WEB TESTING TOOLS - 3

Ø MS APPLICATION CENTRE TEST

Application Center Test is designed to stress test Web servers and analyze performance and scalability problems with Web applications, including Active Server Pages (ASP) and the components they use. Application Center Test simulates a large group of users by opening multiple connections to the server and rapidly sending HTTP requests. Application Center Test supports several different authentication schemes and the SSL protocol, making it ideal for testing personalized and secure sites. Although long-duration and high-load stress testing is Application Center Test's main purpose, the programmable dynamic tests will also be useful for functional testing. Application Center Test is compatible with all Web servers and Web applications that adhere to the HTTP protocol.

During a test run, performance counters on the test client, and all web servers should be monitored. Application Centre Test will automatically monitor HTTP performance statistics during the test run, but performance counters must be explicitly configured before a test run.

Performance counter data is used to determine when a test client or Web server has reached its maximum CPU use. In case where the performance bottleneck for the web application is not the server CPU, performance counters will be the easiest way to determine where the bottleneck is occurring.

IMPORTANT COUNTERS FOR WEB TESTING

OBJECT	PERFORMANCE COUNTER	INDICATES
Memory	Available Bytes	Amount of memory available on the test client.
Active Server Pages	Requests Queued	This should remain to 0. if it exceeds the IIS queue length, “Server too busy” errors result.
Network Interface	Bytes Total/sec	Comparing this value against the total available bandwidth should give a clear indication of the potential network bottleneck. As a general rule, try to keep the bytes/sec under 50% of the total available bandwidth.
Processor	% Processor Time	This is the best counter for viewing processor saturation. Shows the amount of time spent processing threads by all CPUs. A number consistently above 90% on one or more processors indicates that the test is too intense for the hardware. Add the 0 through x instances of this counter for multi-processor servers.

If the web application uses Microsoft SQL Server or relies on any other applications to generate the response, then the performance counters for that program should also be monitored.

OBJECT	PERFORMANCE COUNTER	INDICATES
SQL Server: General Statistics	Logins/sec	This is the count of logins to SQL server per second.
SQL Server: Cache Manager	Cache Hit Ratio (all instances)	Shows the hit rate that data is found in the cache. A number consistently less than 85% indicates a memory problem.
SQL Server: General Statistics	User Connections	Shows the number of active SQL users. Compare this number to the Active Server pages: Requests/Sec counter to get an idea of how much the scripts are working the SQL Server. A large difference may indicate that the test script is not a valid stress of SQL Server.
SQL Server: Databases	Transactions/sec	The total number of transactions that have been started.
SQL Server: Locks	Lock Waits/sec	Shows the number of lock requests per second that force another process to wait until the current process is complete. If consistently greater than 0 it indicates transaction problems.