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Augustas Pelakauskas

Nov 26, 2021 6 min read

To efficiently perform daily tasks, numerous internet applications must remember specific details about their users. Web shopping or simply logging in requires multiple data sets to recognize and remember the visitor and its behaviour.

Web sessions are a universal mechanism to maintain such information. A session is the storage of information on a server kept throughout the user’s interaction with a website or a web application. It is the total time required to complete the desired actions before leaving the digital domain or turning off the device. A single session ensures a uniform experience and persists across multiple pages of the website. Each session is unique for every user and any number of sessions could be used to cover the required volumes. 

This article will give you a general overview of web sessions, their relation to cookies, and their use in web scraping.

How do web sessions work?

All sessions carry a unique data set that persists during the use of a website. A unique identifier, sessionID, is an exclusive tag assigned to each user’s browser upon starting a new session. User interactions with the website’s links trigger the sessionID to transition to the server along with the HTTP requests. The server saves the IDs for recurrent sessions – this way your user credentials are remembered each time, allowing you to sign in automatically.

The exchange between the ID and the server happens during each subsequent visit. Session details, such as viewing history, input data (user’s credentials, selectable variables in drop-down lists), shopping cart contents, and more are stored in a temporary directory on the server and become available to all pages on the visited site.

Inactivity such as loitering will typically result in a timeout. A time limit is set to dissociate the users who don’t send any requests for a prolonged period after which the session expires, deleting all the data. Any further interaction initiates a new session.

Browsers that don’t support cookies use sessions as a substitute to ensure more secure data storage.

Web sessions vs cookies

Both cookies and sessions are used to store information for quick access to persistent data. Cookies store the information on the user’s device until it expires or is deleted manually, whereas sessions hold the temporary information on the server-side automatically. If you’re interested to know more about cookies, check out what HTTP cookies are and their uses.

The main differences between cookies and sessions

In essence, the differences between cookies and sessions are determined by their dependence on each other, file size, storage location, security settings, timing, necessity, and persistence. Take a look at the table below.

CookiesSessions
Cookies don’t depend on sessionsSessions depend on cookies
The maximum file size is usually just 4KBAn expansive data set, reaching up to 128MB
Client-side fileServer-side file
Unencrypted and easily readable data file on the user’s deviceUsually encrypted data, securely stored on the server
Cookies can last as long as the user allowsA session ends with a closure of the site
Can be disabled or enabled depending on the user’s choiceDoes not depend on the user’s preferences; automated procedure
More convenient for continuous usage as input data can persist for prolonged periodsInput data must be reentered each time

Cookies are a more simplistic long-term approach, compromising security for ease-of-use, while sessions are a short-term solution for more sensitive data. Lastly, the general preference of using both methods comes down to a simple question: must persistent data remain after the browser closes? If the answer is yes, cookies are used; if the answer is no, sessions are employed instead.

Sessions in web scraping

The most important link between sessions and web scraping is a proxy. Proxies allow unlimited concurrent sessions to single or multiple websites. Sessions enable you to fill various forms to ensure sustained performance and scrape multiple data sets in parallel.

The main idea of initiating multiple sessions is to resemble organic traffic, which in turn lets you evade getting blocked. Due to this reason, web scraping is typically associated with rotating sessions.

Rotating sessions

Let’s say you have multiple pages of data and you want to scrape them quickly. It usually takes a decent amount of time, and using a single IP will likely lead to various interruptions ranging from CAPTCHAs to bans.

To avoid such hurdles and make the whole process as smooth as possible, you can use rotating proxies. Easily exceed the limited number of requests you can send to a website and keep on rotating until you extract all the target data. The increased flexibility allows you to evade IP and session tracking while avoiding bans.

Rotating sessions change along with the IPs with every connection request automatically. Entering a website with one particular IP address and changing it each time an action is taken allows for a continuous rotation. A pool of rotating proxies with a proxy rotator switches different IP addresses, changing an IP instantly with every new press on a link or page refresh.

Rotating sessions are the most suited for general scraping tasks, such as long lists of product pricings with multiple rows and pages. The rotation propels web scraping and crawling tasks that don’t require logging into an account. If you don’t want your continuous requests linked to a single session and the same device, the rotating sessions are the best choice.

Rotation doesn’t apply to social media automation, sneaker copping, and similar session-sensitive tasks, although some solutions offer great compromises. Extensively prolonged scraping sessions (up to 5 hours) powered by Rotating ISP Proxies enable you to appear as an organic user to meet more specific stability demands.

Significantly improved stability lets you complete the required steps with a single IP address. Nonetheless, if any kind of session time cap is an issue, distinct solutions ensuring permanency are available. Extended (sticky) sessions are suitable for websites that require session maintenance throughout the whole scraping cycle.

Sticky sessions

Session stickiness describes session persistence – the proxy doesn’t change with each new request, and the IP address stays the same for an extended period of time. Extended sessions last as long as your proxy provider allows. Some proxy providers allow you to configure the IP rotation intervals. Typically, a session could be expected to last up to 30 minutes.

Quick IP changes indicate unnatural, inorganic behaviours that are usually associated with automated bots. Such practices lead to suspicion on the web service side and can result in session termination. A unique and exclusive IP address is assigned to each supervised account, seemingly separating it from your main individual account. In reality, a single primary IP manages multiple extended sessions with different accounts using automation.

Accessing and managing your accounts on the internet requires a single continuous session for the whole working cycle, therefore, sticky sessions are maintained for a prolonged period of time before changing. Whether you want to manage your social media accounts, e-commerce platforms, or any other account-dependent medium, sticky IPs excel.

Final thoughts

Sessions allow a certain degree of monitoring and customization for users and service providers alike and, together with cookies, are a crucial part of the web. While sessions rely and are dependent on cookies, both of them serve their individual use cases and applications.

While rotating sessions work best for web scraping and automatization, sticky sessions are suited for account management and persisting tasks with extended working cycles.

If you’re interested in similar topics, make sure to check our blog posts on the differences between web scraping and crawling or web scraping with Java.

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About Augustas Pelakauskas

Augustas Pelakauskas is a Copywriter at Oxylabs. Coming from an artistic background, he is deeply invested in various creative ventures - the most recent one being writing. After testing his abilities in the field of freelance journalism, he transitioned to tech content creation. When at ease, he enjoys sunny outdoors and active recreation. As it turns out, his bicycle is his third best friend.

All information on Oxylabs Blog is provided on an "as is" basis and for informational purposes only. We make no representation and disclaim all liability with respect to your use of any information contained on Oxylabs Blog or any third-party websites that may be linked therein. Before engaging in scraping activities of any kind you should consult your legal advisors and carefully read the particular website's terms of service or receive a scraping license.

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