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Number of subscriptions
February 15, 2016
10:14, EET
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pramanj
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Hi,
Just curious to know what is the overhead involved in creating multiple subscriptions. If I have too many (say 1000) subscriptions with say 100 to 200 nodes in each perhaps with some overlpping nodes in them (say 10% entries are repeated in each), then does it make sense to create 1000 subscriptions with one or two remaining active and others remaining paused or to have a single sunscription with 1000×200 (20,000) entries in a single subscription? Its a trade off between simple implementation of a single sunsbription vs the overhaead of creating and managing 1000’s of subscriptions on client as well as server ovehead! How are subscriptions intended and designed to be used?

BR
PRAMANJ

February 15, 2016
11:02, EET
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Heikki Tahvanainen
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The normal scenario is that multiple monitored items are created per subscription. Using a large amount of monitored items per subscription performs better than using a lot of different subscriptions.

You can easily handle for example 1000 value changes per second in an OPC UA server. However, making 1000 different subscriptions to monitor these values is not efficient. You should aim to make a lot of monitored items and as little separate subscriptions as possible.

February 15, 2016
13:15, EET
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pramanj
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Thanks a lot. Its an important design consideration. Trade off between number of subscriptions and number of items per subscriptions. I will try to keep subscriptions to minimum. It also depends upon the application I guess. If the client is not displaying all the real time data all the time, then why to receive the values from server and increase the netwoek bandwidth! But thanks for the guiding principle of keeping sunscriptions to minimum.

regards
PRAMANJ

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