Mobile Reliability Challenges

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Mobile Reliability Challenges Robert V. Binder

ISSRE 2004

November 2, 2004

© 2004 mVerify Corporation 2

Overview

21st Century IT Trends

Mobile Technology Crisis

Test Effectiveness Levels

Level 4 Case Study

Reliability Arithmetic

Test Performance Envelope

Conclusion


The New IT Reality

Last 25 years

Information driven society

New and better ways to do old things

Focused, skilled interaction

Tethered

Next 25 years

User population 100x

New things

Persistent partial attention

Mobile, ubiquitous

Very low visibility, very high failure impact


The New IT Reality: Ubiquity

Cheap fat pipes everywhere Optical backbone + wireless MAN, LAN, PAN WiMax: 802.16, 802.20 Ad-hoc Mobile networks

Cycles and storage Moore's law Watts per MIPS

No more shrink-wrap Application service provider/subscription model Web services, ultra large databases Grid computing

Converging user device form factor Cell phone + PDA + pager + Pocket PC + ... D-2-B Interfaces – 5 years?

About 10x every five years!


Robert’s Afternoon

Robert’s Afternoon: Seamless Mobility

courtesy Motorola, Inc.

This shows Motorola’s high-level vision.

It is not a product roadmap or indicative of any specific product/service offering.


The Unchanged IT Reality: Software

The Next Big Thing

Extreme Programming ?

Aspect-oriented languages ?

Model-driven Architecture ?

Still no Silver Bullet

Subtractive component reliability

Design limited to human ability and organization

Low-fidelity test suites aren’t effective

Bug barrier: 5/KLOC (pre-test)

any language, any process


Mobile Technology Challenges

Testing wired apps difficult and expensive

20% to 50% of all software development $ on testing

Available test automation technology 10+ years old

Annual cost to U.S. of inadequate testing: $56 billion

Testing mobile apps much harder:

Connectivity: “Can you hear me now?”

Mobility: location-based services

Scalability: at least 10x web user population and mobile

Security: always on, always hackable

PLUS assure functionality, performance, and integration

Mobile App Fault Space Much Bigger


Current software technology

CANNOT

achieve reliable mobile apps

A True Crisis


What Can Testing Do?

Test Performance

Effectiveness (reliability/quality increase)

Efficiency (average cost per test)

Levels

1: Testing by poking around

2: Manual Testing

3: Automated Test Script

4: Model-based

5: Full Test Automation

Each Level 10x Improvement


Level 1: Testing by Poking Around

Manual

“Exploratory”

Testing

•Low Coverage

•Not Repeatable

•Can’t Scale

•Inconsistent System Under Test


System Under Test

Manual

Test Design/

Generation

Test Setup

Level 2: Manual Testing

Manual

Test Input

Test Results

Evaluation

•1 test per hour

•Not repeatable


System Under Test

Manual

Test Design/

Generation

Test Setup

Level 3: Automated Test Script

Test Script

Programming

Test Results

Evaluation

•10+ tests per hour

•Repeatable

•High change cost


System Under Test

Model-based

Test Design/

Generation

Test Setup

Level 4: Automated Model-based

Automatic

Test

Execution

Test Results

Evaluation

•1000+ tests per hour

•High fidelity

•Case study


Level 4 Case Study

Leading financial market

3 million transactions per hour

15 billion dollars per day

650 KLOC Java, Distributed Services …

System Test Process & Environment

Automated, Model-based

Executable operational profile

Simulator generates realistic unique test suites

3 years, version 1.0 live Q4 2001

1,000 to 750,000 unique tests per day


Model-based Testing

Extended Use Case

Mode Machine

Invariant Boundaries

Stealth Requirements Engineering


Simulator

Discrete event simulation

Prolog implementation (50 KLOC)

Rule inversion

Load Profile

Time domain variation

Orthogonal to operational profile

Each event assigned a "port" and submit time


Automated Run Evaluation

Oracle accepts output of simulator

About 500 unique rules

Verification

Splainer – result/rule backtracking tool

Rule/Run coverage analyzer

Comparator

Extract transaction log

Post run database state

End-to-end invariant


Results

Revealed about 1,500 bugs over two years

5% showstoppers

Five person team, huge productivity increase

Achieved proven high reliability

Last pre-release test run: 500,000 events in two hours, no failures detected

No production failures


System Under Test

Level 5: Total Automation

Automated

Test Setup

Automated

Test Results

Evaluation

Automatic

Test

Execution

•10,000 TPH

•Oracle Problem

Model-based

Test Design/

Generation


AMATE: Level 5 for Mobile Apps

Advanced Mobile Application Test Environment

NIST/ATP funded R&D

Highly realistic end-to-end mobile testing

Generate and control Signal variation related to mobility

User behavior related to mobility

Traffic related to mobility

Model-based

Trial Use Q2 2005


Reliability Arithmetic

Reliability: probability of non-failure

MTTR: mean time to

recover, repair, restart …

Availability: percent up-time

Availability = 1 / 1 + (MTTR Reliability)

99.999% availability = 5 min downtime per year

“Five nines”


Reliability (Failures/million hours)

Availability, 6 min MTTR

Some Reliability Data Points

NT 4.0 Desktop 82,000 0.999000000

Windows 2K Server 36,013 0.999640000

Common Light Bulb 1,000 0.999990000

Stepstone OO Framework 5 0.999999500

Telelabs Digital Cross Connect 3 0.999999842


Test Automation Envelope

5 Nines

4 Nines

3 Nines

2 Nines

1 Nine

1 10 100 1,000 10,000

L 4 Case Study

Level 5

AMATE

Reliability (Effectiveness)

Productivity: Tests/Hour (Efficiency)

L 2 Manual

L 3 Scripting


The Mobile Reliability Challenge

Mobile App Fault Space Bigger

Connectivity: “Can you hear me now?”

Mobility: location-based services

Scalability: large and mobile

Security: always on, always hackable

PLUS assure functionality, performance, and integration

What can be done? Test performance envelope the same

Test budget the same


Scenario: Manual Testing

Level 2 manual testing

Mobile app fault space 10x bigger

Reliability slips to Level 1

1 10 100 1,000 10,000

5 9s

4 9s

3 9s

2 9s

1 9s


Scenario: Improve Efficiency 10x

L2 Manual improves 10x to L3 Scripted

L3 Scripted improves 10x to L4 Model-based

Expect same average reliability

1 10 100 1,000 10,000

5 9s

4 9s

3 9s

2 9s

1 9s


Scenario: Mobile 5 Nines

Increase L4 efficiency 10x Realistic mobile

environment Realistic loading Realistic

functional profile Model-based and

automated

AMATE

Expect mobile app 5 Nines

1 10 100 1,000 10,000

5 9s

4 9s

3 9s

2 9s

1 9s


Model-Based mobile testing

CAN

achieve reliable mobile apps

Conclusion


Q & A

Mobile Reliability Challenges

Technology

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