implementation of server synchronization

config/environment.default.js

@@ -20,7 +20,12 @@ module.exports = {
     // NOTE: how long should objects be cached for by default
     msToLive: 15 * 60 * 1000, // 15 minutes
     // msToLive: 1000, // 15 minutes
-    control: 'max-age=60' // revalidate browser
+    control: 'max-age=60', // revalidate browser
+    autoSync: {
+      defaultTime: 0,
+      maxBufferSize: 100,
+      timePerMethod: {'Patch': 30} //time in seconds
+    }
   },
   // Form settings
   form: {

src/app/core/cache/object-cache.actions.ts

@@ -11,7 +11,8 @@ export const ObjectCacheActionTypes = {
   ADD: type('dspace/core/cache/object/ADD'),
   REMOVE: type('dspace/core/cache/object/REMOVE'),
   RESET_TIMESTAMPS: type('dspace/core/cache/object/RESET_TIMESTAMPS'),
-  PATCH: type('dspace/core/cache/object/PATCH')
+  ADD_PATCH: type('dspace/core/cache/object/ADD_PATCH'),
+  APPLY_PATCH: type('dspace/core/cache/object/APPLY_PATCH')
 };
 
 /* tslint:disable:max-classes-per-file */
@@ -56,11 +57,11 @@ export class RemoveFromObjectCacheAction implements Action {
   /**
    * Create a new RemoveFromObjectCacheAction
    *
-   * @param uuid
-   *    the UUID of the object to remove
+   * @param href
+   *    the unique href of the object to remove
    */
-  constructor(uuid: string) {
-    this.payload = uuid;
+  constructor(href: string) {
+    this.payload = href;
   }
 }
 
@@ -83,25 +84,43 @@ export class ResetObjectCacheTimestampsAction implements Action {
 }
 
 /**
- * An ngrx action to add new operations to a specified cached objects
+ * An ngrx action to add new operations to a specified cached object
  */
-export class PatchObjectCacheAction implements Action {
-  type = ObjectCacheActionTypes.PATCH;
+export class AddPatchObjectCacheAction implements Action {
+  type = ObjectCacheActionTypes.ADD_PATCH;
   payload: {
-    uuid: string,
+    href: string,
     operations: Operation[]
   };
 
   /**
-   * Create a new PatchObjectCacheAction
+   * Create a new AddPatchObjectCacheAction
    *
-   * @param uuid
-   *    the uuid of the object that should be updated
+   * @param href
+   *    the unique href of the object that should be updated
    * @param operations
    *    the list of operations to add
    */
-  constructor(uuid: string, operations: Operation[]) {
-    this.payload = { uuid, operations };
+  constructor(href: string, operations: Operation[]) {
+    this.payload = { href, operations };
+  }
+}
+
+/**
+ * An ngrx action to apply all existing operations to a specified cached object
+ */
+export class ApplyPatchObjectCacheAction implements Action {
+  type = ObjectCacheActionTypes.APPLY_PATCH;
+  payload: string;
+
+  /**
+   * Create a new ApplyPatchObjectCacheAction
+   *
+   * @param href
+   *    the unique href of the object that should be updated
+   */
+  constructor(href: string) {
+    this.payload = href;
   }
 }
 
@@ -114,4 +133,5 @@ export type ObjectCacheAction
   = AddToObjectCacheAction
   | RemoveFromObjectCacheAction
   | ResetObjectCacheTimestampsAction
-  | PatchObjectCacheAction;
+  | AddPatchObjectCacheAction
+  | ApplyPatchObjectCacheAction;

src/app/core/cache/object-cache.reducer.ts

@@ -1,11 +1,15 @@
 import {
-  ObjectCacheAction, ObjectCacheActionTypes, AddToObjectCacheAction,
-  RemoveFromObjectCacheAction, ResetObjectCacheTimestampsAction, PatchObjectCacheAction
+  ObjectCacheAction,
+  ObjectCacheActionTypes,
+  AddToObjectCacheAction,
+  RemoveFromObjectCacheAction,
+  ResetObjectCacheTimestampsAction,
+  AddPatchObjectCacheAction, ApplyPatchObjectCacheAction
 } from './object-cache.actions';
 import { hasValue, isNotEmpty } from '../../shared/empty.util';
 import { CacheEntry } from './cache-entry';
 import { ResourceType } from '../shared/resource-type';
-import { Operation } from 'fast-json-patch';
+import { applyPatch, Operation } from 'fast-json-patch';
 
 export enum DirtyType {
   Created = 'Created',
@@ -13,7 +17,11 @@ export enum DirtyType {
   Deleted = 'Deleted'
 }
 
-/**
+export interface Patch {
+  uuid?: string;
+  operations: Operation[];
+}
+/**conca
  * An interface to represent objects that can be cached
  *
  * A cacheable object should have a self link
@@ -37,7 +45,8 @@ export class ObjectCacheEntry implements CacheEntry {
   timeAdded: number;
   msToLive: number;
   requestHref: string;
-  operations: Operation[];
+  patches: Patch[] = [];
+  isDirty: boolean;
 }
 
 /**
@@ -78,9 +87,14 @@ export function objectCacheReducer(state = initialState, action: ObjectCacheActi
       return resetObjectCacheTimestamps(state, action as ResetObjectCacheTimestampsAction)
     }
 
