Collaborating Globally

1. Collaborating Globally … and going via Space too!

2. The network is about people • Want to connect people. • People exchange information in a wide range of ways • Methods depend on personalities • Networking technology determines capabilities

3. The first collaborative network tool • E-mail! • Simple exchange via a very simple set of protocols • Many different ways of moving e-mail around for different kinds of networkin. SMTP used a lot for internet. • Different ways to read mail. From Netscape to your phone!

4. E-mail ain’t so sad • Modern versions support attachments • Flexible way of exchanging information • Delivered asynchronously -- bridges across space and time. • Delivery can work over very old technologies, like HF radio, or over the latest space communication systems. • Interplanetary mailboxes!

5. How e-mail works • Mail client • Connects to a mail delivery server and delivers e-mail, often using Simple Mail Transfer Protocol. • Reads mail from a mailbox server, often using POP3 or IMAP. • Mail delivery • Protocol using Mail Transfer Agents to move mail from one place to another.

6. Text messenging • Simple version of e-mail concepts • Often one way, without a mailbox to review on the remote server • Also light, easy to implement • Great for short communication, emergencies, dates!

7. Text chatting • Also old! Comes from BITNET and other old systems, including HF bulletin boards! • Based on delivery of messages to a server, and then out to one or more users. • Can be simply peer-to-peer, like ICQ, Messenger, Yahoo. • Can be complex, interserver, like IRC, MUDs, MOOs.

8. Next-Gen text chatting • Cellphones • PDAs • Pocket PC • Blackberry devices • You name it! • It’s social!

9. Sharing files - the big need • If you need to work, you often need to share large amounts of content. • The previous tools often make that a little tough, though possible. • Need to structure anything complex. • Windows, Apple file sharing is local, unless you go VPN.

10. File transfer systems • The Web! Basically one big file transfer system, with a nice front end. Invented for black hole physicists! • File Transfer Protocol: the Internet’s standard file transfer process. Comes in secure versions. • NFS: exporting a file system via the Internet.

11. Other file transfer • CVS - more for sharing text-based content or software source code. • ICQ file transfer - synchronous • Netmeeting file transfer - ditto • And so on! • Napster!

12. Whiteboarding

13. Highly synchronous forms of communication. Allows one to communicate the same way as you would in a classroom. Also can share programs, build solutions, at the same time. Not used as much as it could be. Whiteboarding and application sharing

14. Traditionally high-bandwidth, big computers PolyLAB has systems that run on handheld computers. Important for disaster response. Great for science work, and problem diagnosis in the field. Whiteboarding for the world

15. Videoconferencing

16. Peer to Peer or server based. Netmeeting, one to one or many to many (if you buy the expensive version). Low resolution. Multicast Backbone: video transmission based on UDP “multicasting”. High speed, resolution. Expensive infrastructure. Videoconferencing technology

17. Phone is a pretty good collaborative tool! Can now have telephony over IP: Netphone, dialpad, and so on. Can have voice over IP without the telephone bit: Netmeeting, multicast backbone audio. Convergence! Telephones, Telephony

18. Can have Java and other applications on web page Can provide chatting services, file sharing Forms/Java/Javascript can provide interactive access to database systems. Increasingly interactive. Web applications

19. TeleLearning: you collaborate with your teachers TeleMedicine: you collaborate with your doctor TeleSurgery: your doctor collaborates with your internal organs! Remote control: you control robots, access remote data, and so on. Other collaborations

20. Communicate via a spacecraft, from one point on Earth to another. Can have spacecraft in low Earth orbit. Needs LOTS of them, and they move in the sky. Can have spacecraft in geosynchronous Earth orbit: Only need a few, and they don’t move. Works just like wireless networking. Convert packets to radio signals. Space!!!!!!!!!!

21. Can send normal telephone signals over the satellite link. Can use TDMA-type systems to put phone and data, and other services over the satellite link. Can use equipment to send ATM and IP networking directly over the link. Can message across the link. Space networking

22. TCP/IP waits for signals to come back to decide if packets are being lost. Waits a certain amount of time - time designed for standard networks. Assumes any problems with lost packets are due to congestion (too many packets), and slows down! The problems with TCP/IP

23. If a computer stores B bits, and has to wait T seconds to hear back, it can only transmitB bits every T seconds, so max data rate is R=B/T. B=R*T. Most Windows and Apple boxes are set to B=8,192 bytes = 65,536 bits = 64 Kb. Average internet connection, T = 1/8 second. Max data rate = 512 Kbps! ASDL? Bandwidth-delay product problem

24. Round trip time from geosynchronous Earth orbit (GEO) is T = 1/2 second. Max data rate, per connection, on normal computer = 128 Kbps! Independent of how fast the connection is (can be 10 Mbps). Only a property of TCP/IP. Going geosynchronous

25. Not use TCP/IP -- UDP for video is used a lot, even on the Internet. Advanced space protocols being discussed. Can retune the computer -- edit the registry on Windows Change B Change other parameters to keep data rate up. Changes need to be on both ends! Solutions

26. Need bigger computers to have larger buffers Need somebody to retune machines. Who does it in remote communities? Retuning reduces performance of local networks. Different bandwidth needs different buffer sizes. Needs an expert. Issues