Introduction
This article uses to introduce the communication model of the Microsoft Windows CE operating system. Because the applications and services have different communication requirements, Windows CE provides a set of diverse communication function options and related application programming interface APIs. WINDOWS CE-based devices can implement any or all of the function options. We will fully discuss the support capabilities provided by Windows CE-based devices, and how different parts are integrated into the entire model.
WINDOWS CE communication support capability
Communication capabilities are key features of WINDOWS CE-based devices. It ranges from simple cable serial input (I / O) to wireless networks using Transmission Control Protocol (TCP / IP). In addition to built-in communication hardware, such as serial cables or infrared transceivers, support for PCMCIA enables a wide range of communication devices that have been put into the market to be added to the basic support package.
Windows CE supports three ways:
Serial I / O network, including:
Windows Sockets (Winsock) and Infrared Sockets (Irsock) TCP / IP and IRDA (Infrared Data Association, Infrared Data Transport) are used for NDIS 4.0 (Network Device / Driver Interface Specification, Network Device / Driver Interface Specification, Network Device / Drive Interface Specification) by Serialia Line or MODEM Point Protocol (PPP, Point-To-Point Protocol) Network Remote Document Access (WNET API) Remote Access Access Client (RAS) supports browser ( Wininet API) Telephone API (TAPI)
Communication model diagram shows Figure 1
Figure 1. Schematic diagram of Windows CE communication model
Serial communication
Serial I / O is the most basic feature in the Windows CE communication model, which should be available in all devices. On the hardware, serial communication is usually implemented by a cable or IR transceiver.
The cable of the cable can be processed by standard Microsoft Win32 API serial and file system functions. These functions are used to open, close and operate COM (Component Object Model, Component Object Model) port, and read from them and write. Alternation or asynchronous I / O is not supported.
The IR transceiver is assigned to a COM port, which can directly use serial I / O using common serial communication functions. I / O communication is a "original" way, which means that it does not have conflict detection.
Through Irsock, a more powerful serial IR communication using the IRDA protocol will be obtained later by IRSOCK (an extension of Winsock). As an alternative means of directly using Irsock, IRCOMM simulates serial communication, but Irsock and IRDA protocols are used inside.
Telecommunication
Windows CE has a network stack with a variety of different options. It can use a variety of hardware, including infrared, serial, Ethernet, and wireless connection.
Browse and remote file systems
On the top floor of the network, Windows CE supports the subset of Wininet and WNET APIs, and an SMB (Server Message Block, Server Message Block) redirect program (Redirector).
The Wininet API provides support for Internet browsing protocols. These protocols include File Transport Protocol (FTP, File Transfer Protocol) and Hypertext Transfer Protocol (HTTP, Hypertext Transfer Protocol) 1.0, but does not include Gopher. The Wininet API only supports an agent (Proxy) without buffering. It also provides access to the two Internet security protocols, which are SSL (Secure Sockets Layer, Security Sockets) 2.0 and 3.0 and PCT (Private Communication Technology, Private Communication Technology) 1.0. The WNET API provides processing for the SMB redirection program for remote file access. Only join for Microsoft Windows 95 and Windows 95 and Windows NT operating systems are currently supported by the WINDOWS 95 Redirect Programs Support UNC (Universal Naming Convention, universal naming) name (such as // serverxx / sharexx), but does not support drive.
Winsock and Irsock
Application Normally access the network stack through the Winsock interface. Windows CE supports a subset of Winsock 1.0. All standard Winsock functions can be used, but asynchronous functions (including most WSAXXX functions) will not. Windows CE also supports SSL 2.0, 3.0, and PCT 1.0 security protocols.
Irsock is an extension to Winsock to implement Socket-based communications through infrared transceivers. It is designed to support industry standard IRDA protocols. Although some functions are slightly different, the application uses Irsock very similar to using traditional Winsock.
Remote access client
At The Same Level In The Network Stack AS Winsock, But Serving A Different Purpose, Windows CE Supports RAS (Remote Access Server, Remote Access Server) client, which is in the same level in the network stack, but there are different use. Ras is a multi-protocol router for connecting remote services. The Windows CE RAS client is essentially the same as Win32, but it only supports a point-to-point join once.
Transmission and address layers
The TCP / IP protocol is developed for Internet, perhaps the most flexible and widely used network protocol. The protocol is supported by many systems and constitutes the core of the Windows CE network stack.
Many Windows CE-based mobile devices will have wireless communication capabilities. However, conventional TCP / IP stacks typically have good running in wired networks, and may be poor performance when using wireless technology. The Windows CE TCP / IP stack is designed to be able to support the wireless network.
For infrared networks, Windows CE provides a transport layer support for the IRDA protocol.
Data link layer
At the bottom of the network stack, Windows CE supports two data link layers.
Many Windows CE-based devices are connected to their networks through a serial communication connection (such as by modem). In order to support such networks, Windows CE uses the widely used SLIP and PPP protocols. Verification is provided by PAP (Password Authentication Protocol, Password Authentication Protocol, CHAP (Challenge Authentication Protocol, challenge verification), and Microsoft CHAP.
For Lans (Local Area Networks, LAN), Windows CE contains an implementation of NDIS 4.0. The Ethernet micro port is currently only supported. For the WANS (Wide Area Networks, WAN), Windows CE does not support. TAPI / UNIMODEM
The Windows CE includes a TAPI (Telephony API, telephone API) service provider for modem (Telephony API, phone API) based on the AT (Advanced Technology, Advanced Technology) command. It can be attached or used by the PCMCIA modem.
TAPI is a set of tools that make the app to make full use of a variety of telephone and communication services without having to have a detailed knowledge background for specific technologies. The TAPI implementation of Windows CE is used to solve the telephone problem of the outgoing person and provide an outward dialing and address translation service. Dial-in calls are currently not supported. Support for multi-dialing locations can be done by Control Panel. To provide flexibility in hardware, TAPI supports the installed service provider.
to sum up
The Windows CE communication model is designed to work well on a variety of different types of services. It provides an OEM (Original Equipment Manufacturer, Original Device Manufacturer) mode with different options collection. Its modular design makes it possible to be minimized because only one of the specific devices in the model is included therein. For more details on adjusting the communication model according to a particular device, see the Windows CE Oem Adaptation Kit.
For application developers, Windows CE supports the vast majority of communication types. These communication methods can be processed by similar WIN32-based APIs, which makes developers easy to implement relevant communication capabilities in their procedures. For more information about writing a communication capabilities for Windows CE-based devices, see Windows CE Software Development Kit.
