This example shows how to use 51Degrees on-premise device detection to determine details about a device based on its User-Agent and User-Agent Client Hint HTTP header values.
You will learn:
- How to create a Pipeline that uses 51Degrees on-premise device detection
- How to pass input data (evidence) to the Pipeline
- How to retrieve the results
This example is available in full on GitHub.
This example requires a local data file. The free 'Lite' data file can be acquired by pulling the git submodules under this repository (run `git submodule update --recursive`) or from the device-detection-data GitHub repository.
The Lite data file is only used for illustration, and has limited accuracy and capabilities. Find out about the more capable data files that are available on our pricing page
Required NuGet Dependencies:
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* Copyright 2025 51 Degrees Mobile Experts Limited, Davidson House,
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using FiftyOne.Pipeline.Core.FlowElements;
using FiftyOne.Pipeline.Engines;
using FiftyOne.Pipeline.Engines.Data;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
{
public class Program
{
public class Example : ExampleBase
{
public void Run(string dataFile, ILoggerFactory loggerFactory, TextWriter output)
{
// In this example, we use the DeviceDetectionPipelineBuilder and configure it
// in code. For more information about builders in general see the documentation at
// https://51degrees.com/documentation/_concepts__configuration__builders__index.html
// Note that we wrap the creation of a pipeline in a using to control its life cycle
using (var pipeline = new DeviceDetectionPipelineBuilder(loggerFactory)
.UseOnPremise(dataFile, null, false)
// We use the low memory profile as its performance is sufficient for this
// example. See the documentation for more detail on this and other
// configuration options:
// https://51degrees.com/documentation/_device_detection__features__performance_options.html
// https://51degrees.com/documentation/_features__automatic_datafile_updates.html
// https://51degrees.com/documentation/_features__usage_sharing.html
.SetPerformanceProfile(PerformanceProfiles.LowMemory)
// inhibit sharing usage for this example, usually this should be set to "true"
.SetShareUsage(false)
// inhibit auto-update of the data file for this test
.SetAutoUpdate(false)
.SetDataUpdateOnStartUp(false)
.SetDataFileSystemWatcher(false)
.Build())
{
var deviceIDs = new List<string>(ExampleUtils.EvidenceValues.Count);
// carry out some sample detections
// and collect device IDs
foreach (var values in ExampleUtils.EvidenceValues)
{
AnalyseEvidence(values, pipeline, output, out var nextDeviceID);
deviceIDs.Add(nextDeviceID);
}
// carry out detections using pre-acquired deviceIDs
foreach (var nextDeviceID in deviceIDs.Where(d => d is not null))
{
var evidence = new Dictionary<string, object>()
{
{ "query.51D_deviceId", nextDeviceID },
};
AnalyseEvidence(evidence, pipeline, output, out _);
}
ExampleUtils.CheckDataFile(pipeline, loggerFactory.CreateLogger<Program>());
}
}
private void AnalyseEvidence(
Dictionary<string, object> evidence,
IPipeline pipeline,
TextWriter output,
out string deviceID)
{
// FlowData is a data structure that is used to convey information required for
// detection and the results of the detection through the pipeline.
// Information required for detection is called "evidence" and usually consists
// of a number of HTTP Header field values, in this case represented by a
// Dictionary<string, object> of header name/value entries.
//
// FlowData is wrapped in a using block in order to ensure that the unmanaged
// resources allocated by the native device detection library are freed
using (var data = pipeline.CreateFlowData())
{
StringBuilder message = new StringBuilder();
// list the evidence
message.AppendLine("Input values:");
foreach (var entry in evidence)
{
message.AppendLine($"\t{entry.Key}: {entry.Value}");
}
output.WriteLine(message.ToString());
// Add the evidence values to the flow data
data.AddEvidence(evidence);
// Process the flow data.
data.Process();
message = new StringBuilder();
message.AppendLine("Results:");
// Now that it's been processed, the flow data will have been populated with
// the result. In this case, we want information about the device, which we
// can get by asking for a result matching the `IDeviceData` interface.
var device = data.Get<IDeviceData>();
// Display the results of the detection, which are called device properties.
// See the property dictionary at
// https://51degrees.com/developers/property-dictionary
// for details of all available properties.
OutputValue("Mobile Device", device.IsMobile, message);
OutputValue("Platform Name", device.PlatformName, message);
OutputValue("Platform Version", device.PlatformVersion, message);
OutputValue("Browser Name", device.BrowserName, message);
OutputValue("Browser Version", device.BrowserVersion, message);
OutputValue("DeviceId", device.DeviceId, message);
message.AppendLine("Matched");
foreach(var entry in device.UserAgents.Value)
{
message.AppendLine($"\t{entry}");
}
output.WriteLine(message.ToString());
// 'Return' the Device ID string to the caller
deviceID = device.DeviceId.HasValue ? device.DeviceId.Value : null;
}
}
private void OutputValue(string name,
IAspectPropertyValue value,
StringBuilder message)
{
// Individual result values have a wrapper called `AspectPropertyValue`.
// This functions similarly to a null-able type.
// If the value has not been set then trying to access the `Value` property will
// throw an exception. `AspectPropertyValue` also includes the `NoValueMessage`
// property, which describes why the value has not been set.
message.AppendLine(value.HasValue ?
$"\t{name}: " + value.Value :
$"\t{name}: " + value.NoValueMessage);
}
}
static void Main(string[] args)
{
// Use the supplied path for the data file or find the lite file that is included
// in the repository.
var dataFile = args.Length > 0 ? args[0] :
// In this example, by default, the 51degrees "Lite" file needs to be somewhere in the
// project space, or you may specify another file as a command line parameter.
//
// Note that the Lite data file is only used for illustration, and has limited accuracy
// and capabilities. Find out about the Enterprise data file on our pricing page:
// https://51degrees.com/pricing
ExampleUtils.FindFile(Constants.LITE_HASH_DATA_FILE_NAME);
// Configure a logger to output to the console.
var loggerFactory = LoggerFactory.Create(b => b.AddConsole());
var logger = loggerFactory.CreateLogger<Program>();
if (dataFile != null)
{
new Example().Run(dataFile, loggerFactory, Console.Out);
}
else
{
logger.LogError("Failed to find a device detection data file. Make sure the " +
"device-detection-data submodule has been updated by running " +
"`git submodule update --recursive`.");
}
// Dispose the logger to ensure any messages get flushed
loggerFactory.Dispose();
}
}
}