_Representative_Sample
    • LIBMTP_Read_Event

4. Folder Management

  1. The following interfaces shall be adapted as closely as possible
    • LIBMTP_Get_Folder_List
    • LIBMTP_Get_Folder_List_For_Storage
    • LIBMTP_Create_Folder
    • LIBMTP_Set_Folder_Name
  2. The following interfaces shall not be implemented
    • LIBMTP_new_folder_t
    • LIBMTP_destroy_folder_t

5. Object Management

  1. The following interfaces shall be adapted as closely as possible
    • LIBMTP_Delete_Object
      Shall ensure that objects are deleted recursively
    • LIBMTP_Set_Object_Filename
    • LIBMTP_GetPartialObject
    • LIBMTP_SendPartialObject
    • LIBMTP_BeginEditObject
    • LIBMTP_EndEditObject
    • LIBMTP_TruncateObject

Related

Wiki: MTP Daemon