Load Impact is a cloud-based load testing service consisting of a load testing tool and page analyzer. The load testing tool simulates user traffic to test website performance under different load levels. The page analyzer examines how individual pages load. User scenarios describe sequences of HTTP requests to emulate different user types. Load testing is configured by creating test configurations that specify load levels, scenarios, and scheduling. Lua scripts can be used to automate complex scenarios. Page analysis identifies loading bottlenecks while status codes help debug issues.

2. Outline
• What is load impact?
• The main Components of Load Impact.
o Load testing tool.
o Page analyzer.
• Why Load Test?
• What is a test configuration?
• How to create test configuration?
• What is Scheduled tests?
• How to schedule tests?
• Using page analyzer.
• What is user scenarios?
• How to create your own scenarios?
• How to create user scenarios?
o Lua Tutorial.
o Load impact with scripting?
o HTTP status codes.

3. What is load impact?
• Load Impact is a cloud-based service for load
testing and website optimization. It generates traffic
load by simulating users. Load Impact is a so-called
freemium service.

4. The main Components of Load Impact
• Load Impact consists of two main parts:
1. Load testing tool.
2. Page analyzer.

5. 1. Load testing tool
• It generates simulated user traffic to a website. Users can
simulate virtual users who are trying to load the web pages at
the same time.
• Results are displayed in real time throughout the test process.
• There are three different types of load test:
1. Fixed - Test with static load level throughout the test.
2. Ramp-up - Test that starts at a low level and increases stepwise until it
reaches a maximum predetermined level.
3. Timeout - Ramp-up tests that increase the load level until the server
becomes too slow, or when the maximum load level is reached.

6. 2. Page analyzer
• It loads a web page the same way a web browser
would.
• It shows the user what objects were loaded, in what
order, and how long each object took to load.
• It also gives the user information about return
codes, compression ratio, etc.

7. Why Load Test?
• Having a fast website is a key to commercial success on the
Internet.
• A slow website will increase your bounce rate, reduce your rank in
search engines & reduce conversions rates.
• In studies published in says that the average visitor expects a web
page to load in no more than two seconds.
• In 2010, Google has included site speed as part of its search
ranking algorithm.

8. What is a test configuration?
• A test configuration describes the load test you want to run –
how many simulated users the test should load your site with,
and what those users should do on your site (what pages they
should load on the site).

9. How to create test configuration?
1
2
1- choose the “test configuration” section, then click on “Create test
configuration”.
2- Type a name for the test, then enter the target URL

10. How to create test configuration? (CONT>>)
3
This section will allow
you to specify what
load levels the test will
use, and how quickly to
ramp up or down
to/from those load
levels.

11. How to create test configuration? (CONT>>)
3
What are VU and SBU users?
• A Virtual User will only use a single network connection
when loading resources from a target host. Resources
can be loaded from multiple hosts in the same test,
however, that will then result in one connection per
target host, per VU.
• A Simulated Browser User (SBU) can use multiple
concurrent network connections when loading
resources from a single target host. This results in faster
page loads, but also a lot more stress on the target
server that has to serve four connections at once
instead of just one.

12. How to create test configuration? (CONT>>)
4
4 – Add extra IP address! But why?
Let’s take this example “If you are running a 800 SBU test with user
scenarios distributed evenly across a total of 5 loadzones (i.e. 800/5 =
160 SBUs per loadzone), you will have 1 (IP addresses assigned for 160
SBUs per loadzone) x 5 (user scenarios/loadzones) = 5 IP addresses
assigned to your load test”.

13. How to create test configuration? (CONT>>)
5
5 – Finally, click on “Create test configuration and start test” to start
testing.
Or, you could click on, “Create test configuration” to save the
configuration for later use.

14. What is Scheduled tests?
Scheduling allows you to run a load test at some point in the
future, or to run a load test regularly at certain intervals.

15. How to schedule tests?
1
1- choose the “Scheduled tests” section, then click on “Add new
scheduled test”.

16. How to schedule tests?(CONT>>)
2
“Make sure you have created test
configuration” before you start
scheduling.
2- choose the test configuration.
3- Type the schedule data.
4- Type the schedule time.
5- choose the reputation time (Daily,
Weakly, Monthly).
6 – Schedule it.
3
4
5
6

17. Using page analyzer
• To Access the page analyzer section go to:
https://loadimpact.com/page-analyzer
1- Type the target URL.
2- choose the browser
to emulate during
analysis.
3- click on analyze.
1 2 3

18. Case Study: ksu.edu.sa
The load times are represented
as colored bars which is
divided into several
components. They are:
- Time in queue (grey).
- DNS lookup time (orange).
- Connection time (yellow).
- Time to first byte (green).
- Download time (blue).

