What is the use of session attribute in the project?

[srikanthbabu]

in my project we used the following code in many pages and i did not understand the use of this

HttpServletRequest request = (HttpServletRequest) FacesContext
				.getCurrentInstance().getExternalContext().getRequest();
		String path = request.getContextPath();
		String basePath = request.getScheme() + "://" + request.getServerName()
				+ ":" + request.getServerPort() + path;
		this.basePath = basePath;

		HttpSession session = (HttpSession) FacesContext.getCurrentInstance()
				.getExternalContext().getSession(false);
		SessionVO sessionBean = ((SessionVO) session.getAttribute("sessionDto"));
		this.commentVO.setCurUserId(sessionBean.getUserId());