Add McpClientHandlersRegistry #4802
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Kehrlann force-pushed the dgarnier/mcp-client-handlers-registry branch 5 times, most recently from cfce918 to 4835ccc Compare Kehrlann changed the title Kehrlann force-pushed the dgarnier/mcp-client-handlers-registry branch from 4835ccc to 2b1f49b Compare Kehrlann force-pushed the dgarnier/mcp-client-handlers-registry branch 3 times, most recently from 52676cd to 18e986a Compare 
Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
- In febf86c, we broke a dependency cycle ChatClient -> McpClient - With the introduction of ClientMcpSyncHandlersRegistry and the async variant, there is no dependency McpClient -> MCP handlers anymore, breaking the cycle in a simpler way. - Here, we revert most of the changes of febf86c, but keep the tests. Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
Kehrlann force-pushed the dgarnier/mcp-client-handlers-registry branch 3 times, most recently from ad8d987 to 4ab6503 Compare 
tzolov approved these changes Nov 6, 2025
| if (!foundAnnotations.isEmpty()) { | ||
| this.allAnnotatedBeans.add(beanName); | ||
| } | ||
| for (var foundAnnotation : foundAnnotations) { |
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I guess this block can be nested in side the if (!foundAnnotations.isEmpty()) { above
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It's already pretty nested ; I'm reluctant to nest it more.
The code is functionally equivalent anyway.
But that's not a strong opinion.
...main/java/org/springframework/ai/mcp/annotation/spring/AbstractClientMcpHandlerRegistry.java Outdated Show resolved Hide resolved
...main/java/org/springframework/ai/mcp/annotation/spring/AbstractClientMcpHandlerRegistry.java Outdated Show resolved Hide resolved
...c/main/java/org/springframework/ai/mcp/annotation/spring/ClientMcpAsyncHandlersRegistry.java Outdated Show resolved Hide resolved
...rc/main/java/org/springframework/ai/mcp/annotation/spring/ClientMcpSyncHandlersRegistry.java Outdated Show resolved Hide resolved
- Remove custom class resolution method and use AutoProxyUtils instead Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
Kehrlann force-pushed the dgarnier/mcp-client-handlers-registry branch from 0bdeea7 to fa6a1f4 Compare Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
Kehrlann force-pushed the dgarnier/mcp-client-handlers-registry branch from 5baface to 3929649 Compare tzolov pushed a commit that referenced this pull request Nov 7, 2025
…es (#4802) Replace specification factory pattern with centralized handler registries that scan and register MCP client handlers (sampling, elicitation, logging, progress, and list-changed notifications). This simplifies the auto-configuration by: - Introducing ClientMcpSyncHandlersRegistry and ClientMcpAsyncHandlersRegistry that scan beans once for annotations and expose handlers by client name - Removing intermediate specification factory beans and customizers - Directly configuring MCP client specs from registries during client creation - Eliminating need for separate specification classes per handler type - Simplifying ToolCallingAutoConfiguration by removing BeanDefinitionRegistryPostProcessor complexity - In febf86c, we broke a dependency cycle ChatClient -> McpClient - With the introduction of ClientMcpSyncHandlersRegistry and the async variant, there is no dependency McpClient -> MCP handlers anymore, breaking the cycle in a simpler way. - Here, we revert most of the changes of febf86c, but keep the tests. - Remove unused MCP annotated beans auto-configuration - Introduce AbstractClientMcpHandlerRegistry - Find MCP Client annotations on @component beans - AbstractClientMcpHandlerRegistry also discovers proxied beans - Remove custom class resolution method and use AutoProxyUtils instead - Add logging to MCP handlers registry - Throw MCP Error on missing sampling and elicitation handlers in a client - Fix missing auto-configurations McpClientAutoConfigurationIT Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>
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| Rebased, squashed and merged at 2a2f155 |
This was referenced Nov 7, 2025
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Fixes #4670
This PR introduces two variants (sync and async) of a "registry" of handlers,
ClientMcpSyncHandlersRegistry.These registries have two main responsibilities:
This allows to break the dependency between MCP clients and MCP-annotated beans. This was a problem when doing sampling, where there was a cycle MCP Client -> MCP handlers -> ChatClient -> MCP Client.
With this PR, the MCP clients depend on the registry, but the registry does not depend on the MCP-handlers. Instead, it discovers them dynamically and makes handlers available by client name. See #4751 for the initial attempt at fixing the circular dependency.
The flow to capture annotations has two steps:
BeanFactoryPostProcessor. Bean types are scanned for annotations, and the bean names found are recorded for later use. Additionally,@McpSamplingand@McpElicitationannotations are tracked per client name. This allows to bootstrap MCP clients in theMcpClientAutoConfiguration: by the time the clients are created, we know their capabilities, even if the annotated beans have not been instantiated yet.SmartInitializingSingleton, actual bean instances are retrieved, and from the bean instances and annotated methods, MCP handlers are populated in the registry, stored by client name.Notes: