Network Services Susanne Lefvert lefvert@mcs.anl.gov University of Chicago
Outline • Introduction • Limitations of Current Architecture • Enhanced Architecture • Network Services • Example: Debug Service • Exercises
Introduction • Enable users to seamlessly participate in AG meetings. • Middleware • Stream processing Network
Heterogeneous Environment • Devices • VIC, RAT, Quicktime, Realplayer, H.323 clients… • Formats • Different encodings, sample rate … • Network • Available multicast, bandwidth … • Preferences • Surgery: Want high resolution video • Presentation: Want lower resolution video
Class Diagram VenueClient AGNodeService AGServiceManager AGServiceManager AGService AGService AGService AGService
Capability • Role • CONSUMER • PRODUCER • Type • AUDIO • VIDEO • TEXT Not Sufficient
Sequence Diagram Mismatch can not be resolved
Service capability description limited User preferences do not exist No resolution to capability mismatch Limitations of Current Architecture
Schema including: Service capability Device (sample rate, sample size, sample format…) Encoding (name, quality, bit rate, size…) RTP (payload type, profile…) Node capability Available bandwidth, multicast, firewall… User preferences Preferred quality, bandwidth… Enhanced Capabilities
VenueClient User Preferences AGNodeService Node Capability AGServiceManager AGServiceManager AGService AGService AGService AGService Capability Capability Service Capability
Sequence Diagram
Network Service y = Transform(x) x y x y
Matcher 1. Venue Stream Capabilities Node Capabilities Mismatch 2. Stream Capabilities Node Capabilities Network Service Match Match
Network Service • Registers with a venue or a venue server • Includes input and output capabilities • Provides a Transform() method • Has an interface for remote configuration • Emits heartbeats
Example: Video Selector GOAL: Reduce bandwidth EXAMPLE: Connect from home
Example: Video Selector Multicast Multicast Video Selector
Example: Transcoder GOAL: Enable more devices EXAMPLE: H.323 client
Example: Transcoder Linear16 pcmu Multicast Audio Transcoder Multicast
Implementation Details • Add new capabilities (ServiceCapability) to your node services. • Create a network service matching the new capabilities of the node services. • Connect the network service to the venue • Connect your node services to the venue
Network Service Base Class • Initiates the AG environment • Hides SOAP details • Includes logging • Communicates with venues • Includes the Transform() method
Service Capabilities • Describe input and output • Same as node service capabilities • Used during capability negotiation and network service matching
Example: Video Selector class SelectorNetworkService(AGNetworkService): def __init__(self, name): AGNetworkService.__init__(self, name, 'Selector', '1.0') # Create capabilities inconfig = {"Encoding":"H261"} inCap = ServiceCapability(name, 'consumer', 'video', inconfig) outconfig = {"Encoding":"H261", "StreamSelection":"On"} outCap = ServiceCapability(name, 'producer', 'video', outconfig) self.inCapabilities = [inCap.ToXML()] self.outCapabilities = [outCap.ToXML()] # Manage processes self.processManager = ProcessManager() # Start the soap interface self.Start(self) def StopTransform(self, streamList): # Stop video selector self.processManager.TerminateAllProcesses()
Example: Video Selector def Transform(self, streamList): # Start video selector newStreams = [] for s in streamList: cap = s.capability cap.xml = self.outCapabilities[0] # Create new stream description location = MulticastNetworkLocation("224.2.2.2", 8000) ns = StreamDescription("Video Selector Stream", location, cap) newStreams.append(ns) # Create process arguments fromaddr = s.location.host fromport = s.location.port toaddr = ns.location.host toport = ns.location.port executable = os.path.join(os.getcwd(), "Selector.py") options = [executable, fromaddr, fromport, toaddr, toport, 1] # Start process self.processManager.StartProcess(sys.executable, options) return newStreams
Example: Video Selector Consumer Service def __SetCapabilities(self): oldCap1 = Capability( Capability.CONSUMER, "video" ) # Create new capabilities to include in old capability format val = "Off" for c in self.configuration: if c.name == "video selection": val = c.value config = {"StreamSelection": val, "Encoding":"H261"} nsc1 = ServiceCapability('Video Consumer Selector', oldCap1.role, oldCap1.type, config) oldCap1.xml = nsc1.ToXML() self.capabilities = [oldCap1]
Exercises http://www.mcs.anl.gov/fl/research/accessgrid/documentation/tutorial/AGTk_2.4 Exercise 6 – Network Services: • Testing the video selector service • Running a debug network service • Creating a custom SOAP interface for configuration • Creating a client for connecting to the custom SOAP interface
Exercises 1: Video Selector • Install the modified node services with new capabilities. • Enter the venue the video selector is connected to • Switch between video selection on and off
Exercises 2: Debug Service • Install the two modified node serviceswith new service capabilities • Modify the Debug Network Service • Connect the network service to a venue and enter with the two node services to trigger matching.
Exercises 3: SOAP Interface • Add a SOAP interface to the debug service • Create a client that can communicate remotely with the debug network service SOAP interface.
