Cache Invalidation: What is it and Why is it Important?

According to Phil Larlton, There are only two hard things in computer science: cache invalidation and naming things. But what is cache validation and why is it important?

Cache invalidation is a caching process that ensures the data stored in a cache, remains current and consistent with the original data source. 

This cache invalidation is essential to maintain data accuracy, optimal performance, and system integrity.

What is Cache Invalidation?

Cache invalidation is the technique of invalidating a cache by removing the stored data from a system’s cache when the cache data is no longer useful or valid. 

In other words, you are getting rid of outdated content stored in the cache memory to ensure that the cache contains only the relevant and up-to-date content. It can improve data consistency and also prevent 304 errors.

Check out: OPCache

Why is Cache Invalidation Important?

By caching web page contents such as images, CSS stylesheets, JavaScript, and HTML files, a website can improve its performance and reduce its load time. 

However, this cached data could be outdated or erroneous if the content is changed in the origin server.

For example, the bf cache blog on RabbitLoader.com is updated. If the website does not set cache invalidation, the user will see outdated content.

To avoid this issue, cache invalidation is important. Apart from this, cache invalidation is important for several reasons.

• Better Performance:

Cache invalidation deletes the old cached copy from the cache, which frees up the space and enhances the cache hit rate. 

On the other hand, if the cache is not invalidated, it may continue to store the old data, leading to decreased performance and efficiency.

• Improved System Scalability:

Clearing up the outdated content reduces the load time on the database as well as the server. 

Hence, the cache invalidation process can help to improve the system’s scalability and reliability.

• Improved Security:

When the sensitive data is left in the cache and not invalidated, it may become exposed to unauthorized access. 

Cache invalidation reduces this risk by ensuring that sensitive data doesn’t remain in the cache longer than needed.

Must Read: Web Caching

Cache Invalidation with RabbitLoader

We can understand that setting a cache invalidation on your website might be tough. If you are from a non-tech background, you need to try RabbitLoader for an invalidation cache.

RabbitLoader has an advanced cache invalidation feature that automatically updates cached content to avoid stale data.

When any changes are made to your website, RabbitLoader purges the cached files and refreshes them from the origin server. So that, your user can see the updated content every time.

If you have some other requirements in your website, you can implement the manual techniques.

The Scenarios Where Cache Invalidation is Needed?

Cache Invalidation is needed where the cache is already implemented. Some common scenarios where cache invalidation is essential include:

• Web Caching:

Web browsers cache or store web pages’ static resources, such as images, CSS stylesheets, scripts, and HTML files, to improve their pagespeed performance.

An Invalidation cache ensures your user will get the latest content when any change is made to your website.

• Database Caching:

The database cache acts as an adjacent data access layer to your relational and NoSQL databases that your application can utilize to improve its performance. However, when the data changes (through inserts, updates, or deletes), the cached data can become stale.

The invalidation cache mechanism ensures that the cached data is refreshed or invalidated when any change occurs in the original database.

• Edge/ Proxy Server Caching:

In the edge server or CDN server, a caching mechanism reduces latency by temporarily storing frequently accessed data closer to the audience. 

If your website’s content is changed in the origin server, then that cached data will become stale.

This stale content issue can be solved by the caching invalidation mechanism. By using this technique you can ensure that your visitor will receive the up-to-date content. 

Check Out: Persistent Object Cache

Strategies for Caching Invalidation

Several strategies can be used to ensure that the caching invalidation is done properly for a better user experience. 

Explicit Invalidation:

There are three methods involved in the explicit invalidation caching strategy: purge, refresh, and ban.

Below we are explaining these methods in detail.

Purge:

The purge method removes the cached assets for a specific object or URL when the content changes or updates or the cached version is no longer valid.

When a purge request is received, the cached content is removed from the system. The next request will be served from the direct origin server.

Example:  Suppose, you have a news website. You purge a specific article from its cache after making some changes, ensuring that your users receive the latest version.

Refresh:

The refresh method fetches the requested content from the origin server even if the cached data is available.

