Add RFA backend

src/RemoteFileAPI/MessageDefinitions.ts

@@ -0,0 +1,65 @@
+export class RFAMessage {
+    jsonrpc = "2.0";        // Transmits version of JSON-RPC. Compliance maybe allows some funky interaction with external tools?
+    public method?:string; // Is defined when it's a request/notification, otherwise undefined
+    public result?:string; // Is defined when it's a response, otherwise undefined
+    public params?:FileMetadata; // Optional parameters to method
+    public error? :string; // Only defined on error
+    public id?    :number; // ID to keep track of request -> response interaction, undefined with notifications, defined with request/response
+
+    constructor(obj: { method?: string; result?: string; params?: FileMetadata; error?: string; id?: number } = {}){
+        this.method = obj.method;
+        this.result = obj.result;
+        this.params = obj.params;
+        this.error  = obj.error;
+        this.id     = obj.id;
+    }
+}
+
+type FileMetadata = FileData
+                    | FileContent
+                    | FileLocation
+                    | FileServer;
+
+export interface FileData {
+    filename: string;
+    content: string;
+    server: string;
+}
+
+export interface FileContent {
+    filename: string;
+    content: string;
+}
+
+export interface FileLocation {
+    filename: string;
+    server: string;
+}
+
+export interface FileServer {
+    server: string;
+}
+
+export function isFileData(p: unknown): p is FileData {
+    const pf = p as FileData
+    return typeof pf.server === 'string' &&
+        typeof pf.filename === 'string' &&
+        typeof pf.content === 'string'
+}
+
+export function isFileLocation(p: unknown): p is FileLocation {
+    const pf = p as FileLocation
+    return typeof pf.server === 'string' &&
+        typeof pf.filename === 'string'
+}
+
+export function isFileContent(p: unknown): p is FileContent {
+    const pf = p as FileContent
+    return typeof pf.filename === 'string' &&
+        typeof pf.content === 'string'
+}
+
+export function isFileServer(p: unknown): p is FileServer {
+    const pf = p as FileServer
+    return typeof pf.server === 'string'
+}