Custom Deployer Extension in SDL WEB 8.5 - Purge Cache Part - 2

In the previous post, we set up the custom deployer project, discussed its requirement and the use of deployer extension. Today, we are going to continue to use that same project and implement a real-life use-case.

Background:- In our current project we are using SDL WEB 8.5 and .NET DXA 1.8 and to improve the performance of the web application we implemented the custom caching with cache expires after 15 mins, but the business team has this requirement that they want to see the content "Real-time", no delay whenever the publish any new content.

Based on their requirement we came up with this approach and decided to write a custom deployer extension. So, whenever the author publish the page(s), the deployer extension will trigger and clear the cache of that particular page based on the URL extracted from PageMetaData.

In the below code snippet we are reading the page relative URL retrieved from PageMetaData and with the help of string manipulation we've created the absolute URL and based on the Query String parameter we trigger the code to purge the cache. Check the HTTP response code it should be 200 in the logs and refresh the web page to check the latest content.

 // This is called once for each Transport Package that is deployed.  
      @Override  
      public void process(TransportPackage data) throws ProcessingException   
      {  
            log.debug("This is custom logs");  
            String USER_AGENT = "Mozilla/5.0";  
            log.debug("PublicationId : " + String.valueOf(data.getProcessorInstructions().getPublicationId().getItemId()));  
           try  
           {  
            log.debug("Custom Code :- Entered in the try block");  
            PageMetaData pageFile = (PageMetaData)data.getMetaDataFile("Pages");  
            log.debug("Custom code :- Reading PageMetaData");  
            if (pageFile != null)  
      {  
        List<Page> pages = pageFile.getPages();  
        for ( Page page : pages )  
        {  
             log.debug("Custom code :- For loop to get the page url ");  
             log.debug("http://localhost:92"+page.getURLPath()+"?ClearCache=true");   
             String URL = "http://localhost:92"+page.getURLPath()+"?ClearCache=true";  
             URL obj = new URL(URL);  
             HttpURLConnection con = (HttpURLConnection) obj.openConnection();  
             con.setConnectTimeout(5000);  
             log.debug("Custom code :- timeout");  
             con.setRequestMethod("GET");  
             con.setRequestProperty("User-Agent", USER_AGENT);  
             int responseCode = con.getResponseCode();  
             log.debug("Response Code : " + responseCode);  
             if (responseCode == HttpURLConnection.HTTP_OK)  
             {  
              log.debug("Custom Deployer, Cache has been removed and the responseCode is : " + responseCode + "- for URL " + URL);  
             }  
             log.debug("Page ID :" + String.valueOf(page.getId().getItemId()));  
        }  
      }  
            log.debug("Purging is done !! Please check the web page!!");  
           }  
           catch (Exception e)  
     {  
        log.error("Could not get path for publication.", e);  
        return;  
     }  
  }  

Logs generated by the deployer.

Deployer Logs

With the help of the deployer extension, we were able to achieve and deliver the real-time experience and still managing the performance of the site using cache.


Happy Coding and Keep Sharing !!!

Client Side Caching in SDL DXA using Redis

What is Redis?

Redis (Remote Dictionary Server)  is an in-memory data structure store, used as a database, cache and message broker. It supports data structures such as strings, hashes, lists, sets, sorted sets with range queries, bitmaps, hyperloglogs and geospatial indexes with radius queries.

Redis is good for cache, but it's much more than just a cache. It's high speed fully in-memory database.

Not just a cache:-

• In memory key-value storage.
• Support multiple datatypes (strings, hashes, lists, sets, sorted sets, bitmaps, and hyperloglogs).
• It provides an ability to store cache data into physical storage (if needed).
• Support the pub-sub model.
• Redis cache provides replication for high availability (master/slave).

SDL DXA comes up with the pre-defined configuration of Redis for client-side caching to improve the performance of Web-application.

Pre-requisites:-

• SDL Web 8.5
• SDL DXA 
• Redis
• Redis Desktop Manager
• Redis Server and Redis CLI
• And If you want to run this on docker run docker pull redis command. Check out the official Redis repository on the docker 

Installing the Redis

• Download the Redis and extract the zip file in a directory at any location.e;g in c:\redis

  

  Redis

    Next is open the command prompt and run following command

• redis-server.exe to start the Redis server

  

  Redis server

• redis-cli.exe to start the command line interface. redis-cli is the Redis command line interface, a simple program that allows to send commands to Redis and read the replies sent by the server, directly from the terminal.

  

  Redis CLI

Next, is configure DXA to use Redis for client-side caching go to DXA web.config and navigate to <sdl.web.delivery>  node and there we already have Redis configuration setup we just need to update the cacheName. You set the policy of expiry as per the requirement.

Redis Configuration in DXA Web.config

Restart the IIS and spin the DXA Website, the site will trigger the page caching and it will add it to the Redis database.

To test the data is saved in Redis or not install Redis Desktop manager and refresh the page to load the data. In the below image you see data is cached in the Redis.

Redis Desktop Manager

Happy Coding and Keep Sharing!!!