httpxPackage httpx includes various HTTP utilities.
BodyReader implemented the io.Reader and io.Closer and is used to contain the body of a request or response. The access it provides to the underlying []byte array is used for memory optimization purposes.
ResponseRecorder implements the http.ResponseWriter interface and is used as the underlying struct passed in to the request handlers in the w *http.ResponseWriter argument. The ResponseRecorder uses a BodyReader to contain the body of the generated response. Contrary to the httptest.ResponseRecorder, the utils.ResponseRecorder allows for multiple Write operations.
ParseRequestData parses the body and query arguments of an incoming request and populates a data object that represents its input arguments. This type of parsing is used in the generated code of the microservice to process functional requests.
DecodeDeepObject and EncodeDeepObject handle the decoding and encoding of an object into a query string with bracketed nested argument names. Deep object encoding is used to pass nested objects in query arguments of a request.
For example:
{
"color": {
"r": 100,
"g": 200,
"b": 150,
}
}
is encoded to
color[r]=100&color[g]=200&color[b]=150
FragRequest and its counterpart DefragRequest break and reassemble (respectively) large http.Requests. FragResponse and its counterpart DefragResponse break and reassemble (respectively) large http.Responses. Fragmentation is required because NATS sets a limit (1MB by default) to the size for messages that can travel on the bus. During fragmentation, a control header Microbus-Fragment that specifies the index of the fragment out of the total number of fragments is added to the fragments. This information is later used to reassemble the fragments on the other end.
Here’s an example of an HTTP request that was fragmented into 3 fragments of up to 128 bytes each. The client starts by sending the first fragment. Notice the header Microbus-Fragment: 1/3 indicating this is the first of three fragments.
POST /too-big HTTP/1.1
Host: server.example
Content-Length: 128
Microbus-Call-Depth: 1
Microbus-Fragment: 1/3
Microbus-From-Host: client.example
Microbus-From-Id: m3mcmiftmd
Microbus-Msg-Id: P4zpC2Ea
Microbus-Op-Code: Req
Microbus-Time-Budget: 19999
9kHYrhgFdztxSZ00eafjfHoirvROe53j8ooZA14z0CxMV9cMHbjnKeVVHxarmvlyhGqbtiOTGsYfE7eLPImNQgYRKYG01npWZBfqlVbkqw2zxWznetDzD0q5fOr4HKOn
Upon receipt of the first fragment, the server responds with a 100 Continue ack message.
HTTP/1.1 100 Continue
Connection: close
Microbus-Op-Code: Ack
Microbus-From-Host: server.example
Microbus-From-Id: m3mcmiftmd
Microbus-Msg-Id: P4zpC2Ea
Microbus-Queue: server.example
The client then sends the remaining fragments.
POST /too-big HTTP/1.1
Host: server.example
Content-Length: 128
Microbus-Call-Depth: 1
Microbus-Fragment: 2/3
Microbus-From-Host: client.example
Microbus-From-Id: m3mcmiftmd
Microbus-Msg-Id: P4zpC2Ea
Microbus-Op-Code: Req
Microbus-Time-Budget: 19999
IBtVOBMQPjaBTEdwXTeCij9ZY61OOidkYTnwgUk98tC7mZzAgsDTH2pRxKTav0lD34MYJS0haYgWUr0brT1RENDCoffYIzKQYDcAsp73O7X1HD9VjGv0C3parRDPCCEz
and
POST /too-big HTTP/1.1
Host: server.example
Content-Length: 16
Microbus-Call-Depth: 1
Microbus-Fragment: 3/3
Microbus-From-Host: client.example
Microbus-From-Id: m3mcmiftmd
Microbus-Msg-Id: P4zpC2Ea
Microbus-Op-Code: Req
Microbus-Time-Budget: 19999
7SLujUrm4W99YLUp
QArgs is a simplification of the standard url.Values and can be used to encode query strings in a single easily-readable statement:
u := "https://example.com?" + httpx.QArgs{
"foo": "bar",
"count": 5,
}.Encode()
NewRequest, MustNewRequest, NewRequestWithContext and MustNewRequestWithContext are wrappers over the standard http.NewRequest that take in a body of any type rather than just a []byte array. SetRequestBody is responsible for interpreting the body as the correct type. The Must- versions panic instead of returning an error, allowing single statement construction.