com.linkedin.data.schema

Interface DataSchemaResolver

All Known Implementing Classes:

AbstractDataSchemaResolver, ClassNameDataSchemaResolver, ClasspathResourceDataSchemaResolver, DefaultDataSchemaResolver, FileDataSchemaResolver, MultiFormatDataSchemaResolver

public interface DataSchemaResolver

A DataSchemaResolver is used to resolve names to NamedDataSchemas.

A SchemaParser uses existingDataSchema(String) to determine if a name has already been resolved to a NamedDataSchema. The returned NamedDataSchema may not be complete or well-formed due to circular references.

A SchemaParser uses findDataSchema(String, StringBuilder) to request the resolving an unresolved name to a NamedDataSchema. This may be done by searching jar files or directories for files whose file names computed from the provided name similar to how Java resolves class names to source or binary files.

The contract between a SchemaParser and its DataSchemaResolver requires the SchemaParser to invoke bindNameToSchema(Name, NamedDataSchema, DataSchemaLocation) to bind all possible names (its declared name and aliases) to a newly constructed NamedDataSchema before SchemaParser attempts to lookup or resolve names referenced by the NamedDataSchema. This means that when the name is bound, the NamedDataSchema is incomplete. This contract is required to implement circular references.

Method Summary

Modifier and Type	Method and Description
java.util.Map<java.lang.String,NamedDataSchema>	bindings() Return a map of names to NamedDataSchema bindings that have been resolved.
void	bindNameToSchema(Name name, NamedDataSchema schema, DataSchemaLocation location) Bind name to the provided NamedDataSchema and DataSchemaLocation.
NamedDataSchema	existingDataSchema(java.lang.String name) Lookup existing NamedDataSchema with the specified name.
NamedDataSchema	findDataSchema(java.lang.String name, java.lang.StringBuilder errorMessageBuilder) Find a NamedDataSchema for the specified name.
boolean	locationResolved(DataSchemaLocation location) Return whether the specified DataSchemaLocation has been associated with a name.
java.util.Map<java.lang.String,DataSchemaLocation>	nameToDataSchemaLocations() Return a map of names to DataSchemaLocations that have been resolved through this resolver.

Method Detail

bindings

java.util.Map<java.lang.String,NamedDataSchema> bindings()

Return a map of names to NamedDataSchema bindings that have been resolved.

Returns:

map of names to NamedDataSchema bindings that have been resolved.

nameToDataSchemaLocations

java.util.Map<java.lang.String,DataSchemaLocation> nameToDataSchemaLocations()

Return a map of names to DataSchemaLocations that have been resolved through this resolver.

Returns:

a map of names to DataSchemaLocations that have been resolved through this resolver.

findDataSchema

NamedDataSchema findDataSchema(java.lang.String name,
                               java.lang.StringBuilder errorMessageBuilder)

Find a NamedDataSchema for the specified name. If a NamedDataSchema with the specified name is not found, the resolver will should try its best to find and instantiate a NamedDataSchema with the specified name.

Parameters:

name - of the schema to find.

errorMessageBuilder - to append error messages to.

Returns:

the NamedDataSchema if it can be located, else return null.

bindNameToSchema

void bindNameToSchema(Name name,
                      NamedDataSchema schema,
                      DataSchemaLocation location)

Bind name to the provided NamedDataSchema and DataSchemaLocation.

Parameters:

name - to bind to.

schema - provides the NamedDataSchema

location - provides the DataSchemaLocation

Throws:

java.lang.IllegalStateException - if name is already bound.

existingDataSchema

NamedDataSchema existingDataSchema(java.lang.String name)

Lookup existing NamedDataSchema with the specified name. This is a pure lookup operation. If a NamedDataSchema with the specified name does not already exist, then this method will return null, else it returns the existing NamedDataSchema.

Parameters:

name - of the schema to find.

Returns:

the NamedDataSchema if it already exists, else return null.

locationResolved

boolean locationResolved(DataSchemaLocation location)

Return whether the specified DataSchemaLocation has been associated with a name.

Parameters:

location - provides the DataSchemaLocation to check.

Returns:

true if the specified DataSchemaLocation has been associated with a name.