some missing parts added

Author: MarcG-TUE

.gitignore

@@ -1,2 +1,2 @@
 .vscode
-database
+/database

README.md

@@ -18,7 +18,7 @@ If it occurs it leads to a failure on a test that was added for this purpose. In
 If the repository was cloned without recursively cloning submodules, clone them now.
 
 ``` sh
- git submodule update --init
+git submodule update --init
 ```
 
 The following will build and run the CMWB using [docker](docker.com).

webapplication/webapp/exercises/exercise1/exercise.json

@@ -0,0 +1,17 @@
+{
+    "description": "question.md",
+    "models": [
+        {
+            "name": "Exercise 1", 
+            "file": "models/exercise1.dtmc"
+        }
+    ],
+    "answers": [
+        {
+            "type": "multipleChoice", 
+            "question": "What is the Markov Chain Type?", 
+            "choices": ["ergodic unichain", "non-ergodic unichain", "ergodic non-unichain", "non-ergodic non-unichain"], 
+            "solution": 0
+        }
+    ]
+}

webapplication/webapp/exercises/exercise1/models/exercise1.dtmc

@@ -0,0 +1,8 @@
+markov chain Exercise1 {
+        A [p: 1; r: 1] -- 1/2 -> A
+        A -- 1/2 -> B
+        B [p: 0; r: 2] -- 1/2 -> B
+        B -- 1/2 -> C
+        C [p: 0; r: -3] -- 1/2 -> C
+        C -- 1/2 -> B
+}

webapplication/webapp/exercises/exercise1/question.md

@@ -0,0 +1,8 @@
+# Exercise 1
+
+In your scratch models you find a Markov Chain model named `Exercise1`.
+
+Please determine the type of the Markov Chain.
+You are expected to determine the type by inspection of the Markov Chain, as you would on a written exam.
+
+If you have determined your answer, please go to the "Submit Answer" page to submit your result.

webapplication/webapp/src/database/access.ts

@@ -0,0 +1,32 @@
+import { ICompModModel } from "./modelsschema";
+import { PasswordUserDb } from "./passwdb";
+
+export function CheckWriteAccess(model: ICompModModel, sessionUserId: string) {
+    return model.isOwnedBy(sessionUserId)
+}
+
+export function CheckReadAccess(model: ICompModModel, sessionUserId: string) {
+    return model.isAccessibleTo(sessionUserId)
+}
+
+export async function CheckAdminAccess(passwordUserDb: PasswordUserDb, sessionUserId: string): Promise<boolean> {
+    return await passwordUserDb.isAdmin(sessionUserId)
+}
+
+export function WriteAccessBarrier(model: ICompModModel, sessionUserId: string) {
+    if (! CheckWriteAccess(model, sessionUserId)) throw new Error("Model is not write-accessible")
+}
+
+export function ReadAccessBarrier(model: ICompModModel, sessionUserId: string) {
+    if (! CheckReadAccess(model, sessionUserId)) throw new Error("Model is not read-accessible")
+}
+
+export async function AdminAccessAsyncBarrier(passwordUserDb: PasswordUserDb, sessionUserId: string): Promise<void> {
+    const accessible = await CheckAdminAccess(passwordUserDb, sessionUserId)
+    if (! accessible) throw new Error("User is not an administrator")
+}
+
+export function LocalModeBarrier() {
+    if (! global.localMode) throw new Error("Server is not in local mode.")
+}
+