Towards Self-Adaptive Software Dipl.-Inf. Andreas Rasche Hasso-Plattner-Institute University of...

Towards Self-Adaptive

SoftwareDipl.-Inf. Andreas Rasche

Hasso-Plattner-Institute

University of Potsdam

Outline

Why Self-Adaptive Software ? Approaches for Adaptive Software – A History Development of adaptive applications using

Adapt.Net Basic Building Blocks Dynamic Reconfiguration Algorithms Runtime State Transfer: Migration & Updates On-demand deployment Tool Support for application creation

The term adaptation

Adaptation - “the process of adapting to something (such as environmental conditions)” Origin: L. Adaptare = to fit

Adaptive – “possessing an ability to change to suit different conditions”

Self-Adaptive – Automatic Adaptation without manual intervention

Dynamic World needs Adaptation Mobility

Location Awareness Power Awareness, Battery Life

CPU frequency scaling Changing Communication Network Properties Offline-/Online Computation Display

Complexity Reaction to failures

Variety of Communication Networks& Dynamically Changing Properties GSM, UMTS, WLAN, Bluetooth, Satellite

Communication, IrDA Quality of Service Parameter depend on

Geographic Position, Environmental conditions (reflection, distance to base station, countryside)

Moving users (Doppler Effect) Utilisation (number of users / cell)

Adaptation: How to integrate ? Hard-wired integration into the application

Problem: Application concurrency Application Transparent Adaptation: CODA

Legacy applications run unmodified Application Aware: Collaboration of

application and operating system/middleware

[Noble et. al. 97]

Adaptivity: Quality Measurements Agility: Speed and accuracy of detection and

reaction to changes in resource availability Resource demand different agility:

Network Bandwidth vs. Battery Power

Fidelity: Application Data Quality delivered to users compared to maximum available Video data: frame rate, image quality of frames Spatial data (topografical maps) : resolution,

feature size Adaptivity: Trade-offs among fidelity dimensions

Adaptation: Building Blocks

ObservationMonitoring

React on Changes

• Environment- Network, CPU, Battery

• Component properties• Component behavior

• Reconfiguration• Parameter • Architecture• Data

• Profiles - Map Conditions to According Configurations

Adaptation

Adaptive Control Systems

50s – 60s : Gain scheduling controller Self-adjustment of controller parameters Open-loop adaptation scheme

[Sastry and Bodson “Adaptive Control: Stability, Convergence, and Robustness”, 1994]

Adaptive Control Systems cont. Closed-loop adaptation Self-tuning controller (Kalman `58)

[Sastry and Bodson “Adaptive Control: Stability, Convergence, and Robustness”, 1994]

The Adapt.Net Framework

Dynamic reconfiguration of component-based applications

Runtime Deployment Tool-support for building self-adaptive applications Building alternative configurations: architectural

patterns Runtime Updates and Migration Monitoring infrastructure: environmental properties,

component parameter, component state Choosing configrations: Adaptation Profiles

Application Model

Based on a work of J. Magee, J. Kramer, M. Wermelinger Components: Interconnected computational entities

Provide interfaces : in-ports Require other components: out-ports

Components connected by connectors No cycles in application topology graph A transaction virtually combines a number of bidirectional

interactions between components completes in bounded time Initiator is informed about completion

A transaction T1 is dependent on a subsequent transaction T2 (T1/T2) if its completion depends on the completion of this transaction

XML-Based Configuration Description “A Configuration of a component-based

application denotes the set of its parameterized components and the connections among them.”

Configuration Description: List of components Component attributes Component ports Connectors

Configuration Infrastructure

Configuration Manager

XML-

Configuration

Description

IConfigure

IConfigure

IConfigureIConfigure

Monitoring

AdaptationProfile

AdaptationEngine

Reconfiguration Algorithm

1. Loading of new components 2. Bringing application into reconfigurable state

Application consistency must be preserved during reconfiguration

Blocking all connections: Wait for all on-going transactions to complete; don’t allow initialization of new ones

Blocking must be ordered due to dependent transactions

3. Transferring state of migrated/updated components4. Setting changed component parameters5. Reconnecting components (create connectors)6. Restarting component processing7. Removing old components

Dynamic Reconfiguration

A

B

C

compression=30

A

D

C

compression=30

B

Configuration 1

Configuration 2


A

B

C

compression=30


Configuration 2

XML-Description

1

D

2Create

new Component

3 Calculate Connections to block

Read


A

B


Configuration 2

XML-Description

1

D

Read

C

compression=30


A

B


Configuration 2

XML-Description

1

D

Read

C

compression=30

Block Connection

4

5

Block new connectionsWait for on-going to complete

6

Reconfigurable State


A

B


Configuration 2

XML-Description

1

D

Read

C

compression=30

7

Reconnect A7

Connect D


A

B


Configuration 2

XML-Description

1

D

Read

C

compression=30

8 Restart processing

Blocking a Connection Component Code calls

TransactionBegin:If(blocked) Wait(block_semaphore);processing=true;Wait(proc_semaphore);

