Gateway Tunnel A gateway is a server that appears to Tunnel performs no operation on the client as if it were an origin Http requests and responses A tunnel is simply a relay point It acts on behalf of other servers between two TCp connections that may not be able to communicate directly with a client Http messages pass the tunnel WiThout any changes a Two scenarios need use gateway Security intermediary .Non-httpservers Http Messages Http Message stRucture Request Request Line Request Header or Response Response lin Entity Hender General header Request header Entity Body General Header Fields Request Methods Cache control Request-line= Method <sp> Request_url <sp>htTp-versIon a Connection Methods: a Date Forwarded Keep alive MIME version Pragma rade Extersion-method 88 哈工大计算机学院 李全龙 Network Application Development Server Software Design 43 Gateway „ A gateway is a server that appears to the client as if it were an origin server. „ It acts on behalf of other servers that may not be able to communicate directly with a client. „ Two scenarios need use gateway: „ Security intermediary „ Non-HTTP servers 哈工大计算机学院 李全龙 Network Application Development Server Software Design 44 Tunnel „ Tunnel performs no operation on HTTP requests and responses. „ A tunnel is simply a relay point between two TCP connections. „ HTTP messages pass the tunnel without any changes. „ Use? 哈工大计算机学院 李全龙 Network Application Development Server Software Design 45 HTTP Messages „ Requests „ Client to server „ Responses „ Server to client „ Request line „ Response line „ General header „ Request header „ Response header „ Entity header „ Entity body 哈工大计算机学院 李全龙 Network Application Development Server Software Design 46 HTTP Message Structure 哈工大计算机学院 李全龙 Network Application Development Server Software Design 47 General Header Fields „ Cache control „ Connection „ Date „ Forwarded „ Keep alive „ MIME version „ Pragma „ Upgrade 哈工大计算机学院 李全龙 Network Application Development Server Software Design 48 Request Methods „ Request-Line = Method <SP> Request_URL <SP> HTTP-Version <CRLF> „ Methods: „ Options „ Get „ Head „ Post „ Put „ Patch „ Copy „ Move „ Delete „ Link „ Unlink „ Trace „ Wrapped „ Extension-method