1.What is load testing? - Load testing is to test that if the application works fine with the loads that result from large number of simultaneous users, transactions and to determine weather it can handle peak usage periods.

2.What is Performance testing? - Timing for both read and update transactions should be gathered to determine whether system functions are being performed in an acceptable timeframe. This should be done standalone and then in a multi user environment to determine the effect of multiple transactions on the timing of a single transaction.

3.Explain the Load testing process? -
Step 1: Planning the test. Here, we develop a clearly defined test plan to ensure the test scenarios we develop will accomplish load-testing objectives. Step 2: Creating Vusers. Here, we create Vuser scripts that contain tasks performed by each Vuser, tasks performed by Vusers as a whole, and tasks measured as transactions. Step 3: Creating the scenario. A scenario describes the events that occur during a testing session. It includes a list of machines, scripts, and Vusers that run during the scenario. We create scenarios using LoadRunner Controller. We can create manual scenarios as well as goal-oriented scenarios. In manual scenarios, we define the number of Vusers, the load generator machines, and percentage of Vusers to be assigned to each script. For web tests, we may create a goal-oriented scenario where we define the goal that our test has to achieve. LoadRunner automatically builds a scenario for us. Step 4: Running the scenario.
We emulate load on the server by instructing multiple Vusers to perform tasks simultaneously. Before the testing, we set the scenario configuration and scheduling. We can run the entire scenario, Vuser groups, or individual Vusers. Step 5: Monitoring the scenario.
We monitor scenario execution using the LoadRunner online runtime, transaction, system resource, Web resource, Web server resource, Web application server resource, database server resource, network delay, streaming media resource, firewall server resource, ERP server resource, and Java performance monitors. Step 6: Analyzing test results. During scenario execution, LoadRunner records the performance of the application under different loads. We use LoadRunner’s graphs and reports to analyze the application’s performance.

4.When do you do load and performance Testing? - We perform load testing once we are done with interface (GUI) testing. Modern system architectures are large and complex. Whereas single user testing primarily on functionality and user interface of a system component, application testing focuses on performance and reliability of an entire system. For example, a typical application-testing scenario might depict 1000 users logging in simultaneously to a system. This gives rise to issues such as what is the response time of the system, does it crash, will it go with different software applications and platforms, can it hold so many hundreds and thousands of users, etc. This is when we set do load and performance testing.

5.What are the components of LoadRunner? - The components of LoadRunner are The Virtual User Generator, Controller, and the Agent process, LoadRunner Analysis and Monitoring, LoadRunner Books Online.

6.What Component of LoadRunner would you use to record a Script? - The Virtual User Generator (VuGen) component is used to record a script. It enables you to develop Vuser scripts for a variety of application types and communication protocols.

7.What Component of LoadRunner would you use to play Back the script in multi user mode? - The Controller component is used to playback the script in multi-user mode. This is done during a scenario run where a vuser script is executed by a number of vusers in a group.

8.What is a rendezvous point? - You insert rendezvous points into Vuser scripts to emulate heavy user load on the server. Rendezvous points instruct Vusers to wait during test execution for multiple Vusers to arrive at a certain point, in order that they may simultaneously perform a task. For example, to emulate peak load on the bank server, you can insert a rendezvous point instructing 100 Vusers to deposit cash into their accounts at the same time.

9.What is a scenario? - A scenario defines the events that occur during each testing session. For example, a scenario defines and controls the number of users to emulate, the actions to be performed, and the machines on which the virtual users run their emulations.

10.Explain the recording mode for web Vuser script? - We use VuGen to develop a Vuser script by recording a user performing typical business processes on a client application. VuGen creates the script by recording the activity between the client and the server. For example, in web based applications, VuGen monitors the client end of the database and traces all the requests sent to, and received from, the database server. We use VuGen to: Monitor the communication between the application and the server; Generate the required function calls; and Insert the generated function calls into a Vuser script.

11.Why do you create parameters? - Parameters are like script variables. They are used to vary input to the server and to emulate real users. Different sets of data are sent to the server each time the script is run. Better simulate the usage model for more accurate testing from the Controller; one script can emulate many different users on the system.

12.What is correlation? Explain the difference between automatic correlation and manual correlation? - Correlation is used to obtain data which are unique for each run of the script and which are generated by nested queries. Correlation provides the value to avoid errors arising out of duplicate values and also optimizing the code (to avoid nested queries). Automatic correlation is where we set some rules for correlation. It can be application server specific. Here values are replaced by data which are created by these rules. In manual correlation, the value we want to correlate is scanned and create correlation is used to correlate.