TransactionEnd:processing=false;Release(proc_semaphore)

Configuration interface BlockConnection

blocked=true;Wait(block_semaphore)if(processing) Wait(proc_semaphore)Release(proc_semaphore)

Start of Configuration interfaceblocked=false;Release(block_semaphore);

int a = 3;

int b = 5;

Transaction.Begin();

b = calc.Add(1,b);

a = calc.Sub(a,b);

Transaction.End();

Configurable Components

Each component has to implement a configuration hook IConfigure: Start component processing Block connections Set properties Connect/disconnect out-going ports Initialization / Finalization

Implementation for IConfigure can be generated Integrated into graphical development tool of Adapt.Net

Configurable Components + AOP Aspect-Oriented Programming (AOP)

Separation of Concerns Component configuration is a separate

concern Usage of Loom.Net static aspect weaver Based on Communation between functional component

and configurtion code via .NET Reflection

public class ConfiguredFilter:Filter,IConfigure{ void SetProperty(string name, string val){ cval = Convert(val); this.GetField(name).SetValue(cval) } void Connect(string port, obj target){ this.GetField(port).SetValue(obj); } void BlockConnection(string conn){ mutex.Aquire(); } void StartProcessing(){ mutex.Release(); }}

Configurable Components

public class Filter{ [AdaptNet.Property] int compression; [AdaptNet.Connection] IViewer viewer; public void Send(byte[] data) { Transaction.Begin(viewer); viewer.Send(data); Transaction.End(viewer); }}

Configurable Components Loom.Net Aspect Codeusing AdaptNet;

[Serializable]class Configurable/*[CLASSNAME]*/:/*[CLASSNAME]*/, IConfigure{ ...

public bool SetProperty(string name, string attvalue) { FieldInfo _field = this.GetType().GetField(name); _field.SetValue(this,Convert.ChangeType(attvalue, GetFieldofThis(name).FieldType,null)); return true; }

...}

Configuration Annotations

public class Counter : MarshalByRefObject{

[Property] // Configuration Hookprivate long step;

private long count = 0; // State

public void Reset() {

count = 0;}

public void Increase(){

count += step;}public long GetCount(){

return count;}

}

public class CounterClient {

[Connection]private Counter counter = null;public void Main(){ while(true)

{Transaction.Begin("counter"); counter.Increase();Console.WriteLine("Counter

Value :" + counter.GetCount());

Transaction.End("counter"); Thread.Sleep(1000);

}}

}

CoFRA Infrastructure

Component Type Loaders

Component configurators hide implementation details of component instances during runtime

Available Component Type Loaders manage components life cycle : loading, initialization, deletion, finalization

Existing Component Type Loaders and component start Simple Object

Created using new language construct .NET Remoting Object

Registration of Remote Service Process Component Type

CreateProcess and Registration of Management Service Interface Java-based CORBA Object

Initialization of CORBA runtime, object creation and registration

Connector Architecture

Connector between components exchangeable during runtime Connector establishment implemented in IConfigure.Connect method .NET Remoting Connector

.NET-.NET Local Call Connector

Between simple Objects IIOP Connector

CORBA -.NET and CORBA-CORBA

Planned connector patterns: Tupelspace connector for online/offline configurations Webservice connector to integrate available functionality Gridservice connector to exploit available computing grids

The Component Configurator -abstracting away CORBA, Java, and .NET

IIOP .NET Remoting Channel Protocol

Mon

itorin

g

CoC

o F

act

ory

Tra

nsa

ctio

nM

ana

ger

Adaption & ConfigurationService

CoFRA

Transaction HandlingAssembly DeploymentReconfiguration Engine

Adaptation EngineMonitoring

CoFRA

Transaction HandlingMonitoring

C1CORBA

C2.NET

Remoting

C4simpleobject

C3simpleobject

IIOP .NET Remoting local

CoCo CoCo CoCoCoCo

.NET RemotingJacorb Janeva .NET Remoting

Java/Corba .NET

Java .NET

Adaptation Profiles

Architectural Patterns for Adaptive Applications Voter Pattern

Compare output of 3 objects supporting the same interface Safe update pattern

Update a running object to a new version Load balancer pattern Migration pattern

Migrate an object from one host to another Filter, Compression, Encryption Pattern Simplex Pattern

