Post on 05-Jan-2016
description
COTS Testing
Diff. With in-house components
Interface (pre and post conditions) are not clearly specified.
No Arch. and code. Black boxes to component user.
Why use COTS
Why COTS Testing
Failure of Ariane5.
• explosion resulted from insufficiently tested software reused from the Ariane 4 launcher.
COTS Evaluation and selection
Why rigorous evaluation of COTS?
Large number of alternative products. Multiple stakeholders. Large number of Quality criteria. Compatibility with other products.
Why evaluation difficult
Large number of evaluation criteria. Different opinions are usually encountered among
different stakeholders. Evaluation criteria are not easily measurable at
evaluation time. Gathering relevant info. is prohibitively expensive. COTS market is changing fast, evaluation must be
performed several times during lifecycle. Evaluation deals with uncertainty info.
AHP Technique
Originally designed for economic and political science domains.
Requires a pair wise comparison of alternatives and pair wise weighting of selection criteria.
Enables consistency analysis of comparisons and weights, making possible to assess quality of gathered info.
AHP Technique (contd.)
Allows alternatives to be measured on a ratio scale,we can determine how much better an alternative compared to other.
Practically usable if number of alternatives and criteria are sufficiently low, because comparisons are made by experts.
Selection in practice
Follows three stages Informal screening for a set of requirements
using selection thresholds. More systematic evaluation using AHP
process. Detailed Information gathering involves
testing, prototyping and reading technical documents.
State of the art in COTS testing
How to provide information to user
Component meta-data approach. Retro-components approach. Component test bench approach. Built-in test approach. Component+ approach. STECC strategy.
Component meta-data approach
Binary code
Metadata
Call graphs,Testing info.
done by provider
Component
Component metadata (contd.)
server MetaDB
Component
functionality
Metadata req
Metadata
Retro-components approach
server MetaDB
Component
functionalityMetadata req and test data
Metadata
Component test bench approach
A set of test cases called test operation is associated with each interface of a component.
A test operation defines the necessary steps for testing a specific method.
The concrete test inputs and expected test output packaged in a test operation.
Built-in test approach.
Functionality
Test casegenerator
Tester
Component
Built-in test approach(contd.)
Functionality
Normal mode.
Functionality
Test casegenerator
Tester
Maintenance mode.
Built-in test approach(contd.)
Inheritance
Base Component
Derived Component
Component+ approach
Functionality
Test executor
Built-in testing enabled component
Tester
Test casegenerator
FailureRecovery
mech.s
Handler
Interface
Disadv. of BIT and component+
Static nature. Generally do not ensure that tests are
conducted as required by the component user
The component provider makes some assumptions concerning the requirements of the component user, which again might be wrong or inaccurate.
STECC strategy
functionality
TesterServer
MetaDB
query
Test generator
Metadata Req.
Metadata
Levels of Testing
Unit Testing. Integration Testing. System Testing
Types of testing
Functionality Testing . Reliability Testing. Robustness Testing. Performance Testing. Load Testing. Stress Testing. Stability Testing. Security Testing.
Certifying COTS
When considering a candidate component, developers
need to ask three key questions: Does component C fill the developer’s needs? Is the quality of component C high enough? What impact will component C have on system S?
Certifying COTS(contd.)
CERTIFICATION TECHNIQUES
Black-box component testing. System-level fault injection. Operational system testing. Software Wrapping. Interface propagation Analysis.
Black box Testing
To understand the behavior of a component, various inputs are executed and outputs are analyzed.
To catch all types of errors all possible combinations of input values should be executed.
To make testing feasible, test cases are selected randomly from test case space.
Black box test reduction using Input-output Analysis
Random Testing is not complete. To perform complete functional testing,
number of test cases can be reduced by Input-output Analysis.
How to find I/O relationships By static analysis or execution analysis of
program.
Fault Injection
ComponentFault
simulation tool
Faultsimulation
tool
Erroneous or malicious input
Exceptions, No response
request
Operational System Testing
complements system-level fault injection. System is operated with random inputs (valid
and invalid inputs) Provides more accurate assessment of COTS
quality. To ensure that a component is a good match
for the system.
Software Wrapping
ComponentInput output
Input wrapper Output wrapper
Instrumentation configuration file
Interface propagation Analysis
COTS Component 1
COTSComponent 2
Fault Injector
Modify input, call correct method.
Call correct method, modify output.
Call perturbed function.
Fault Injection used for
Robustness Testing. Error propagation Analysis. Reliability Testing. Security Testing.
Robustness Testing
COTS testing for OS failures
COTS component
OperatingSystem
Wrapper
Ballista approach
Based on fault injection technique. Test cases are generated using parameter
types of an interface. Independent of internal functionality. Testing is not complete.
