A Poller makes a scheduled request to a remote system.
In cases where it is not possible for a remote system to send us the data, we can make a scheduled request for it using Pollers. All Pollers belong to an integration. Although a Poller belongs to only one integration, an integration can have multiple Pollers.
A Poller is a configuration record which defines the frequency of polling and which logic to use (the logic itself is defined in the Poll Processor). Each time it is run, it creates a corresponding Poll Request record.
Depending on the use case, the use of a Poller to collect data from a remote system poses some development challenges which need to be considered. Namely, there is an additional responsibility and workload placed on the host system to store and check some returned data in order to evaluate what has changed.
For example, in order to decide whether the state has changed, or what comments have been added, or even which system has made the updates to the data (we don't want to pull back data we have changed), checks have to be built into the scripts. This is aided by holding a copy of the relevant returned data, using Data Stores (see the relevant page in the Administration section).
Poll Processors are used to setup, execute and process Poll Requests.
The Poll Processor is a configuration record which contains the logic that will be applied when polling a remote system for data. There are three main scripts which are used to setup, execute and process the Poll Requests.
The Setup Script is the first script to run (it runs at the point in time the Poll Request is created). It is used to build the environment for the poll and define what it will do (for example, create/setup the URL that will be called). It also supplies a params object as one of the arguments, which will be passed through to the subsequent scripts (and on to further Pollers, if required).
The Request Script is used to reach into the remote system and execute the request. This is usually done by making a REST call to the URL defined in the Setup Script.
The Response Script is used to process the information returned from the remote system. This could include converting the data from its proprietary format to a more usable format, sending the data to Unifi, or even kicking off a new poll.