[DRAFT] Adding HttpWebRequest to HttpClient Migration Guide #42242
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docs/fundamentals/networking/http/httpclient-migrate-from-httpwebrequest.md
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Yes, this is ongoing work and this is on my todo list, and I'll actually add specific links to those sections in Notes section in the table. |
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I like the examples for specific scenarios, it's very practical. I also like the quick reference tables with the mapping.
Overall, I like the direction here, keep going!
I left some comments, mostly about sample code. I think we should be very careful with the code as people will copy-paste this as-is.
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| string host = context.DnsEndPoint.Host; | ||
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| DnsCache? cacheItem; | ||
| if (!dnsCache.TryGetValue(host, out cacheItem) || DateTime.Now > cacheItem.CacheExpireTime) |
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Don't use DateTime.Now, it's affected by daylight saving changes!
You can use Environment.TickCount64 instead.
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Shameless plug since this is quite a bit of code for someone to copy-paste: https://github.com/MihaZupan/DnsRoundRobin
| dnsCache.TryRemove(host, out _); | ||
| cacheItem = new DnsCache(await Dns.GetHostAddressesAsync(host, cancellationToken), DateTime.Now.Add(dnsRefreshTimeout), 0); | ||
| dnsCache.TryAdd(host, cacheItem); |
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ConnectCallback doesn't guarantee thread safety. This will work, but it might unnecessarily issue multiple DNS requests for the same host, while also unintentionally removing freshly inserted results.
| int index = cacheItem.Index; | ||
| connectAddress = cacheItem.Addresses[index]; | ||
| cacheItem.IncreaseIndex(); |
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| # HttpWebRequest to HttpClient Migration Guide | ||
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| This document aims to guide developers through the process of migrating from <xref:System.Net.HttpWebRequest>, <xref:System.Net.ServicePoint>, and <xref:System.Net.ServicePointManager> to <xref:System.Net.Http.HttpClient>. The migration is necessary due to the obsolescence of the older APIs and the numerous benefits offered by <xref:System.Net.Http.HttpClient>, including improved performance, better resource management, and a more modern and flexible API design. By following the steps outlined in this document, developers will be able to transition their codebases smoothly and take full advantage of the features provided by <xref:System.Net.Http.HttpClient>. |
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While mentioning performance, should we mention that it's not just a "nice to have" bump in perf by migrating?
It's really that their existing WebRequest logic's perf is likely going to completely tank once they move to Core since WebRequest is just a minimal compat layer (e.g. no connection reuse in tons of cases).
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I was actually thinking to add a note or warning for this, to make sure that people who reads this doc will be aware of that WebRequest is compat layer on top of HttpClient.
| | `TransferEncoding` | <xref:System.Net.Http.Headers.HttpRequestHeaders.TransferEncoding> | See: [Example: Set Request Headers](#example-set-request-headers). | | ||
| | `UnsafeAuthenticatedConnectionSharing` | No equivalent API | No workaround | | ||
| | `UseDefaultCredentials` | No direct equivalent API | See: [Example: Setting SocketsHttpHandler Properties](#example-setting-socketshttphandler-properties). | | ||
| | `UserAgent` | <xref:System.Net.Http.Headers.HttpRequestHeaders.UserAgent> | See: [Example: Set Request Headers](#example-set-request-headers). | |
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Nit: A bunch of these are for headers that have 1:1 mappings.
It might be easier to follow if those have a separate "For setting headers like MediaType, Referer, ... see [Example])".
On the other hand your list is in alphabetical order so maybe that's better 🤷♂️
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| string host = context.DnsEndPoint.Host; | ||
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| DnsCache? cacheItem; | ||
| if (!dnsCache.TryGetValue(host, out cacheItem) || DateTime.Now > cacheItem.CacheExpireTime) |
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Shameless plug since this is quite a bit of code for someone to copy-paste: https://github.com/MihaZupan/DnsRoundRobin
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Summary
This is still ongoing effort, created this PR to get early feedback from folks.
Fixes dotnet/runtime#92690
/cc @dotnet/ncl
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