Page 265 -

Chapter 6 The Cloud
264
Chicago Site
Local Area
Network 1

Remote
Client
Figure 6-21
Remote Access Using VPN;
Apparent Connection

sends the plain text message to the original address inside the LAN. In this way, secure private
messages are delivered over the public Internet.
Using a Private Cloud

A private cloud is a cloud owned and operated by an organization for its own benefit. To
create a private cloud, the organization creates a private internet and designs applications
using Web services standards just as shown in Figure 6-19 (page 261). The organization
then creates a farm of servers and manages those servers with elastic load balancing just
as the cloud service vendors do. Because of the complexity of managing multiple database
servers, most organizations choose not to replicate database servers. Figure 6-22 illustrates
this possibility.
Private clouds provide security within the organizational infrastructure but do not provide
secure access from outside that infrastructure. To provide such access, organizations set up a VPN
and users employ it to securely access the private cloud as shown in Figure 6-23.
Private clouds provide the advantages of elasticity, but to questionable benefit. What can
organizations do with their idle servers? They could realize some cost savings by shutting down
the idle servers. But unlike the cloud vendors, they cannot repurpose them for use by other com-
panies. Possibly a large conglomerate or major international company could balance processing
loads across subsidiary business units and across different geographical regions. 3M, for example,

Private Cloud
Browsers in
Browsers in
Sales Dept
Browsers in
Sales Dept
Browsers in
Sales Dept
Browsers in
Sales Dept
Browsers in
Sales Dept Browsers in
Browsers in
Sales Dept Browsers in
Browsers in
Sales Customer
Customer
Browsers in
Elastic Load Service
Customer
Customer
Balancer Service
Inventory Service
Application Inventory Service
service requests Application
& responses
Inventory & Other service requests
Applications & responses
Web servers
Database server Browsers in
Browsers in
Browsers in service requests & Accounting
Browsers in
Browsers in responses Accounting
Shipping Accounting
Browsers in
Shipping
Browsers in
Shipping
Browsers in
Shipping DBMS DB
Shipping
Database Server
Figure 6-22
Private Cloud for Inventory
and Other Applications