Look at Microsoft Message Queue Server (MSMQ). It is designed to do exactly what you need.


>Hi,
>I have a client who ask for our Point of sale system, to be implemented in his Supermarket. However, we know that, that is a limitation in our Point of sale system. That is, our Point of sale system will connect to the server to retrieve/update data directly using buffering. If the server down, our Point of sale will be hang and the Point of sale workstaion will not able to operate.
>
>I know that, we may need to manipulate data offline, however, my client want to see the stock status time to time (online). Do you have any ideas on this scenario?
>
>I have the following ideas, but it may not effective, please advise.
>
>1. Once the Point of sale application start on workstation, it will re-load the item info from server and save it locally.
>
>2. Every sales transactions done for each workstation will be saved locally either. Then, a timer object will check the local sales table intervally. If any new/updated sales record, it will add/update the record on server site. After update record to server successully, the sales record will be marked as processed.
>
>3. If any changes made to the particular sales record such as return, the flag processed will be unmarked. Then the timer object will reprocess this record again. If error occured if the server down, timer object will handle it.. and retry after a period of time.
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>4. To prevent the Point of sale system temporary hang while trying to update record from local to server, i plan to implement the timer using COM EXE.
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>Any advise for the design above? Any better ideas?
>
>Please advise too for any technical aspect that you think I should consider in this case.
>
>Thank you very much