Test value Data Base
Test value Data Base(contd.)
Integer data type: 0, 1, -1, MAXINT, -MAXINT, selected powers of two, powers of two minus one, and powers of two plus one.
Float data type: 0, 1, -1, +/-DBL_MIN, +/-DBL_MAX, pi, and e.
Pointer data type: NULL, -1 (cast to a pointer), pointer to free’d memory, and pointers to malloc’ed buffers of various powers of two in size.
Test value Data Base(contd.)
String data type (based on the pointer base type): includes NULL, -1 (cast to a pointer), pointer to an empty string, a string as large as a virtual memory page, a string 64K bytes in length.
File descriptor (based on integer base type): includes -1;MAXINT; and various descriptors: to a file open for reading, to a file open for writing, to a file whose offset is set to end of file, to an empty file, and to a file deleted after the file descriptor was assigned.
Test case generation
All combinations of values for the parameter types are generated.
Number of test cases generated are product of number of parameters and test base for that type.
Error propagation analysis
Interface Propagation Analysis is used by injecting faults at one component.
This is done at component integration level. A known faulty input is injected using fault injector
into the system. Components effected by this input are observed
(how they handle the faulty input).
Performance Testing
Middleware
Application’s execution and Middleware cannot be divorced in any meaningful way.
In order to predict the performance of application component, performance of its middleware should be analyzed.
Performance prediction Methodology
Application’s performance prediction isthree step process.
Obtaining Technology performance. Analyzing Architecture specific
behavioral characteristics. Analyzing Application specific
behavioral characteristics.
Technology performance profile
Technology performance profile (contd.)
Technology performance profile (contd.)
Architecture behavior
Identity Application
Effect of database access thru Middleware
The performance of the entity bean architecture is less than 50% of the performance of the session bean only Architecture.
Sessionbean
Entitybean
Container
DB
Effect of Server Thread
The performance increases from 2 threads to 32 threads, stabilizes around 32 to 64 threads, and gradually decreases as more threads are added due to contention.
The Effect of Client Request Load.
Client response time increases with concurrent client request rate due to contention for server threads.
Effect of Database Contention
Effect of database contention leads to performance that is between 20% and 49%.
Optimal Number of threads
Load Testing
Load Testing
It is just Performance testing under various loads.
Performance is measured as Connections per second (CPS), throughput in bytes per second, and round trip time (RTT) .
Load Test Application
Load testApp
Ethernet
Webserver
Appserver
DBserver
System Under Test
Testing strategy
Load tests will be conducted in three phases.1. Consumption of server resources as a function
of the volume of incoming requests will be measured.
2. Response time for sequential requests will be measured.
3. Response time for concurrent client request load will be measured.
Security Testing
Security Risks with COTS
Component design. Component procurement. Component integration. System maintenance.
Component Design
Inadvertently flawed component design. Intentionally flawed component design. Excessive component functionality. Open or widely spread component design. Insufficient or incorrect documentation.
System maintenance Insecure updating. Unexpected side effects. Maintenance backdoors.
Component integration
Mismatch between product security levels.
Ex. UNIX and CORBA security integration.
Privacy Data Base Risks
Risks revealed
Trojan horse in client. Information leaking to swap file. DBMS log files. DBMS ordering of records.
Piracy avoidance techniques
Hardware and software tokens. Dynamic Decryption of Code. Watermarking. Code Partitioning.
Regression testing for COTS
I-BACCI process
1. Decomposing the binary file of the component; and filtering trivial information.
2. Comparison the code sections between the two versions.
3. Identification of glue code functions.4. Identification of change propagation in other
components/system. 5. Selection of test cases to cover only the affected
glue code functions (functions in firewall).
Black box understanding of COTS
Methods for understanding
Binary reverse Engg. Interface probing. Partial automation of interface probing.
Binary reverse Engg.
Derives the design structure (call graph, control graph) from binary code.
Source code can also be partially extracted using decompilation.
Decompiled source code will have no comments and variable names will not be meaningful.
Licenses forbid decompilation back to source code.
Interface probing
System Developer designs a set of test cases, executes, and analyzes outputs.
Done in an iterative manner.
Disadvantages
A large number of test cases have to be generated and analyzed.
Some properties may require significant probing which may be tedious,labor intensive, expensive.
Developers miss certain limitations and make incorrect assumptions.
Partial Automation of interface probing
Based on interface probing. Test cases are generated based on scenarios. Testing is done in three phases
1. Scenario description phase.
2. Search space specification phase.
3. Test case generation phase.