Class: FastMcp::Server

Inherits:
Object
  • Object
show all
Includes:
ServerFiltering
Defined in:
lib/mcp/server.rb

Constant Summary collapse

DEFAULT_CAPABILITIES = 
{
  resources: {
    subscribe: true,
    listChanged: true
  },
  tools: {
    listChanged: true
  }
}.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from ServerFiltering

#contains_filters?, #create_filtered_copy, #filter_resources, #filter_tools

Constructor Details

#initialize(name:, version:, logger: FastMcp::Logger.new, capabilities: {}) ⇒ Server

Returns a new instance of Server.



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# File 'lib/mcp/server.rb', line 29

def initialize(name:, version:, logger: FastMcp::Logger.new, capabilities: {})
  @name = name
  @version = version
  @tools = {}
  @resources = []
  @resource_subscriptions = {}
  @logger = logger
  @request_id = 0
  @transport_klass = nil
  @transport = nil
  @capabilities = DEFAULT_CAPABILITIES.dup
  @tool_filters = []
  @resource_filters = []
  @on_error_result = nil

  # Merge with provided capabilities
  @capabilities.merge!(capabilities) if capabilities.is_a?(Hash)
end

Instance Attribute Details

#capabilities ⇒ Object (readonly)

Returns the value of attribute capabilities.



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# File 'lib/mcp/server.rb', line 17

def capabilities
  @capabilities
end

#logger ⇒ Object

Returns the value of attribute logger.



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# File 'lib/mcp/server.rb', line 47

def logger
  @logger
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/mcp/server.rb', line 17

def name
  @name
end

#resources ⇒ Object (readonly)

Returns the value of attribute resources.



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# File 'lib/mcp/server.rb', line 17

def resources
  @resources
end

#tools ⇒ Object (readonly)

Returns the value of attribute tools.



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# File 'lib/mcp/server.rb', line 17

def tools
  @tools
end

#transport ⇒ Object

Returns the value of attribute transport.



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# File 'lib/mcp/server.rb', line 47

def transport
  @transport
end

#transport_klass ⇒ Object

Returns the value of attribute transport_klass.



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# File 'lib/mcp/server.rb', line 47

def transport_klass
  @transport_klass
end

#version ⇒ Object (readonly)

Returns the value of attribute version.



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# File 'lib/mcp/server.rb', line 17

def version
  @version
end

Instance Method Details

#handle_json_request(request, headers: {}) ⇒ Object

Handle a JSON-RPC request and return the response as a JSON string



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# File 'lib/mcp/server.rb', line 135

def handle_json_request(request, headers: {})
  request_str = request.is_a?(String) ? request : JSON.generate(request)

  handle_request(request_str, headers: headers)
end

#handle_request(json_str, headers: {}) ⇒ Object

Handle incoming JSON-RPC request



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# File 'lib/mcp/server.rb', line 142

def handle_request(json_str, headers: {}) # rubocop:disable Metrics/MethodLength
  begin
    request = JSON.parse(json_str)
  rescue JSON::ParserError, TypeError
    return send_error(-32_600, 'Invalid Request', nil)
  end

  @logger.debug("Received request: #{request.inspect}")

  method = request['method']
  params = request['params'] || {}
  id = request['id']

  # Check if it's a valid JSON-RPC 2.0 request
  return send_error(-32_600, 'Invalid Request', id) unless request['jsonrpc'] == '2.0'

  case method
  when 'ping'
    send_result({}, id)
  when 'initialize'
    handle_initialize(params, id)
  when 'notifications/initialized'
    handle_initialized_notification
  when 'tools/list'
    handle_tools_list(id)
  when 'tools/call'
    handle_tools_call(params, headers, id)
  when 'resources/list'
    handle_resources_list(id)
  when 'resources/templates/list'
    handle_resources_templates_list(id)
  when 'resources/read'
    handle_resources_read(params, id)
  when 'resources/subscribe'
    handle_resources_subscribe(params, id)
  when 'resources/unsubscribe'
    handle_resources_unsubscribe(params, id)
  when nil
    # This is a notification response, we don't need to handle it
    nil
  else
    send_error(-32_601, "Method not found: #{method}", id)
  end
rescue StandardError => e
  @logger.error("Error handling request: #{e.message}, #{e.backtrace.join("\n")}")
  send_error(-32_600, "Internal error: #{e.message}, #{e.backtrace.join("\n")}", id)
end

