qryq

— 3 minute read

Pronunciation

/ˈkwərik/

What it is

qryq is a NodeJs library that allows one to express a series of API queries and define the dependencies between them. These queries may be executed in parallel, in sequence, or in a directed acyclic graph.

Despite being non-RESTful, this makes code more readable and composable, and affords a number of benefits.

Benefits

  • Allows the programmer to state client-server interactions declaratively, and thus avoid both callback spaghetti code and promise spaghetti code.
  • A reduction in total bandwidth and latency.
  • A reduction in duplication of business logic on the client and the server.
  • A treatment of several queries as an atomic unit, makes it easier to write asynchronous user interfaces.

Example

    [
      {"id":"qGeocodeOrigin","depends":[],"api":"gmapsGeoLookup","qry":{"address":"36 Meadow Wood Walk, Narre Warren VIC 3805"}},
      {"id":"qGeocodeDestination","depends":[],"api":"gmapsGeoLookup","qry":{"address":"19 Bourke Street, Melbourne, VIC 3000"}},
      {"id":"qScore","depends":["qGeocodeOrigin","qGeocodeDestination"],"api":"score","qry":{
          "origin":{"address":"36 Meadow Wood Walk, Narre Warren VIC 3805","lat":"#{qGeocodeOrigin}.lat","lon":"#{qGeocodeOrigin}.lon"},
          "journeyPlanner":"melbtrans",
          "destinations":[
            {
              "fixed":true,"class":"work","weight":0.8,
              "location":{"address":"19 Bourke Street, Melbourne, VIC 3000","lat":"#{qGeocodeDestination}.lat","lon":"#{qGeocodeDestination}.lon"},
              "modes":[{"form":"transit","max":{"time":2400}}]
            }
          ]
        }
      }
    ]
  • Here we can see that we have defined three queries, named qGeocodeOrigin, qGeocodeDestination, qScore.
  • The first two do not define any dependencies, but the thirds does.
    • qryq will figure out that it needs to execute qScore, only when both qGeocodeOrigin and qGeocodeDestination have completed, so that it may use its results.
  • The qScore invokes the function that handles the score API, and passes in a set of presently known values through qry
  • The qry for qScorealso passes in variables, whose values are not known at the time of making the query.
    • An example: "lon":"#{qGeocodeOrigin}.lon".
    • qryq will substitute the computed values for these variables when it is this query’s turn to execute.

More Details

A full presentation on qryq

qryq is a project that has spun off from another project of mine, walkre. Most of the development of qryq has thus far occurred in walkre, and currently the qryq repository is merely a snapshot of the qryq code used in walkre. A proper extraction is on the plans.

Open Source

qryq is open source, and you can find it on github