1. Grid Message Infrastructure
Edinburgh e-Science Centre December
PTLIU Laboratory for Community Grids
Geoffrey Fox, Shrideep Pallickara
Computer Science, Informatics, Physics
Indiana University, Bloomington IN 47404
2/21/2019
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2. Some Basic Observations/Goals
Grids manage and share asynchronous resources in a rather centralized fashion
Peer-to-peer networks are “just like” Grids with different implementations of services like registration and look-up
Web Services interact with messages and Everything will be a Web Service
Microsoft Office will be a WS?
Computers are fast and getting faster. One can afford many strategies that used to be unrealistic
Software/Application-level message processing/routing sensitive to performance information
Uniform messaging framework for Middle-tier, “High performance layer”, Multimedia (audio-video) etc.
2/21/2019
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3. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Deduction?
Grids or P2P Networks consist of a sea of message-based Services
Services inject and extract messages whose transport and manipulation is support by a logically distinct “MessageGrid” of brokers/routers supplying “Grid Message Layer”
The message brokers support adaptive routing, filtering, workflow
They have publish/subscribe queued connection semantics
They separate logical and actual transport
They form a federated XML database and support asynchronous collaboration
They process real-time messages in about a millisecond and support synchronous collaboration
NaradaBrokering is a prototype of this idea
2/21/2019
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4. Peer to Peer Grid Peers Peers
Database
Database
Peers
Service Facing Web Service Interfaces
Event/ Message Brokers
Peer to Peer Grid
Peers
User Facing Web Service Interfaces
Peer to Peer Grid of Resources supported by internal “MessageGrid” of message or event brokers
Events are “just” Time-stamped messages
2/21/2019
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5. Event (Message) Service
Shared Input Port (Replicated WS) Collaboration
Collaboration as a WS Set up Session with XGSP
Web Service F I U O R
WS Display
WS Viewer
Master
Web Service F I U O R
WS Display
WS Viewer
Event (Message) Service
Other Participants
Web Service F I U O R
WS Display
WS Viewer
2/21/2019
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6. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
NaradaBrokering
Based on a network of cooperating broker nodes
Cluster based architecture allows system to scale to arbitrary size
Originally designed to provide uniform software multicast to support real-time collaboration linked to publish-subscribe for asynchronous systems.
Now has four major core functions
Message transport (based on performance measurement) in heterogeneous multi-link fashion
General publish-subscribe including JMS & JXTA and support for RTP-based audio/video conferencing
Filtering for heterogeneous clients
Federation of multiple instances of Grid services
2/21/2019
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7. Role of Event/Message Brokers
We will use events and messages interchangeably
An event is a time stamped message
Our systems are built from clients, servers and “event brokers”
These are logical functions – a given computer can have one or more of these functions
In P2P networks, computers typically multifunction; in Grids one tends to have separate function computers
Event Brokers “just” provide message/event services; servers provide traditional distributed object services as Web services
There are functionalities that only depend on event itself and perhaps the data format; they do not depend on details of application and can be shared among several applications
NaradaBrokering is designed to provide these functionalities
MPI provided such functionalities for all parallel computing
2/21/2019
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8. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Note on Optimization
Note in parallel computing, couldn’t do much dynamic optimization as aiming (in MPI) at microsecond latency
Natural to use hardware routing
In Grid, time scales are different
100 millisecond quite normal network latency
30 millisecond typical packet time sensitivity (this is one audio or video frame) but even here can buffer frames on client (conferencing to streaming)
1 millisecond is time for a Java server to “think”
Jitter in latency (transit time) due to routing, processing (in NB) or packet loss recovery is important property
Grid needs and can tolerate significant dynamic optimization
2/21/2019
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9. Architecture of Message Layer
Need to optimize not only routing of particular messages but classic publish/subscribe problem of integrating different requests with related topics (subscribe to sports/basketball/lakers and sports)
Related to Akamai, AOL … caching and Server optimization problem
Hypercube of NB Brokers (logical
not physical)
N≈100 for
Distance
Education
Scale to billions of grid nodes?
