Geoffry, > And if the downstream node has a failure for 30 minutes and then a new > replacement comes up, will it receive notifications for the products that > appeared during that 30 minutes? That is, do the downstream and upstream > nodes coordinate acknowledgement of receipt? Your mental model of the LDM is incorrect. For a connection in primary mode, the downstream LDM doesn't receive notifications of product availability; instead, the upstream LDM transmits data-products to the downstream LDM that match the subscription that the downstream LDM registered with the upstream LDM as soon as the products are available at the upstream site. The transmission of data-products in this mode is asynchronous and uni-directional (i.e., the downstream LDM doesn't reply). For a second connection in alternate mode with an identical subscription, the upstream LDM synchronously sends a notification of a newly-available data product to the downstream LDM and awaits a reply. Typically, the response by the downstream LDM will be that it already has the product (from the primary mode connection). Occasionally, however, the downstream LDM replies that it doesn't have the product, in which case the upstream LDM transmits it. If and when the downstream LDM determines th at most of its products are being received on the alternate mode connection, then it breaks that connection and re-establishes it in primary mode. The reverse is done by the downstream LDM if and when it determines that the minority of products are being received on the primary mode connection. As long as the downstream site is offline for less than the minimum residency time of the upstream site's product-queue, the downstream LDM won't miss any products (providing the network bandwidth is sufficient, of course). > What about if a download is started, the downstream node dies, a new node > comes upâwill the new node receive notice of that partially (but not > successfully downloaded and processed) file? No. An upstream LDM treats each connection as unique. > If there's any more detailed documentation of the behavior I'd appreciate > the pointer. There were some state transition diagrams, but they were too confusing. You might find them in the online documentation for the older versions (e.g., 6.4). > Cheers, > Geoffry Regards, Steve Emmerson Ticket Details =================== Ticket ID: HEQ-649192 Department: Support LDM Priority: Normal Status: Closed
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