19. Case Study: ksu.edu.sa (CONT>>)

20. What is user scenarios?
A user scenario is a sequence of HTTP transactions that emulates a
certain type of user on your site. You can have several user scenarios in
a single load test, emulating several different types of users.

21. What is Lua?
Lua is a lightweight multi-paradigm programming language designed
as a scripting language.
Why Lua?
• Lua is cross-platform.
• It’s simple, elegant and easy to learn.
• It’s also light-weight and very suitable for resource-intensive
applications such as load testing.

22. A Quick tutorial: Introduction to
let’s

23. Types in Lua
There are 8 types in Lua:
1- Number : Numeric value represented in double.
2- String: A sequence of arbitrary characters.
3- Boolean : "true" and "false“.
4- function : First-class object in Lua.
5- Table : Heterogeneous[1] hash table.
6- Thread : C data structures defined by C users.
7 – Userdata : Lua coroutine, a cooperative threading.
8- Nil : Nothing.
[1] : Heterogeneous composed of parts of different kinds.

24. Functions in Lua
function foo(a, b, c)
local sum = a + b
return sum, c --A function can return multi values.
End
var1, var2 = foo(1, '123', ‘KSU') --Parallel assignment
print(var1, var2)
output:
124 KSU

25. Tables in Lua
To create Table:
> t = {} -- construct an empty table and assign it to variable "t"
> print(t)
Output: table: 0035AE18
Tables as arrays:
> t = { 1,1,2,3,5,8,13 }
> print( t[1] )
Output: 1
> print( t[0] )
Output: nil
> print( t[4] )
Output: 3
What about this:
> = # t --
Output: 7
guess what?To find the size of the table

27. How to create your own scenarios?
Scenario
name
Target
URL
Generate
the scenario
automatically
Validate
script
documentation
Editor
Validation results

28. How to create your own scenarios?
Examples:
1- load test a single recourse
http.request_batch({
{"GET", http://loadimpact.com/"}
})
2- POST requests
http.request_batch({
{"POST", "http://test.loadimpact.com/login.php" ,
data="login=test_user&password=123"}
})
3- Load-test multiple resources
http.request_batch({
{“GET”, “http://test.loadimpact.com/news.php”}
})
http.request_batch({
{“GET”, “http://test.loadimpact.com/contacts.php”}
})

29. How to create your own scenarios?(CONT>>)
Examples:
4- Random delays between requests
http.request_batch({
{"GET", "http://test.loadimpact.com/news.php"},
})
client.sleep(
math.random(1, 15) --Sleeps between 1 - 15 seconds before continuing
)
http.request_batch({
{"GET", "http://test.loadimpact.com/news.php"},
})
5- Read HTTP headers from a response
local response = http.request_batch({
{"GET", "http://google.com"},
})
log.info(
"google.com uses `" .. tostring(response[1].headers["Server"][1])
.. "' as a server software"
)

30. How to create your own scenarios?(CONT>>)
Examples:
6- Setting headers for a request
Sometimes you need to set custom HTTP headers for your request. One reason is
to see if your server handles client-side caching.
local response = http.request_batch({
{"GET", "http://test.loadimpact.com/",
headers = {
["If-Modified-Since"] = "Tue, 18 Jun 2013 03:30:00 GMT";
}
}
})
if response[1].status_code==304 then
log.info("not modified")
elseif response[1].status_code==200 then
log.info("modified")
else
log.error("unexpected code" .. tostring(response[1].status_code))
end

31. Some HTTP status codes:
Categories: 1xx Informational , 2xx Success , 3xx Redirection , 4xx Client
Error , 5xx Server Error.
Status code Description
304 Not Modified
Indicates that the resource has not been modified since the version
specified by the request headers If-Modified-Since or If-Match.
400 Bad Request
The request cannot be fulfilled due to bad syntax.
401 Unauthorized
Similar to 403 Forbidden, but specifically for use when authentication
is required and has failed or has not yet been provided.
403 Forbidden
The request was a valid request, but the server is refusing to respond
to it.
404 Not Found
The requested resource could not be found but may be available
again in the future
500 Internal Server
Error
A generic error message, given when no more specific message is
suitable.
503 Service
Unavailable
The server is currently unavailable (because it is overloaded or down
for maintenance).

33. For more information
Visit the knowledge base
http://support.loadimpact.com/

34. References
• https://loadimpact.com/learning-center/
• http://support.loadimpact.com/knowledgebase/articles/
• http://en.wikipedia.org/wiki/List_of_HTTP_status_codes
• http://www.lua.org/pil/contents.html

35. This file is licensed under a Creative Commons Attribution