As discussed on the last Code Sprint, some schema based validation similar to
http://json-schema.org/ for arrays would be very useful for FLOW3.

Goal¶

The JSON schema should be used to verify the syntax of:

• Settings
• Routes
• Image Processing Instructions
• Content Type Definitions
• Security Settings

Currently a typo in those sometimes leads to very confusing effects. By validation against a pre-made schema, we can tell the user meaningful errors. We could even integrate that in the exception handling: If an exception happens, we could validate the configuration, as an error in configuration most likely results in exceptions.

Generally, we want to use schemata to validate arrays.

Specification¶

we should forward-port JSON-schema from http://tools.ietf.org/html/draft-zyp-json-schema-03 to PHP. We are only listing the differences here. We will refer to this work as PHP schema. Some major differences are:

• JSON schema validation does only distinguish between valid and invalid. We should furthermore have a third, in-between style; something like "Bad smell", which hints to errors. TODO how to implement it?
• We aim for an implementation of 1. - 5.25 of JSON Schema Draft 03.

3.1. Terminology¶

For this specification, schema will be used to denote a PHP Schema
definition, and an instance refers to a PHP value that the schema
will be describing and validating.

5.8. dependencies¶

• TODO do we need them?

5.20 default¶

• We don't need this.

5.23 format¶

We support the following additional formats:

• classname: A class name which is known to the object manager // TODO: should it be classname or objectname?

5.26. extends, 5.27 id, 5.28. ref, 5.29 $schema¶

• We don't need this.

6 Hyper Schema¶

• We don't need this.

Implementation¶

Implementation-wise, the validator should be split into two parts: One for the implementation of the PHP schema, the second part for the FLOW3-specific additions.

• We should use \FLOW3\FLOW3\Error\Result
• the system should be developed test-driven.

Future Work¶

The schema could even be self-learning to some extend (see https://github.com/kore/XML-Schema-learner for a similar example).