org.apache.samza.system.descriptors

Class GenericSystemDescriptor

java.lang.Object

org.apache.samza.system.descriptors.SystemDescriptor<GenericSystemDescriptor>

org.apache.samza.system.descriptors.GenericSystemDescriptor

All Implemented Interfaces:

OutputDescriptorProvider, SimpleInputDescriptorProvider

public final class GenericSystemDescriptor
extends SystemDescriptor<GenericSystemDescriptor>
implements SimpleInputDescriptorProvider, OutputDescriptorProvider

A GenericSystemDescriptor can be used for specifying Samza and system-specific properties of an input/output system. It can also be used for obtaining GenericInputDescriptors and GenericOutputDescriptors, which can be used for specifying any Samza and system-specific properties of input/output streams.

If the system provides its own system and stream descriptor implementations, use them instead. Otherwise, use this GenericSystemDescriptor to specify Samza-specific properties of the system, and SystemDescriptor.withSystemConfigs(java.util.Map<java.lang.String, java.lang.String>) to specify additional system specific properties.

System properties provided in configuration override corresponding properties specified using a descriptor.

Constructor Summary

Constructors

Constructor and Description
GenericSystemDescriptor(java.lang.String systemName, java.lang.String factoryClassName) Constructs a GenericSystemDescriptor instance with no system level serde.

Method Summary

Modifier and Type	Method and Description
<StreamMessageType> GenericInputDescriptor<StreamMessageType>	getInputDescriptor(java.lang.String streamId, Serde<StreamMessageType> serde) Gets an InputDescriptor for an input stream on this system.
<StreamMessageType> GenericOutputDescriptor<StreamMessageType>	getOutputDescriptor(java.lang.String streamId, Serde<StreamMessageType> serde) Gets an OutputDescriptor representing an output stream on this system that uses the provided stream specific serde instead of the default system serde.

Methods inherited from class org.apache.samza.system.descriptors.SystemDescriptor

getExpander, getSystemName, getTransformer, toConfig, withDefaultStreamConfigs, withDefaultStreamOffsetDefault, withSystemConfigs

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GenericSystemDescriptor

public GenericSystemDescriptor(java.lang.String systemName,
                               java.lang.String factoryClassName)

Constructs a GenericSystemDescriptor instance with no system level serde. Serdes must be provided explicitly at stream level when getting input or output descriptors.

Parameters:

systemName - name of this system

factoryClassName - name of the SystemFactory class for this system

Method Detail

getInputDescriptor

public <StreamMessageType> GenericInputDescriptor<StreamMessageType> getInputDescriptor(java.lang.String streamId,
                                                                                        Serde<StreamMessageType> serde)

Description copied from interface: SimpleInputDescriptorProvider

Gets an InputDescriptor for an input stream on this system. The stream has the provided stream level serde.

The type of messages in the stream is the type of the provided stream level serde.

Specified by:

getInputDescriptor in interface SimpleInputDescriptorProvider

Type Parameters:

StreamMessageType - type of messages in this stream

Parameters:

streamId - id of the input stream

serde - stream level serde for the input stream

Returns:

an InputDescriptor for the input stream

getOutputDescriptor

public <StreamMessageType> GenericOutputDescriptor<StreamMessageType> getOutputDescriptor(java.lang.String streamId,
                                                                                          Serde<StreamMessageType> serde)

Description copied from interface: OutputDescriptorProvider

Gets an OutputDescriptor representing an output stream on this system that uses the provided stream specific serde instead of the default system serde.

An OutputStream<KV<K, V>>, obtained using a descriptor with a KVSerde<K, V>, can send messages of type KV<K, V>. An OutputStream<M> with any other Serde<M> can send messages of type M without a key.

A KVSerde<NoOpSerde, NoOpSerde> or NoOpSerde may be used if the SystemProducer serializes the outgoing messages itself, and no prior serialization is required from the framework.

Specified by:

getOutputDescriptor in interface OutputDescriptorProvider

Type Parameters:

StreamMessageType - type of messages in the output stream

Parameters:

streamId - id of the output stream

serde - serde for this output stream that overrides the default system serde, if any.

Returns:

the OutputDescriptor for the output stream