tracdap-ext-http 0.10.0.dev3

An extension for TRAC D.A.P. that lets models connect to HTTP endpoints

HTTP Extension for the TRAC Model Runtime

This extension allows TRAC models to make calls to external systems using HTTP and HTTPS.

• Make HTTP endpoints available to models, to use directly in model code
• Connection settings managed by TRAC for both local and deployed models
• Supports http.client and urllib3

Models that make external calls are not considered repeatable, and will be flagged as not repeatable when they run on the TRAC platform.

This extension is a pre-release and will be finalized inTRAC 0.10.

Installing

The HTTP extension can be installed with pip:

$ pip install tracdap-ext-http

The package has the following dependencies:

• tracdap-runtime (version 0.10.0-beta1 or later)
• urllib3 (optional, version 2.x)

Using the http.client API

Here is a minimum working example of a TRAC model using the http.client API:

import tracdap.rt.api as trac
import http.client as hc

class TestModel(trac.TracModel):

    # ... define parameters, inputs and outputs

    def define_resources(self):

        return {
            "github": trac.define_external_system("http", hc.HTTPSConnection)
        }

    def run_model(self, ctx: trac.TracContext):

        with ctx.get_external_system("github", hc.HTTPSConnection) as github:

            github.connect()
            github.request("GET", "finos/tracdap/refs/heads/main/README.md")

            response = github.getresponse()
            response_text = response.read().decode("utf-8")
            first_line = response_text.splitlines()[0]

            ctx.log.info(first_line)

if __name__ == '__main__':
    import tracdap.rt.launch as launch
    launch.launch_model(TestModel, "config/job_config.yaml", "config/sys_config.yaml")

To make this example work, you will need to add github as a resource in the system config file:

resources:

  github:
    resourceType: EXTERNAL_SYSTEM
    protocol: http
    properties:
      host: raw.githubusercontent.com
      port: 443
      tls: true

The following configuration properties are supported:

• host, string, required
• port, int, optional
• tls, bool, default = true
• timeout, float, optional

Models using the client type HTTPSConnection will only work if tls = true is set in the configuration. Models requesting HTTPConnection will work with tls = true or tls = false, and will receive an HTTPSConnection if tls = true.

Using the urllib3 API

Here is a minimum working example of a TRAC model using the urllib3 API. In order to use this API, the urllib3 package must be installed.

import tracdap.rt.api as trac
import urllib3

class TestModel(trac.TracModel):

    # ... define parameters, inputs and outputs

    def define_resources(self):

        return {
            "github": trac.define_external_system("http", urllib3.HTTPSConnectionPool)
        }

    def run_model(self, ctx: trac.TracContext):

        with ctx.get_external_system("github", urllib3.HTTPSConnectionPool, timeout=10.0) as github:

            response = github.request("GET", "/finos/tracdap/refs/heads/main/README.md")

            response_text = response.data.decode("utf-8")
            first_line = response_text.splitlines()[0]

            ctx.log.info(first_line)

if __name__ == '__main__':
    import tracdap.rt.launch as launch
    launch.launch_model(TestModel, "config/job_config.yaml", "config/sys_config.yaml")

The resource configuration for the urllib3 API is identical to the http.client API.