Module io.helidon.webclient.api

Package io.helidon.webclient.spi

Interface HttpClientSpi

All Superinterfaces:

ReleasableResource

All Known Implementing Classes:

Http2ClientImpl

public interface HttpClientSpi
extends ReleasableResource

Integration for HTTP versions to provide a single API.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static enum	HttpClientSpi.SupportLevel	How does the provider support the request.

Method Summary

Modifier and Type	Method	Description
ClientRequest<?>	clientRequest(FullClientRequest<?> clientRequest, ClientUri clientUri)	Create a client request based on the provided HTTP request that is for the version of this client.
default boolean	isTcp()	For TCP based protocols, we can do ALPN negotiation, obtain a connection, and then let the client handle the protocol.
HttpClientSpi.SupportLevel	supports(FullClientRequest<?> clientRequest, ClientUri clientUri)	Return whether this HTTP version can handle the provided request.

Methods inherited from interface io.helidon.webclient.api.ReleasableResource

closeResource, releaseResource

Method Details

supports

HttpClientSpi.SupportLevel supports(FullClientRequest<?> clientRequest,
 ClientUri clientUri)

Return whether this HTTP version can handle the provided request.

Examples:

• HTTP/1.1 always returns true, as it is the fallback protocol of all other protocols
• HTTP/2 returns true when upgrade is enabled, false when prior-knowledge is specified (as we can always attempt to upgrade and fallback to 1.1 in the first case, but we would fail with prior-knowledge, unless the endpoint is known to be HTTP/2
• HTTP/3 would always return true, as it cannot fallback once a connection is attempted

So how can we get to HTTP/2 with prior knowledge, or HTTP/3? There are the following options:

• An explicit protocol id is configured for the request - HttpClientRequest.protocolId(String)
• There is no fallback protocol enabled, in such a case, we use the one with highest priority - see WebClientConfig.BuilderBase.addProtocolPreference(String)
• We get an Alt-Svc header from a response that points us to a protocol version (we only support permanent protocol changes, Alt-Svc with timeout will be ignored
• This protocol version already handled a request to such an endpoint and has the connection available

Note that this response is cached.

Parameters:

clientRequest - HTTP request

clientUri - URI to invoke

Returns:

true if we are sure we can handle this request with this protocol version

clientRequest

ClientRequest<?> clientRequest(FullClientRequest<?> clientRequest,
 ClientUri clientUri)

Create a client request based on the provided HTTP request that is for the version of this client.

Parameters:

clientRequest - request configuration

clientUri - URI to invoke (resolved)

Returns:

a new request

isTcp

default boolean isTcp()

For TCP based protocols, we can do ALPN negotiation, obtain a connection, and then let the client handle the protocol. Similar for proxies - we can establish a proxy connection, and then let the client handle the protocol. For UDP based protocols, we need to wait for Alt-Svc headers before attempting anything, or have an explicit version configured.

Returns:

whether this is a TCP based HTTP protocol, defaults to true