gtps3m0uSystem Performance and Measurement Reference

Details of Message Reduction

All Reports

As noted on the Message Summary Report, the phrase output messages refers to output message segments, not output messages as viewed by the terminal operator. It may take three message segments to fill up a CRT screen with what appears, to the terminal operator, to be one output message.

Action Code Summary, Application Summary - Mean Existence Time

For a continuous mode run only, an input message followed by an output message with the same LNIATA or resource ID (for SNA devices) is considered to be a message pair; its existence time is calculated by subtracting time stamps (except for line 01 because there is no time stamp on the input message).

Action Code Summary - Mean Output Length

 Method: 
When an input message is followed by more than one output message with the same LNIATA, it is assumed this is an output message comprised of more than one segment. The character count field in the additional segments is added to that of the first output message segment.

 Result: 
The total mean output length may not correspond to the mean output length figures seen in other message reports because this is the only report where output message segment lengths of one logical message are added together. This figure then is the mean output message length as seen by the terminal operator, not by the line over which the segments were transmitted.

Action Code Summary, Application Detail - Unmatched Output

When an output message has not been preceded by an input message with the same LNIATA or resource ID (for SNA devices), it is considered unmatched. Its message type cannot be determined, nor can an existence time be calculated.

City Summary

 Method: 
Because line 01 does not have a city code in the DA record, data from messages on this line is not included in City Summary totals.

 Result: 
City Summary totals may not correspond with Message Summary and Action Code Summary totals which include line 01 data.

Terminal Activity

Only those terminals for which activity was intercepted are reported.

Plot/Dist Option - Message

Those variables which have the same value every interval are not plotted.

Weighted Message Rate

 Environment: 
The weighted message rate is obtained from the data reduction driver.

 Effect: 
The message rate is an average over the life of collection, not the rate for just the file collector intervals.

If the weighted message rate is insignificant, the File Access Summary Report is not printed.

Message Stream - Output Messages

 Method: 
If the optioned city code is followed by an A, a new print line will be advanced to each time a carriage return is encountered in the output message text.

 Result: 
The output message will be printed in the format seen by the terminal operator. Otherwise, as many as the first 60 characters only are printed unformatted as they appear in the message block.

Message Summary - Max/Min

The maximum and minimum values of those parameters which are not reported on a per second basis are actual observed values. They are not the maximum mean or minimum mean calculated for an interval, nor do they necessarily occur in the same interval.

Use of DA Records

There are two methods of searching through the DA records in order to match a city with its LNIAs:

 Method 1: 
If the City Summary is optioned, the records are searched by LNIA. Each time a new LNIA is encountered, it is matched with the city code name of the first terminal on that LNIA - unless the device is a CRT on a 2962 (Remote Display Interchange) in which case the next terminal's city code is used. The net result is a table of city code names and their associated LNIAs.

For all subsequent options by city, this created table is searched for the appropriate LNIAs on the optioned city, rather than researching all the DA records for the necessary information.

 Method 2: 
If the City Summary is not optioned, the DA records are searched by each city requested for the option being processed. Each unique LNIA associated with the optioned city in the DA record is entered in that city's table unless it is in another city's table.

 Result: 
Message counts for all terminals on a LNIA will be attributed to the city with which the LNIA has been matched. Occasionally, however, all terminals on one LNIA may not have the same city code name in the DA records. For example, a terminal in the back room may have a different city code name from those terminals used by the reservation agents. The message counts for all these terminals will still be attributed to the one city matched with the LNIA as stated previously.

Limitations of Message Stream Reports

A logical unit (LU) resource is included in the LU message stream, message stream, and distributed data management (DDM) message stream reports only if a resource vector table (RVT) entry exists for that LU resource when data collection is started. If an RVT entry is created for an LU resource after data collection is started, that LU resource is not included in the Message Stream reports.