An Introduction to Sitecore Pipelines

What is a Sitecore Pipeline?

In Sitecore pipelines describe a series of discrete steps that are taken to achieve some objective.  If you think about writing code to handle an HTTP request for example you could create a monolithic class that does the job from end to end; however the pipeline approach is a number of classes that can be invoked in order.  First do this and then do that etc. 

There are many Pipelines in Sitecore.  You can view existing pipelines and the processors that they call using Sitecore Rocks in Visual Studio.  Right click on the site connection and choose Manage. Click on the Pipelines tab in the Visual Studio edit pane.  Click on one of the listed pipelines to see all the processors that are executed as part of the pipeline.  There are pipelines with a single processor at one end of the scale to the httpRequestBegin pipeline with 45 distinct steps at the other.

Why are they useful?

Thinking about the monolithic class above it would be very difficult to maintain or modify, It would also be truly massive.  So modularising it would make it much easier to maintain. 

It also makes it much easier to customise.  For example, if we consider a pipeline that has three processors it might be drawn something like

To add to the existing functionality we could include a new step like

Where we add some custom function after Step 1 and before Step 2. 

We could also replace an existing step completely

How are they defined?

Pipelines are defined using XML in sitecore.config.  In the example below we can see the httpRequestEnd pipeline definition.  The three processors are called in the order in which they are listed.  A parameters object is passed between them to provide continuity.  The final processor is also receiving four additional parameters from the config file.

<?xml version="1.0" encoding="utf-8"?>
<sitecore database="SqlServer" xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:role="http://www.sitecore.net/xmlconfig/role/" xmlns:security="http://www.sitecore.net/xmlconfig/security/">
…
<pipelines>   
… 
<httpRequestEnd>
      <processor type="Sitecore.Pipelines.PreprocessRequest.CheckIgnoreFlag, Sitecore.Kernel" />
      <processor type="Sitecore.Pipelines.HttpRequest.EndDiagnostics, Sitecore.Kernel" role:require="Standalone or ContentManagement" />
      <!--<processor type="Sitecore.Pipelines.HttpRequest.ResizePicture, Sitecore.Kernel"/>-->
      <processor type="Sitecore.Pipelines.HttpRequest.StopMeasurements, Sitecore.Kernel">
        <ShowThresholdWarnings>false</ShowThresholdWarnings>
        <TimingThreshold desc="Milliseconds">1000</TimingThreshold>
        <ItemThreshold desc="Item count">1000</ItemThreshold>
        <MemoryThreshold desc="KB">10000</MemoryThreshold>
      </processor>
    </httpRequestEnd>
…
    </pipelines>
…
  </sitecore>

How can I work with Sitecore Pipelines?

Existing Sitecore pipelines can be customised as outlined above and it is also possible to create a brand new pipeline from scratch

Customise existing Pipelines

First thing to do is to create a configuration patch to add the new processor class into the pipeline at the desired location.  As you can see from the code it is possible to pass variables to the processor.  Here we are adding a processor called NewsArticleLogEntryProcessor into the httpRequestBegin pipeline after the ItemResolver

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
    <pipelines>
      <httpRequestBegin>
        <processor type="Fourbyclub.CustomCode.CustomCode.Pipelines.httpRequestBegin.NewsArticleLogEntryProcessor,Fourbyclub.CustomCode" patch:after="processor[@type='Sitecore.Pipelines.HttpRequest.ItemResolver, Sitecore.Kernel']">
          <NewsArticleTemplateID>{B871115E-609F-44BB-91A4-A37F5E881CA6}</NewsArticleTemplateID>
        </processor> 
      </httpRequestBegin>
    </pipelines>
  </sitecore>
</configuration>

Then we need to create the processor.  Inherit the HttpRequestProcessor and Implement the Process method.  All we are doing here is writing to the log if the requested item is a NewsArticle.

namespace Fourbyclub.CustomCode.CustomCode.Pipelines.httpRequestBegin
{
    using Sitecore.Pipelines.HttpRequest;
    using Sitecore.Diagnostics;

    // TODO: \App_Config\include\NewsArticleLogEntryProcessor.config created automatically when creating NewsArticleLogEntryProcessor class.

    public class NewsArticleLogEntryProcessor : HttpRequestProcessor
    {
        
        // Declare a property of type string:
        private string _newsArticleTemplateID;
        public string NewsArticleTemplateID { get { return _newsArticleTemplateID; } set { _newsArticleTemplateID = value; } }

        public override void Process(HttpRequestArgs args)
        {
            Assert.ArgumentNotNull(args, "args");
            if ((Sitecore.Context.Item != null) && (!string.IsNullOrEmpty(_newsArticleTemplateID)))
            {
                Assert.IsNotNull(Sitecore.Context.Item, "No item in parameters");
                // use util to get id from string property
                if (Sitecore.Context.Item.TemplateID == Sitecore.MainUtil.GetID(_newsArticleTemplateID))
                {
                    // view in log file later, so add FourbyclubCustomCode
                    Log.Info(string.Format("FourbyclubCustomCode: News Article requested is {0} and the item path is {1}", Sitecore.Context.Item.DisplayName, Sitecore.Context.Item.Paths.FullPath), this);
                }
            }
        }

    }
}

Create a new Pipleline

To create and new pipeline is a little more work but still very simple.  The first thing to do is to declare the pipeline with a configuration patch

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
    <pipelines>
      <logWriter>
        <processor type="Fourbyclub.CustomCode.CustomCode.Pipelines.logWriter.logWriterProcessor,Fourbyclub.CustomCode" />
      </logWriter>
    </pipelines>
  </sitecore>
</configuration>

The XML above will create a pipeline called logWriter that has a single processor called logWriterProcessor, which will be in the Fourbyclub.CustomCode.dll.

