tracdap-ext-http 0.10.0b3

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

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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-beta2 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.