WebClient-based client transport. Requires the `mcp-spring-webflux` dependency.
```java theme={null}
WebClient.Builder webClientBuilder = WebClient.builder()
.baseUrl("http://your-mcp-server");
McpTransport transport = WebClientStreamableHttpTransport
.builder(webClientBuilder)
.build();
```
```java theme={null}
WebClient.Builder webClientBuilder = WebClient.builder()
.baseUrl("http://your-mcp-server");
McpTransport transport = WebFluxSseClientTransport(webClientBuilder)
.builder(webClientBuilder)
.build();
```
**WebClient: Customizing HTTP requests**
To customize outgoing HTTP requests, provide a custom `WebClient.Builder`.
When using a custom builder, every request sent by the transport will be customized.
For example, this is useful for providing a never-expiring security token in a header.
To add a `X-Custom-Header` header to every request, use:
```java theme={null}
var webClientBuilder = WebClient.builder()
.defaultHeader("X-Custom-Header", "some header value");
McpTransport transport = WebClientStreamableHttpTransport
.builder(webClientBuilder)
.build();
```
To dynamically modify HTTP request, the builder has a dedicated API, `ExchangeFilterFunction`.
In that function, the new request can be computed at run time, and additional information can
be obtained from the [Reactor context](https://projectreactor.io/docs/core/release/reference/advancedFeatures/context.html).
It is common to store context information in an `McpTransportContext` within the Reactor context,
typically in McpSyncClient, but any context key can be used. For example:
```java theme={null}
WebClient.builder()
.filter((request, next) -> {
return Mono.deferContextual(ctx -> {
var transportContext = ctx.get(McpTransportContext.KEY);
var otherInfo = ctx.get("your-context-key");
Mono token = obtainAccessToken(transportContext, otherInfo);
return token.map(t -> {
var newRequest = ClientRequest.from(request)
.header("Authorization", "Bearer " + t)
.build();
// Ensure you call next.exchange to execute the HTTP request
return next.exchange(newRequest);
});
});
});
```
To learn how to populate context information, see [adding context information](#adding-context-information).