Optimization and compression techniques

When the Optimizer receives control of a data stream, it uses several methods to produce a much smaller data stream that accomplishes the same function as the larger one. The techniques that are controlled from the Monitor are as follows:

• Conventional optimization
• Imaging Stage One optimization
• Imaging Stage Two optimization
• Input Suppression optimization
• Erase Input Key Allowed optimization
• SCS Printer optimization
• SCS Horizontal Tabs optimization
• SNA Data Compression

Conventional optimization

The Conventional optimization technique eliminates the following items:

• Repeating strings of characters
• Unnecessary or redundant user data
• Unnecessary 3270 control characters

The Conventional optimization technique also sorts data streams. The Conventional optimization technique is used when the following conditions exist:

• SUPEROPT Imaging techniques cannot be used
• SUPEROPT is installed, but Imaging is turned off

Conventional and imaging optimization features

SUPEROPT has several Conventional and Imaging optimization features:

• Attribute Elimination eliminates unnecessary attributes embedded in outbound data streams that are sent to printers.
• Blank Elimination removes blanks from protected fields in outbound data streams that are sent to CRTs and printers.
• Field Merge allows your installation to eliminate start field orders from consecutive protected fields, when the field attributes are the same.
• Non-Display Fields eliminates protected non-display fields from outbound data streams that are sent to CRTs and printers.

Imaging stage one optimization

This technique remembers what is displayed on each terminal screen. It transmits only the data that is required for appropriate changes to the screen. Imaging optimization also supports partitioned terminals (for example, 3179, 3180, 3193, 3290, and 3775).

Imaging stage two optimization

The Imaging Stage Two optimization technique uses Imaging Stage One as a base and uses highly sophisticated algorithms to achieve better optimization.

Input suppression optimization

Depending on the hardware that your installation is using, inbound data streams are usually transmitted in pieces (or segments) of 256 or 512 bytes. When each piece is transmitted from the terminal to the host, the host must acknowledge that it has received the data before the next piece can be transmitted. The protocol that the hardware and software follow to accomplish this verification process is called line turnaround.

Using the Input Suppression optimization technique, the Optimizer reduces the length of inbound data streams. Input Suppression optimization performs the following functions:

• Uses the Imaging optimization technique to remove all unnecessary data and control characters from the data stream that is transmitted from a terminal to your host application, This function is accomplished with the optimization software in your host CPU. No hardware changes are needed.
• Allows additional adjustments to outbound data streams to further reduce their lengths
• Reduces the number of transmitted characters and the number of line turnarounds

If Input Suppression can reduce your inbound data streams from two pieces to only one piece, the number of line turnarounds is also reduced.

Erase input key allowed optimization

Erase Input Key Allowed optimization is a partial implementation of Input Suppression optimization. It is provided for sites where terminal operators use the Erase Input (ErInp) key.

The difference between Input Suppression and Erase Input Key Allowed is the percentage of reduction in the lengths of data streams. The reduction is greater with Input Suppression.

Erase Input and Erase EOF (ErEOF) are separate keys on the keyboard, with different functions. Erase EOF can be used with Input Suppression.

SCS printer optimization

SCS Printer optimization optimizes outbound data streams for SCS printers. The effect is to speed up your SCS printers by using SCS features to reduce the amount of data to be printed.

SCS horizontal tabs optimization

SCS Horizontal Tabs optimization is another technique that reduces the length of SCS printer data streams. It uses the following horizontal formatting codes:

• Set Horizontal Format
• Horizontal Tab

If you have SCS printers that do not support these codes, this technique cannot be used.

SNA data compression

SNA Data Compression compresses outbound data streams for 3600/4700 controllers and 3790 user programs that run application programs that support SNA data decompression. This optimization technique expands compressed inbound data streams that were compressed by application LUs.