Unlike the purge method, the refresh method does not remove the existing cached content, but it updates it with the most updated version

Example: You have an e-commerce website. When a new sale is launched, the product page uses the refresh method to display the updated pricing information.

Ban:

The ban method helps invalidate cached resources based on specific criteria, such as a URL pattern or HTTP header. 

After receiving a ban request, any cached content matching that specific criteria is deleted immediately. The next request will be served from the origin server.

Example: Maybe your Content Management System (CMS) has some dynamic data. Implementing the ban method to all cached data with a specific cache tag when it is modified, ensures that your users only see your fresh content. 

2. Implicit Invalidation:

Implicit invalidations happen when a cache entry timeout. Several mechanisms can be used for implicit invalidation.

• Event-Based Invalidation:

The event-based caching invalidation technique is used when the cached data is associated with a specific event and must be updated properly.

In simple words, when the data is updated or modified in the backend, an event is fired, notifying to invalidate the cached content or the cache update cache entities.

Let’s understand with an example. An event-based validation may occur when you have updated your blog post. The previously cached content must be invalidated to ensure your users see the updated information on the blog.  

• Command-Based Invalidation:

Command-based invalidation cache occurs when your user triggers a specific command or action, leading to an invalidation ID. A dependency ID is generated and associated with a cached object.

So, when the commands with an invalidation ID are executed, any objects in the cache with matching invalidation and dependent IDs are invalidated.

Example: when your user deletes a file from the storage, in that file the cache must be invalidated to ensure that your user does not see the file again.  

3. Time-To-Live (TTL) Expiration Caching Invalidation:

With this TTL expiration invalidation cache technique, cached content is given a time limit after which it becomes invalid and needs to be refreshed. 

When your user requests content, the cache checks the TTL values and serves the cached content only if the TTL value hasn’t expired.

Example: You have a weather website and set a 1 hour TTL for weather forecast data. This TTL ensures that your users receive up-to-date information without overloading the origin server. 

Conclusion

The cache invalidation strategy should be chosen very carefully to maintain performance and data accuracy. By understanding different cache invalidation strategies, you must select the appropriate one to optimize cache performance and reduce the latency.

If you are from a non-tech background, you should consider a solution like RabbitLoader to ensure that the cached copy is accurate and up-to-date.  

5 Web Caching Strategies to Boost Your Website’s PageSpeed Score

Web caching, the ultimate solution to supercharge your website’s pagespeed and enhance the user experience. But what is this web caching and what they actually do?

Technically, web caching is a temporary storage location for copies of static files or data. , let’s discuss web caching in detail and you will learn the powerful strategies to develop web caching that you can implement on your website to improve the pagespeed.

What is Web Caching?

Web caching is the concept of temporarily storing or caching the static resources of a website for reuse.

It makes a website faster by saving the heavier website’s resources. Example of what web cache stores are:

• Media files ( logo, images, videos)

• HTML files ( bits of code that create the content of a webpage)

• CSS stylesheets (a bit of code to add style to the webpage content)

• JavaScript files ( Scripting language to make the webpage more interactive)

Let’s understand with an example. You are visiting our website RabbitLoader.com. The first time the browser downloads and temporarily stores the RabbitLoader logo into the web cache. Every time you go to a different webpage on rabbitloader.com, the logo on the left top corner is loaded from the web cache. It will reduce the web page loading time.

Type of Caching on the Web?

Now you have a basic idea of web cache. Let’s discuss the different types of web cache. Web caching can be categorized into two parts: client-side and server-side. 

1.Client-Side Caching

happens when the browser saves the static resource files locally on the user’s computer. So that the files don’t have to be downloaded again.

2.Server-Side Caching

Indicates the web server temporarily stores the content of the webpage before it’s sent to the user’s browser. 

Here, we will explain the different types of cache such as browser cache (using client-side caching mechanism), proxy cache, and CDN cache which are well-known server-side caches.

• Browser Cache:

Browser cache is a client-side cache used to store images, Stylesheets, scripts, and other resources from the website. So,  when a user revisits the website, the cached content doesn’t need to be downloaded again. 

