Merge branch 'master' of https://github.com/hyperflow-wms/hyperflow

Author: balis

examples/TaskStatusRedis/README.md

@@ -1,12 +1,12 @@
 ## Job notification mechanism example
-This example demonstrates how remote job executors can notify the HyperFlow engine about job completion using Redis. 
+This example demonstrates how HyperFlow can communicate with remote job executors using Redis. 
 
- - The workflow invokes function `task_status_redis_test` from `functions.js` 100 times. This function simulates submission of jobs by starting 100 parallel processes of `handler.js`.
+ - The workflow invokes function `job_status_redis_test` from `functions.js` 100 times. This function simulates submission of jobs by starting 100 parallel processes of `handler.js`.
  - `handler.js` represents a remote job executor which is passed two parameters: `taskId` and `redis_url`. 
- - In order to notify that the job has completed, `handler.js` connects to Redis and performs a `RPUSH` operation on the `taskId` key.
- - On the HyperFlow engine side, the Process Function is passed `context.taskStatus` function which can be used to wait for the notification. This function returns a [`Promise`](https://javascript.info/promise-basics), so the async/await syntax can be used as shown in the example.
- - The Process Function also gets the Redis URL in `context.redis_url` which can be passed to the remote executors.
+ - `handler.js` gets `jobMessage` from Redis, and then sends back a notification that the job has completed; `taskId` is used to construct appropriate Redis keys.
+ - On the HyperFlow engine side, the Process Function can use two functions: `context.sendMsgToJob` to send a message to the job, and `context.taskStatus` to wait for the notification. These functions return a [`Promise`](https://javascript.info/promise-basics), so the async/await syntax can be used as shown in the example.
  - The parameter to the `context.taskStatus` function is a timeout in seconds (0 denotes infinity). One can use a retry library, such as [promise-retry](https://www.npmjs.com/package/promise-retry), to implement an exponential retry strategy.
+ - The Process Function also gets the Redis URL in `context.redis_url` which can be passed to the remote job executors.
 
- To run the workflow, simply do `hflow run .` in this directory. 
+ To run the workflow, simply do `hflow run .` in this directory. You might need to run once `npm install` to install dependencies.