org.apache.pekko.http.javadsl.common

Class EntityStreamingSupport

java.lang.Object

org.apache.pekko.http.javadsl.common.EntityStreamingSupport

Direct Known Subclasses:

EntityStreamingSupport

public abstract class EntityStreamingSupport
extends java.lang.Object

Entity streaming support trait allowing rendering and receiving incoming Source[T, _] from HTTP entities.

See JsonEntityStreamingSupport or CsvEntityStreamingSupport for default implementations.

Constructor Summary

Constructors

Constructor and Description
EntityStreamingSupport()

Method Summary

Modifier and Type	Method and Description
abstract ContentType	contentType() Write-side, defines what Content-Type the Marshaller should offer and the final Content-Type of the response.
static CsvEntityStreamingSupport	csv() Default text/csv(UTF-8) entity streaming support.
static CsvEntityStreamingSupport	csv(int maxLineLength) Default text/csv(UTF-8) entity streaming support.
abstract org.apache.pekko.stream.javadsl.Flow<org.apache.pekko.util.ByteString,org.apache.pekko.util.ByteString,org.apache.pekko.NotUsed>	getFramingDecoder() Read-side, decode incoming framed entity.
abstract org.apache.pekko.stream.javadsl.Flow<org.apache.pekko.util.ByteString,org.apache.pekko.util.ByteString,org.apache.pekko.NotUsed>	getFramingRenderer() Write-side, apply framing to outgoing entity stream.
static JsonEntityStreamingSupport	json() Default application/json entity streaming support.
static JsonEntityStreamingSupport	json(int maxObjectLength) Default application/json entity streaming support.
abstract int	parallelism() Write-side / read-side, defines if (un)marshalling should be done in parallel.
abstract ContentTypeRange	supported() Read-side, what content types it is able to frame and unmarshall.
abstract boolean	unordered() Write-side / read-side, defines if (un)marshalling of incoming stream elements should be preserved or not.
abstract EntityStreamingSupport	withContentType(ContentType range) Write-side, defines what Content-Type the Marshaller should offer and the final Content-Type of the response.
abstract EntityStreamingSupport	withParallelMarshalling(int parallelism, boolean unordered) Write-side / read-side, defines parallelism and if ordering should be preserved or not of Source element marshalling.
abstract EntityStreamingSupport	withSupported(ContentTypeRange range) Read-side, allows changing what content types are accepted by this framing.

Methods inherited from class java.lang.Object

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

Constructor Detail

EntityStreamingSupport

public EntityStreamingSupport()

Method Detail

json

public static JsonEntityStreamingSupport json()

Default application/json entity streaming support.

Provides framing (based on scanning the incoming dataBytes for valid JSON objects, so for example uploads using arrays or new-line separated JSON objects are all parsed correctly) and rendering of Sources as JSON Arrays. A different very popular style of returning streaming JSON is to separate JSON objects on a line-by-line basis, you can configure the support trait to do so by calling withFramingRendererFlow.

Limits the maximum JSON object length to 8KB, if you want to increase this limit provide a value explicitly.

See also https://en.wikipedia.org/wiki/JSON_Streaming

Returns:

(undocumented)

json

public static JsonEntityStreamingSupport json(int maxObjectLength)

Default application/json entity streaming support.

Provides framing (based on scanning the incoming dataBytes for valid JSON objects, so for example uploads using arrays or new-line separated JSON objects are all parsed correctly) and rendering of Sources as JSON Arrays. A different very popular style of returning streaming JSON is to separate JSON objects on a line-by-line basis, you can configure the support trait to do so by calling withFramingRendererFlow.

See also https://en.wikipedia.org/wiki/JSON_Streaming

Parameters:

maxObjectLength - (undocumented)

Returns:

(undocumented)

csv

public static CsvEntityStreamingSupport csv()

Default text/csv(UTF-8) entity streaming support. Provides framing and rendering of \n separated lines and marshalling Sources into such values.