However, the browser cache has some drawbacks. It can introduce inconsistency. If the website’s content (like image or script) is changed then, the user will get a 304 Not Modified error for the stale cache content until they delete the cache. 

How to clear the web browser cache?

Let’s find out the steps to clear the browser cache in Google Chrome!

• Step 1: In Google Chrome go to the top right side and click on More (three dots). 
• Step 2:  Click on Clear browsing data or press Cntl+Shift+Del.

• Step 3: Select one time range, like All time or Last hour, and the type of information you want to remove from your browser.

• Step 4:  Click on Clear data.

• Proxy Cache:

A proxy cache is the most common type of server-side cache that lies between the user and the origin server. This cache is used for performance optimization, privacy, and security purposes.

When a user requests the content of the website, it can be fetched from the proxy server cache instead of its origin server. It will help to reduce the traffic and overload on the origin server.

Proxy servers also enhance security by filtering network traffic, scanning for viruses, encrypting data, and preventing malicious requests.

• CDN Cache:

A Content Delivery Network (CDN) is a group of proxy caching servers that are geographically distributed. It will reduce the real-world distance between the user and the original server. 

Content Delivery Network will help to improve the website pagespeed performance by reducing the latency. 

When a user requests content from a website through HTTP headers,  the HTTP request will arrive at the nearest PoP of the user.

• Cache Miss: happens If the requested content of the website is not present at the nearest server, The Content Delivery Network will retrieve that content from the origin server.

• Cache Hit: happens in a Content Delivery Network, If the requested content is present, then CDN can fulfill the request of the user by fetching the content through an HTTP response. 

What is the Cache Hit Ratio?

A cache hit ratio is used to measure the success of a Content Delivery Network (CDN) server’s cache system. The cache hit ratio is defined as the number of content requests a cache can deliver from the cache storage.

Let’s understand with an example. If a cache hit ratio is 75%, that means 75% of the requested content is served from the CDN cache, and the remaining 25% must be retrieved from the origin server.

The Impact of Web Caching 

Web caching has several significant impacts on the website’s performance. Let’s discuss a few reasons why a website needs web caching layers.

1. Web caching improves the website’s pagespeed performance:

By storing copies of the website’s static resources such as HTML files, CSS stylesheets, JavaScript files, and media files (images and videos) in the nearest edge location server, it will increase the website’s pagespeed by reducing latency. 

2. Web caching makes your website more secure:

Web caching allows you to access sensitive resources without exposing the resources to the server. You can control the web cache to restrict it based on an IP address and any other criteria. 

It will make this easier to audit and identify the hackers as well as bots.

3. Web caching reduces the server load:

When the cached resources are fetched from the web cache server rather than the origin server, it will reduce the load on the origin server. This also allows the server to handle more requests and improve the overall scalability.

So, web caching can be used as dependable and quick hosting to enhance the website’s performance.

Developing a Web Caching Strategy

Now, you have already covered the most important concepts of web caching. From here, we will discuss the strategies to develop a web cache.

There are certain strategies that you need to follow to develop web caching.

1.Identify cache resources:

First, you need to determine which resources should be cached if your website has some specific need. 

Usually, this may include static resources of website content such as HTML files, CSS stylesheets, JavaScript files, and media files ( images and videos), as well as dynamic content that is not changed frequently.

2.Understand cacheability:

You need to understand the cacheability of the resource files like how often they are changed or whether these resource files are sensitive to the user-specific data. Understanding cacheability is critical to setting a cache-control header.

3.Choose a caching mechanism:

After understanding the cacheability, you need to choose any caching mechanism like browser caching, proxy caching, or CDN caching. 

4.Set a cache-control header:

A cache control HTTP header carries the instructions for both requests and responses which control the whole caching process in the client-side cache as well as server-side cache.

Use an appropriate HTTP header such as Cache-Control to control the cache’s behaviours. By using this, you can set the max-age to specify how long the resources should be cached, no-cache which indicates the response must be stored in the cache but the response will validate with the backend or original server before reuse, and many more. 