13.How do you find out where correlation is required? Give few examples from your projects? - Two ways: First we can scan for correlations, and see the list of values which can be correlated. From this we can pick a value to be correlated. Secondly, we can record two scripts and compare them. We can look up the difference file to see for the values which needed to be correlated. In my project, there was a unique id developed for each customer, it was nothing but Insurance Number, it was generated automatically and it was sequential and this value was unique. I had to correlate this value, in order to avoid errors while running my script. I did using scan for correlation.

14.Where do you set automatic correlation options? - Automatic correlation from web point of view can be set in recording options and correlation tab. Here we can enable correlation for the entire script and choose either issue online messages or offline actions, where we can define rules for that correlation. Automatic correlation for database can be done using show output window and scan for correlation and picking the correlate query tab and choose which query value we want to correlate. If we know the specific value to be correlated, we just do create correlation for the value and specify how the value to be created.

Regards
Devarajan.V

Here are some FAQ's with answers,

1. What is correlation?

Explain the difference between automatic correlation and manual correlation? - Correlation is used to obtain data which are unique for each run of the script and which are generated by nested queries. Correlation provides the value to avoid errors arising out of duplicate values and also optimizing the code (to avoid nested queries). Automatic correlation is where we set some rules for correlation. It can be application server specific. Here values are replaced by data which are created by these rules. In manual correlation, the value we want to correlate is scanned and create correlation is used to correlate.
2. Where do you set automatic correlation options?

Automatic correlation from web point of view, can be set in recording options and correlation tab. Here we can enable correlation for the entire script and choose either issue online messages or offline actions, where we can define rules for that correlation. Automatic correlation for database, can be done using show output window and scan for correlation and picking the correlate query tab and choose which query value we want to correlate. If we know the specific value to be correlated, we just do create correlation for the value and specify how the value to be created.

3. What is a function to capture dynamic values in the web vuser script?

Web_reg_save_param function saves dynamic data information to a parameter.

4. Types of Goals in Goal-Oriented Scenario - Load Runner provides you with five different types of goals in a goal oriented scenario:
The number of concurrent Vusers
The number of hits per second
The number of transactions per second
The number of pages per minute
The transaction response time that you want your scenario

5. Analysis Scenario (Bottlenecks): In Running Vuser graph correlated with the response time graph you can see that as the number of Vusers increases, the average response time of the check itinerary transaction very gradually increases. In other words, the average response time steadily increases as the load increases. At 56 Vusers, there is a sudden, sharp increase in the average response time. We say that the test broke the server. That is the mean time before failure (MTBF). The response time clearly began to degrade when there were more than 56 Vusers running simultaneously.


_shanthi

1.How did you find web server related issues?

Using Web resource monitors we can find the performance of web servers. Using these monitors we can analyze throughput on the web server, number of hits per second that
occurred during scenario, the number of http responses per second, the number of downloaded pages per second.

2. How did you find database related issues?

By running “Database” monitor and help of “Data Resource Graph” we can find database related issues. E.g. You can specify the resource you want to measure on before running the controller and than you can see database related issues

3. What is the difference between Overlay graph and Correlate graph?

Overlay Graph: It overlay the content of two graphs that shares a common x-axis. Left Y-axis on the merged graph show’s the current graph’s value & Right Y-axis show the value of Y-axis of the graph that was merged. Correlate Graph: Plot the Y-axis of two graphs against each other. The active graph’s Y-axis becomes X-axis of merged graph. Y-axis of the graph that was merged becomes merged graph’s Y-axis.

4. How did you plan the Load? What are the Criteria?

Load test is planned to decide the number of users, what kind of machines we are going to use and from where they are run. It is based on 2 important documents, Task Distribution Diagram and Transaction profile. Task Distribution Diagram gives us the information on number of users for a particular transaction and the time of the load. The peak usage and off-usage are decided from this Diagram. Transaction profile gives us the information about the transactions name and their priority levels with regard to the scenario we are deciding.

5. What does vuser_init action contain? - Vuser_init action contains procedures to login to a server.


-Shanthi

What does vuser_init action contain?

Vuser_init action contains procedures to login to a server.

What does vuser_end action contain?

Vuser_end section contains log off procedures.

What is think time? How do you change the threshold?

