Remove or optionally ignore app ID

New Feature / Enhancement Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.

Current Limitation

Parse Server is historically capable of running multiple apps, differentiated based on their app ID. However, it can be assumed that the vast majority of Parse Server deployments run a single app. This puts the purpose of an app ID in question.

Feature / Enhancement Description

Optionally ignore the app ID in Parse Server. This means that requests won't require to send an app ID in the request header or as part of the URL. That means the URLs can be shorted from https://<domain>/<mount>/apps/<appId>/<path> to https://<domain>/<mount>/<path>.

Historically, the parse.com app ID was 40 characters long, so especially for legacy apps this could reduce overhead and resource requirements across the whole network infrastructure incl. logs.

This requires a comprehensive study regarding its effects. The app ID is currently used in Parse SDK clients to scope the accessibility of user session tokens in native storage.

Alternatives / Workarounds

Remove the support of app ID completely. This would require a careful deliberation as the feature may be used by some developers. It may however allow to simplify the Parse Server codebase by removing logic that deals with app ID.

Start by tracing how Parse Server handles the app ID in request headers and URL paths, then review the Parse SDK client behavior that scopes session tokens. Determine the effects of optionally ignoring the app ID and define compatible shortened URLs, request handling, and migration behavior before implementation.