Networking Services Quick Start

Getting started with Networking Services

Networking Services is used in the following circumstances:

• If you are writing an application or application level protocol that needs access to the Internet, use the Internet Sockets interface and the Communications Framework Sockets Server client.

• If you are a licensee and need to extend or modify the behaviour of the TCP/IP implementation, write a plug-in using the IPHook interface.

• If you want to debug existing application software and configure network settings.

Architecture

Networking Services enable mobile devices to connect to the internet and network applications using protocols such as TCP/IP and IPSec. The main areas of Networking Services are:

• Link Layer Protocols

  The Link Layer Protocols collection groups the networking protocols for the Data Link Layer, including Ethernet and PPP. For more information, see Link Layer Protocols.

• Network Security

  The Network Security collection is the set of components that provide security protocols for an IP connection. For more information, see Network Security.

• Network Test and Utilities

  The Network Test and Utilities collection provides components that are used to measure network performance. For more information, see Network Performance Testing.

• Network Protocols

  The Network Protocols collection is a set of plug-ins to the Sockets Server. The plug-ins implement network protocols, such as TCP/IP, that can be accessed through a sockets type interface. For more information, see Network Protocols.

• Network Control

  The Network Control collection controls the resource availablity for applications in mobile devices. It prioritises the applications on the device to ensure performance consistancy and application access to the network. For more information, see Network Control.

• PPP Compression Plugins

  This collection contains the Point-to-Point Protocol (PPP) Compression Plugins used by the Point-to-Point Protocol component. For more information, see PPP Compression Plugins.

• TCP/IP Utilities

  The TCP/IP Utilities collection provides libraries used by TCP/IPv4/v6 for the DNS and DHCP protocols. For more information, see TCP/IP Utilities.

The Symbian platform Networking Services structure can be compared to the standard OSI Model for the layering of network protocols. The OSI Model defines seven layers. Each layer defines a stage that data must go through to travel from one device to another over a network. A layer corresponds to a group of components that perform similar tasks in the Operating System.

The uppermost OSI Model layer is the Application Layer, which provides application services to the end user software applications. The lowest OSI Model layer is the Physical Layer, which deals with network connections and other physical network attributes.

The following section lists the OSI Model layers and gives a brief description of each:

• Application Layer

  The Application Layer interacts with the operating system or application when the user wants to transfer files, read messages or perform other network related activities.

• Presentation Layer

  The Presentation Layer takes data from the Application Layer and converts it into a format that the other layers can interpret.

• Session Layer

  The Session Layer establishes, maintains, and ends communication with the receiving device.

• Transport Layer

  The Transport Layer takes the incoming data from applications and combines it into a single stream. This stream is then passed on to the Network Layer.

• Network Layer

  The Network Layer determines the way the data is sent to the recipient device. Logical protocols, routing, and addressing are all dealt with in this layer.

• Data Layer

  The Data Layer assigns physical protocol to the data.

• Physical Layer

  The Physical Layer defines the physical characteristics such as connections, voltage levels and timing.

Technologies

The following table maps the various communications technologies implemented in Symbian platform to the layers defined by the OSI Model. Networking Services implements technologies that mostly map to the Transport and Network Layers. Other Symbian platform modules implement higher level application layer protocols and device drivers that implement the bottom layers of the stack.