plugin XEP-0353, XEP-0234, jingle: WebRTC data channel signaling implementation: Implement XEP-0343: Signaling WebRTC Data Channels in Jingle. The current version of the XEP (0.3.1) has no implementation and contains some flaws. After discussing this on xsf@, Daniel (from Conversations) mentioned that they had a sprint with Larma (from Dino) to work on another version and provided me with this link: https://gist.github.com/iNPUTmice/6c56f3e948cca517c5fb129016d99e74 . I have used it for my implementation. This implementation reuses work done on Jingle A/V call (notably XEP-0176 and XEP-0167 plugins), with adaptations. When used, XEP-0234 will not handle the file itself as it normally does. This is because WebRTC has several implementations (browser for web interface, GStreamer for others), and file/data must be handled directly by the frontend. This is particularly important for web frontends, as the file is not sent from the backend but from the end-user's browser device. Among the changes, there are: - XEP-0343 implementation. - `file_send` bridge method now use serialised dict as output. - New `BaseTransportHandler.is_usable` method which get content data and returns a boolean (default to `True`) to tell if this transport can actually be used in this context (when we are initiator). Used in webRTC case to see if call data are available. - Support of `application` media type, and everything necessary to handle data channels. - Better confirmation message, with file name, size and description when available. - When file is accepted in preflight, it is specified in following `action_new` signal for actual file transfer. This way, frontend can avoid the display or 2 confirmation messages. - XEP-0166: when not specified, default `content` name is now its index number instead of a UUID. This follows the behaviour of browsers. - XEP-0353: better handling of events such as call taken by another device. - various other updates. rel 441

from typing import (
    Dict, Iterator, List, Literal, Optional, Tuple, TypeVar, Union, overload
)


URI = str
Name = str
QName = Tuple[Optional[URI], Name]
AttributeKey = Union[QName, Name]
Attributes = Dict[AttributeKey, str]
Prefix = str


D = TypeVar("D")


# Note: these typings are incomplete and evolve as needed.
class Element:
    uri: Optional[URI]
    name: Name
    defaultUri: Optional[URI]
    children: List[Union["Element", str]]
    attributes: Attributes

    def __init__(
        self,
        qname: QName,
        defaultUri: Optional[URI] = None,
        attribs: Optional[Attributes] = None,
        localPrefixes: Optional[Dict[URI, Prefix]] = None
    ) -> None:
        ...

    def __getitem__(self, key: AttributeKey) -> str:
        ...

    def __setitem__(self, key: AttributeKey, value: str) -> None:
        ...

    @overload
    def getAttribute(
        self,
        attribname: AttributeKey,
        default: None = None
    ) -> Union[str, None]:
        ...

    @overload
    def getAttribute(self, attribname: AttributeKey, default: D) -> Union[str, D]:
        ...

    def addChild(self, node: "Element") -> "Element":
        ...

    def addContent(self, text: str) -> str:
        ...

    def addElement(
        self,
        name: Union[QName, Name],
        defaultUri: Optional[URI] = None,
        content: Optional[str] = None
    ) -> "Element":
        ...

    def elements(
        self,
        uri: Optional[URI] = None,
        name: Optional[Name] = None
    ) -> Iterator["Element"]:
        ...

    def toXml(
        self,
        prefixes: Optional[Dict[URI, Prefix]] = None,
        closeElement: Literal[0, 1] = 1,
        defaultUri: str = "",
        prefixesInScope: Optional[List[Prefix]] = None
    ) -> str:
        ...