The gateway software is provided for Member States' remote access to ECMWF computing and archiving facilities. Throughout the guide, the terms "gateway" and "ECaccess gateway" are used interchangeably. Gateways include a model for the management of "plugin" services. A plugin is a piece of code that handles requests/responses flowing through the gateway. Currently, there are plugins for incoming FTP, HTTP/S, X11, SSH and Telnet (MSgateways only) requests to ECMWF. Additional plugins are planned. On top of the SSH plugin the NX application can be used for interactive access to ECMWF. The ECMWF ECaccess gateway (hereafter referred to as "ECgateway") can be used on its own. Nevertheless, using a Member State ECaccess gateway (hereafter referred to "MSgateway") instead offers the following features and advantages over using the ECgateway on its own:

• Secure tunnel between ECMWF and MSgateway: all services are channelled through SSL (Secure Socket Layer) secure connections to ensure data integrity. For confidentiality, administrators can set up encryption.
• Security authentication: protocols such as FTP or Telnet use only basic security mechanisms during their login process. The MSgateway plugins invoke an SSL protocol component for user authentication.
• Low resource usage / fast response: opening and closing SSL connections takes a significant amount of CPU time, bandwidth and memory. MSgateways maintain a set of permanent SSL connections (to the ECaccess server) for their plugins.
• Web memory cache: pages collected by the MSgateway from ECMWF and passed to Member State browsers can be stored in a memory cache. If the same page is required again, it is retrieved from this cache. Since this cache is located on the MSgateway, this is quicker than access through the Internet.