Pipelines must pass a PipelineArgs object to each processor as it is called so that needs to be defined

using Sitecore.Pipelines;

namespace Fourbyclub.CustomCode.CustomCode.Pipelines.logWriter
{
    public class LogWriterPipelineArgs : PipelineArgs
    {
        public string LogMessage { get; set; }
    }
}

At least one processor is needed to do the work of our pipeline

using Sitecore.Diagnostics;

namespace Fourbyclub.CustomCode.CustomCode.Pipelines.logWriter
{
    public class logWriterProcessor
    {
        public void Process(LogWriterPipelineArgs args)
        {
            Log.Info(string.Format("FourbyclubCustomCode: The message was {0}", args.LogMessage), this);
        }
    }
}

Finally we need to invoke the pipeline in our code somewhere.  Instantiate the LogWriterPipelineArgs and set the LogMessage.  Then call CorePipeline.Run and pass it the name of the pipeline and the args.object

var pipelineargs = new LogWriterPipelineArgs();
pipelineargs.LogMessage = "Requested item is not a News Article";
CorePipeline.Run("logWriter", pipelineargs);

Conclusion

Thank you for reading and I hope that this short introduction to Sitecore Pipelines has shown the power of pipelines to customise Sitecore and help to build maintainable code.  However we should always check if there is a way we can implement something using existing Sitecore functionality rather than going for a pipeline as a first resort. As with any customisation does each pipeline or processor added have a potential to increase the challenge of Sitecore upgrades?

Responsive Images and Sitecore

responsive

By February 2018 Australians already spent more than double the amount of time on smartphones than on their desktop1. With the greater variety of devices consumers use to access sites, it’s important to serve images which appropriately cater to those devices.

“Responsive images” describes a technique where an image is served to the browser depending (usually) on the width of the browser window. Desktop browsers would generally receive a larger version of the image with a greater download size, and mobile devices a smaller version better suiting the smaller display size of the device and being quicker to download.

One of our clients has a Sitecore 7.2 site which uses both MVC and legacy code in ASP.NET WebForms. The legacy code had multiple ways of handling image resizing, mostly inline HTML hard coding of dimensions. My aim was to provide a single C# library function that could work both with legacy code and new development and allow consistent results.

imagetag

In the newer part of the website, the designer had used a JavaScript based image processor which would allow the browser to determine the optimal resolution of the image required and only request an appropriately sized image from the server.

As you can see from the above HTML sample each image tag has multiple URLs in the data-srcset attribute. From this list the JavaScript library determines the optimal size for the image, based on device and browser size, and only requests that version of the image from the server.

Sitecore provides a tool to provide the resized image files based on the request URL and also caches these resized images. We created a helper function that could take a Sitecore image as input and return all of the URLs representing valid image sizes as a delimited string. The valid sizes are determined by a setting in a config file. This return value is used to populate the data-srcset attribute of our img.

ImageCodeSample

Sitecore 7.5 and beyond require a hash code to be added to the URL2 to prevent Denial of Service attacks by making numerous requests for images of various sizes. Because our new helper function now provides a centralised and configurable way to deliver the required URL string, this will be quite easy to change after the upgrade.

References

  1. http://www.nielsen.com/au/en/press-room/2018/february-2018-digital-ratings.html
  2. http://www.seanholmesby.com/images-not-resizing-in-sitecore-7-5-sitecore-8-0/

Sitecore 7.5 highlights

MongoMemeHi, welcome to my Sitecore 7.5 highlights.

This blog post is intended for those of you who would like a high level overview of Sitecore 7.5, need a reminder or have not had the time to investigate this release. At the bottom of this post is a list of useful resources related to Sitecore 7.5.

Highlights

  1. Sitecore 7.5 = Sitecore 7.2 + xDB.
  2. xDB (Experience Database) is the new name for the Analytics database.
  3. New Contact entity allows tracking an individual across devices, visits and cookies.
    • Requires some sort of mechanism of identifying the user( login, form submission, checkout etc)
  4. New scalable analytics data architecture
    • Session DB (private and shared) (inProc, Sql or Mongo)
    • Collection DB i.e. xDB (Mongo)
    • Reporting DB (SQL)
  5. Experience profile (xFile) i.e the contact
  6. xDB Cloud
    • Sitecores cloud hosting offering for xDB
    • Pricing based on numbers of stored contacts.
  7. Mongo DB
    • Data stored in documents not tables
    • Collections of documents rather than tables with rows.
    • Scales horizontally not vertically
    • Data stored in BSON binary Json
  8. Upgrade key points
    • Analytics API has many small changes
    • Migration of data from Analytics DB to xDB i.e. SQL to Mongo
    • Review of hosting structure to suit xDB.
  9. Other name changes:
    • Customer Engagement Platform = Sitecore Experience Platform (Sitecore XP)
    • Digital Marketing System (DMS) = Experience Marketing
    • Email Campaign Manger = Email Experience Manager
    • Engagement Analytics = Experience Analytics
    • Adaptive Print Studio = Print Experience Manger
    • Engagement Automation = Experience Automation

Sitecore 7.5 Resources