Convert HTML from ZIP archive to PDF – C# example

In this article, we create a custom Message Handler to do a specific task – convert HTML from ZIP archive to PDF.

There are many reasons why would you require to convert HTML from ZIP archive to PDF format. PDF comes with many advantages that other files don’t have. For example, many programs and apps support PDF documents, most web browsers such as Chrome and Firefox can display a PDF. PDF files are optimized for printing; they are ideal for creating physical copies of your documents. PDF supports many compression algorithms. You can configure the security settings for your PDF file, etc.

Create a Custom Message Handler

Aspose.HTML for .NET offers functionality for custom message handlers creating. Let’s design a custom handler that we can use to work with ZIP archives. Take the following steps:

  1. Use the necessary Namespace, which is the Aspose.Html.Net. This Namespace is presented by classes and interfaces which are responsible for helping easy network processing.

  2. To create a custom Message Handler, you need to define your own class that will be derived from the MessageHandler class. The MessageHandler class represents a base type for message handlers. Inheriting from IDisposable is necessary to provide a mechanism for the deterministic release of unmanaged resources.

1using Aspose.Html.Net;
4	class ZipArchiveMessageHandler : MessageHandler, IDisposable
5	{
6	}

So, you have defined your own ZipArchiveMessageHandler class, now you need to do some operations within it.

  1. Initialize an instance of the ZipArchiveMessageHandler class and define a Filter property for it.

  2. Override the Invoke() method of the MessageHandler class to implement the custom message handler behaviour.

 1using System.Net;
 2using Aspose.Html;
 3using Aspose.Html.Net;
 4using Aspose.Html.Net.MessageFilters;
 5using Aspose.Zip;
 8	// Define ZipArchiveMessageHandler class that is derived from the MessageHandler class
 9	class ZipArchiveMessageHandler : MessageHandler, IDisposable
10	{
11	    private string filePath;
12	    private Archive archive;
14	    // Initialize an instance of the ZipArchiveMessageHandler class
15		public ZipArchiveMessageHandler(string path)
16	    {
17	        this.filePath = path;
18	        Filters.Add(new ProtocolMessageFilter("zip"));
19	    }
21	    // Override the Invoke() method
22		public override void Invoke(INetworkOperationContext context)
23	    {
24	        // Call the GetFile() method that defines the logic in the Invoke() method
25			var buff = GetFile(context.Request.RequestUri.Pathname.TrimStart('/'));
26	        if (buff != null)
27	        {
28	            // Checking: if a resource is found in the archive, then return it as a Response
29	            context.Response = new ResponseMessage(HttpStatusCode.OK)
30	            {
31	                Content = new ByteArrayContent(buff)
32	            };
33	            context.Response.Headers.ContentType.MediaType = MimeType.FromFileExtension(context.Request.RequestUri.Pathname);
34	        }
35	        else
36	        {
37	            context.Response = new ResponseMessage(HttpStatusCode.NotFound);
38	        }
40	        // Call the next message handler
41			Next(context);
42	    }
43	}

Let’s take a closer look at this code snippet:

Define the GetFile(), GetArchive(), and Dispose() Methods

 1using System.IO;
 2using Aspose.Zip;
 5	byte[] GetFile(string path)
 6	{
 7	    path = path.Replace(@"\", @"/");
 8	    var result = GetArchive().Entries.FirstOrDefault(x => path == x.Name);
 9	    if (result != null)
10	    {
11	        using (var fs = result.Open())
12	        using (MemoryStream ms = new MemoryStream())
13	        {
14	            fs.CopyTo(ms);
15	            return ms.ToArray();
16	        }
17	    }
18	    return null;
19	}
21	Archive GetArchive()
22	{
23	    return archive ??= new Archive(filePath);
24	}
26    public void Dispose()
27    {
28        archive?.Dispose();
29    }

You can download the complete examples and data files from GitHub.

Add ZipArchiveMessageHandler in the Pipeline

You would now need to add ZipArchiveMessageHandler in the pipeline. Use Add() method that takes a zip object as a parameter and adds ZipArchiveMessageHandler to the end of the message handlers’ collection.

The INetworkService.MessageHandlers property gets a list of MessageHandler instances to be invoked as a RequestMessage executes.

 1using System;
 2using Aspose.Html;
 3using Aspose.Html.Net;
 4using Aspose.Html.Rendering.Pdf;
 5using Aspose.Html.Services;
 8	// Prepare path to a source zip file
 9	string documentPath = Path.Combine(DataDir, "");
11	// Prepare path for converted file saving
12	string savePath = Path.Combine(OutputDir, "zip-to-pdf.pdf");
14	// Create an instance of ZipArchiveMessageHandler
15	using var zip = new ZipArchiveMessageHandler(documentPath);
17	// Create an instance of the Configuration class
18	using var configuration = new Configuration();
20	// Add ZipArchiveMessageHandler to the chain of existing message handlers
21	configuration
22	    .GetService<INetworkService>()
23	    .MessageHandlers.Add(zip);
25	// Initialize an HTML document with specified configuration
26	using var document = new HTMLDocument("zip:///test.html", configuration);
28	// Create the PDF Device  
29	using var device = new PdfDevice(savePath);
31	// Render ZIP to PDF
32	document.RenderTo(device);

In the example, the ZIP archive ( has the HTML document (test.html) in which all related resources have paths relative to the HTML document.

Note: The HTMLDocument(address, configuration) constructor takes the absolute path to the ZIP archive. But all related resources have relative paths in the HTML document and in the example’s code.

Please read the Fine-Tuning Convserters article to learn more about converting HTML to PDF using Renderto(device) method.

Aspose.HTML provides a free online ZIP to PDF Converter that allows you to quickly, easily and clearly convert HTML from ZIP archive to PDF. Upload, convert files and get results in seconds. No additional software is required. Try our robust Converter for free now!

Text “Banner ZIP to PDF Converter”

Subscribe to Aspose Product Updates

Get monthly newsletters & offers directly delivered to your mailbox.