Requirements storage (in network / backend) simulation of events / algorithms support of a wide variety of technologies synchronization of several data streams (cope with unavailability of a global clock) highly component based (very basic components that can easily be ported) standardized data streaming format no assumption on type of sensor / comm. service discovery (maybe as a component) UPNP? Simplicity interchangeable components

Requirement Groups GROUP1: storage (in network / backend?) GROUP2: synchronization of several data streams GROUP3: component based architecture/work GROUP4: standardized data (streaming) format

paul:keyDown:ALT:KeyStub paul:key:TAB:KeyStub paul:keyUp:ALT:KeyStub

network Y-StubX-Stub Application (mapping) ButtonLight YXBXML Stub mandatory optional Retrieve state Ask for keep-alive emit event receive event Description query Stream: > 10 Hz, unicast/multicast Event: < 10 Hz, broadcast Reply to keep-alive Answer to description query

network Y-StubX-Stub Application (mapping) ButtonLight YXBXML Stub mandatory optional Stream control event Ask for keep-alive Description query Stream: > 10 Hz, unicast/multicast Receiver Send still-alive event Receive stream Answer to description query

network Y-StubX-Stub Application (mapping) ButtonLight YXBXML Stub mandatory optional Receive stream control event Description query Stream: > 10 Hz, unicast/multicast Sender Receive still-alive event Send stream Answer to description query

Stub mandatory optional Receive stream control event Description query Stream: > 10 Hz, unicast/multicast Sender Receive still-alive event Send stream Answer to description query Receive initiate stream request Stub Stream control event Ask for keep-alive Description query Stream: > 10 Hz, unicast/multicast Receiver Send still-alive event Receive stream Answer to description query Send initiate stream request Stub Retrieve state Ask for keep-alive emit event receive event Description query Reply to keep-alive Answer to description query events: < 10 Hz, broadcast

Stub Retrieve state Ask for keep-alive emit event receive event Description query Reply to keep-alive Answer to description query events: < 10 Hz, broadcast Implementation details: Port number Message format (B)XML according to some specified schema

Implementation details: Port number for control (event) messages Control Message: - format (B)XML according to some specified schema - contains information about stream communication - specified default behaviour (e.g.; UDP, unicast/multicast, standard port) Streaming format, e.g. binary - Sender unicasts and receiver can specify on which port (stream replication) - multicast / broadcast: sender specifies the port; need handshake for port conflict resolution Stub mandatory optional Receive stream control event Description query Send stream as multicast … Stream: > 10 Hz, unicast/multicast Sender Receive still-alive event Send stream as unicast Answer to description query Receive initiate stream request

Example Y-StubX-Stub Application (mapping) ButtonLight YXBXML network …..

Event Specification Events: General Packet Properties: [ ]

Event Specification Stream description: Use MIME types; enables many existing applications to handle streams Own data streams: define MIME type Broadcast streams: Sender starts streaming automatically Sender streams as long as alive packets are sent to it Multicast streams: Sender receives stream requests from clients Have a timeout (globally defined / queryable) Sender streams as long as alive packets are sent to it Directed Streams (unicast): not necessary

Thanks CU next time.

Stream Description Specification Stream description: encoding rate of transmission (bits/sec, events/min, frame/s,…) (also to be able to control still-alive packets)

Stub Interface Description Stub interface description: list of events list of streams state? (only through interface) foreach event: method header (name, parameter) method description (documentation) rate minimum, maximum, (average) foreach stream encoding rate of transmission (bits/sec, events/min, frame/s,…) (also to be able to control still-alive packets) ability for a certain client to subscribe