Active Worlds SDK 4.2 Build 77

For example, the SDK could be used to develop an automated program that explores a world and creates a map. Also, the SDK allows universe administrators to develop administration utilities to help manage their own Active Worlds universes.

The core component of the SDK is the file aw.dll, a Windows DLL that implements the entire Active Worlds client/server protocol. To develop an application using the Active Worlds SDK, a programmer simply writes a C program which includes the header file aw.h and links to the import library aw.lib.

The compiled executable can be run from any PC anywhere as long as that PC has a network connection to the Active Worlds Universe and aw.dll is available on that PC.

For developers who want to avoid having to deal with a separate DLL, the SDK also ships as the static library aw_static.lib. By linking to aw_static.lib, developers can encapsulate the entire Active Worlds SDK within their program executable and not worry about shipping a separate DLL along with their application. To link to aw_static.lib, developers should define the pre-processor symbol AW_STATIC before including the header file aw.h in their source files.

The Active Worlds SDK uses event handlers to communicate with your application whenever something occurs in the Active Worlds environment.

The Active Worlds SDK uses attributes for communicating data back and forth between the application and the SDK. Attributes are similar to variables in that they store values that can be queried and changed. Many SDK attributes are read only, meaning that they cannot be changed by the application and exist only for communicating information to the application from the SDK.

The Active Worlds SDK can support multiple simultaneous instances. This means it is possible to write an SDK application that creates and manipulates dozens or even hundreds of bots at once. The only practical limit on the number of instances is the limit on the number of bots that a citizen can have running in the universe at one time.

By default, all API methods that generate responses from the Active Worlds servers will block until the response is received. For some SDK applications, such as interactive programs that need to respond to events from a user interface, this blocking behavior may be undesirable. In this case the application can switch a particular method or methods into asynchronous mode by installing a callback for that particular method. If a method has a callback installed, that method will return immediately without waiting for a reply from the server. The callback function will be called later by the SDK when the servers response is received.

Examining and modifying Active Worlds property (objects) is probably the most complex aspect of the SDK. The reason for this complexity is the need to organize property so that clients and browsers are able to easily remain up to date with the current contents of a world without using a lot of bandwidth.