Think time is the time that a real user waits between actions. Example: When a user receives data from a server, the user may wait several seconds to review the data before responding. This delay is known as the think time. Changing the Threshold: Threshold level is the level below which the recorded think time will be ignored. The default value is five (5) seconds. We can change the think time threshold in the Recording options of the Vugen.


What is the difference between standard log and extended log?

The standard log sends a subset of functions and messages sent during script execution to a log. The subset depends on the Vuser type Extended log sends a detailed script execution messages to the output log. This is mainly used during debugging when we want information about: Parameter substitution. Data returned by the server. Advanced trace.

Explain the following functions:

- lr_debug_message - The lr_debug_message function sends a debug message to the output log when the specified message class is set.

lr_output_message - The lr_output_message function sends notifications to the Controller Output window and the Vuser log file. lr_error_message

The lr_error_message function sends an error message to the LoadRunner Output window. lrd_stmt - The lrd_stmt function associates a character string (usually a SQL statement) with a cursor. This function sets a SQL statement to be processed. lrd_fetch - The lrd_fetch function fetches the next row from the result set.

Throughput :

If the throughput scales upward as time progresses and the number of Vusers increase, this indicates that the bandwidth is sufficient. If the graph were to remain relatively flat as the number of Vusers increased, it would
be reasonable to conclude that the bandwidth is constraining the volume of
data delivered.

1.How does traceroute work?

a.Traceroute works by sending packets with low time to live (TTL) fields. the TTL specifies how many hops the packet is allowed before it is returned. when a packet can't reach it's destination because the TTL value is too low, the last host returns the packet and identifies itself. by sending the sending the series of packets and incrementing the TTL value with each successive packet, trace route finds out who all the intermediary hosts are.

b.trace route is used to find the quality of internet connection.

the cmd is used as: tracer yahoo.com

depending on the ms values displayed after the processing of the cmd, the latency is found and the quality is determined.

Regards
devarajan

__________________
Regards,
devarajan

Which layer of the TCP/IP five-layer model contains ICMP?
A. Internet Layer
B. Hardware Layer
C. Transport Layer
D. Application Layer
E. Network Interface Layer


Ans : A (Internet Layer)


Regards
devarajan

__________________
Regards,
devarajan

Which is the maximum layer reached by all IPv6 datagrams when passing through a router?
A. Internet Layer
B. Physical Layer
C. Transport Layer
D. Application Layer
E. Network Interface Layer

Ans : A(Internet Layer)


Regards,
devarajan

__________________
Regards,
devarajan

Which layer within the seven layer OSI/ISO model ensures that messages reach the correct
application?
A. Network layer
B. Data link layer
C. Transport layer
D. Presentation layer



Ans : C [Transport layer]

Regards
devarajan

__________________
Regards,
devarajan

Hui guys

In the Load runner Why it is recommended to add verification checks to your all your scenarios?

- Vignesh

Load Testing Process :


> System Analysis :

This is the first step when the project decides on load testing for its system. Evaluation of the requirements and needs of a system, prior to load testing will provide more realistic test conditions. For this one should know all key performance goals and objectives like number of concurrent connections, hits per second etc.,Another important analysis of the system would also include the appropriate strategy for testing applications. It can be load testing or stress testing or capacity testing.

Load Testing is used to test the application against a requested number of users. The
objective is to determine whether the site can sustain a requested number of users with acceptable response times. Stress testing is nothing but load testing over extended periods of time to validate an application’s stability and reliability. Similarly capacity testing is used to determine the maximum number of concurrent users that an application can manage. Hence for businesses capacity testing would be the benchmark to say that the maximum loads of concurrent users the site can sustain before the system fails.



> User Scripts :


Once the analysis of the system is done the next step would be the creation of user scripts. A script recorder can be used to capture all the business processes into test
scripts and this more often referred as virtual users or virtual user scripts. A virtual
user is nothing but an emulated real user who drives the real application as client. All the business process should be recorded end to end so that these transactions will assist in breakdown of all actions and the time it takes to measure the performance of business process


> Settings :


Run time settings should be defined the way the scripts should be run in order to accurately emulate real users. Settings can configure the number of concurrent connections,
test run time, follow HTTP redirects etc., System response times also can vary based on the connection speed. Hence throttling bandwidth can emulate dial up connections at varying modem speeds (28.8 Kbps or 56.6 Kbps or T1 (1.54M) etc.


