CHttp Visual Studio Code Extension
10/20/2023
4 minutes
I have been recently working on CHttp which is a tool to send HTTP requests and to measure the performance of REST APIs.
The primary goal of the tool is the ability to measure GET HTTP requests using version HTTP/2 and HTTP/3. As the tool is based on .NET (currently version 8), it requires a reasonably up-to-date Windows installation or the libmsquic package in case of Linux.
The standalone tool can be installed from GitHub, as a dotnet tool by using the dotnet tool install -g LaDeak.CHttp command or by as a Visual Studio Code Extension.
Using CHttp Visual Studio Code Extension
The extension works with CHttp files. It is based on a file format that has been introduced by Huachao's REST Client extension.
Let's take a simple example to send an HTTP request:
GET https://localhost:5001/endpointNote, that the tool in the VS Code Extensions uses HTTP/2 by default. To change it, one can specify a different HTTP version as:
GET https://localhost:5001/endpoint HTTP/1.1One can define headers and content. Separate headers and content with an empty line.
POST https://localhost:5001/jsonrequest
Content-Type:application/json
{
"message": "hello world"
}To add comments use #or // characters. To separate queries, use the ### character combination.
Variables
It is possible to define and re-use file level variables using the @variable syntax. Then a variable can be referenced with the {{variable}} syntax.
@baseUrl = localhost:5001
@path = delay
###
GET https://{{baseUrl}}/{{path}} HTTP/2Variables may also reference another request's response content or headers. To achieve this, create a named request:
###
# @name jsonSample
GET https://localhost:5001/jsonresponse
###
@nextRequestContent = {{jsonSample.response.body.message}}
###
# echo
GET https://localhost:5001/echo
{{nextRequestContent}}In the above case the top request is named by the # @name jsonSample attribute. A variable @nextRequestContent references the response body's message JSON field. Use json-path to refer to a custom element of the response. Use the [requestname].response.header.content-type to refer to response headers.
Then use this variable in another request with {{nextRequestContent}} reference.
Attributes
Use attributes to change the HTTP request behavior. At the time of writing the following attributes are supported:
clientscount
requestcount
timeout (in seconds)
no-certificate-validation
no-redirect
name
kerberos-auth
For example, to ignore certificate validation errors, set the @no-certificate-validation attribute with value true.
# @no-certificate-validation true
GET https://localhost:5001/endpoint HTTP/1.1Performance Measurements
Run performance measurements by defining either @clientscount or @requestcount attributes. Their default values are 10 and 100 respectively.
@baseUrl = localhost:5001
###
# @clientsCount 10
# @requestCount 100
GET https://{{baseUrl}}While it is possible to set a request content, for performance measurements it is not suggested as larger requests can impact the performance measurement on client side.
Such requests will result an output of:
RequestCount: 100, Clients: 10 | Mean: 322,698 us | | StdDev: 80,236 us | | Error: 8,024 us | | Median: 310,700 us | | Min: 198,700 us | | Max: 652,700 us | | 95th: 473,700 us | | Throughput: 0.000 B/s | | Req/Sec: 2,82E+04 | ------------------------------------------------------------------------ 244,100 us ######### 289,500 us ################### 334,900 us ################### 380,300 us ############## 425,700 us #### 471,100 us ## 516,500 us ## 561,900 us # 607,300 us 652,700 us # ------------------------------------------------------------------------ HTTP status codes: 1xx: 0, 2xx: 100, 3xx: 0, 4xx: 0, 5xx: 0, Other: 0 ------------------------------------------------------------------------
The output has three sections. The top section displays statistical results. The middle section draws a distribution of requests. The last section displays an aggregate view of the response codes.
I this case the mean execution time is 322.698 us. The distribution has a single mode. All requests 100 returned status codes from the 200-299 range.
Diff Performance Measurements
Compare two named performance measurement results with the DIFF command. Use the @name [value] pattern to give a referrable name to a query:
### # @name comparison # @clientsCount 10 # @requestCount 100 GET https://{{baseUrl}}/post HTTP/2 ### # @name basePerformance # @clientsCount 10 # @requestCount 100 POST https://{{baseUrl}}/post {"data":"hello world"} ### DIFF basePerformance comparison
Diff results an aggregate view of the differences between the two requests.
RequestCount: 100, Clients: 10 | Mean: 448,127 us -55,265 us | | StdDev: 151,588 us +120,312 us | | Error: 15,159 us +12,031 us | | Median: 413,600 us -115,100 us | | Min: 265,300 us -137,600 us | | Max: 1,285 ms +225,800 us | | 95th: 763,700 us +220,100 us | | Throughput: 0.000 B/s 0 B/s | | Req/Sec: 1,16E+04 +9244,993 | ------------------------------------------------------------------------ 266,040 us +++++++++++++ 404,380 us =============### 542,720 us ====############ 681,060 us =++ 819,400 us ## 957,740 us = 1,096 ms =+ 1,234 ms 1,373 ms 1,511 ms + ------------------------------------------------------------------------ HTTP status codes: 1xx: 0 +0, 2xx: 100 +0, 3xx: 0 +0, 4xx: 0 +0, 5xx: 0 +0, Other: 0 +0 ------------------------------------------------------------------------ *Warning: session files contain different urls: https://localhost:5001/,https://localhost:5001/post ------------------------------------------------------------------------