Package org.apache.juneau.rest.client.mcp.v20260728

Interface McpElicitationHandler

Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface public interface McpElicitationHandler
Caller-supplied callback that answers one round of server→client MCP 2026-07-28 SEP-2322 elicitation requests during a client-side Multi-Round-Trip-Request (MRTR) auto-resume loop.

Passed to McpClient.callToolWithElicitation(java.lang.String, java.util.Map<java.lang.String, java.lang.Object>, org.apache.juneau.rest.client.mcp.v20260728.McpElicitationHandler), McpClient.getPromptWithElicitation(java.lang.String, java.util.Map<java.lang.String, java.lang.Object>, org.apache.juneau.rest.client.mcp.v20260728.McpElicitationHandler), and McpClient.readResourceWithElicitation(java.lang.String, org.apache.juneau.rest.client.mcp.v20260728.McpElicitationHandler): each time the server pauses a call with an input_required result, the client decodes that round's pending requests (there may be more than one) and invokes elicit(Map) to obtain the matching answers, which it then echoes back on the resume call. This turns the otherwise hand-driven McpClient.callRaw(java.lang.String, org.apache.juneau.bean.mcp.v20260728.RequestParams<?>)/ElicitationRequests/ElicitationResponses loop into a single call plus one handler.

A handler answers by returning, keyed by the same server-assigned ids it was given, an ElicitResult per request it wishes to answer — an ElicitAction.ACCEPT with content, or an ElicitAction.DECLINE/ElicitAction.CANCEL to refuse. Decline/cancel answers are still sent back to the server (which decides the terminal outcome of a refused elicitation); the client does not short-circuit them locally.

Since:
10.0.0

  • Method Details

    • elicit

      Map<String,ElicitResult> elicit(Map<String,ElicitRequest> requests) throws IOException
      Answers one round of elicitation requests.

      The returned map may legitimately omit ids the handler chooses not to answer (the server may then re-pause, bounded by the auto-resume loop's max-rounds guard); returning null outright is illegal and causes the auto-resume loop to throw IllegalArgumentException; and any extra/unknown ids present in the returned map are echoed back to the server unvalidated.

      Parameters:
      requests - The pending requests for this round, keyed by server-assigned id (decoded via ElicitationRequests.requests(Map)). Never null; may contain more than one entry, and an individual value may be null if the corresponding raw entry was absent/null.
      Returns:
      The answers keyed by the same server-assigned ids. Must not be null. An ElicitResult value must not be null. Use a LinkedHashMap for deterministic ordering of the echoed inputResponses. May legitimately omit ids the handler chooses not to answer (the server may then re-pause, bounded by the loop's max-rounds guard).
      Throws:
      IOException - If the handler performs its own I/O (e.g. prompting a remote user) and it fails; the auto-resume loop propagates it to the caller unchanged.