> Performance Monitoring :


Every component of the system needs monitoring :the clients, the network, the webs
server, the application server, the database etc., This will result in instantly identifying
the performance bottle necks during load testing. But if the tools support real time monitoring then testers would be able to view the application performance at any time
during the test.

Thus running the load test scenario and monitoring the performance would accelerate
the test process thereby producing a more stable application.


> Analyzing Results :


The last but most important step in load testing is collecting and processing the data to resolve performance bottlenecks. The reports generated can be anything ranging from Number of hits, number of test clients, requests per second, socket errors etc.,

Hence analyzing the results will isolate bottle necks and determine which changes are
needed to improve the system performance. After these changes are made the tests must re run the load test scenarios to verify adjustments

Hi, guys

Testing and levels and Techniques

Levels of Testing Testing Techniques

Unit Testing Structural Testing

Integration Structural & Functional

System Functional, Risk based

Acceptance Functional, Risk based


Test Design Methods

Black-Box and White-Box are Test Design Methods

Regards
devarajan

__________________
Regards,
devarajan

Hi, guys

Some Black Box tips and techniques.

Black-Box Testing

* Black Box Testing is testing technique having no knowledge of the internal functionality/structure of the system
* Synonyms for Black-Box are Behavioral, Functional, Opaque-Box, Closed-Box etc.
* Black-box Testing focuses on testing the function of the program or application against its specification
* Determines whether combinations of inputs and operations produce expected results
* When black box testing is applied to software engineering, the tester would only know the "legal" inputs and what the expected outputs should be, but not how the program actually arrives at those outputs

Focus of Black-Box Testing

In this technique, we do not use the code to determine a test suite; rather, knowing the problem that we're trying to solve, we come up with four types of test data:

* Easy-to-compute data
* Typical data
* Boundary / extreme data
* Bogus data

Black-Box Testing Techniques

Equivalence Partitioning
Boundary Value Analysis
Error Guessing
Cause-Effect Graphing

Equivalence Partitioning

An equivalence class is a subset of data that is representative of a larger class
Equivalence partitioning is a technique for testing equivalence classes rather than undertaking exhaustive testing of each value of the larger class

Example - EP

For example, a program which edits credit limits within a given range ($10,000 - $15,000) would have three equivalence classes
< $10,000 (invalid)
Between $10,000 and $15,000 (valid)
> $15,000 (invalid)

Boundary Analysis

This technique consists of developing test cases and data that focus on the input and output boundaries of a given function

In the same credit limit example, boundary analysis would test.

Low boundary -/+ one ($9,999 and $10,001)
On the boundary ($10,000 and $15,000)
Upper boundary -/+ one ($14,999 and $15,001)

Error Guessing

* Test cases can be developed based upon the intuition and experience of the tester
* For example, where one of the inputs is the date, a tester may try February 29, 2001

Cause-Effect Graphing

Cause-effect graphing is a technique for developing test cases for programs from the high-level specifications (A high-level specification states desired characteristics of the system)
These characteristics can be used to derive test data

Example – Cause Effect

For example, a program that has specified responses to eight characteristic stimuli (called causes) given some input has 256 "types" of input (i.e., those with characteristics 1 & 3; 5, 7 & 8 etc.).
A poor approach is to generate 256 test cases.
A more methodical approach is to use the program specifications to analyze the program's effect on the various types of inputs.
The program's output domain can be partitioned into various classes called effects.
For example, inputs with characteristic 2 might be subsumed by those with characteristics 3 & 4. Hence, it would not be necessary to test inputs with characteristic 2 and characteristics 3 & 4, for they cause the same effect.
This analysis results in a partitioning of the causes according to their corresponding effects
A limited entry decision table is then constructed from the directed graph reflecting these dependencies (i.e., causes 2 & 3 result in effect 4; causes 2, 3 & 5 result in effect 6 etc.)
The decision table is then reduced and test cases chosen to exercise each column of the table.
Since many aspects of the cause-effect graphing can be automated, it is an attractive tool for aiding in the generation of Functional Test cases.

