The Watson Explorer Engine query service uses local configuration information to identify the collection service that is associated with a given search collection, and then contacts that collection service to locate the indexer service that is associated with that search collection. The query service then forwards the query to that indexer service, and retrieves and returns the results of the query.
Once started, the query-service will automatically restart itself if it crashes. The query-service maintains a set of general-purpose threads to process the web requests for search results or cached pages. The service attempts to maintain at least Minimum idle threads and at most Maximum idle threads ready for handling new requests. The defaults should normally be acceptable.
The query service accepts HTTP connections on a specified port. It also accepts HTTPS connections, if you supply your own SSL certificate in PEM format with private key. You can allow other hosts to contact this query service by entering approved IP addresses or wildcards (such as 192.168.0.*) in the Allowed IPs field on the Management > Services > Search Engine > Options screen in the Watson Explorer Engine administration tool. This is usually done to allow Watson Explorer Engine front-end installations to contact a back-end query service in a multi-tier architecture, or to permit queries from Application Builder or BigIndex components.