1 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies ECOOP 2000 Workshop on Quality of Service in Distributed Object Systems June 13, 2000 Cannes, France Christian Becker John Zinky

2 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies Distributed Object Middleware has Emerged to Solve Heterogeneity and Distribution Problems Middleware makes programming distributed applications easier Standard programming interfaces hide platform and system dependencies Standard protocols, e.g., message formats, allow applications on different systems to interoperate Middleware provides higher level, application oriented programming building blocks Host 2 Impl Host 1 Impl Applications Host 2 Simulation Distributed Object Middleware Impl IDL Collaborative Planning IDL Hosts/Systems Workflow

3 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies The Problem: Wide-Area Distributed Applications Are (Still) Hard to Build and Maintain WANs resources are dynamic, unpredictable, and unreliable Different user communities have different usage patterns Quality of Service (QoS) requirements change Administrative constraints on resources change The same function can be done in multiple ways that use different resource mix Host1 Client1 Host2 Client2 Host4 Client3 Object Resource Constrained Wide Area Network LAN Host3 Client4

4 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies PPP The Simple Abstraction of TCP/IP Networks Allowed Networks and Applications to Grow Independently FTP Telnet WWW X.25 New Networking Technologies were added without the need to understand anything about applications beyond their use of TCP/IP New Types of Applications were added without the need to understand anything about networks beyond the Sockets API Ethernet TCP/IP *Dave Clark from a talk at MIT circa 1996

5 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies But Applications and Networks could be Implemented More Efficiently, if More Information were Available Ethernet TCP/IP QoS Video Conference ATM RSVP Multicast Some Applications need guarantees on the Quality of Service (QoS) from the network Networks could make better optimizations if they knew the application’s requirements. Research is ongoing on how to widen TCP/IP choke point to exchange QoS information

6 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies Distributed Objects with QoS Extensions is a Powerful Abstraction Layer on which to Build Applications DOS + QoS Collaborative Planning WorkFlow Simulation Application’s beyond Multimedia Distributed Objects are the first abstraction layer that unifies CPU, Storage, and Communications QoS Communication interface needs to be hidden from applications. It is too complicated It is changing too quickly Multimedia QoS issues are also being addressed for CPU and Storage Unix QoS CPU Realtime SQL QoS Storage Realtime TCP/IP QoS Comm WinSock

7 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies QoS is well-controlled Client and Object are at the same location QoS is unruly across the network How can we resolve this? Who is Responsible for the The QoS Problem? ClientObject ClientObject Network ClientObject ClientObject ClientObjectQoS Gateway

8 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies Current ORBs Must be Extended for Adaptive QoS Interface and Control Logical Method Calls Bandwidth Control Status Collection Configuration Management Client HostNetwork Operating System Middleware Applications Client Servant Host Operating System Middleware Applications Object Resource Managers Resource Managers Network Based Services Property Managers Policy Managers... Event Services Name Services... QoS Adaptive Layer Distributed Objects COTS ORB Schedulers Distributed Objects COTS ORB Schedulers Specialized Protocols Group Communications Specialized Protocols Group Communications

9 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies What Support Should be Given to Different Roles ClientNetwork Server Application Developer Mechanism Developer Client ORB Proxy Specialized ORB Object ORB Proxy Specialized ORB Network Mechanism/Property Manager Logical Method Call QoS Developer?

10 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies Organize System Properties –Observe –Summarize imperfect observations –Translate –Actively negotiate Alternative Behavior –Change policy –Control resources Emit Events –Reevaluate observations –Change reservations Recover From Errors –Mask undesirable behavior Dispatch X Behavior Y Behavior Z Behavior Enforce Object Resources System Properties User Client Managing QoS is a Feedback Loop for Changing Behavior Based on System Properties Environment Server

11 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies Questions What kind of QoS is being handled? –Realtime, Dependability, Security, Resource Management What roles are supported? –Application programmer, Mechanism Designer, System Administrator How is QoS adaptability reused? –Service, Library, OS extension, Programming Language How is QoS requirements specified? –Specialized Language, QoS Translation, Where does QoS adaptability occur? –Above, In, or Below the Middleware/ORB What time horizons does Adaptability occur? –Design time, System Configuration, Connection time, Invocation time

12 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies Workshop Objectives Collect a common understanding of QoS Discuss dependencies of QoS on different layers, – e.g. below, in, above ORBs The QoSDOS Reference Model for Provisioning QoS in Middleware?

13 06/00 Questions 10/6/2015 QoS in DOS ECOOP 2000John Zinky BBN Technologies Sessions 9:00 Overview 9:15 QoS Support in and below ORBs 10:00 Break 10:15 QoS Specifications 12:00 Lunch 1:00 QoS Frameworks "above the ORB“ 2:15 Break 2:30 QoS Frameworks "above the ORB“ (cont) 4:00 Break 4:15 QoS Streaming in OO, QoS enabled applications 5:15 Close