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HTTP counter

Overview​

The example demonstrates a counter dapp and an HTTP interface. It is essentially an iteration on the counter canister which adds native HTTP interfaces.

This sample dapp provides an interface that exposes the following methods:

  • http_request, which can:
    • GET some static gziped data if gzip is accepted.
    • GET the counter otherwise.
    • Refer POSTs to call http_request_update.
    • Returns 400 all other requests.
  • http_request_update, which can:
    • POST to increment the counter.
      • returning some static gziped data if gzip is accepted.
      • otherwise returning the new counter value.
    • Returns 400 all other requests.

Prerequisites​

This example requires an installation of:

Begin by opening a terminal window.

Step 1: Navigate into the folder containing the project's files and start a local instance of the Internet Computer with the command:​

cd examples/motoko/http_counter
dfx start --background

Step 2: Deploy the canister:​

dfx deploy

Step 3: Take note of canister ID to form URLs at which the http_counter is accessible.​

CANISTER_ID=$(dfx canister id http_counter)

echo "http://localhost:4943/?canisterId=$CANISTER_ID"

echo "http://$CANISTER_ID.localhost:4943/"

Step 4: All functionality of the canister can be exercised with the following commands:​

CANISTER_ID=$(dfx canister id http_counter)

# Get the counter
curl "$CANISTER_ID.localhost:4943/" --resolve "$CANISTER_ID.localhost:4943:127.0.0.1"

# Get the static gziped query content
curl --compressed "$CANISTER_ID.localhost:4943/" --resolve "$CANISTER_ID.localhost:4943:127.0.0.1"

# Increment the counter
curl -X POST "$CANISTER_ID.localhost:4943/" --resolve "$CANISTER_ID.localhost:4943:127.0.0.1"

# Increment the counter and get the static gziped update content
curl --compressed -X POST "$CANISTER_ID.localhost:4943/" --resolve "$CANISTER_ID.localhost:4943:127.0.0.1"