AutobahnJS how to correctly unsubscribe?

Hi,

I’m afraid the following might be more of a generic Javascript question than a specific AutobahnJS question. But I thought I should give it a try and ask politely:

I’m using AutobahnJS to visualize measurement data received via different WAMP events. Works pretty good. Sometimes I need to unsubscribe from a topic and instead subscribe to a different topic. For this exercise lets assume I’m switching between the reception of data from two sensors. Furthermore lets assume I have a global variable called sensorSubscription that stores my subscription and is initialized with NULL.

The subscription process works and sensorSubscription becomes a Subscription object. So far so good. The problem now is that after wampSession.unsubscribe(sensorSubscription) I thought that my subscription object is being destroyed and my sensorSubscription variable is becoming NULL again. After I realized that sensorSubscription still references the same Subscription object I checked if it might contain some property that I can use to verify if my subscription is still valid or not (before overwriting it with a new subscription). I found the active property but realized that it’s always set to FALSE. No matter if I unsubscribed or not.

I guess my question is simply how to correctly unsubscribe in AutobahnJS so that I can reuse my sensorSubscription variable for a new subscription.

Many thanks for your help,

Franz

Interesting Franz, could you not just overwrite your subscription var? What happens if you just try and use the car for new assignment?

As to your next question regarding active. I don't know, but maybe active is dependent on the server side for single source of truth. Maybe have a subscriptionCheck topic that will look for active subscription on client and if that succeeds (or doesn't) then go check at the server. A little jankie but would give the whole picture.... Just thinking out loud :grin:

I could indeed overwrite the sensorSubscription variable. But only at the time when I make a new subscription. While there is no new subscription the old object remains kinda orphaned and other components in the program aren’t able to easily verify if this is a valid subscription or not.

I just have the feeling I should invalidate the object somehow and don’t understand why this isn’t done by the unsubscribe process.

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Am Donnerstag, 14. Juni 2018 16:08:42 UTC+2 schrieb Dave Thomas:

Interesting Franz, could you not just overwrite your subscription var? What happens if you just try and use the car for new assignment?

As to your next question regarding active. I don’t know, but maybe active is dependent on the server side for single source of truth. Maybe have a subscriptionCheck topic that will look for active subscription on client and if that succeeds (or doesn’t) then go check at the server. A little jankie but would give the whole picture… Just thinking out loud :grin: