TitanicAPI

Pet project to explore the "Model-as-a-Service" concept via API creation. Docker image available here.

⚠️ This project isn't maintained anymore, the docker app and api may not succesfully run.

Lots of the underlying packages have undergone through numerous changes since this proof-of-concept was originally created and as such modifications may be needed, in particular with respect to plumber's growth in the last couple of years.

Overview

Pet project for creating a simple Naïve Bayes classifier with the Titanic data set (as an example) and deploying it as an API through Docker and a container-hosting service.

This project is heavily dependent on two R packages:

• plumber, for creating the API with R --- see more here
• mlr, to create and use the model --- see more here

HTTPS can be set via the platform of delivery (tested with Microsoft Azure) instead of burdening the Docker container with a server. However, it is straightforward to integrate an apache server with custom certificates. See the security note below for more information.

Model Creation

It is assumed that the model is created locally, by sourcing the createModel.R. The API itself needs only the the final model and one row of example data (which contains all relevant metadata), which are both stored as .rds files inside the model folder, along with the parameter validation function contained in valParams.R, already inside the model folder.

Running the API locally (without Docker)

To test the API locally (without the Docker container), assuming that both plumber and mlr packages are installed, all that is needed is to source the runAPI.R script, which will automatically plumb mainAPI.R.

You should be able to find the basic introductory page at http://localhost:8000.

The /titanic endpoint handles the actual prediction. The parameters to be passed into the model are included in the request itself for simplicity. The pattern is /titanic?param1=value1&param2=value2.

• Example query: http://localhost:8000/titanic?pClass=2&pSex=male&pAge=70&pFare=125&pFamily=0

• Example response: [{"prob.FALSE":0.0479,"prob.TRUE":0.9521,"response":"TRUE"}]

Running the API locally (with Docker)

If you've built the Docker container (or pulled it from here), then you don't need to have an R installation - that's already taken care of via the container, with all the necessary packages installed.

Simply

• run locally with: docker run --rm --user docker -p 8000:8000 titanic_api
• and see results on http://localhost:8000/

For an example query and response, see the previous section.

Running the API from a hosted container

Simply navigate to the URL for the container. That should load the introductory page. Appending /titanic?... as above should result in the expected behaviour (see the running locally section), as the API maps to the endpoints directly, without any need for further manual configuration or routing.

Data Provenance

Data was acquired from Stanford's CS109 publicly accessible page here.

A note regarding security

It is assumed that the container would be online behind other security measures such as user authentication and HTTPS. The container itself validates the parameters passed to it (thus avoiding the most obvious security breach) but does not implement other security features. However, such measures are easily implemented and usually already in place. Container hosting services may also offer solutions as well (as mentioned above, tested with Microsoft Azure).

If needed, HTTPS can be implemented via the container by including an apache server and the necessary certificates. For an example of such an implementation, see T-mobile's repository.

Naïve-Bayes probabilities from the Titanic dataset used

A-priori probabilities

Survival

FALSE	TRUE
0.614	0.386

Conditional probabilities (categorical features)

Passenger class

Class	1	2	3
FALSE	0.147	0.178	0.675
TRUE	0.398	0.254	0.348

Sex

Sex	female	male
FALSE	0.149	0.851
TRUE	0.681	0.319

Numerical features

Naïve-Bayes assumes Gaussian distribution for non-categorical features.

Age

Age	mean	std. deviation
FALSE	30.139	13.898
TRUE	28.408	14.428

Fare

Fare	mean	std. deviation
FALSE	22.209	31.484
TRUE	48.395	66.597

Family members on board

While the feature is obviously an ordinal (and equally spaced by one person at a time), it has been left as a numerical to be able to predict previously unseen combinations. During input validation, it is ensured that an integer is passed to the model.

Family	mean	std. deviation
FALSE	0.89	1.836
TRUE	0.939	1.186