Caching External Api Calls In Wordpress For Performance

Why API Calls Can Slow Down Your Site

External API calls are essential for many WordPress sites to fetch dynamic data from third-party services. However, each API request typically adds a few hundred milliseconds of load time or more while retrieving data from an external server.

For sites that make frequent API calls, such as listing websites that display property data from real estate APIs or sites showing product information from ecommerce APIs, these network requests can significantly slow down page load times.

Slower page loads have concrete negative impacts like:

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Higher bounce rates from impatient visitors
Lower organic rankings in search engines
Loss of revenue due to slower conversions

Caching API responses allows WordPress sites to avoid making multiple external requests for the same data. By caching data locally, sites only fetch data once from the API for a given query then reuse it to serve repeated requests.

Introducing Transients for Caching Data

WordPress offers a simple built-in caching API using transients. The transient API stores data in the WordPress database temporarily with automatic cache expiration.

Compared to some other caching methods, benefits of using transients include:

Easy to implement in any WordPress site without additional plugins
Stored data automatically expires after a configured timeout
Simple API handles cache reading, writing, and deleting
Cached transients are deleted automatically when content is changed

The transient API is ideal for small chunks of data that needs to be cached for minutes up to a few days. Using transients to cache API responses can significantly speed up WordPress sites!

Using Transients to Cache API Responses

Leveraging transients for API response caching involves just a few simple steps:

Check if transient exists already – no API call needed if data found
If no transient, make API call and fetch response
Store API response in transient, setting expiration time
Return transient value

For example, to cache products from an ecommerce API:

function get_products() {

  $products = get_transient( 'cached_products' );

  if ( false === $products ) {

    // API call to fetch products
    $response = wp_remote_get( 'https://api.example.com/products' );

    $products = json_decode( wp_remote_retrieve_body( $response ) );
      
    set_transient( 'cached_products', $products, DAY_IN_SECONDS );

  }

  return $products;

}

That covers the basic usage! When get_products() is called, it first checks if the transient exists. If not, it makes the API request then caches the response.

Subsequent calls will hit the cached data instead of making the slower external API call. The transient expires automatically after a day to keep the data fresh.

Configuring Caching Parameters

When using transients, you can customize caching behavior by configuring these parameters:

Transient name – Unique name identifying cached data
Expiration time – Lifespan before cached data is deleted
Cache invalidation – Hooks to clear cache on data changes

1. Transient Name

The transient name parameter acts as a unique ID referencing the cached data. For example, namespaced transient names help avoid conflicts:

set_transient( 'app_name_products', $products );

Use descriptive transient names indicating the cached data. Keeping names unique also prevents accidentally overwriting unrelated cached values.

2. Expiration Time

The expiration time determines how long the cached data remains before WordPress deletes it automatically. Expiration is set using the timeout parameter on saving:

// Expire after 1 hour 
set_transient( 'cached_products', $products, HOUR_IN_SECONDS );

Shorter expirations keep data fresh but require more frequent API calls. Longer expiration reduces API traffic but may serve out-of-date information.

For most applications, expiring cached API responses every 1-12 hours provides a good balance. But this depends on needs – products likely change less frequently than news or weather data, for example.

3. Cache Invalidation

Cache invalidation aims to delete outdated transient data automatically when content changes. This prevents serving stale cached data.

WordPress has hooks to clear transients when changes occur like publishing content. For example, invalidating all cached data on new posts:

add_action( 'save_post', 'flush_all_transients' );

With strategic cache invalidation, transients only exist when valid improving efficiency.

Refreshing Cached Data Programmatically

In some cases, you may need to manually refresh cached API response data on demand rather than relying only on expiration times.

WordPress includes helper functions for this. For example, immediately deleting a specific transient:

delete_transient( 'cached_products' );

Or clearing all cached transients site-wide:

flush_all_transients();

You might call these transient refreshing functions on site events like:

User profile updated – refresh user data
Product filters applied – fetch latest products
Category page accessed – invalidate old category posts

Custom logic can determine when to forcibly refresh API response caches.

Alternative Caching Methods in WordPress

While the built-in transient API offers a simple solution for caching API responses, WordPress includes other relevant caching frameworks depending on needs:

Object Caching with Redis

Redis is an open-source in-memory data store often used for object caching. High-traffic WordPress sites frequently leverage Redis for its high performance.

Compared to the transient API, benefits of Redis caching include:

Lower database load – Redis is separate from the database
Faster read/write performance, especially for bulk operations
Better scalability for large cache workloads

The open-source Redis Object Cache plugin implements Redis support in WordPress. Configuration requires setting up a Redis server but can significantly improve cache performance.

Database Query Caching

WordPress sites generating many custom queries to show data can apply database query caching. This caches query results saving heavy processing re-running the same lookups.

Query caching plugins like Query Monitor or Cavalcade decorate queries, then serve cached copies on following executions. This approach reduces backend load and can accelerate sites with complex queries.

Content Delivery Networks for Asset Caching

Content Delivery Networks (CDNs) like Cloudflare cache static site assets globally distributed across edge servers. Resources can be served faster from locations closer to visitors.

While CDNs do not directly cache API responses, they can improve perceived performance by caching assets like images, CSS, and JS files. This unloads origin infrastructure by serving files from the CDN instead.

Finding the Right Caching Strategy for Your Site

In summary – caching external API responses using WordPress transients is an easy first step to accelerate sites relying on remote data sources. But alternative options like Redis or CDNs might become relevant as traffic scales up.

Consider these factors when assessing caching strategies:

Type of data – Transients for light JSON responses, Redis for heavier objects
Performance needs – From small gains to complex caching layers
Development resources – Balancing infrastructure effort against benefits

Monitoring tools help identify exactly where optimization opportunities exist. This allows pinpointing the most effective caching techniques for your architecture and traffic.

With thoughtful API response caching, WordPress sites can reap significant performance wins serving dynamic content to visitors worldwide!

Caching External Api Calls In WordPress For Performance