A session is a temporary logical connection between two end-user application processes for message exchange. Which of the following statements about the session is not true?
A. The session layer in the ISO OSI model maps to the application layer in TCP/IP.
B. The establishment of a session is independent of underlying transports.
C. The RESTful-style architecture prescribes how a session is managed.
D. A session can maintain state information even if the transport is connectionless.
Kindly be reminded that the suggested answer is for your reference only. It doesn’t matter whether you have the right or wrong answer. What really matters is your reasoning process and justifications.
My suggested answer is C. The RESTful-style architecture prescribes how a session is managed.
“Representational state transfer (REST) is a software architectural style that defines a set of constraints to be used for creating Web services.”
The RESTful-style architecture doesn’t prescribe how a session is managed, specifically how a session is established, maintained, and closed. Instead, it defines constraints imposed on the software architecture such as client-server architecture, statelessness, cacheability, layered system, code on demand (optional), and uniform interface.
The most well-known REST feature is the standardization of CRUD operations (create, retrieve, update, and delete) on data as the following diagram shows:
ISO OSI Model and TCP/IP Mapping
What is a Session?
There are various definitions of session across contexts. From the ISO OSI model and TCP/IP perspective, a session can be defined as a temporary logical connection between two end-user application processes for message exchange. It’s commonly referred to as a user or application session.
The establishment of a session is independent of underlying transports. Where there is a session, there is an application. Any appropriate protocol can support an application. It doesn’t have to be TCP or UDP. For example, a session can start with authentication, which can be completed in any transport protocol, e.g., TCP, UDP, NetBEUI, to name a few.
A session can maintain state information even if the transport is connectionless. The state information can be transmitted between the client and the server and persisted at either the client or the server. It doesn’t matter if the underlying transport protocols or transports are connection- or connectionless-oriented.
In a stateless communication supported by connectionless-oriented transports, the state information may not be actually transmitted; it typically relies on the client’s presenting the Session ID for the server to retrieve the persisted version on the server. HTTP cookies, HTML inputs, and the URL query string are common mechanisms used to transmit the state information and the session ID in web applications.
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A. ISO OSI模型中的會話層映射到TCP/IP中的應用層。