IPC interface example
The purpose of this example is to provide a quickstart for interfacing with external q processes using PyKX. The example presented should operate in the presence or absence of a
k4.lic, and as such is intended to show the flexibility of this interface for users who had previously used both PyKX and those who are familiar with qPython.
To follow along with this example please feel free to download this zip archive that contains a copy of the python script and this writeup.
This example shows a basic tickerplant configured as follows
Here we have: 1. A q data feed publishing trade messages to a tick process 2. A q process running a modified tick.q 3. A Python process subscribing to the tick process, running a Python analytic on the trade data and pushing the results to another process 4. A q process to which the results of the Python analytic can be pushed
For more information about the differences between the licensed and unlicensed version of this example please consult
readwrite.py this has a breakdown of the steps taken in the presence/absence of a licensed shared object.
Start the required q processes
// run tick.q
$ q tick/tick.q sym ./log/
// run the mock feed
$ q tick/feed.q
// Start the q process to receive data from PyKX
$ q -p 5130
Start the pykx subscriber/publisher
// When running with a valid k4.lic in $QHOME
$ python readwrite.py
Running example in presence of licensed q
// When running in the absence of a valid k4.lic in $QHOME
'2021.04.02T11:32:41.006 license error: k4.lic
Running example in absence of licensed q
What should be observed on invocation of the above is that the process running on 5130 should begin to receive summaries of the average size/price of the individual tick symbols being published. The licensed and unlicensed versions are not the same in this regard.
- The licensed version will return the average over the entire trade table that it is subscribed to
- The unlicensed version will display the the average over the most recent batch of data received