Minimal User Interface (C++)

psidk can provide a minimal UI to your services. This UI can help get you started developing your own services, but isn't suitable for end users.

Here is the service definition. Place example.cpp and CMakeLists.txt in an empty folder.

example.cpp

#include <psibase/psibase.hpp>

struct ExampleService
{
   int32_t add(int32_t a, int32_t b) { return a + b; }
   int32_t multiply(int32_t a, int32_t b) { return a * b; }

   // This action serves HTTP requests
   std::optional<psibase::HttpReply> serveSys(psibase::HttpRequest request)
   {
      // serveSimpleUI serves UI files to the browser and
      // provides an RPC interface for preparing transactions.
      return serveSimpleUI<ExampleService, true>(request);
   }
};

PSIO_REFLECT(ExampleService,  //
             method(add, a, b),
             method(multiply, a, b),
             method(serveSys, request))

PSIBASE_DISPATCH(ExampleService)

CMakeLists.txt

CMakeLists.txt is the same as the one in Basic Service.

Building

This will create example.wasm:

mkdir build
cd build
cmake `psidk-cmake-args` ..
make -j $(nproc)

Deploying the service

This will deploy the service to the chain:

psibase deploy -ip example example.wasm

The -p option will register the service with the http-server service. This allows the service to handle web requests. See the registerServer docs for more details.

Trying the service

If you're running a test chain locally, then it will typically be at http://psibase.127.0.0.1.sslip.io:8080/ or http://psibase.127.0.0.1.sslip.io:8079/. To try the service, prefix your host with your service name (e.g. http://example.psibase.127.0.0.1.sslip.io:8080/).

How it works

• psinode forwards most http requests to the http-server service.
• If the URL begins with /common, http-server forwards the request to the common-api service. common-api provides shared resources, such as js library code and an RPC request handler for packing transactions.
• http-server looks at the request domain. If it begins with the name of a registered service, it calls that service's serveSys action to process the request.
• psibase::serveSimpleUI handles the following requests:
  • GET / returns a minimal html file which references the /common/SimpleUI.mjs script. This script generates the UI dynamically.
  • GET /action_templates returns a template json structure (below). This lets the UI know which actions are available and sample values for their arguments. This isn't a schema; it's only suitable for simple cases.
  • POST /pack_action/add accepts the arguments for the add action as a JSON object, converts it to binary, and returns the result.

For more detail, see Web Services.

/action_templates result

{
  "add": {
    "a": 0,
    "b": 0
  },
  "multiply": {
    "a": 0,
    "b": 0
  },
  "serveSys": { ... }
}