5.Testing:

After configuring the caching you need to check in different browsers and devices to ensure consistent performance.

How RabbitLoader will help you in web caching?

The above strategies, which we’ve mentioned, are time-consuming and you need to do them manually, which requires a piece of coding knowledge. But why are you putting extra effort into this? 

There are many optimization plugins available such as RabbitLoader, WP Rocket, W3 total cache, and WP super cache to implement web caching in WordPress. You can also use RabbitLoader for your PHP, and Laravel custom website optimization. 

However, RabbitLoader is an all-in-one performance optimization plugin. No other optimization tools are required to enhance the website’s performance like other plugins when using RabbitLoader.

RabbitLoader will improve everything that’s needed for optimal performance. Not only that, RabbitLoader will enable premium CDN with 300+ POPs, and many more.

Conclusion

Here, you have a clear idea about web caching and how it helps you to improve your website’s performance and also learn the strategies to implement web caching on your website through as well as by using any plugin.

Now, you must implement web caching to improve the pagespeed of websites for a better user experience as well as higher SEO rankings.

Boost Your Website’s Pagespeed Performance With Caching Strategies

Implementing efficient caching strategies can boost the PageSpeed performance of your WordPress website by temporarily storing the static resources in the cache, which includes mechanisms such as browser caching and CDN caching.

Additionally, database caching and in-memory caching mechanisms can be included on the server side to improve a website’s pageSpeed performance.   

Before diving into cache strategies, it’s essential to understand what caching is and its importance to your website’s performance. We will also explore different types of caching mechanisms and how RabbitLoader can help you with implementing these strategies without an expert or coding skills. 

What Is Caching And How Does This Mechanism Work?

Caching is one of the essential optimization techniques that is used to store your website’s static content such as media files (images, videos, maps), CSS stylesheets, scripting files like JavaScript, and HTML files to improve the loading time of your website.

Let’s understand how it works. When a user visits a web page, the browser generally sends a request to the origin server. The server processes the browser’s HTTP request and provides a response to the user’s browser. This process can delay the loading speed, especially when the traffic is very high.

However, you can enhance your web page’s loading time by adding an efficient caching mechanism. When you use a caching mechanism, the browser request goes to the cache instead of the origin server. Here, two cases can be occurred:

• Cache Hit

Due to the availability of the requested content in the edge server, the requested content can be successfully retrieved from the CDN cache. This is known as a cache hit. By calculating the cache hit ratio, you can determine a cache’s efficiency. For more details, read the cache hit ratio blog.  

• Cache Miss

A cache miss is one of the metrics of cache memory to determine the cache’s inefficiency. It happens when the requested content is not present in the edge server and the CDN cache can’t fulfill the browser’s request. 

Type Of Caching

Several types of caching mechanisms are available to enhance the page speed performance. Let’s explore them. 

• Browser Caching

Browser caching is one of the most common web optimization techniques for temporarily storing a website’s static content in the browser cache when a visitor opens the website for the first time.

Therefore, when the user re-opens the same webpage, the browser can render the cached content. By reducing this web page loading time, the browser cache can improve the website’s PageSpeed performance. 

• CDN Caching 

A high physical distance between the user and the origin can typically increase the loading time by increasing latency. CDN caching is the only solution to reduce the latency.  

A CDN cache distributes frequently accessed resources to the edge servers. So, when a browser requests some content, the request goes to the proxy server instead of the origin server, improving the loading time.

• In-Memory Caching

In-memory database caching is used to minimize the number of queries by storing the frequently accessed data in the system’s RAM memory instead of the database. This in-memory caching is as volatile as the stored data can be lost if the system is restarted or shut down. 

Why Do We Need Caching?

Now, you might wonder why we need a caching mechanism. Here, we will clear up any doubts about the importance of implementing this mechanism on your website.  

