Use last module as a facade in AppService (#34)

engine/src/errors.rs

@@ -77,9 +77,7 @@ impl std::fmt::Display for FCEError {
             FCEError::NoSuchFunction(msg) => {
                 write!(f, "FCE doesn't have a function with such a name: {}", msg)
             }
-            FCEError::NoSuchModule(module_name) => {
-                write!(f, "FCE doesn't have a module with name {}", module_name)
-            }
+            FCEError::NoSuchModule(err_msg) => write!(f, "{}", err_msg),
             FCEError::HostImportError(host_import_error) => write!(f, "{}", host_import_error),
             FCEError::WITParseError(err) => write!(f, "{}", err),
             FCEError::IncorrectWIT(err_msg) => write!(f, "{}", err_msg),

fluence-app-service/src/service.rs

@@ -33,6 +33,7 @@ const SERVICE_TMP_DIR_NAME: &str = "tmp";
 
 pub struct AppService {
     faas: FluenceFaaS,
+    facade_module_name: String,
 }
 
 impl AppService {
@@ -44,25 +45,44 @@ impl AppService {
         AppServiceError: From<C::Error>,
     {
         let mut config: AppServiceConfig = config.try_into()?;
+        let facade_module_name = config
+            .faas_config
+            .modules_config
+            .last()
+            .ok_or_else(|| {
+                AppServiceError::ConfigParseError(String::from(
+                    "config should contain at least one module",
+                ))
+            })?
+            .0
+            .clone();
+
         let service_id = service_id.into();
         Self::set_env_and_dirs(&mut config, service_id, envs)?;
 
         let faas = FluenceFaaS::with_raw_config(config.faas_config)?;
 
-        Ok(Self { faas })
+        Ok(Self {
+            faas,
+            facade_module_name,
+        })
     }
 
     /// Call a specified function of loaded module by its name.
     // TODO: replace serde_json::Value with Vec<u8>?
-    pub fn call<MN: AsRef<str>, FN: AsRef<str>>(
+    pub fn call<S: AsRef<str>>(
         &mut self,
-        module_name: MN,
-        func_name: FN,
+        func_name: S,
         arguments: serde_json::Value,
         call_parameters: crate::CallParameters,
     ) -> Result<Vec<IValue>> {
         self.faas
-            .call_with_json(module_name, func_name, arguments, call_parameters)
+            .call_with_json(
+                &self.facade_module_name,
+                func_name,
+                arguments,
+                call_parameters,
+            )
             .map_err(Into::into)
     }
 
@@ -131,6 +151,18 @@ impl AppService {
 // This API is intended for testing purposes (mostly in FCE REPL)
 #[cfg(feature = "raw-module-api")]
 impl AppService {
+    pub fn call_with_module_name<MN: AsRef<str>, FN: AsRef<str>>(
+        &mut self,
+        module_name: MN,
+        func_name: FN,
+        arguments: serde_json::Value,
+        call_parameters: crate::CallParameters,
+    ) -> Result<Vec<IValue>> {
+        self.faas
+            .call_with_json(module_name, func_name, arguments, call_parameters)
+            .map_err(Into::into)
+    }
+
     pub fn load_module<S, C>(&mut self, name: S, wasm_bytes: &[u8], config: Option<C>) -> Result<()>
     where
         S: Into<String>,

tools/repl/src/repl.rs

@@ -115,17 +115,18 @@ impl REPL {
 
                 let start = Instant::now();
                 // TODO: add support of call parameters
-                let result =
-                    match self
-                        .app_service
-                        .call(module_name, func_name, module_arg, <_>::default())
-                    {
-                        Ok(result) => {
-                            let elapsed_time = start.elapsed();
-                            format!("result: {:?}\n elapsed time: {:?}", result, elapsed_time)
-                        }
-                        Err(e) => format!("execution failed with {:?}", e),
-                    };
+                let result = match self.app_service.call_with_module_name(
+                    module_name,
+                    func_name,
+                    module_arg,
+                    <_>::default(),
+                ) {
+                    Ok(result) => {
+                        let elapsed_time = start.elapsed();
+                        format!("result: {:?}\n elapsed time: {:?}", result, elapsed_time)
+                    }
+                    Err(e) => format!("execution failed with {:?}", e),
+                };
                 println!("{}", result);
             }
             Some("envs") => {