Advantages of Black-Box Testing

* More effective on larger units of code than glass box testing
* Tester needs no knowledge of implementation, including specific programming languages
* Tester and programmer are independent of each other
* Tests are done from a user's point of view
* Will help to expose any ambiguities or inconsistencies in the specifications
* Test cases can be designed as soon as the specifications are complete

Disadvantages of Black-Box Testing



* Only a small number of possible inputs can actually be tested, to test every possible input stream would take nearly forever
* Without clear and concise specifications, test cases are hard to design
* There may be unnecessary repetition of test inputs if the tester is not informed of test cases the programmer has already tried
* May leave many program paths untested
* Cannot be directed toward specific segments of code which may be very complex (and therefore more error prone)

White-Box Testing

* White-box test design allows one to peek inside the "box“
* Synonyms for White-box are Structural, Glass-box and Clear-box
* White-box Testing assumes that the path of logic in a unit or program is known
* White-box Testing consists of testing paths, branch by branch, to produce predictable results
* Focuses specifically on using internal knowledge of the software to guide the selection of test data

White-Box Testing Techniques

Statement Coverage
execute all statements at least once
Decision Coverage
execute each decision direction at least once
Condition Coverage
execute each decision with all possible outcomes at least once

Decision/Condition Coverage
execute all possible combinations of condition outcomes in each decision
Multiple Condition Coverage
invoke each point of entry at least once

Choose the combinations of techniques appropriate for the application

Regards
devarajan

__________________
Regards,
devarajan

Advantage of Load Testing Tool :

• Overcomes resource limitations
• Replaces testers with “Virtual Users”
• Runs many Vusers on few machines
• Controller manages the Vusers
• Meaningful results with analysis tools
• Repeats tests with scripted actions


- Vignesh

Disadvantage of Performance testing through Manual Testing :

• Difficult to maintain resources like test engineers and Client machines
• Difficult to synchronize users
• Difficult to collect and analyze results
• Difficult to achieve test repeatability


- Vignesh

Terminology & Concepts in Performance Testing :

Think Time: Is the idle time of user with the web application between one request and next request.

Load Generator Machine: It is a computer used to send requests remotely, also called as Host machine or Load Driving machine.


> Load distribution among load generators is useful to generate heavy load.

• Remote command launcher enables the controller to start the application on the Host machine. ---RCL is whatever local request can be converted into remote request.

• Agent is interface between host machine and controller.

Console Machine: It is a computer, which controls and manages the load test.

Vusers: Vusers emulate the actions of human users working with your applications. A scenario can contain tens, hundreds or even thousands of Vusers

Vuser Script : Recorded script that, when played back, emulate a real user performing the actions.

Business Process: A set of user actions performed in an application to accomplish a business task. Often referred to as a “transaction.”

- Vignesh

Evaluate System:

The major activities of this phase are

• Application walk through
• Access to the application
• Gathering all requirements
 Identify the Performance Goals
 Identify the Performance Testing Completion Criteria
 Software and Hardware Specifications of the production server

- Vignesh

Components of load Runner:

Virtual User Generator ( VUGen) : Captures end-user Business process and Creates automated Performance testing script also know as Virtual User Development environment

LoadRunner Controller: Generates load and collects test results
LoadRunner Analysis: Compiles and displays test results with graphical format

Virtual User Generator
Navigation: Start-Programs- Mercury Load Runner- Virtual user generator
Recording:
Load runner supports 40 types of Applications (HTTP, SAP, CRM, FTP Protocols) .Our discussion limited only to HTTP Protocol.

Navigation: Vugen-File Menu- New-Web(HTTP/HTML)-Click on OK
-VUser Menu –Start Recording-Enter URL-Click on ok- Perform Actions
(Business Process)-Vuser menu –Click on Stop Recording (or Click Square black color button to stop recording).
Note: There are two Views of requests in the Vugen

- Vignesh

How Vugen working:
1. VuGen Captures HTTP To Create a Vuser
2. Replicates outgoing HTTP
3. Passes incoming HTML to browser
Toolbar:
Record Toolbar Run Toolbar Tree view toolbar
1.Start,End LoadRunner
Transaction
2. Insert Rendezvous
3. Insert Comment
4.Start, Pause, Stop Recording
5. Select Action File
6. New Action File
7.Recording Options 1. Run
2.Pause Run
3. Stop Run
4.Break Point
5. RunTime Settings
6.Visual Log
7. Launch Scenario 1. Step Properties
2. Insert step After
3. Insert step Before
4. Delete step

- Vignesh

Action Files:

Definition: A recorded business process that, when played back, emulates a real user performing the business process actions on a system.
By default three Action files in the Vugen.
1. Vuser_init
2. Action
3. Vuser_end

Recording in Action1 File:
Invoke Vugen-Click Start recording-Enter URL of site under test –Select Action in the list box-Conduct business process – And click Stop recording.


- Vignesh