Class CombineResponse

java.lang.Object

org.frontcache.include.combine.CombineResponse

public class CombineResponse
extends Object

The origin's half of the combine contract: build and write the response envelope. See docs/archive/combine-reduce-proposal.md section 6. Parts must be added in the order the members arrived - parts[i] answers fc-part-i. writeTo(HttpServletResponse) is what sets the x-frontcache-combine header, which is the only signal the edge has that the origin understood the request at all; an origin that writes the JSON by hand and forgets that header will be treated as not implementing combining.

Constructor Summary

Constructors

Constructor	Description
CombineResponse()

Method Summary

Modifier and Type	Method	Description
CombineResponse	add(String body)	A part with no echo, no explicit status and no headers - i.e.
CombineResponse	add(String q, int status, Map<String, List<String>> headers, String body)
CombineResponse	add(String q, String body, Map<String, List<String>> headers)	A part with cache directives.
CombineResponse	addComponent(String q, String body, String maxAge, String tags)	A cacheable part, spelled the way the <fc:component> tag spells it.
CombineResponse	addError(String q, int status)	A member the origin could not render.
CombineEnvelope	getEnvelope()
int	size()
String	toJson()
void	writeTo(jakarta.servlet.http.HttpServletResponse response)	Writes the envelope: content type, the x-frontcache-combine support signal, an explicit content length, and the JSON body.

Methods inherited from class Object

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

Constructor Details

CombineResponse

public CombineResponse()

Method Details

add

public CombineResponse add(String body)

A part with no echo, no explicit status and no headers - i.e. an uncacheable 200 fragment.

add

public CombineResponse add(String q,
 String body,
 Map<String, List<String>> headers)

A part with cache directives. Keys are the x-frontcache-component-* names in FCHeaders.

add

public CombineResponse add(String q,
 int status,
 Map<String, List<String>> headers,
 String body)

addComponent

public CombineResponse addComponent(String q,
 String body,
 String maxAge,
 String tags)

A cacheable part, spelled the way the <fc:component> tag spells it.

Parameters:

q - echo of this member's query string, or null to omit it

body - the fragment

maxAge - x-frontcache-component-maxage, e.g. "10d"; null means not cacheable

tags - x-frontcache-component-tags, e.g. "coin|coin-42"; null to omit

addError

public CombineResponse addError(String q,
 int status)

A member the origin could not render. Not cached by the edge; that member falls back.

size

public int size()

getEnvelope

public CombineEnvelope getEnvelope()

toJson

public String toJson()
              throws IOException

Throws:

IOException

writeTo

public void writeTo(jakarta.servlet.http.HttpServletResponse response)
             throws IOException

Writes the envelope: content type, the x-frontcache-combine support signal, an explicit content length, and the JSON body. The length is set explicitly because the body is already fully in hand - letting the container fall back to chunked encoding for a response whose size is known costs the edge a read-until-EOF where it could have read a known number of bytes.

Throws:

IOException