Whenever you link two or more computers together, you have to prepare yourself for certain questions. How do you keep personal information private? How do you protect the system from malicious hackers? How do you control who can access the system and use its resources? How do you make sure the user doesn't tie up all the system's resources?
The short answer to this question is middleware. There's nothing inherent in a grid computing system that can answer these questions. The emerging protocols for grid computing systems are designed to make it easier for developers to create applications and to facilitate communication between computers.
The most prevalent technique computer engineers use to protect data is encryption. To encrypt data is to encode it so that only someone possessing the appropriate key can decode the data and access it. Ironically, a hacker could conceivably create a grid computing system for the purpose of cracking encrypted information. Because encryption techniques use complicated to encode data, it would take a normal computer several years to crack a code (which usually involves finding the two largest prime divisors of an incredibly large number). With a powerful enough grid computing system, a hacker might find a way to reduce the time it takes to decipher encrypted data.
It's hard to protect a system from hackers, particularly if the system relies on open standards. Every computer in a grid computing system has to have specific software to be able to connect and interact with the system as a whole -- computers don't know how to do it on their own. If the computer system's software is proprietary, it might be harder (but not impossible) for a hacker to access the system.
In most grid computing systems, only certain users are authorized to access the full capabilities of the network. Otherwise, the control node would be flooded with processing requests and nothing would happen (a situation called deadlock in the IT business). It's also important to limit access for security purposes. For that reason, most systems have authorization and authentication protocols. These protocols limit network access to a select number of users. Other users are still able to access their own machines, but they can't leverage the entire network.
The middleware and control node of a grid computing system are responsible for keeping the system running smoothly. Together, they control how much access each computer has to the network's resources and vice versa. While it's important not to let any one computer dominate the network, it's just as important not to let network applications take up all the resources of any one computer. If the system robs users of computing resources, it's not an efficient system.
How are people using grid computing systems right now? Keep reading to find out.