Limits the maximum line-length to 8KB, if you want to increase this limit provide a value explicitly.

Returns:

(undocumented)

csv

public static CsvEntityStreamingSupport csv(int maxLineLength)

Default text/csv(UTF-8) entity streaming support. Provides framing and rendering of \n separated lines and marshalling Sources into such values.

Parameters:

maxLineLength - (undocumented)

Returns:

(undocumented)

supported

public abstract ContentTypeRange supported()

Read-side, what content types it is able to frame and unmarshall.

contentType

public abstract ContentType contentType()

Write-side, defines what Content-Type the Marshaller should offer and the final Content-Type of the response.

getFramingDecoder

public abstract org.apache.pekko.stream.javadsl.Flow<org.apache.pekko.util.ByteString,org.apache.pekko.util.ByteString,org.apache.pekko.NotUsed> getFramingDecoder()

Read-side, decode incoming framed entity. For example with an incoming JSON array, chunk it up into JSON objects contained within that array.

Returns:

(undocumented)

getFramingRenderer

public abstract org.apache.pekko.stream.javadsl.Flow<org.apache.pekko.util.ByteString,org.apache.pekko.util.ByteString,org.apache.pekko.NotUsed> getFramingRenderer()

Write-side, apply framing to outgoing entity stream.

Most typical usage will be a variant of Flow[ByteString].intersperse.

For example for rendering a JSON array one would return Flow[ByteString].intersperse(ByteString("["), ByteString(","), ByteString("]")) and for rendering a new-line separated CSV simply Flow[ByteString].intersperse(ByteString("\n")).

Returns:

(undocumented)

withSupported

public abstract EntityStreamingSupport withSupported(ContentTypeRange range)

Read-side, allows changing what content types are accepted by this framing.

EntityStreamingSupport traits MUST support re-configuring the accepted ContentTypeRange.

This is in order to support a-typical APIs which users still want to communicate with using the provided support trait. Typical examples include APIs which return valid application/json however advertise the content type as being application/javascript or vendor specific content types, which still parse correctly as JSON, CSV or something else that a provided support trait is built for.

NOTE: Implementations should specialize the return type to their own Type!

Parameters:

range - (undocumented)

Returns:

(undocumented)

withContentType

public abstract EntityStreamingSupport withContentType(ContentType range)

Write-side, defines what Content-Type the Marshaller should offer and the final Content-Type of the response.

EntityStreamingSupport traits MUST support re-configuring the offered ContentType. This is due to the need integrating with existing systems which sometimes excpect custom Content-Types, however really are just plain JSON or something else internally (perhaps with slight extensions).

NOTE: Implementations should specialize the return type to their own Type!

Parameters:

range - (undocumented)

Returns:

(undocumented)

parallelism

public abstract int parallelism()

Write-side / read-side, defines if (un)marshalling should be done in parallel.

This may be beneficial marshalling the bottleneck in the pipeline.

See also parallelism and withParallelMarshalling.

Returns:

(undocumented)

unordered

public abstract boolean unordered()

Write-side / read-side, defines if (un)marshalling of incoming stream elements should be preserved or not.

Allowing for parallel and unordered (un)marshalling often yields higher throughput and also allows avoiding head-of-line blocking if some elements are much larger than others.

See also parallelism and withParallelMarshalling.

Returns:

(undocumented)

withParallelMarshalling

public abstract EntityStreamingSupport withParallelMarshalling(int parallelism,
                                                               boolean unordered)

Write-side / read-side, defines parallelism and if ordering should be preserved or not of Source element marshalling.

Sometimes marshalling multiple elements at once (esp. when elements are not evenly sized, and ordering is not enforced) may yield in higher throughput.

NOTE: Implementations should specialize the return type to their own Type!

Parameters:

parallelism - (undocumented)

unordered - (undocumented)

Returns:

(undocumented)