HTTPProtocol

Metadata-dependent Behavior

The metadata argument to HTTPProtocol.getProtocolOutput() can affect the behavior of the protocol. The following metadata keys are detected by HTTPProtocol implementations and utilized in performing the request:

• last-modified: If this key is present in metadata, the protocol will use the metadata value as the date for the If-Modified-Since header field of the HTTP request. If the key is not present, the If-Modified-Since field won't be added to the request header.

• protocol.etag: If this key is present in metadata, the protocol will use the metadata value as the ETag for the If-None-Match header field of the HTTP request. If the key is not present, the If-None-Match field won't be added to the request header.

• http.accept: If this key is present in metadata, the protocol will use the value to override the value for the Accept header field of the HTTP request. If the key is not present, the http.accept global configuration value is used instead. (Available in v1.11+)

• http.accept.language: If this key is present in metadata, the protocol will use the value to override the value for the Accept-Language header field of the HTTP request. If the key is not present, the http.accept.language global configuration value is used instead. (Available in v1.11+)

• protocol.set-cookie: If this key is present in metadata and http.use.cookies is true, the protocol will sent cookies stored from the response this page was linked to given the cookie is applicable to the domain of the link.

• http.method.head: If this key is present in metadata, the protocol sends a HEAD request. (Available in v1.12+ only for httpclient, see #485)

• http.post.json: If this key is present in metadata, the protocol sends a POST request. (Available in v1.12+ only for okhttp, see #641)

• protocol.set-headers: If this key is present in metadata, the protocol add the specified headers to the request. See #993

Md example : "protocol%2Eset-header": [ "header1=value1", "header2=value2" ]

Notes:

• metadata values starting with protocol. may start with a different prefix instead, see protocol.md.prefix and #776
• metadata used for requests needs to be persisted, e.g.

  metadata.persist:
   - last-modified
   - protocol.etag
   - protocol.set-cookie
   - ...

• cookies need to be transferred to outlinks by setting

  metadata.transfer:
   - set-cookie