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Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI
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Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Dec 19, 2015

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Page 1: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Reflective Middleware for Mobile Environments

Nalini VenkatasubramanianDistributed Systems Middleware GroupUCI

Page 2: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

QoS Aware Information Infrastructure

QoS Enabled WideArea Network

BattlefieldVisualization

BattlePlanning

BattlefieldVisualization

Collaborative Multimedia

(Telemedicine)Collaborative task ClientsData servers

BattlePlanning

ElectronicCommerce Distance Learning

Requirements - Availability, Reliability, Quality-of-Service, Cost-effectiveness, Security

Page 3: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Global Information Infrastructure

Proliferation of devicesSystem support for multitude of smart devices that

• attach and detach from a distribution infrastructure• produce large volume of information at a high rate• limited by communication and power constraints

Require a customizable global networking backbone.

Explore effective middleware infrastructures which can be used to support efficient QoS-based resource provisioning algorithms in a highly dynamic environment

Complex interactions • risks include non-termination, information loss, inconsistencies and incorrect

execution semantics

Page 4: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Composable Middleware

In providing such an environment, interactions between various components as well as system-level correctness must be maintained Incorporate effective mechanisms into a composable middleware

framework to ensure safety and QoS enforcement in distributed and mobile environments.

Customizable, Composable Middleware Frameworks Provide for dynamic network and system customization, dynamic

invocation/revocation/installation of services To adapt to the above dynamic changes in modern applications

and manage distributed components

Page 5: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Reflection

Provides a plug-and-play environment for enabling run-time modification of policies

An efficient technique to build composable middleware Features

Separation of concerns Introspection Flexibility, Adaptability Composition

Implies concurrent execution of multiple resource management policies

Page 6: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Why Reflective Middleware?

Wireless communication, mobile computing and real-time applications demand

High adaptability

dynamic customization of systems, services and communication protocols

Safe flexibility

constrain composition of services and protocols in order to prevent functional interference that could lead to an inconsistent state of the system

required to protect the system from security threats and failure

Cost-effective QoS guarantees

In achieving these goals, one must be careful to maintain consistency and correctness – need a semantic model (TLAM)

Page 7: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

A New Paradigm for ODS

Two Level Actor Machine (TLAM) for ODS Separate enforcement of system level requirements from application level

activities to permit customizability Basis for CompOSE|Q implementation

Layered Specifications End-to-end service specification System-level architecture specification Local behavior specification

Isolate complex interactions in well understood core services for managing composition

Page 8: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Core Services

DistributedSnapshot

Remote Creation

Directory Services

Replication

Migration

DGC

Check-pointing

AccessControl

System (Meta) Level

Application (Base) Level

Applying Core Services

Page 9: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

QoS Broker

Composability is essential in ensuring cost-effective QoS in distributed multimedia systems Safe composability of resource management services

QoS Brokers coordinate multiple activities in such systems interactions between multiple QoS sessions interactions with multiple system services

Functions of a QoS broker: Deal adaptively with incoming requests Re(configure) data to service requests

Must maintain resource allocation invariants

Page 10: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

RemoteCreation

RemoteCreation

The CompOSE/Q Framework

DistributedSnapshotDistributedSnapshot

DirectoryServicesDirectoryServices

QoSBroker

QoSBroker

MigrationMigrationReplicationReplication

RequestMgmt

DataMgmt

MessageScheduling

RequestScheduling

Data Placement De-replication

Clock SyncClock Sync

InteractionwithCore Services

CoreServices

ApplicationObjects

Page 11: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Extension of TLAM model consisting of a composable reflective communication framework (CRCF) to support customizable communication services.

Distinguishes and handles different types of messages and communication protocols

Integrates QoS parameters into resource management and message handling processes. It provides High-level communication services through composition of basic

protocols

Dynamic installation of protocols

4 levels of message customization

Efficient implementation

Communication Model

Page 12: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

CRCF Architecture

Communication manager

Pool-actorsi k l p n... ... ... ...