#notify_resource_updated(uri) ⇒ Object

Notify subscribers about a resource update



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# File 'lib/mcp/server.rb', line 191

def notify_resource_updated(uri)
  @logger.warn("Notifying subscribers about resource update: #{uri}, #{@resource_subscriptions.inspect}")
  return unless @client_initialized && @resource_subscriptions.key?(uri)

  resource = @resources[uri]
  notification = {
    jsonrpc: '2.0',
    method: 'notifications/resources/updated',
    params: {
      uri: uri,
      name: resource.name,
      mimeType: resource.mime_type
    }
  }

  @transport.send_message(notification)
end

#on_error_result(&block) ⇒ Object 



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# File 'lib/mcp/server.rb', line 84

def on_error_result(&block)
  @on_error_result = block
end

#read_resource(uri) ⇒ Object 



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# File 'lib/mcp/server.rb', line 209

def read_resource(uri)
  @resources.find { |r| r.match(uri) }
end

#register_resource(resource) ⇒ Object

Register a resource with the server



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# File 'lib/mcp/server.rb', line 73

def register_resource(resource)
  @resources << resource

  @logger.debug("Registered resource: #{resource.resource_name} (#{resource.uri})")
  resource.server = self
  # Notify subscribers about the list change
  notify_resource_list_changed if @transport

  resource
end

#register_resources(*resources) ⇒ Object

Register multiple resources at once

Parameters:

  • resources (Array<Resource>) —

    Resources to register



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# File 'lib/mcp/server.rb', line 66

def register_resources(*resources)
  resources.each do |resource|
    register_resource(resource)
  end
end

#register_tool(tool) ⇒ Object

Register a tool with the server



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# File 'lib/mcp/server.rb', line 58

def register_tool(tool)
  @tools[tool.tool_name] = tool
  @logger.debug("Registered tool: #{tool.tool_name}")
  tool.server = self
end

#register_tools(*tools) ⇒ Object

Register multiple tools at once

Parameters:

  • tools (Array<Tool>) —

    Tools to register



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# File 'lib/mcp/server.rb', line 51

def register_tools(*tools)
  tools.each do |tool|
    register_tool(tool)
  end
end

#remove_resource(uri) ⇒ Object

Remove a resource from the server



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# File 'lib/mcp/server.rb', line 89

def remove_resource(uri)
  resource = @resources.find { |r| r.uri == uri }

  if resource
    @resources.delete(resource)
    @logger.debug("Removed resource: #{resource.name} (#{uri})")

    # Notify subscribers about the list change
    notify_resource_list_changed if @transport

    true
  else
    false
  end
end

#start ⇒ Object

Start the server using stdio transport



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# File 'lib/mcp/server.rb', line 106

def start
  @logger.transport = :stdio
  @logger.info("Starting MCP server: #{@name} v#{@version}")
  @logger.info("Available tools: #{@tools.keys.join(', ')}")
  @logger.info("Available resources: #{@resources.map(&:resource_name).join(', ')}")

  # Use STDIO transport by default
  @transport_klass = FastMcp::Transports::StdioTransport
  @transport = @transport_klass.new(self, logger: @logger)
  @transport.start
end

#start_rack(app, options = {}) ⇒ Object

Start the server as a Rack middleware



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# File 'lib/mcp/server.rb', line 119

def start_rack(app, options = {})
  @transport_klass = options.delete(:transport) || FastMcp::Transports::RackTransport
  transport_name = @transport_klass.name.split('::').last

  @logger.info("Starting MCP server with #{transport_name}: #{@name} v#{@version}")
  @logger.info("Available tools: #{@tools.keys.join(', ')}")
  @logger.info("Available resources: #{@resources.map(&:resource_name).join(', ')}")

  @transport = @transport_klass.new(app, self, options.merge(logger: @logger))
  @transport.start

  # Return the transport as middleware
  @transport
end