Client: handle server responses with Content-Length: 0 #588
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chemicL
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Oct 1, 2025
| if (contentType.isBlank()) { | ||
| String contentLength = responseEvent.responseInfo() | ||
| .headers() | ||
| .firstValue("Content-Length") |
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Happy to use a constant but it is inconsistent with the rest of the file (e.g. instances of Content-Type, a Cache-Control and an Access).
In that case I think we should standardize the whole transport. Agreed?
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Yep, let's add the headers to the HttpHeaders class since they are either part of the specification of the HTTP-based remote transports or are simply needed to make it work. Last-Event-ID is not MCP specific but is part of the MCP remote transport logic so there's no need to think of other places for the common header names.
chemicL
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Oct 1, 2025
...rc/main/java/io/modelcontextprotocol/client/transport/HttpClientStreamableHttpTransport.java
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- When the client sends `notification/initalized`, servers must respond with HTTP 202 and an empty body. We checked for the absence of a Content-Type header to verify whether the body was empty. - However, some servers will send an empty body with a Content-Type header, and that header may have an unsupported, default type such as `text/html` or `text/plain`. - Now we we also use the Content-Length header to check for an empty body. This header is optional in HTTP/2, so we do not make it our primary mechanism for detecting empty bodies. - As part of this PR, we also move hard-coded HTTP header names to the HttpHeaders interface. While they are not defined by the MCP spec, they are used by it and are core to implementing the protocol. Therefore, they have their place in a core interface. - Fixes #582 Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
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chemicL
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notification/initalized, servers MUST respond with HTTP 202 and an empty body. Before this PR, we checked for the absence of a Content-Type header to know whether the body was empty.text/htmlortext/plain.Types of changes