@modelcontextprotocol/server-everything/dist/resources/session.js

MCP server that exercises all the features of the MCP protocol

/**
 * Tracks registered session resources per server, by URI, to allow updating/removing on
 * re-registration. This prevents "Resource already registered" errors when a tool creates
 * a resource with the same URI multiple times during a session, without touching another
 * session's server that registered the same URI (#4808).
 */
const registeredResources = new WeakMap();
/**
 * Generates a session-scoped resource URI string based on the provided resource name.
 *
 * @param {string} name - The name of the resource to create a URI for.
 * @returns {string} The formatted session resource URI.
 */
export const getSessionResourceURI = (name) => {
    return `demo://resource/session/${name}`;
};
/**
 * Registers a session-scoped resource with the provided server and returns a resource link.
 *
 * The registered resource is available during the life of the session only; it is not otherwise persisted.
 *
 * @param {McpServer} server - The server instance responsible for handling the resource registration.
 * @param {Resource} resource - The resource object containing metadata such as URI, name, description, and mimeType.
 * @param {"text"|"blob"} type
 * @param payload
 * @returns {ResourceLink} An object representing the resource link, with associated metadata.
 */
export const registerSessionResource = (server, resource, type, payload) => {
    // Destructure resource
    const { uri, name, mimeType, description, title, annotations, icons, _meta } = resource;
    // Prepare the resource content to return
    // See https://modelcontextprotocol.io/specification/2025-11-25/server/resources#resource-contents
    const resourceContent = type === "text"
        ? {
            uri: uri.toString(),
            mimeType,
            text: payload,
        }
        : {
            uri: uri.toString(),
            mimeType,
            blob: payload,
        };
    const serverResources = registeredResources.get(server) ?? new Map();
    registeredResources.set(server, serverResources);
    // Check if a resource with this URI is already registered on this server and remove it
    const resourceKey = uri.toString();
    const existingResource = serverResources.get(resourceKey);
    if (existingResource) {
        existingResource.remove();
        serverResources.delete(resourceKey);
    }
    // Register file resource
    const registeredResource = server.registerResource(name, uri, { mimeType, description, title, annotations, icons, _meta }, async () => {
        return {
            contents: [resourceContent],
        };
    });
    // Track the registered resource for potential future removal
    serverResources.set(resourceKey, registeredResource);
    return { type: "resource_link", ...resource };
};