How can you improve API performance and scalability with caching?

Let's take the example of Swiggy. Your past orders or profile information, once completed are hardly going to change. So rather than making a call to the database every time to fetch these details, it's better to cache those details. Everytime user places a new order or updates his/her information, you can use an asynchronous function to update the cache too. Caching will provide faster delivery with less network overhead, providing better performance to the user :)

Whenever question come around the reduce the API call/API improvement we can definitely think about Caching. In general,the cache is nothing but holding the information and reusing it again and again so instead of fetching from the Database or making API calls we can cache it & and use it. Also while using cache we have to take care of cache invalidations. There are several techniques around it to how to invalidate cache & store cache listed below. 1) Cache-Aside 2)Write-Through 3)Write-Behind 4)Read-Through Let's say we have API to fetch a list of countries from the database but just think that in a week how much time this is changing? most probably not more than 5 times so we can definitely think for cache in this case & reduce API calls.

When implementing caching, consider cache invalidation. It's vital to know when data becomes outdated, as stale data can mislead users or systems. Also, not every API request suits caching. Dynamic data, frequently updated, might not benefit much and can even degrade the user experience. Consider time-sensitive operations where current data is essential—for example, real-time stock prices. Over-relying on caching can introduce subtle bugs or inaccuracies, so always balance between performance gains and potential data staleness.

Caching mechanisms like Redis or Memcached store frequently accessed data in memory, reducing the need for expensive database operations or external API calls. This speeds up response times and provides a better user experience. When implementing caching, it is important to consider the following: Cache Expiration Time: Set an appropriate cache expiration time to ensure that the cached data is up-to-date. Eviction Policy: Define a policy for evicting data to make room for new data and prevent cache overload. Monitoring: Monitor cache hit rates, cache size, and overall system performance to fine-tune caching configurations and ensure optimal API performance and scalability.

Caching is a powerful tool for mitigating network latencies and cutting down on API expenses. On one occasion, I implemented a straightforward solution for an API responsible for converting pincodes into latitude and longitude coordinates. This particular API relied on the Google Maps Places API and initiated a call to it each time it was used. The solution was remarkably simple: I cached the initial pincode API request in a database. It significantly reduced the frequency of subsequent calls to the Google Maps Places API. Consequently, our application's response time for pincode-to-coordinate conversions improved, enhancing its overall responsiveness. Additionally, we observed a noteworthy reduction in Google Maps API utilization costs.

It's essential to pick the right cache type for your situation. Client-side caching can be quick but risks stale data if not regularly updated. Server-side caching offers control but adds server load. Proxy caching, like with CDNs, offers a balance, distributing load but may introduce latency if nodes are far from users. Don't forget cache eviction: how will old or less-used data be removed to make space for new? Each caching type has its eviction strategies. Also, consider data sensitivity. Caching personal user data client-side or on a shared proxy may raise security concerns. Always evaluate the trade-offs.

?? Diving into Caching: Client-side Caching: Like a local grocery; data is stored close to users, reducing network calls and enhancing their experience. Server-side Caching: Imagine a kitchen pantry. Commonly accessed data is kept here, sparing frequent database trips and boosting server efficiency. Proxy Caching: Think big warehouses (like CDNs). Positioned between user and server, they enhance speed and availability. Caching is a game-changer, but it needs the right setup. Handle with care! ???

Distribution of cache is also very crucial in perceived performance. Static assets such as pre-rendered HTML, CSS, JS and other files such as fonts, images etc., should live as close to client as possible and replicated globally with reasonable consistency at place. I/O driven use cases, such a API responses can also be cached or replicated in similar fashion but should also come with a strategy to burst those cache. Database reads can also be cached with in-memory or a mix of in-memory and disk services so that overall throughput can be controlled over heavy database instances.

Types of caching include Page, Object, Bytecode, CDN, Browser, Database, Opcode, Reverse Proxy, and Full-page caching, each optimizing different aspects of data retrieval for performance improvement.

Use HTTP cache to cache stable or infrequently changing data at the client side to reduce network calls. Utilize in-memory caching tools like Redis or Memcached for frequently accessed data, speeding up responses and bypassing database fetches. Leverage CDNs for geographically spread API consumers, serving static assets or immutable API responses closer to the user and cutting down latency. Implement application-level caching for commonly accessed data segments or computations, such as lookup tables (list of genres, role titles), and token verifications, to minimize repetitive processes. Adopt distributed caching solutions when operating multiple API instances across servers or regions, ensuring a consistent cache view.

While cache reduces latency we also have to look at data staleness. If TTL > frequency at which data refreshes it will lead to staleness TTL < frequency at which data change it will lead to multiple misses but data will be accurate The best scenario is TTL = frequency, The second way is to use an event based system to update the cache when data gets changed.

