Class: SchemaRegistry::Client

Inherits:
Object
  • Object
show all
Defined in:
lib/schema_registry_client.rb

Constant Summary collapse

MAGIC_BYTE =

Provides a way to encode and decode messages without having to embed schemas in the encoded data. Confluent’s Schema Registry is used to register a schema when encoding a message – the registry will issue a schema id that will be included in the encoded data alongside the actual message. When decoding the data, the schema id will be used to look up the writer’s schema from the registry.

1: github.com/confluentinc/schema-registry docs.confluent.io/platform/current/schema-registry/fundamentals/serdes-develop/serdes-protobuf.html docs.confluent.io/platform/current/schema-registry/fundamentals/serdes-develop/index.html#wire-format

[0].pack("C").freeze

Instance Method Summary collapse

Constructor Details

#initialize(registry: nil, registry_url: nil, schema_context: nil, registry_path_prefix: nil, logger: nil, proxy: nil, user: nil, password: nil, ssl_ca_file: nil, client_cert: nil, client_key: nil, client_key_pass: nil, client_cert_data: nil, client_key_data: nil, connect_timeout: nil, resolv_resolver: nil, schema_type: SchemaRegistry::Schema::Protobuf) ⇒ Client

Instantiate a new SchemaRegistry instance with the given configuration.

registry - A schema registry object that responds to all methods in the

SchemaRegistry::ConfluentSchemaRegistry interface.

registry_url - The String URL of the schema registry that should be used. schema_context - Schema registry context name (optional) registry_path_prefix - The String URL path prefix used to namespace schema registry requests (optional). logger - The Logger that should be used to log information (optional). proxy - Forward the request via proxy (optional). user - User for basic auth (optional). password - Password for basic auth (optional). ssl_ca_file - Name of file containing CA certificate (optional). client_cert - Name of file containing client certificate (optional). client_key - Name of file containing client private key to go with client_cert (optional). client_key_pass - Password to go with client_key (optional). client_cert_data - In-memory client certificate (optional). client_key_data - In-memory client private key to go with client_cert_data (optional). connect_timeout - Timeout to use in the connection with the schema registry (optional). resolv_resolver - Custom domain name resolver (optional). schema_type - A SchemaRegistry::Schema::Base subclass.



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# File 'lib/schema_registry_client.rb', line 52

def initialize( # rubocop:disable Metrics/ParameterLists
  registry: nil,
  registry_url: nil,
  schema_context: nil,
  registry_path_prefix: nil,
  logger: nil,
  proxy: nil,
  user: nil,
  password: nil,
  ssl_ca_file: nil,
  client_cert: nil,
  client_key: nil,
  client_key_pass: nil,
  client_cert_data: nil,
  client_key_data: nil,
  connect_timeout: nil,
  resolv_resolver: nil,
  schema_type: SchemaRegistry::Schema::Protobuf
)
  @logger = logger || Logger.new($stderr)
  @registry = registry || SchemaRegistry::CachedConfluentSchemaRegistry.new(
    SchemaRegistry::ConfluentSchemaRegistry.new(
      registry_url,
      schema_context: schema_context,
      logger: @logger,
      proxy: proxy,
      user: user,
      password: password,
      ssl_ca_file: ssl_ca_file,
      client_cert: client_cert,
      client_key: client_key,
      client_key_pass: client_key_pass,
      client_cert_data: client_cert_data,
      client_key_data: client_key_data,
      path_prefix: registry_path_prefix,
      connect_timeout: connect_timeout,
      resolv_resolver: resolv_resolver
    )
  )
  @schema = schema_type
end

Instance Method Details

#decode(data) ⇒ Object

Decodes data into the original message.

Parameters:

  • data (String) —

    a string containing encoded data.

Returns:

  • (Object) —

    the decoded data.



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# File 'lib/schema_registry_client.rb', line 117

def decode(data)
  stream = StringIO.new(data)

  # The first byte is MAGIC!!!
  magic_byte = stream.read(1)

  raise "Expected data to begin with a magic byte, got `#{magic_byte.inspect}`" if magic_byte != MAGIC_BYTE

  # The schema id is a 4-byte big-endian integer.
  schema_id = stream.read(4).unpack1("N")
  schema = @registry.fetch(schema_id)
  @schema.decode(stream, schema)
rescue Excon::Error::NotFound
  raise SchemaNotFoundError, "Schema with id: #{schema_id} is not found on registry"
end

#encode(message, subject: nil, schema_text: nil, schema_name: nil) ⇒ String

Encodes a message using the specified schema.

Parameters:

  • message (Object) —

    The message that should be encoded. Must be compatible with the schema.

  • subject (String) (defaults to: nil) —

    The subject name the schema should be registered under in the schema registry (optional).

  • schema_name (String) (defaults to: nil) —

    the name of the schema to use for encoding (optional).

Returns:

  • (String) —

    the encoded data.



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# File 'lib/schema_registry_client.rb', line 99

def encode(message, subject: nil, schema_text: nil, schema_name: nil)
  id = register_schema(message, subject, schema_text: schema_text, schema_name: schema_name)

  stream = StringIO.new
  # Always start with the magic byte.
  stream.write(MAGIC_BYTE)

  # The schema id is encoded as a 4-byte big-endian integer.
  stream.write([id].pack("N"))

  @schema.encode(message, stream, schema_name: schema_name)
  stream.string
end