Used in Foucault’s Pendulum

Grafical Support for Pattern Integration

Pendulum Experiment Control Configurations

USB-Driver

Event Queuing

SafetyController

UserProgram

Event Duplicator

UserProgram

Configuration 1 : safety controller

Configuration 2 : user program (cold standby)

Configuration 3 : user program (warm standby)

USB

SafetyController

SafetyController

Reconfiguration and State

Reconfiguration and State - Overview

Component Updates: An Algorithm Bring components into reconfigurable state Traversal of whole object graph Member-wise investigation of nodes using

Reflection Investigation of each node for update Update specified via assembly mapping:

Specification of updated assemblies State transfer via member-wise close

Component State Transfer - Iclass People{ public string Name; public People[] friends; public IAnimal animal;}

enum Color{gray, black, white};

class Animal { string name; Color color; People[] likes;}

People[ ]People1

People2

people3

People„Andre“

friends

animal

People„Christiane“

friends

animal

People„Torsten“

friends

animal

Animal„Wuffi“

Color:black

likes

Animal„Blacki“

Color:black

likes

root

Component Update State Transfer - IIobject UpdateObjectGraph(object node, Type type, Hashtable updateMapping)

{ Type newType = GetUpdate(type,updateMapping); if(newType!=null) object updatedNode = FormatterServices.GetUninitializedObject(newType); foreach(FieldInfo _field in type.GetFields()) { if(LeafNode(_field.GetValue(node),_field.GetValue(node).GetType()) { if(updatedNode!=null) _updatedField.SetValue(updatedNode,_field.GetValue(node)); } else if(updatedNode!=null) { _updatedField.SetValue(updatedNode,UpdateObjectGraph(_field.GetValue(node),_field.GetValue(node).GetType())); } else { _field.SetValue(node,UpdateObjectGraph(_field.GetValue(node),_field.GetValue(node).GetType())); } }}

People„Torsten“

friends

animal

Animal„Blacki“

Color:black

likes

root

Animal >Animal1.dll V 2.0

People

root



People„Torsten“

friends

animal

Animal„Blacki“

Color:black

likes

root




People„Torsten“

friends

animal

Animal„Blacki“

Color:black

likes

root

Animal.dll V 1.0:Animal.dll V 2.0

No Update here



People„Torsten“

friends

animal

Animal„Blacki“

Color:black

likes

root


friends

„Torsten“

animal

object UpdateObjectGraph(object node, Type type, Hashtable updateMapping){ Type newType = GetUpdate(type,updateMapping); if(newType!=null) object updatedNode = FormatterServices.GetUninitializedObject(newType); foreach(FieldInfo _field in type.GetFields()) { if(LeafNode(_field.GetValue(node),_field.GetValue(node).GetType()) { if(updatedNode!=null) _updatedField.SetValue(updatedNode,_field.GetValue(node)); } else if(updatedNode!=null) { _updatedField.SetValue(updatedNode,UpdateObjectGraph(_field.GetValue(node),_field.GetValue(node).GetType())); } else { _field.SetValue(node,UpdateObjectGraph(_field.GetValue(node),_field.GetValue(node).GetType())); } }}



People„Torsten“

friends

animal

Animal„Blacki“

Color:black

likes

root


animal

Animal

animal



People„Torsten“

friends

animal

Animal„Blacki“

Color:black

likes

root


Animal V2



People„Torsten“

friends

animal

Animal„Blacki“

Color:black

likes

root


Animal V2

„Blacki“

„Blacki“

Color:blackColor:black

Color:black

„Blacki“



People„Torsten“

friends

animal

Animal„Blacki“

Color:black

likes

root


Animal V2

Color:black

likes

likes

„Blacki“

Color:black



People„Torsten“

friends

animal

root


Animal V2

Animal„Blacki“

Color:black

likes

Color:black

„Blacki“

Color:black

likes

GC

People

root



People„Torsten“

friends

animal

root


Animal V2

Animal„Blacki“

Color:black

likes

Color:black

„Blacki“

Color:black

likes

GC

Running in new version now

Component Update State Transfer III Cycle recognition – visited nodes:

bool firstTime;

long id = idGenerator.GetId(node,out firstTime);

if(!firstTime)

return visitedNodes[id];

Save updated nodes in visited nodes list Investigation of all arrays

Traverse all reference type members Create new version in case of base-type update Copy content of updated arrays

Component Update: Delegates

Funtion pointers in .NET Traverse all targets of delegates Multicast delegates contain multiple

delegates Updating multicast delegates:

Extract all delegates from multicast delegate Create new versions: Delegate.CreateDelegate Combine to new multicast delegate

public abstract class Delegate{ private System.Type target_type; private object m_target; private string method_name; private int method_ptr;}

Towards Self-Adaptive Software Dipl.-Inf. Andreas Rasche Hasso-Plattner-Institute University of...

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