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Georgia SoftWorks
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| Failure Detection and RecoveryFor Industrial applications excellent failure detection and recovery is expected and required. This is one area that separates the toys from the tools. The ability to operate in industrial and commercial environments was a design goal from the beginning not an afterthought. Commercial applications require that remote link, PC and Client failures be detected and handled as minimize the impact to other users of the system. Georgia SoftWorks pioneered every feature listed . Some have been copied but none have been equaled. Essential for RF Applications
Georgia SoftWorks has again pioneered another outstanding feature for NT/2000 Telnet Servers. This feature Saves the Telnet Session in the event of a link or client failure and allows users to reconnect to the same session the next time they log in and resume the work in progress, exactly where they left off. Extremely useful when connectivity is across the Internet or with Radio Frequency Barcode/Scanner applications where it is important to continue work in progress, even after a connectivity failure. If a reconnection is not performed within a specified time period then Graceful Termination will initiate. For the fastest reconnection and minimal prompting you may want to couple the Session Saver with AutoLogon. Especially useful in RF Datacollection applications. Upon a client or link failure, the telnet session and associated NTVDM are normally terminated eliminating any orphaned sessions. This is the default behavior. However there are times when it may be desirable to Save the Session giving the user the opportunity to reconnect to the session to resume work in progress. This session is termed to be Saved or Suspended. The Georgia SoftWorks Telnet Server for NT/2000 provides features that ensure that all telnet sessions are properly terminated, even during abnormal client and link failures. Many internal session cleanup methods are automatic; others are configurable using the different Inactivity and Heartbeat timers, termination strings and scripts. Properly terminating telnet sessions ensure that all sessions are available for use and that problems do not accumulate over a long term. The Georgia SoftWorks Telnet Server has employed very complex and sophisticated proprietary algorithms to detect, identify and eliminate “orphanded" NTVDM’s directly initiated by applications when using telnet. In many cases orphaned NTVDM’s or processes can consume all of the server’s processing power rendering the server crippled or useless. Realizing that NTVDM cleanup is essential in industrial, commercial and mission critical applications, a great amount of design and development resources were expended to ensure proper operation in this area. Server Side Inactivity Timer - Details Server Side Inactivity Timer allows implementing an optional administrative policy to terminate sessions after a period of inactivity. For example; ACME Company purchased Georgia SoftWorks Telnet Server with a single session. User Bob connects a session locks his office and goes home. No one else can connect due to the licensing limit. If data (keyboard or mouse events) is not received from a client within the specified server side inactivity time then the client session is terminated. This feature is useful to ensure that an abandoned 3rd party client session is terminated properly, releasing the telnet session for others to use. Server Side Heartbeat - Details The Server Side Heartbeat Timer is used for setting the frequency in seconds which to poll the 3rd party client for presence. If the client is not present then Graceful Termination is initiated. Client Side Heartbeat - Details To aid in the detection of failed links or failed remote PC's the Georgia SoftWorks Client software supports a Client Timeout value. The client will send a heartbeat to the server at specified time intervals. At installation, this value is set to 300 seconds. This can be changed using the shortcut properties. If the server does not receive data from the client in the specified time, the connection is terminated. The data can be keyboard, or mouse input as well as the heartbeat. When keyboard or mouse data is transmitted, or when a heartbeat detected the server's timer is restarted. Graceful Termination of DOS Applications - Details The Georgia SoftWorks Windows Telnet Server is outstanding feature. In the case of a link or remote PC failure we attempt to gracefully terminate the executing DOS application, therefore saving important data that may otherwise be lost. Many applications are terminated by sending a sequence of characters to the application such as ESC-ENTER. Applications may have specific sequences. We allow a termination string to be defined as an environment variable in the k_start.bat or c_start.bat file. When a session is to be terminated due the client heartbeat timer expiring or the server side inactivity timer expiring then the defined termination string will be sent to the associated application. Approximately 3 seconds later the session is terminated if still running. Termination scripting is analogous to the Logon Scripting except it is executed when the telnet session is terminated. The commands within the file cleanup.bat are invoked upon termination of a telnet session. This is invoked with both normal and abnormal terminations. Cleanup scripting is available on both a global and per user basis as with Logon Scripting.
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