• Improve PageSpeed Performance

Serving data from an efficient cache can significantly reduce the initial server responding time. This would boost all performance metrics, especially First Contentful Paint (FCP), Largest Contentful Paint(LCP), and Interaction to Next Paint (INP).  Therefore, the PageSpeed of the website would automatically improve. 

• Boost User Experience

When a user expects a fast-loading website, a slow website can harm the user experience, especially for mobile users. According to the thrive my way website, a website takes 87% longer to load its content on mobile than on desktop.  

So, the optimization pageSpeed is more essential for mobile users. By caching the static content you can speed up your website. It would improve the user experience, resulting in the improvement of conversion rate as well as the Google rankings.

What Are The Caching Strategies

Caching strategies are methods used for managing how static content is stored and retrieved from the cache. They are used depending on the website’s requirements. Here we will discuss the most common 4 caching strategies which include:  

• Cache-aside
• Write-through 
• Write-behind
• Read through

Cache-Aside

In the cache aside strategy, the browser’s HTTP request first goes to the cache memory, and if the requested content is present, a cache hit occurs. However, when the requested data is not available in cache memory, the data is retrieved from the origin server. 

This strategy is a flexible strategy but it requires proper management to ensure that the data are always up-to-date.  

Write-Through 

In the write-through strategy, the data is written in cache memory and the origin server at the same time. In simple words, when data is updated on a website, it’s updated in both cache memory as well as the origin server simultaneously. 

The advantage of this write-through strategy is that it ensures data consistency, which means that the data always remains up-to-date in a cache as well as the original database.   

Write-Behind

In the write-behind caching strategy, when data is updated, it is first written into a cache memory and then later written in the original database. The key advantage of caching strategies is that they improve write performance by minimizing the write operation in the origin server.  

Read Through

In a read-through caching strategy, the cache acts as a primary data source. When a data request is received in a cache, it first checks whether the data is present. If the requested data is unavailable in the cache memory, the cache itself retrieves it from the origin server and stores it in the cache memory before returning anything.   

Caching Strategies With RabbitLoader

Implementing the above caching strategies on your website requires extensive technical knowledge. When you are using RabbitLoader for your website’s pageSpeed optimization purpose, it will take care of your caching strategies.

By implementing an advanced browser caching mechanism, RabbitLoader stores all your static resources, such as HTML, stylesheets, scripting, and media files, in the browser cache. It allows you to set a maximum time for how long the content can be cached, ensuring that the content is state-free. 

Even, when content is updated on your website, RabbitLoader will automatically update the content in the cache by it’s caching strategies. 

RabbitLoader helps you reduce the distance between server and user by disturbing the content between 300+ edge servers, which are available in its premium CDN, minimizing the latency.

Therefore, when you are looking for an effortless solution, RabbitLoader is the best option for implementing caching strategies in your website. 

Enhance Your Website’s Pagespeed Performance With Web Caching  

When it comes to web optimization, implementing a web caching mechanism is one of the most effective methods for improving a website’s PageSpeed performance. Now you may wonder what web caching is and why it’s important for the website’s PageSpeed performance.

We will break the ice by explaining the details of web caching, including what it is, its impact on a website’s performance, and how RabbitLoader implements browser caching and CDN caching to improve your website’s PageSpeed performance.  

What Is Web Caching 

Web caching is an optimization method for temporarily storing static content such as HTML, CSS, JavaScript, and media files (images, maps, videos) for quicker retrieval, improving the website’s loading speed. 

To understand the web caching mechanism, let’s briefly explain how a browser displays a website’s content to a user. 

• When a user requests a web page, the browser makes HTTP requests. 
• That HTTP request goes to the origin/ backend server.
• The server processes the request and sends back a response. 

This process can make the loading time high, especially when the physical distance between the user and the server is very high or the website has high traffic. This is when the web cache comes into play.

A Web cache temporarily stores the website’s static resources and delivers the content when it’s required. When a website implements a web caching mechanism, the requested content can be fetched from the web cache instead of the backend, reducing the latency. Therefore, the loading speed is automatically improved.  

We will explain different caching mechanisms with real-life examples below. 

