Cisco Cisco Computer Telephony Integration Option 9.0 Developer's Guide

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CTI OS Developer’s Guide for Cisco Unified Contact Center Enterprise
Release 8.5(3)
Chapter 2      CTI OS Client Interface Library Architecture
Client Interface Library Architecture
Figure 2-2
Client Interface Library Three-Tiered Architecture
Connection Layer
The Connection layer provides basic communication and connection recovery facilities to the CIL. It 
creates the foundation, or bottom tier of the CIL’s layered architecture, and decouples the higher-level 
event and message architecture from the low-level communication link (TCP/IP sockets). The 
Connection layer sends and receives socket messages to the CTI OS Server, where it connects to a 
server-side connection layer. 
In addition to basic communication facilities, the connection layer provides fault tolerance to the CIL by 
automatically detecting and recovering from a variety of network failures. The Connection layer uses a 
heartbeat-by-exception mechanism, sending heartbeats to detect network-level failures only when the 
connection is silent for a period of time. 
The C++ CIL connection objects offered a parameter for setting QoS markings (DSCP packet markings).  
This mechanism does not work when the Desktop is deployed on Windows Vista, or Windows 7. If QoS 
markings are required on these platforms, it is recommended that QoS be managed across the enterprise 
with a Group Policy. Group Policies are administered using Active Directory, but that information is 
beyond the scope of this document.
For more information on C++ CIL connection objects, see 
.
Cisco Unified Intelligence Center Solution ReferenceNetwork Design (SRND)
.
For additional information about CTI OS QoS support, see the Quality of Service/Type of Service (QoS/ToS) 
section of the 
CTI OS System Manager Guide
.
Service Layer
The Service layer sits between the connection layer and the Object Interface layer. Its main purpose is 
to translate the low-level network packets the connection layer sends and receives and the high-level 
command and event messages the Object Interface layer uses. The Service layer implements a generic 
message serialization protocol which translates key-value pairs into a byte stream for network