Executable code in service task / any other task

[shashank-yelluri-dn]

Hello @ralphhanna,
Hope you are doing well.

Is there any way that we can write the code in camunda to execute. I know that we have task / execution listeners, but

1. We cannot have imports in the code right ? for example, i want to use mongoose in the code for which i need to import the package.
2. Can we write the code in any other language ? like python ? again with some imports ?

For solving my question 1, i know that we can write functionalities in appservices, but for that it would need to make a code change in the PROD to support this. I'm looking for a solution to write some small code blocks to execute.

Please share your thoughts ? also @ALL, please share me any solutions if you already had ins solving the above mentioned problems.

Thank You in advance 🚀

[ralphie2025]

bit confused about your mention of camunda? you mean in the XML file.

1. There are sever security concerns with this approach
2. No, You can't install new packages, without restarting the app
3. We can work around imports by including them in the JavaScript handler class, but they need to be determined at the application level
4. To allow Python instead of JavaScript require changes to ScriptHandler, to invoke Python code.

It is easy to customize your own scriptHandler and modify the configuration.ts class to include it

		scriptHandler: function(server) {
			return new ScriptHandler();
		},

In Summary, the answer is Yes, you can allow JavaScript code to access installed libraries and Yes you can allow Scripts to be Python code

[shashank-yelluri-dn]

@ralphie2025 - Good Morning !!

1. Understood.
2. Ahhh. Make sense, and we can have some defined libraries stitched already to the project for support.
3. Oh is it, could you please share me the link for reference ?
4. Crazy. Any document or example code would help.

Thank You for the quick response and would like to have some examples to refer or a documentation where these things are mentioned.

[ralphie2025]

To customize ScriptHandler, (src/engine/ScriptHandler.ts) just copy or inherit the existing class and let the configuration.ts load it:

	scriptHandler: function(server) {
			return new CustomScriptHandler();
		},

As for Python; have a look at this link

[ralphie2025]

Ok, I was able to invoke python as a web service from a workflow:

1. add webService method to AppServices

    async webService(input,context) {
        const axios = require('axios');

        let url='http://localhost:5000/run';
        let data={ a: 2, b: 3 };

        let res=await axios.post(url, data) 
        console.log('Result from Python:', res.data);

    }

2 have a python running as a web server

from flask import Flask, request, jsonify

app = Flask(__name__)


@app.route('/hi', methods=['GET'])
def say_hi():
    return "Hi there! 👋", 200

@app.route('/run', methods=['POST'])
def run():
    data = request.json
    result = data['a'] + data['b']
    return jsonify({'result': result})

if __name__ == '__main__':
    app.run(port=5000)

3. Invoke from workflow (any node start/end trigger)

appServices.webService({},this);

[shashank-yelluri-dn]

Thank you for your efforts. But running a different web server and again from our code, we are making a HTTP request was always a possibility in my opinion.
I just need to write the piece of code in XML and watch it getting executing, may be a service task or an execution listener anything …

[ralphie2025]

However, If you are looking at just python snippet throughout the workflow here is another option we can entertain:

$py print("Hi Python")

By Inserting `$py ' at the start of any script, we execute as a python code by spawning a separate process

[ralphie2025]

This is now available in latest release 2.3.2