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For those of you who are familiar with Reactive Extensions you should know all about observables already, but did you know that there’s another kind of observable sequence – Rx.ConnectableObservable.
The difference between the two types of observable sequences is well explained here, in short, a connectable observable sequence allows you to share the same source sequence of values with multiple subscribers whilst the normal observable sequence gives each subscriber its own sequence of values. Whilst in most cases this difference doesn’t have any practical impacts as each subscribers are given the same values in the same order, however, consider this observable sequence of random numbers between 0 and 1000:
As you can see, each time the iterator is invoked it’ll generate a different value, hence subscribers will receive a different value each time (see demo below):
Instead, if you want to ensure that all the subscribers receive the same values, your best bet is to ‘publish‘ the source:
which returns you a connectable observable that you can then attach subscribers to:
and once you ‘connect‘ to the underlying source, the subscribers will start receiving values from the stream:
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Here is a complete list of all my posts on serverless and AWS Lambda. In the meantime, here are a few of my most popular blog posts.
- Lambda optimization tip – enable HTTP keep-alive
- You are thinking about serverless costs all wrong
- Many faced threats to Serverless security
- We can do better than percentile latencies
- I’m afraid you’re thinking about AWS Lambda cold starts all wrong
- Yubl’s road to Serverless
- AWS Lambda – should you have few monolithic functions or many single-purposed functions?
- AWS Lambda – compare coldstart time with different languages, memory and code sizes
- Guys, we’re doing pagination wrong