After the GRAPPLE analysis segment has produced the generel concept of the Digital Library system, a system engineer will strat thinking about how the physical structure should look. He or she will start considering alternative network topologies and how to implement them, and will start figuring out which software components belong on which nodes in the network.
The development team have made decision that a library local network will take part in the Digital Library system, and that an Internet interface will be implemented on the LAN's server.
First let's look at the physical architecture of the library's local area network.
The Deployment diagram for the library LAN |
As you can see from this deployment diagram, library LAN consists from these hardware components:
Component name | Amount |
Server | 1 |
DataEntry PC | 2 |
Lender's PC | 1 |
Search terminal | 6 |
Passive hub | 2 |
Server and DataEntry PCs are located in the same room, also one Passive hub is located in that room. A cable from this passive hub goes out from the room, to the corridor. There another passive hub is located. From this hub cables goes to the Search terminals located in the corridor, and to the Lender's PC located in the Lending area.
When we have a physical architecture in front of us, let's look at possibility od implementing an Internet interface on the Server. This interface will be used locally from the Search terminals, from Lender's PC and from DataEntry PCs and trough the Internet from member's homes or offices. Therefore a new hardware must be implemented in the library's LAN.
Library's LAN will have the same structure. New hardware will be added only to the Server's side, and that is a Network Interconnection Facility (NIF). The NIF consists of a name server (a database that validates connections), a router (a device for linking networks together), and a gateway (a device for translating information from one communication protocol to another). The gateway allows Internet members to access the Digital Library from home or from their office.
On the member's side only a computer with Internet connection, and Internet browser is necessary. Also a member must have an alias and password to make access to the Digital Library's Web page.
To ilustrate the deployment, the System Engineer delivers the deployment diagram shown on the following picture:
The Deployment diagram for the Digital Library system |