Workload programming tips

External programming control

Protocol level routines

Tracing socket level I/O

Related links:
Using Rational Suite TestStudio to analyze a Domino application

Performance Perspectives: Creating a Lotus Workplace Messaging test scenario with Rational Suite TestStudio

Performance Perspectives: Optimizing Lotus Workplace Messaging: Early experience

Lotus Workplace Messaging live demo

Rational Developer Domain

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• iSeries Model 730 running OS/400 Version 5 Release 2
• 8 GB of main memory
• 8-way processor

• The workload can be started and run to completion with little or no Rational tool or workload knowledge by the operator.
• Many of the workload operating parameters, such as server name, can be changed (via command line in the desktop shortcut) with no changes to the test script.
• Operating parameters can be stored in a configuration file separate from the test script.

• Initialization phase:
  - Setup server name
  - Setup user name(s)
  - Connect to server
  - Fail if connection fails
  
• Activity phase
  - Generate FROM, RCPT, DATA, … data calls
  - Accept expected status, Fail if error
  - Close connection

• Random number of RCPTs (each RCPT command adds an additional mail destination)
• Random user names (RCPT, From) to ensure a more even, real-life distribution
• Random length of mail messages to model actual mail activity

string file_path = "";
string base = "c:";
string file_sep = "/";
string name = "autoexec.bat";

file_path = base;
file_path += file_sep;
file_path += name;

• To ensure no unwanted collisions between variables of like usage in separate routines, prefix what would be the local variable name with the routine’s name. For example:
  
  func foo(){
  
  int foo_a;
  string foo_b;
  }

• Place all header files in the script directory.
• Place generic work functions in separate include header files. We did this because there are no separately compiled functions (not counting DLLs).
• Implement your code in small parts and recompile and run them often. VU compilation error diagnostics are often of the form parse error with limited information on the location of the actual mistake. Be advised that the location of the error diagnostic is not always an absolute indication of the actual location of the problem (a common issue with other compilers because it often is essentially impossible to determine accurately where the actual user error may be). Errors such as unterminated quotations (“), undefined variables, and undefined functions give similar parse error diagnostics.
• When modifying code in a header file, make a simple change (for example, add then delete a space character in the including script file) then recompile. Include or header (.S or .SBH) files are not automatically rescanned when the including file is recompiled. This means that if you make a change in the header file and then recompile the including VU script (.S) file, the change in the header file will not necessarily be seen. Rescanning the header files appears to take place if the including script is changed. (Note that we used .SBH extensions because the Rational Suite TestStudio editor defaults to this extension for project header files. However, many Rational developers also use the .S extension for VU scripts and use .SBH for GUI scripts.)

// smtp_message.s 19-May-2003 crs,
// Message info
DATAPOOL_CONFIG "smtp_message" DP_RANDOM DP_PRIVATE DP_WRAP
{
INCLUDE, "messagelen", "string","100";
}

// smtp_message.s 19-May-2003 crs,
// Message info
int DP_MESSAGE; // message length
string dp_message = "smtp_message";
DATAPOOL_CONFIG "smtp_message" DP_RANDOM DP_PRIVATE DP_WRAP
{
INCLUDE, "messagelen", "string","100";
}
proc smtp_message_open()
{
DP_MESSAGE = datapool_open(dp_message);
}

proc smtp_message_close()
{
datapool_close(DP_MESSAGE);
}

string func smtp_message_next()
{
datapool_fetch(DP_MESSAGE);
return datapool_value(DP_MESSAGE, "messagelen");
}

1. A command line script (for instance, a Perl script) decodes command line specifications.
2. The script creates a suitable header file with a fixed name (for example, _command.sbh) containing VU code with assignment statements of the form variable_name=value.
3. The primary VU script file contains the following include statement:
   
   include “_command.sbh”;
   
   This include statement logically places the assignment statements where they will be executed, setting the variables to the appropriate values.
4. The command line script executes the Rational TestManager that, in turn, executes the test script.

Perl.exe workload.pl command:cmd_servername=server.ibm.com

//c:\smtp\TestDatastore\DefaultTestScriptDatastore\TMS_Scripts\_command.sbh
// - Automatically generated - Do not edit by hand
cmd_servername = "server.ibm.com";

rtmanager smtp16 /user admin /runsuite /project c:\smtp\smtp.rsp

// smtp16.s 17-Jun-2003 crs, include .sbh files
#include <VU.h>
...
// Default server name
string cmd_servername = "default.ibm.com";
...
{
string servername; // Local copy
...
#include "_command.sbh" // Bring in settings
servername = cmd_servername;
...
}

// Get smtp response
// till \d\d\d <sp>
// Placing cumulative response in smtp_get_str
proc smtp_get(label)
string label;
{
string smtp_get_str = "";
string smtp_get_reply_code;
string smtp_get_tail;
string smtp_get_desc;
if (socket_rtns_display_in)
printf("smtp_get(%s)\n", label);
while (1)
{
socket_get("smtp_get:" + label); // Get next line - till “\n”
smtp_get_str += _response;
if (!match("^([0-9]+)$0([- ])$1(.*)$2$", _response,
&smtp_get_reply_code, &smtp_get_tail,
&smtp_get_desc))
{
user_exit(-1, "Unexpected smtp response " + _response);
}
if (smtp_get_tail == " ")
{
return;
}
}
}

Convert data into readable form
Print out converted data

Do actual output

…
smtp_get(smtp_connect)
socket_get(smtp_get:smtp_connect); - 55 bytes
220 rchasmil.rchland.ibm.com Nagano SMTP Server Ready\r\n

socket_send();
EHLO joedoe\r\n

smtp_get(smtp_ehlo)
socket_get(smtp_get:smtp_ehlo); - 43 bytes
250-rchasmil.rchland.ibm.com Hello joedoe\r\n

socket_get(smtp_get:smtp_ehlo); - 9 bytes
250-DSN\r\n

socket_get(smtp_get:smtp_ehlo); - 18 bytes
250 SIZE 2000000\r\n
…

• Learn the capabilities of the VU (Virtual User) language and how they can support your requirements, while paying attention to the differences between VU and its “first cousin” C.
• Judicious design and implementation of protocol-based routines is key in combating the inherent complexity involved with the protocol. Also consider the complexity of the protocol with which you are working.
• Dynamic tracing display of the network traffic is critical for the type of workload described in this article.