Most Impactful Web Caching techniques for PageSpeed Performance improvement  

Several web caching mechanisms are possible such as browser caching, CDN caching, Object caching, database caching, and many more. Here we will explain the two most impactful web caching mechanisms that are essential in order to optimize a website’s PageSpeed performance:

1. Browser Caching
2. CDN Caching 

What Is Browser Caching?

Browser caching (also known as client-side caching) is a web caching mechanism for temporarily storing a website’s static content in the browser cache. Let’s understand this with an example.

When a user visits a website for the first time, the browser loads and stores the static content in the browser cache. Therefore, when the user re-opens the website, the browser doesn’t have the exigencies to load it again; it fetches the cached content from the browser cache instead of loading from the origin server. This can positively impact a website’s loading speed.  

For example, if you visit a blog on our website for the first time, your browser loads static content such as images, CSS stylesheets, scripting files, and HTML files and stores them in your browser’s cache memory. When you revisit our blog the content will be delivered from the browser cache, reducing the page loading time. 

What Is CDN Caching? 

CDN caching is also known as a server-side caching mechanism. In this mechanism, a Content Delivery Network (CDN) stores static content (images, CSS stylesheets, HTML, and JavaScript files) on the proxy server. 

When a user requests content, it can be fetched from the nearest proxy server instead of the origin server, improving the PageSpeed performance by reducing the network latency. Let’s understand CDN caching with an example.

Assume our website RabbitLoader.com is hosted on a California datacenter and you visited it from NewYork. The physical distance can be a reason behind your high network latency. However, a CDN distributes the static content between the proxy servers worldwide. Thus, when a browser makes an HTTP request, it will go to the nearest edge server instead of the origin server. It would reduce the network latency and boost your website’s PageSpeed performance. 

Note: To determine a cache’s efficiency, you need to measure the cache hit & cache miss ratio. To know about these two cache metrics, read our blog on the cache hit ratio. 

The Importance Of Implementing A Web Caching Mechanism On A Website

Web caching has several positive impacts on the PageSpeed performance of a website. Let’s explore the most common reason behind using web caching on your website which includes:

• Enhance your website’s PageSpeed performance
• Reduce the server overloading
• Increase the website’s security 

Enhance Your Website’s Pagespeed Performance

A web cache can significantly improve your website’s PageSpeed performance by temporarily storing its cached content. This can positively affect your user experience and help you achieve a desirable conversion rate. So, PageSpeed is an essential factor for your website.

Reduce The Server Overloading

After implementing an efficient web caching mechanism on your website, its content will quickly be retrieved from the web cache. This automatically reduces server overloading by minimizing the HTTP request to the origin server.  

Increase The Website’s Security 

Using CDN caching can increase your website’s security by allowing you to access the website’s content without exposing its origin server. 

Implement Web Caching With Rabbitloader 

Implementing browser caching and CDN caching can be daunting, especially when you are not a tech wizard. Investing your money & time in different plugins for browser caching and CDN caching doesn’t make much sense when RabbitLoader can do both for you. 

Let’s see how RabbitLoader can implement browser caching as well as CDN caching in your website.  

Implement Browser Caching With RabbitLoader

RabbitLoader implements an advanced browser caching mechanism with efficient caching strategies. When you make changes to your website’s content, RabbitLoader automatically updates the cached content, so your visitors can enjoy stale-free content.

While manually implementing a browser cache requires a lot of time and a little bit of expertise, installing RabbitLoader allows you to implement an advanced browser mechanism with a few clicks. It also allows you to set how long you want to cache content.  

Implement CDN Caching With RabbitLoader

The advantage of installing RabbitLoader on your website is that you don’t need to invest in an external Content Delivery Network (CDN). RabbitLoader has an integrated premium CDN that reduces network latency by sharing static content between its 300+ edge servers all over the world, improving the website’s Pagespeed performance. 

If you are considering optimizing your website by implementing a web caching mechanism, Try RabbitLoader now and see your website’s PageSpeed score jump up within just a few minutes.