1-> N Grid Nodes
2/21/2019
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10. Performance in Message-based Architecture I
Satellite UDP
Firewall HTTP
Dial-up Filter A B1
Hand-Held Protocol
Fast Link
Software Multicast B2
Useful analogies with transportation grids and parallel computing
In traveling from cities A to B (say 3 separate passengers), one chooses between and changes transport mechanism at waystations to optimize cost, time, comfort, scenic beauty …
Waystations are now NB brokers where one chooses transport protocol
Able to choose between car, type of car, plane, train etc
Able to dynamically create waystations to cope with problems and acts as hubs for multicast messages
Knows about traffic jams and can assign the “HOV lane” B3
2/21/2019
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11. Performance in Message-based Architecture II
Application level QoS – can optimize among managed streams (audio versus video) using performance subsystem
This is just a variant of the NP complete load balancing problem of parallel computing where all reasonable heuristics worked
Load-balance in Space-time (strings) not just Space (particles)
“Performance” needs to measured carefully as includes QoS
I delayed shared application update to ensure audio quality and filtered image to lower resolution
So “application” has changed to satisfy performance constraints
2/21/2019
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12. NaradaBrokering Communication
Applications interface to NaradaBrokering through UserChannels which NB constructs as a set of links between NB Broker waystations which may need to be dynamically instantiated
UserChannels have publish/subscribe semantics with XML topics
Links implement a single conventional “data” protocol.
Interface to add new transport protocols within the Framework
Administrative channel negotiates the best available communication protocol for each link
Different links can have different underlying transport implementations
Implementations in the current release include support for TCP,UDP, Multicast, SSL and RTP. HTTP, HTTPS support will be available in Feb 2003 release.
Supports communication through proxies such as iPlanet, Netscape and Apache.
Supports communication through firewalls such as Microsoft ISA, Checkpoint.
2/21/2019
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13. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Sender/receiver/broker - (Pentium-3, 1 GHz, 256 MB RAM). 100 Mbps LAN. JDK-1.3, Red Hat Linux 7.3
2/21/2019
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14. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
H.263 video file Average bit-rate of 600Kbps. Frame-rate of 30 frames/sec
Jitter J = J + (|D(i-1, i)| - J)/16
Jitter J is defined by the RTP RFC as the mean deviation (smoothed absolute value) of the difference D in packet spacing at the receiver compared to the sender for a pair of packets
Jitter represents the jitter value up until that point in the sample.
2/21/2019
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15. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
JMS Performance: Transit Delay and Std Deviation (NaradaBrokering & SonicMQ)
Transit Delay
Standard Deviation
NaradaBrokering is Java Message Service (JMS) compliant
Applications ported include
Anabas – JMS based distance education system.
OKC – Online Knowledge Center project at IU
2/21/2019
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16. uri="http://www.naradabrokering.org" email="gcf@indiana.edu"
Futures
Redo performance with insight of this workshop – we desperately need a distributed testbed to support scaling tests
Test Scaling with construction of dynamic NB broker network (what is best topology? Hypercube like?)
Understand clients per broker for various applications including large multimedia sessions
Complete transport/performance infrastructure
Develop nifty “load balancing heuristics”
Implement Web Service message-based Security
Understand better how to implement distributed XML database
Develop NB to support federation of Grid Services
Generalize Filtering mechanism
Download from
2/21/2019
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17. NaradaBrokering as an XML database
NB is inevitably a distributed XML database supporting real-time update and access (JMS uses SQL like syntax)
Performance data
Event Logging
Published “properties” of publish/subscribe messages
Publish as XML topic; subscribe using XQuery?
We use NB as a simple XML database for News groups and other “XML nuggets” see
XML Instance==Message; what is difference between a message and a database record except performance but Moore’s law is rewriting rules here
Subscribe a real database (Oracle) to all topics for reliable storage
2/21/2019
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18. Federation of Services
If you have a service – Notification (as with Grid or JXTA advertisements), Search, Scheduling, Audio-Video conferencing ….
With a standard which client and server components
Then can build a “server” that services all clients
Alternatively can hierarchically consider collection of existing Server-client domains
IBM or Globus OGSA islands
Sun Grid Engine Schedulers
Polycom/Access Grid A/V sessions
Enterprise Search Engines
Federation links islands together
JXTA Search has XML specified federation approach – will try to include and generalize as a NaradaBrokering federation framework
DoD High Level Architecture HLA does this for simulation
NB Hub
2/21/2019
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