vws-python-mock 2018.9.10.6

A mock for the Vuforia Web Services (VWS) API.

VWS Python Mock

Python mock for the Vuforia Web Services (VWS) API and the Vuforia Web Query API.

Contributing

See CONTRIBUTING.rst for details on how to contribute to this project.

Installation

This package has not yet been uploaded to PyPI.

For now it is possible to install the work in progress:

pip install git+https://github.com/adamtheturtle/vws-python-mock@master

This requires Python 3.6+. Get in touch with [e-mail] if you would like to use this with another language.

Mocking Vuforia

Requests made to Vuforia can be mocked. Using the mock redirects requests to Vuforia made with requests to an in-memory implementation.

import requests
from mock_vws import MockVWS

with MockVWS():
    # This will use the Vuforia mock.
    requests.get('https://vws.vuforia.com/summary')

However, an exception will be raised if any requests to unmocked addresses are made.

Allowing HTTP requests to unmocked addresses

This can be done by setting the parameter real_http to True in the context manager’s instantiation.

For example:

import requests
from mock_vws import MockVWS

with MockVWS(real_http=True):
    # This will use the Vuforia mock.
    requests.get('https://vws.vuforia.com/summary')
    # No exception is raised when a request is made to an unmocked address.
    requests.get('http://example.com')

Authentication

Connecting to the Vuforia Web Services requires an access key and a secret key. The mock also requires these keys as it provides realistic authentication support.

By default, the mock uses random strings as the access and secret keys.

It is possible to access these keys when using the context manager as follows:

from mock_vws import MockVWS

with MockVWS() as mock:
    access_key = mock.server_access_key
    secret_key = mock.server_secret_key

To set custom keys, set any of the following parameters in the context manager’s instantiation:

• server_access_key

• server_secret_key

• client_access_key

• client_secret_key

The mock does not check whether the access and secret keys are valid. It only checks whether the keys used to set up the mock instance match those used to create requests.

Setting the database name

This can be done with the database_name parameter. By default this is a random string.

Mocking error states

Sometimes Vuforia is in an error state, where requests don’t work. You may want your application to handle these states gracefully, and so it is possible to make the mock emulate these states.

To change the state, use the state parameter when calling the mock.

import requests
from mock_vws import MockVWS, States

def my_function():
    with MockVWS(state=States.PROJECT_INACTIVE) as mock:
        ...

The states available in States are:

• WORKING. This is the default state of the mock.

• PROJECT_INACTIVE. This happens when the license key has been deleted.

The mock is tested against the real Vuforia Web Services. This ensures that the implemented features of the mock behave, at least to some extent, like the real Vuforia Web Services. However, the mocks of these error states are based on observations as they cannot be reliably reproduced.

Custom base URLs

MockVWS mocks the Vuforia Web Services (VWS) API and the Vuforia Web Query API. These APIs have base URLs https://vws.vuforia.com and https://cloudreco.vuforia.com respectively.

MockVWS takes the optional parameters base_vws_url and base_vwq_url to modify the base URLs of the mocked endpoints.

Processing time

Vuforia Web Services processes targets for varying lengths of time. The mock, by default, processes targets for half a second. To change the processing time, use the processing_time_seconds parameter.

Differences between the mock and the real Vuforia Web Services

The mock attempts to be realistic, but it was built without access to the source code of the original API. Please report any issues here. There is no attempt to make the image matching realistic.

Speed and summary accuracy

The mock responds much more quickly than the real Vuforia Web Services.

Targets in the mock are set to ‘processing’ for half a second by default. This is customisable, with the processing_time_seconds parameter. In the real Vuforia Web Services, the processing stage takes varying lengths of time.

The database summary in the real Vuforia Web Services takes some time to account for images. Sometimes the real summary skips image states such as the processing state. The mock is accurate immediately.

Image quality and ratings

Targets are assigned a rating between 0 and 5 of how good they are for tracking purposes. In the mock this is a random number between 0 and 5.

Image targets which are not suited to detection are given ‘failed’ statuses. The criteria for these images is not defined by the Vuforia documentation. The mock is more forgiving than the real Vuforia Web Services. Therefore, an image given a ‘success’ status by the mock may not be given a ‘success’ status by the real Vuforia Web Services.

When updating an image for a target on the real Vuforia Web Services, the rating may stay the same. The mock changes the rating for a target to a different random number when the image is changed.

Matching targets in the processing state

Matching a target which is in the processing state sometimes returns a successful response with no results. Sometimes a 500 (INTERNAL SERVER ERROR) response is given. The mock always gives a 500 response.

Matching deleted targets

Matching a target which has been deleted returns a 500 (INTERNAL SERVER ERROR) response within the first few seconds. This timeframe is not consistent on the real Vuforia Web Services. On the mock, this timeframe is three seconds by default. MockVWS takes a parameter query_recognizes_deletion_seconds to change this.

Accepted date formats for the Query API

The Query API documentation is not clear on which date formats are expected exactly in the Date header. The mock is strict. That is, it accepts only a few date formats, and rejects all others. If you find a date format which is accepted by the real Query API but rejected by the mock, please create a GitHub issue.

Targets stuck in processing

On the real Vuforia Web Services, targets sometimes get stuck in the processing state. For example, targets with the name \uffff get stuck in the processing state. On the mock, no targets get stuck in the processing state.

Database summary quotas

The database summary endpoint returns quotas which match the quotas given for a free license.