How to run a job through Queue in arangodb - arangodb

Question

I am moving from ArangoDb 2.5.7 to ArangoDb 3.1.7. I have managed to make everything work except the Jobs. I look at the documentation and I don't understand If I have to create a separate service just for that ?
So, I have a foxx application myApp
manifest.json
{
"name": "myApp",
"version": "0.0.1",
"author": "Deepak",
"files":
{
"/static": "static"
},
"engines":
{
"arangodb": "^3.1.7"
},
"scripts":
{
"setup": "./scripts/setup.js",
"myJob": "./scripts/myJob.js"
},
"main": "index.js"
}
index.js
'use strict';
module.context.use('/one', require('./app'));
app.js
const createRouter = require('org/arangodb/foxx/router');
const controller = createRouter();
module.exports = controller;
const queues = require('#arangodb/foxx/queues');
queue = queues.create('myQueue', 2);
queue.push({mount:"/myJob", name:"myJob"}, {"a":4}, {"allowUnknown": true});
myJob.js
const argv = module.context.argv;
var obj = argv[0];
console.log('obj:'+obj);
I get following error:
Job failed:
ArangoError: service not found
Mount path: "/myJob".
I am not sure if I have to expand myJob as an external service. Can you help me. I don't see a complete example of how to do it.

Answer 1

To answer your question:
You do not have to extract the job script into a new service. You can specify the mount point of the current service by using module.context.mount.
You can find more information about the context object in the documentation: https://docs.arangodb.com/3.1/Manual/Foxx/Context.html
By the way, it's probably not a good idea to arbitrarily create jobs at mount-time. The common use case for the queue is to create jobs in route handlers as a side-effect of incoming requests (e.g. to dispatch a welcome e-mail on signup).
If you create a job at mount-time (e.g. in your main file or a file required by it) the job will be created whenever the file as executed, which will be at least once for each Foxx thread (by default ArangoDB uses multiple Foxx threads to handle parallel requests) or when development mode is enabled once per request(!).
Likewise if you create a job in your setup script it will be created whenever the setup script is executed, although this will only happen in one thread each time (but still once per request when development mode is active).
If you need e.g. a periodic job that lives alongside your service, you should put it in a unique queue and only create it in your setup script after checking whether it already exists.
On the changes in the queue API:
The queue API changed in 2.6 due to a serious issue with the old API that would frequently result in pending jobs not being properly rescheduled when the ArangoDB daemon was restarted after a job had been pushed to the queue.
Specifically ArangoDB 2.6 introduced so-called script-based (rather than function-based) job types: https://docs.arangodb.com/3.1/Manual/ReleaseNotes/UpgradingChanges26.html#foxx-queues
Support for the old function-based job types was dropped in ArangoDB 2.7 and the cookbook recipe was updated to reflect script-based job types: https://docs.arangodb.com/2.8/cookbook/FoxxQueues.html
A more detailed description of the new queue can be found in the documentation: https://docs.arangodb.com/3.1/Manual/Foxx/Scripts.html