API Reference > imodeljs-backend > IModelHost > IModelHost IModelHost Class IModelHost initializes imodeljs-backend and captures its configuration. A backend must call IModelHost.startup before using any backend classes. See the learning article Methods Name Description getAccessToken(requestContext?: ClientRequestContext): Promise<AccessToken> Static Get the active authorization/access token for use with various services shutdown(): Promise<void> Static This method must be called when an iModel.js services is shut down. startup(configuration: IModelHostConfiguration = ...): Promise<void> Static This method must be called before any iModel.js services are used. Properties Name Type Description appAssetsDir Accessor StaticReadOnly undefined | string The directory where application assets may be found applicationId Accessor Static string The Id of this application - needs to be set only if it is an agent application. applicationVersion Accessor Static string The version of this application - needs to be set if is an agent application. authorizationClient Static undefined | AuthorizationClient backendVersion Static string cacheDir Accessor StaticReadOnly string Root of the directory holding all the files that iModel.js caches configuration Static undefined | IModelHostConfiguration iModelClient Accessor StaticReadOnly IModelClient isUsingIModelBankClient Accessor StaticReadOnly boolean isValid Accessor StaticReadOnly boolean Returns true if IModelHost is started. logTileLoadTimeThreshold Accessor StaticReadOnly number The backend will log when a tile took longer to load than this threshold in seconds. logTileSizeThreshold Accessor StaticReadOnly number The backend will log when a tile is loaded with a size in bytes above this threshold. onAfterStartup StaticReadonly BeEvent<() => void> Event raised just after the backend IModelHost was started onBeforeShutdown StaticReadonly BeEvent<() => void> Event raised just before the backend IModelHost is to be shut down sessionId Accessor Static string A uniqueId for this session snapshotFileNameResolver Static undefined | FileNameResolver The optional FileNameResolver that resolves keys and partial file names for snapshot iModels. tileCacheService Static CloudStorageService Defined in core/backend/src/IModelHost.ts Line 203 Last Updated: 29 November, 2022