1. A computer-implemented method for dynamically generating classes and methods in memory in order for a host programming language to transmit or receive instance data to or from an application programming interface comprising: receiving a schema, which describes the format and properties of instance data to be transmitted or received; converting, using a client library, raw schema data into an intermediate hierarchical data structure, an upper level of the hierarchical data structure including the properties of the instance object, and each property including data representing attributes of that property; dynamically at runtime generating parser classes for deserialization and methods from the properties and attributes described in the intermediate hierarchical data structure based on the schema, wherein generating the parser classes comprises: iterating over each property defined in the schema and in any other schema referenced in the schema, and defining a new class for each non-scalar, non-array property defined by the schema; and storing the generated parser classes and methods in memory in order for the host programming language to transmit or receive instance data to or from the application programming interface.