Question:We do have a service which is taking few inputs and that service will inturn calling a childservice for processing the flow.
We are seeing an issue wherein when we enable the cache property of child service to true the actual inputs which are coming from parent service is getting overwritten after the child step execution.
Since we need to enable the cache property of child step without overwriting the actual run time input of parent service.Can someone help me on this?
Kindly let me know if you need anyother details
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when a service is set up for caching, it will always return the cached output when it is invoked with the same inputs from an earlier invocation.
Please explain, why you need the child service to be set up for caching.
Provide a screen shot with the outline of the parent flow and describe where the inputs get changed unexpectedly.
To limit Caching to the child serviceās inputs and outputs, you must invoke the child as a Transformer.
Alternatively, I think the āScopeā property might also work, if your cached output is within a single document (it has been long since I developed anything).
Updated per Holgerās comment below - thanks Holger, that was my intention.
should be read as
āTo limit Caching to the child serviceās inputs & outputs, you must invoke the child as a Transformer.ā
as caching uses the input pipeline as the key and the output pipeline as the value for the cache entry.
Even when not explicitly in the sginature of the service, the complete pipeline is used, when not invoking as a Transformer in a MAP-step instead of a normal INVOKE-step.
As of wm 10.15 we introduced a new extended setting āwatt.server.serviceResults.cache.strictā that restricts the cache to only the output of the given service. It is disabled by default i.e. false.
Set this property to true to both improve efficiency and avoid having to invoked cached services via a transformer.
regards,
John.
This is the key aspect. The cache captures the entire pipeline ā and when used restores the entire pipeline. As the others have noted, calling via transformer or with a scope lets you control that.
But people never remember to do that and so we just avoid caching. It almost never matters for speed anyway.
We could resolve the issue by involving transformer for calling child service which is having cache property enabled.When we use transformer ,parent service inputs are not getting overwritten by child service.
As a side āacademic interestā trip, what is prompting the use of service caching in this case? Is it because gathering metrics shows that it improves performance in a meaningful way for the overall process? Or is it simply anticipated that it will be āfaster?ā
I ask because over the years Iāve never had occasion where using caching (or trying to use multi-threading) would be useful in a meaningful way. Most of the integrations we implement are ābehind the scenesā activities and so 5 seconds vs 3 seconds doesnāt matter.
Using caching also introduces the need to manage the cache. How long to keep it? How/when to force it to refresh? How to recover from issues because the cache was kept too long and did not refresh when it should have?
Iām interested in learning about the scenario where this added level of activity is offset by meaningful improvement in processing/response time.