. . .

messenger

down

upin

out

messenger

downup

in

out

NodeBase actor m

and its messenger

Base actor 1and its messenger

m 1

CommunicationProtocol 1

. . .CommunicationProtocol n

Page 13: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Compose|Q Architecture (cont…)

SendPot

ReceivePot

Router

DedicatedMessageReceiver

RemoteMessageReceiver

NodeManager

Postman

CommunicationManager NodeInfoManager

Directory

MessageQManager

.

.

.

MessageQ aid67math2

34brow5

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56ferg6

query

querystart

register

spawn

Incomingmessages

Outgoingmessages

Node

Page 14: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

QoS-based Resource Provisioning

Degree of network awareness that middleware and applications must have to deal with network conditions

Resource provisioning algorithms utilize current system resource availability information to ensure that applications meet their QoS requirements

Additional Challenges In highly dynamic (e.g. mobile) environments, system

conditions are constantly changing

Page 15: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

QoS-provisioning in Mobile Environments

Directory Service as a core service For QoS Based Resource Management in Mobile Environments

State information enables decision making for resource provisioning - e.g. Routing, Scheduling and Placement

Maintaining accurate and current system information is important to efficient execution of resource provisioning algorithms

Global Approximations of System State• Information Acquisition• Directory Organization and Manipulation• Scalability: Hierarchical directory organization + Caching

Goal: Ensure effective utilization of network and server resources while tolerating imprecision

Page 16: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Resource Management Tasks

Scheduling Given a client requests R(Ci, Vi, Qi), schedule the request to the server

node that satisfies the QoS constrains.

Routing For an OD pair, choose a path among feasible paths to satisfy the QoS

requirements, maximize the overall network throughput.

Placement Predict the future requests based on history and locality, reallocate

resources to the server node to maximize the overall throughput.

Page 17: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Combined Path and Server Selection

lDLlavailBWl ,:

s1

s2

s3

O O

s1

s2

s3 CD

lDLnrlUFl ),,,(:

sRSPnrsUFs ),,,1(:

Left: Graph G:<N,E> with the client requesting at point O and a set of feasible servers S: s1,s2,s3.Right: Graph G’:<N’,E’> extended from G, adding a point CD and artificial edges e1,e2 and e3

Page 18: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Dynamic Service Brokering for Mobile Environments

Goal To provide information good enough for resource provisioning

tasks such as admission control, load balancing etc.Need an information collection mechanism that is :

• is aware of multiple levels of imprecision in data• is aware of quality requirements of applications• makes optimum use of the system (network and server)

resources Collected Parameters

Network link status, Data server capacity (Remote disk bandwidth, Processor capacity)

Page 19: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

AutoSeC Framework

Directory service

Server

Router

Client

Get inf

ormati

onFeedback

Update directory

Dynamic Service Broker

Information Collection Module

System snapshot based collection

Static interval based collection

Throttlebased collection

MA modelbased collection

Resource Provisioning Module

Load-basedserver selection

Combined path and server select ion

Network path provisioning

Proximity-basedserver selection

Network Monitoring Module

Push modelmonitoring

Pull modelmonitoring

Req

uest

with

QoS

req

.

Prob

ing

para

met

ers

Probing results

Status query/reply

Status query/reply

Setup

path

Setup

path

Request rejection

Page 20: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Data Placement in Mobile Environments

Design load management mechanisms that Provide fault tolerance, i.e. a high degree of data

availability and Ensure effective resource management Ensure QoS for admitted clients

Data availability provided via replication and intelligent data placement mechanisms. Predictive Fault Tolerant Data Placement

Mechanisms

Page 21: Reflective Middleware for Mobile Environments Nalini Venkatasubramanian Distributed Systems Middleware Group UCI.

Future Work (cont…)

Further study on the use of Directory Services: Scalability analysis/techniques Security issues, service discovery, store for binaries, data etc.

Provision of an Access Control Model for security: Capability-based architecture Object-level granularity with flexibility in implementing custom policies

depending on the applications being supported Inter-domain security based on various security levels. Composability issues with existing core services (Remote Creation, Snapshot,

etc.), semantic model. Support for Real-time applications:

Soft real-time guarantees for actors with such requirements