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                   B O S T O N   U N I V E R S I T Y
                                       
                      Computer Science Department
                                       
                          C O L L O Q U I U M

    The Future of Internet Applications: Enabling Network-Adaptive Design

                             Srini Seshan
			     
                     IBM T.J. Watson Research Center

 			  Monday,  March 27 
			      11:00 AM
                       (Coffee served at 10:45AM)

                                       
                         Seminar Room / MCS 135
                                       

    As the Internet continues to become more heterogeneous, applications must
    adapt to network conditions to improve the user experience. There are two
    modes of adaptation: over long time scales (on the order of minutes) and
    over short ones (on the order of connection round-trip times). On long time
    scales, applications need performance estimates to complete tasks such as
    selecting between mirror sites or choosing among various file formats. On
    shorter time scales, applications need information about the current
    congestion state of the network to decide when and what data to transmit.

    In this talk, I will describe two systems that address these needs. The
    SPAND (Shared PAssive Network performance Discovery) system is designed to
    provide applications with predictions about the performance of transfers
    between hosts. SPAND passively monitors the networks in a local domain and
    collects performance statistics about transfers between the local domain
    and distant hosts. The system uses the performance statistics of past
    network transfers to predict future performance. The CM (Congestion
    Manager) system helps applications monitor and adapt to the progress of
    active transfers. CM achieves this by exposing an API that enables
    applications to learn about network characteristics, pass information to
    CM, and schedule data transmissions. This API provides a simple way for
    applications to perform correct congestion control and enables applications
    to adapt their transmissions to the current congestion state of the
    network.

    The combination of SPAND and CM provides applications the necessary tools
    to adapt their behavior to the state of the network. Various adaptive
    applications have been built using these systems. In this talk, I will also
    describe an application that uses SPAND to control the transcoding of data
    to match network speeds and an implementation of TCP that uses CM to
    perform congestion control.

    Additional information about SPAND is available at 
    http://www.seshan.org/spand and information about CM is available at
    http://wind.lcs.mit.edu/projects/cm. SPAND was developed jointly with Mark
    Stemm who was a graduate student at UC, Berkeley and CM was developed
    jointly with Prof. Hari Balakrishnan at MIT.


    Host:  John Byers (byers@cs.bu.edu)

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