Performance

1<!-- Web.config: compress JSON responses (needs the IIS Dynamic Content Compression feature) -->
2<system.webServer>
3  <urlCompression doStaticCompression="true" doDynamicCompression="true" />
4  <httpCompression>
5    <dynamicTypes>
6      <add mimeType="application/json" enabled="true" />
7      <add mimeType="application/json; charset=utf-8" enabled="true" />
8    </dynamicTypes>
9  </httpCompression>
10</system.webServer>

1using System;
2using System.Data.Entity;
3using System.Linq;
4using System.Net;
5using System.Net.Http;
6using System.Net.Http.Headers;
7using System.Runtime.Caching;
8using System.Threading.Tasks;
9using System.Web.Http;
10using ShopApi.Data;
11using ShopApi.Models;
12

13public class CatalogController : ApiController
14{
15    private static readonly MemoryCache Cache = MemoryCache.Default;
16    private static readonly HttpClient Http = new HttpClient();     // reused, never per request
17    private readonly ShopDbContext _db;
18

19    public CatalogController(ShopDbContext db) { _db = db; }
20

21    // Rarely changes → cache on the server for 10 minutes and in browsers for 5
22    [HttpGet, Route("api/categories")]
23    public async Task<HttpResponseMessage> Categories()
24    {
25        var categories = Cache.Get("categories") as string[];
26        if (categories == null)
27        {
28            categories = await _db.Products.AsNoTracking()
29                .Select(p => p.Category).Distinct().OrderBy(c => c)
30                .ToArrayAsync();
31            Cache.Set("categories", categories, DateTimeOffset.UtcNow.AddMinutes(10));
32        }
33

34        var response = Request.CreateResponse(HttpStatusCode.OK, categories);
35        response.Headers.CacheControl = new CacheControlHeaderValue { Public = true, MaxAge = TimeSpan.FromMinutes(5) };
36        return response;
37    }
38

39    // Lean query: no tracking, only needed columns, bounded result
40    [HttpGet, Route("api/products/cheap")]
41    public async Task<IHttpActionResult> Cheap()
42    {
43        var items = await _db.Products.AsNoTracking()
44            .Where(p => p.Price < 100)
45            .OrderBy(p => p.Price)
46            .Take(50)
47            .Select(p => new ProductDto { Id = p.Id, Name = p.Name, Price = p.Price, Category = p.Category })
48            .ToListAsync();
49        return Ok(items);
50    }
51

52    // Outgoing calls: async and with a shared HttpClient
53    [HttpGet, Route("api/exchange-rate")]
54    public async Task<IHttpActionResult> ExchangeRate()
55    {
56        string json = await Http.GetStringAsync("https://rates.example.com/inr-usd");
57        return Ok(json);
58    }
59}

GET /api/categories  (first call)    → SQL runs (~40 ms)   Cache-Control: public, max-age=300
GET /api/categories  (next 10 min)   → served from MemoryCache (<1 ms), no SQL
GET /api/products/cheap              → one SELECT TOP (50) with 4 columns, no change tracking
With IIS dynamic compression on: a 180 KB JSON list arrives as ~22 KB (Content-Encoding: gzip).