Cisco Cisco Computer Telephony Integration Option 8.5 Developer's Guide

Synchronous execution is the most common programming approach used by most 
applications. In a synchronous execution mode, a method call will execute all of 
the code required to complete the request and provide return values as well as 
error codes. Client-server programming can be synchronous (the client 
application will make a blocking request and will continue execution when the 
request is completed) or asynchronous (the client application makes a request, and 
continues processing immediately, with the result of the request to follow at a 
later time). 

CTI programming is unique in that requests are often serviced by third-party 
servers or applications, such as a PBX/ACD in the contact center. The 
asynchronous nature of CTI programming requires developers to note the 
distinction between an error code and the response to a request. In non-CTI 
programming, developers test the error codes (return values from method calls) to 
determine whether a method request succeeded or failed. However in a distributed 
architecture such as CTI OS, success or failure is often determined by some 
external server or component such as the PBX/ACD. 

The CTI OS Client Interface Library API specifies error codes, which are return 
values for method calls. These error codes relate to the success or failure of the 
method call, but not the success or failure of the underlying operation. By the 
success of the method call, we mean that the parameters sent were of the correct 

String

Long

None

Integer

Integer

Boolean

Argumen
ts

Arg

BSTR

long 
OR int

unsigned int short

unsigned 
short

VARIAN
T_BOOL

IArgume
nts *

IArg*

String

int

long

short

int

Boolean

Argumen
ts

Arg

System.St
ring

System
.Int32

System.Int6
4

System.In
t16

System.Int32

System.
Boolean

Argumen
ts

Arg