SocketTools Development  

The SocketTools ActiveX Edition provides a comprehensive collection of ActiveX controls for performing a variety of Internet related programming tasks. Although the number of properties, methods and events may appear daunting, once you begin using SocketTools in your own applications you'll find that the various controls are designed to work together in a cohesive fashion. After you've familiarized yourself with one control, the others will become much simpler to use.

Throughout the Developer's Guide there are some general concepts and terminology used that are essential to understanding how SocketTools works. Each of these concepts is explored in detail, however a general, broad overview can also be useful when you are just getting started.


A protocol, in terms of how the word is used in SocketTools, refers to the rules for how programs communicate with one another over a network. There are low level networking protocols such as TCP and UDP, as well as high level application protocols like FTP and HTTP. It can be helpful to think of a protocol as a sort of language; for two programs to communicate with each other, they must agree upon a protocol and understand how it is implemented.


The process of establishing a connection enables one program to communicate with another. Connection requests are made by client applications, and accepted by server applications. When the server accepts the connection request, the connection is completed. When you use the Connect method to successfully establish a connection to a server, a client session is created. SocketTools uses a one-to-one relationship between an instance of a control and a client session. By creating multiple instances of a control, an application can create multiple client/server sessions if necessary.


A session refers to an active connection between a client and server program. This term is typically used interchangeably with connection; however in some cases a single session may involve multiple network connections. For example, the File Transfer Protocol control establishes one connection, called the command channel, when the client initially connects to the server. However, when a file is being uploaded or downloaded, a second connection called the data channel is created just for that transfer. When the transfer completes, the second connection is terminated while the original command channel connection remains active. Even though there are multiple connections being made, SocketTools considers it to be a single client session. An active session is referenced by the instance of the control that was used to create the session. When the session is no longer needed, the control's Disconnect method will terminate the connection to the server and release the resources allocated for that session. After that point, the session is no longer valid and subsequent function calls using the control cannot be made until another connection is established.


Many servers require that clients authenticate themselves by providing user names and passwords. Different application protocols implement several different types of authentication, and some protocols may support more than one authentication method. SocketTools provides one of two general types of authentication methods, depending on the protocol. For protocols which require the client to authenticate itself, the controls will provide a Login method. For protocols where authentication is optional, the controls will provide an Authenticate method. Refer to the technical reference for the specific protocol to determine if authentication is required.


Developers who use programming languages such as Visual Basic will find the concept of events and event handling to be very familiar. In general terms, the SocketTools documentation uses "event" to refer to a mechanism where the control notifies the application that an operation has completed, some action has taken place or a change in status has occurred. One example of an event is a connection event, which is generated whenever an asynchronous network connection is completed by the client. Another example is a progress event, which is generated periodically by the control to inform the client of its progress as it sends or receives data. To determine what events are available in a specific control, refer to the documentation. More specific information about event handling is provided later in this guide.