java-sdk/docs/class-diagrams.puml

@startuml Core Components

' Core Interfaces
interface McpTransport {
  +Mono<Void> connect(Function<Mono<JSONRPCMessage>, Mono<JSONRPCMessage>> handler)
  +Mono<Void> sendMessage(JSONRPCMessage message)
  +void close()
  +Mono<Void> closeGracefully()
  +<T> T unmarshalFrom(Object data, TypeReference<T> typeRef)
}

interface McpSession {
  +<T> Mono<T> sendRequest(String method, Object requestParams, TypeReference<T> typeRef)
  +Mono<Void> sendNotification(String method, Map<String, Object> params)
  +Mono<Void> closeGracefully()
  +void close()
}

' Core Implementation Classes
class DefaultMcpSession {
  -McpTransport transport
  -ObjectMapper objectMapper
  +interface RequestHandler
  +interface NotificationHandler
}

' Client Classes
class McpClient {
  +{static} Builder using(McpTransport transport)
  +{static} McpAsyncClient async(McpTransport transport)
  +{static} McpSyncClient sync(McpTransport transport)
}

class McpAsyncClient {
  +Mono<InitializeResult> initialize()
  +Mono<CallToolResult> callTool(CallToolRequest request)
  +Mono<ListToolsResult> listTools()
  +Mono<ListResourcesResult> listResources()
  +Mono<ReadResourceResult> readResource(ReadResourceRequest request)
  +Mono<ListResourceTemplatesResult> listResourceTemplates()
  +Mono<ListPromptsResult> listPrompts()
  +Mono<GetPromptResult> getPrompt(GetPromptRequest request)
}

class McpSyncClient {
  +InitializeResult initialize()
  +CallToolResult callTool(CallToolRequest request)
  +ListToolsResult listTools()
  +ListResourcesResult listResources()
  +ReadResourceResult readResource(ReadResourceRequest request)
  +ListResourceTemplatesResult listResourceTemplates()
  +ListPromptsResult listPrompts()
  +GetPromptResult getPrompt(GetPromptRequest request)
}

' Server Classes
class McpServer {
  +{static} Builder using(McpTransport transport)
}

class McpAsyncServer {
  +Mono<Void> addTool(ToolHandler toolHandler)
  +Mono<Void> removeTool(String toolName)
  +Mono<Void> notifyToolsListChanged()
  +Mono<Void> notifyResourcesListChanged()
  +Mono<Void> notifyPromptsListChanged()
  +interface ToolHandler
}

class McpSyncServer {
  +void addTool(ToolHandler toolHandler)
  +void removeTool(String toolName)
  +void notifyToolsListChanged()
  +void notifyResourcesListChanged()
  +void notifyPromptsListChanged()
  +McpAsyncServer getAsyncServer()
}

' Transport Implementations
class StdioClientTransport {
  -Process serverProcess
  -ServerParameters parameters
}

class SseClientTransport {
  -WebClient webClient
}

class StdioServerTransport {
}

class SseServerTransport {
}

' Schema and Error Classes
class McpSchema {
  +class ErrorCodes
  +interface Request
  +interface JSONRPCMessage
  +interface ResourceContents
  +interface Content
  +interface ServerCapabilities
  +{static} JSONRPCMessage deserializeJsonRpcMessage()
}

class McpError {
  -int code
  -String message
}

' Relationships
McpTransport <|.. StdioClientTransport
McpTransport <|.. SseClientTransport
McpTransport <|.. StdioServerTransport
McpTransport <|.. SseServerTransport

McpSession <|.. DefaultMcpSession
DefaultMcpSession --o McpAsyncClient
DefaultMcpSession --o McpAsyncServer

McpClient ..> McpAsyncClient : creates
McpClient ..> McpSyncClient : creates
McpSyncClient o-- McpAsyncClient

McpServer ..> McpAsyncServer : creates
McpServer ..> McpSyncServer : creates
McpSyncServer o-- McpAsyncServer

DefaultMcpSession o-- McpTransport
McpSchema <.. McpSession : uses
McpError ..> McpSession : throws

@enduml

@startuml Message Flow

package "MCP Schema" {
  interface JSONRPCMessage {
    +String jsonrpc()
  }
  
  interface Request {
  }
  
  class InitializeRequest
  class CallToolRequest
  class ListToolsRequest
  class ListResourcesRequest
  class ReadResourceRequest
  class ListResourceTemplatesRequest
  class ListPromptsRequest
  class GetPromptRequest
}

package "Resource Types" {
  interface ResourceContents {
    +String uri()
    +String mimeType()
  }
  
  class TextResourceContents
  class BlobResourceContents
  
  interface Content {
    +String type()
  }
  
  class TextContent
  class ImageContent
  class EmbeddedResource
  
  interface Annotated {
    +Annotations annotations()
  }
  
  interface PromptOrResourceReference {
    +String type()
  }
  
  class PromptReference
  class ResourceReference
}

JSONRPCMessage <|.. Request
Request <|.. InitializeRequest
Request <|.. CallToolRequest
Request <|.. ListToolsRequest
Request <|.. ListResourcesRequest
Request <|.. ReadResourceRequest
Request <|.. ListResourceTemplatesRequest
Request <|.. ListPromptsRequest
Request <|.. GetPromptRequest

ResourceContents <|.. TextResourceContents
ResourceContents <|.. BlobResourceContents

Content <|.. TextContent
Content <|.. ImageContent
Content <|.. EmbeddedResource

PromptOrResourceReference <|.. PromptReference
PromptOrResourceReference <|.. ResourceReference

@enduml