Session Tracking for Personalized IKS Apps — HttpSession, Cookies, and Hidden Fields Explained

byBCA School •17:40:00

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Session Tracking for Personalized IKS Apps

Personalize your Indian Knowledge Systems (IKS) applications by using session tracking techniques such as HttpSession, cookies, hidden fields, and URL rewriting. These methods help you implement features like saved favorite Ayurvedic herbs or stored Yoga routines while keeping security and privacy in mind.

Quick overview

HttpSession — server-side session storage for per-visit state (recommended for ephemeral visitor data).
Cookies — client-side small key/value pairs for short-lived or persistent preferences (use secure tokens only).
Hidden fields — include state inside HTML forms (good when JavaScript is off or for CSRF tokens).
URL rewriting — fallback to keep session when cookies are disabled (response.encodeURL()).

Example use-cases

Show a user's favorite herbs for the current visit (HttpSession).
Offer a persistent "Remember me" feature using a secure cookie with an opaque token.
Save a yoga routine using a hidden CSRF token in the form to protect against forgery.

1) HttpSession — store favorites for the current session

Store only small identifiers (IDs) in session. Fetch full records from DB when rendering the page.

// AddFavoriteHerbServlet (simplified)
@WebServlet("/add-favorite")
public class AddFavoriteHerbServlet extends HttpServlet {
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    String herbId = req.getParameter("herbId");
    if (herbId == null) {
      resp.sendError(HttpServletResponse.SC_BAD_REQUEST);
      return;
    }

    HttpSession session = req.getSession(true); // create if not exist
    @SuppressWarnings("unchecked")
    Set favs = (Set) session.getAttribute("favHerbs");
    if (favs == null) {
      favs = new LinkedHashSet<>();
      session.setAttribute("favHerbs", favs);
    }
    favs.add(herbId);

    resp.sendRedirect(req.getHeader("Referer"));
  }
}

To read favorites in JSP / servlet:

HttpSession session = request.getSession(false);
if (session != null) {
  Set favs = (Set) session.getAttribute("favHerbs");
  // fetch details from DB by IDs and render
}

2) Cookies — persist a “remember me” token or a simple preference

Store only opaque tokens in cookies (never passwords). Set Secure and HttpOnly flags and validate token server-side.

// After successful login: create token, save it to DB and set cookie
String token = UUID.randomUUID().toString();
// save token -> userId mapping in DB with expiry

Cookie c = new Cookie("iks_rem", token);
c.setHttpOnly(true);
c.setSecure(true);     // requires HTTPS in production
c.setPath("/");
c.setMaxAge(30*24*60*60); // 30 days
resp.addCookie(c);

On each request, if session is missing but cookie exists, validate token and recreate session server-side.

3) Hidden fields — form state and CSRF protection

Include CSRF token and small state values in forms:

<form method="post" action="/save-routine">
  <input type="hidden" name="csrfToken" value="${csrfToken}" />
  <input type="hidden" name="returnUrl" value="/yoga/list" />
  <!-- other fields for routine -->
  <button type="submit">Save Routine</button>
</form>

// Validate on server
String formToken = req.getParameter("csrfToken");
String sessionToken = (String) req.getSession().getAttribute("csrfToken");
if (sessionToken == null || !sessionToken.equals(formToken)) {
  resp.sendError(HttpServletResponse.SC_FORBIDDEN, "CSRF token invalid");
  return;
}

4) URL rewriting — fallback if cookies disabled

Use response.encodeURL() to preserve session by appending ;jsessionid=... when necessary.

String url = response.encodeURL("/panchang?date=2025-08-10");
response.sendRedirect(url);

5) Example flow: favorite herb persistence

Short-term (session): user clicks favorite → add herb ID to HttpSession.
Long-term (persistent): save favorites to DB (user must be logged in) and optionally set secure cookie token for convenience.
UI sync: always fetch metadata by ID from DB to display up-to-date info.

6) Security & best practices

Use HTTPS in production; set cookie Secure flag.
Set HttpOnly on cookies to prevent JavaScript access.
Use SameSite (Lax/Strict) and CSRF tokens for forms.
Validate and sanitize all user inputs (IDs, dates, text).
Keep sessions small — store only IDs and small flags.
Invalidate session on logout: session.invalidate().
Log changes for provenance (who saved what and when).

7) Performance & scaling tips

Use a connection pool and shared DAO for DB access.
For scale, use distributed session stores (Redis) or sticky sessions behind a load balancer.
Cache frequently-read IKS records (metadata) rather than storing them in session.
For very large favorite lists, store in DB with pagination instead of session arrays.

8) Code snippet — restore session from cookie (remember-me)

Cookie[] cookies = req.getCookies();
if (cookies != null) {
  for (Cookie c : cookies) {
    if ("iks_rem".equals(c.getName())) {
      String token = c.getValue();
      Integer userId = TokenDao.getUserIdByToken(token); // validate & check expiry
      if (userId != null) {
        HttpSession session = req.getSession(true);
        session.setAttribute("userId", userId);
        session.setAttribute("permFavs", UserDao.getFavoriteHerbIds(userId));
      }
    }
  }
}

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