Specifies caching directives like "public" (cachable by anyone) or "private" (for a specific user). It can set the maximum age of a cached resource. Expires: Indicates the date and time when a cached resource expires and should be fetched again. Last-Modified: Specifies when the resource was last modified, helping the browser decide if the cached version is still valid. A unique identifier for a resource, used to check if it has changed since it was last cached. If-Modified-Since: A request header that asks the server to send the resource only if it has been modified since a certain date. A request header that sends the ETag of the cached resource, asking the server to send the resource only if the ETag doesn't match the current version.

Cache headers are a way to communicate or direct where should the content be cached, for how long, and if this content is invalid now and should be refreshed immediately.

What are you trying to cache? If you're caching static files like HTML, CSS, and JS, you want the cache to be as close to the end user as possible. This is why CDNs or Content Delivery Networks are widely used worldwide. On the other hand, for results of API calls or database queries, you can use different tools like browser storage, server storage (RAM), or even a dedicated cache service like Redis or Memcached.

Choosing the right caching system is essential for effective API optimization. Systems like Redis and Memcached provide powerful caching capabilities, and there are various libraries, frameworks, and middleware that can simplify the implementation process. Redis is an open-source, in-memory data structure store known for its speed and flexibility. It supports advanced data types and offers features like replication, pub/sub messaging, and built-in Lua scripting. Memcached, on the other hand, is a distributed memory caching system that excels at handling high-traffic websites and applications. It is designed to be simple and lightweight, focusing on key-value storage and retrieval.

You can consider caching both on client-side and server-side. There is also a CDN option (like cloud services) available. In client-side caching, you store client-related content (such as order list or profile information) on it's own device. You should be aware of proper caching invalidation to ensure data validity. On the other hand, server-side caching is generally involved with globally accessed data among different users (like product list or site settings). CDNs can help you to reduce physical requirements (storage, memory, etc.) by storing shared staff (like CSS, JS, media, etc.) on cloud servers. This also improves load speed by storing data on different servers and load automatically from geographically closer one to the client.

Choose a data structure (e.g., hash table). Set cache size and eviction policy (e.g., LRU). Initialize the cache. Implement cache operations (Get and Put). Handle cache item expiration. Address concurrency issues. Test, monitor, and optimize. Integrate into your application. Document and maintain the cache system.

When setting up caching for APIs, the specific context matters. Not all cache types are equal. Differentiating between application-level and database-level caching is essential. Also, refrain from storing regulated or personally identifiable data in caches. And always monitor your cache's hit rate; a low rate signals inefficiencies. Every API's caching need is unique, so make sure to always adapt to the specific scenario.

An important aspect of caching is deciding the boundaries of caching data. In the microservices context, more often than not, application designers build local caches of data so as to avoid making network calls to other applications/services. However it leads to issues like building mechanisms for cache refresh through 1.) async event consumption from the service owning it 2.) periodic polling to refresh cache data 3.) Expiry mechanism to flush Each of these brings its own challenges. Architecturally applications might be better off caching data closer to the source of truth. The application owning the piece of data can decide caching tools, strategy for refresh etc. While designing cache strategy do consider source of truth criterion also

Implementing best practices for caching is crucial for ensuring optimal performance and scalability of your API. By following these practices, you can maximize the efficiency of data retrieval and improve the overall user experience. - Monitor Cache Performance with Metrics and Logs: Regularly monitor cache metrics and logs to gain insights into your caching system's performance. - Establish Baseline Performance and Test Scenarios: Before implementing caching, establish baseline performance metrics for your API without caching. - Utilize Caching Techniques: There are various caching techniques that can further enhance the performance of your API.

Consider carefully the expiration time. It depends on the feature you're caching, and each must be considered individually. A too-short expiration time can make the app face the same issue but in an even more complex way. A too-long expiration time can produce untrustable data. Creating policies is also recommended. Even more if your application serves multiple clients. Some apps require a cache-revoking system; think about implementing and testing it. Last but not least, consider implementing a monitor tool for your cache. Overloads and leaks are more common than you think and can potentially cause severe issues to the business. Friendly reminder: ensure your cache is removing expired content!

Understand data access patterns. Choose the right cache type. Handle cache invalidation. Optimize cache keys and eviction policies. Set appropriate TTLs. Monitor cache performance. Size the cache correctly. Ensure concurrency control. Plan for fallback mechanisms. Secure sensitive data. Test and document cache usage. Perform regular maintenance. Integrate caching seamlessly. Scale and replicate as needed. Implement error handling.

Caching STATIC data is an easy win for performance gain and enhance user experience reduces latency and ultimately infra cost. e.g an address lookup APIs and others reference data APIs where data doesn’t change frequently. it is crucial to consider role and responsibilities of various layers in entire architecture and equip cache with one which adheres industry best practices, comply with APIs security and still serves the performance. Caching at service layer using in memory cache or equivalent is not recommended as it makes services stateful and posses scalability challenge. However caching at API gateway layer, or outsourcing to redis cache or equivalent will enable better management and keep API / service layer clean.

Educate your development and operations teams about the caching strategies in place. Well-documented caching policies and regular training can prevent misconfigurations and ensure everyone understands the role of caching in API performance.