-    case ObjectCacheActionTypes.PATCH: {
-      return patchObjectCache(state, action as PatchObjectCacheAction);
+    case ObjectCacheActionTypes.ADD_PATCH: {
+      return addPatchObjectCache(state, action as AddPatchObjectCacheAction);
     }
+
+    case ObjectCacheActionTypes.APPLY_PATCH: {
+      return applyPatchObjectCache(state, action as ApplyPatchObjectCacheAction);
+    }
+
     default: {
       return state;
     }
@@ -104,7 +118,7 @@ function addToObjectCache(state: ObjectCacheState, action: AddToObjectCacheActio
       timeAdded: action.payload.timeAdded,
       msToLive: action.payload.msToLive,
       requestHref: action.payload.requestHref,
-      operations: []
+      isDirty: false
     }
   });
 }
@@ -156,16 +170,41 @@ function resetObjectCacheTimestamps(state: ObjectCacheState, action: ResetObject
  * @param state
  *    the current state
  * @param action
- *    a PatchObjectCacheAction
+ *    an AddPatchObjectCacheAction
  * @return ObjectCacheState
  *    the new state, with the new operations added to the state of the specified ObjectCacheEntry
  */
-function patchObjectCache(state: ObjectCacheState, action: PatchObjectCacheAction): ObjectCacheState {
-  const uuid = action.payload.uuid;
+function addPatchObjectCache(state: ObjectCacheState, action: AddPatchObjectCacheAction): ObjectCacheState {
+  const uuid = action.payload.href;
   const operations = action.payload.operations;
   const newState = Object.assign({}, state);
   if (hasValue(newState[uuid])) {
-    newState[uuid].operations = state[uuid].operations.concat(operations);
+    const patches = newState[uuid].patches;
+    newState[uuid].patches = [...patches, {operations} as Patch];
+    newState[uuid].isDirty = true;
+  }
+  return newState;
+}
+
+/**
+ * Apply the list of patch operations to a cached object
+ *
+ * @param state
+ *    the current state
+ * @param action
+ *    an ApplyPatchObjectCacheAction
+ * @return ObjectCacheState
+ *    the new state, with the new operations applied to the state of the specified ObjectCacheEntry
+ */
+function applyPatchObjectCache(state: ObjectCacheState, action: ApplyPatchObjectCacheAction): ObjectCacheState {
+  const uuid = action.payload;
+  const newState = Object.assign({}, state);
+  if (hasValue(newState[uuid])) {
+    // flatten two dimensional array
+    const flatPatch: Operation[] = [].concat(...newState[uuid].patches);
+    const newData = applyPatch( newState[uuid].data,  flatPatch);
+    newState[uuid].data =  newData.newDocument;
+    newState[uuid].patches = [];
   }
   return newState;
 }

src/app/core/cache/object-cache.service.ts

@@ -7,8 +7,8 @@ import { IndexName } from '../index/index.reducer';
 
 import { CacheableObject, ObjectCacheEntry } from './object-cache.reducer';
 import {
-  AddToObjectCacheAction,
-  PatchObjectCacheAction,
+  AddPatchObjectCacheAction,
+  AddToObjectCacheAction, ApplyPatchObjectCacheAction,
   RemoveFromObjectCacheAction
 } from './object-cache.actions';
 import { hasNoValue, isNotEmpty } from '../../shared/empty.util';
@@ -18,13 +18,15 @@ import { pathSelector } from '../shared/selectors';
 import { NormalizedObjectFactory } from './models/normalized-object-factory';
 import { NormalizedObject } from './models/normalized-object.model';
 import { applyPatch, Operation } from 'fast-json-patch';
+import { RestRequestMethod } from '../data/request.models';
+import { AddToSSBAction } from './server-sync-buffer.actions';
 
 function selfLinkFromUuidSelector(uuid: string): MemoizedSelector<CoreState, string> {
   return pathSelector<CoreState, string>(coreSelector, 'index', IndexName.OBJECT, uuid);
 }
 
 function entryFromSelfLinkSelector(selfLink: string): MemoizedSelector<CoreState, ObjectCacheEntry> {
-  return pathSelector<CoreState, ObjectCacheEntry>(coreSelector, 'data/object', selfLink);
+  return pathSelector<CoreState, ObjectCacheEntry>(coreSelector, 'cache/object', selfLink);
 }
 
 /**
@@ -52,10 +54,10 @@ export class ObjectCacheService {
   }
 
   /**
-   * Remove the object with the supplied UUID from the cache
+   * Remove the object with the supplied href from the cache
    *
-   * @param uuid
-   *    The UUID of the object to be removed
+   * @param href
+   *    The unique href of the object to be removed
    */
   remove(uuid: string): void {
     this.store.dispatch(new RemoveFromObjectCacheAction(uuid));
@@ -87,13 +89,17 @@ export class ObjectCacheService {
 
   getBySelfLink<T extends NormalizedObject>(selfLink: string): Observable<T> {
     return this.getEntry(selfLink).pipe(
+      map((entry: ObjectCacheEntry) => {
+          // flatten two dimensional array
+          const flatPatch: Operation[] = [].concat(...entry.patches);
+          const patchedData = applyPatch(entry.data, flatPatch).newDocument;
+          return Object.assign({}, entry, { data: patchedData });
+        }
+      ),
       map((entry: ObjectCacheEntry) => {
         const type: GenericConstructor<NormalizedObject> = NormalizedObjectFactory.getConstructor(entry.data.type);
         return Object.assign(new type(), entry.data) as T
-      }),
-      // map((entry: ObjectCacheEntry) =>
-      //   applyPatch(entry.data, entry.operations).newDocument
-      // )
+      })
     );
   }
 
@@ -205,14 +211,16 @@ export class ObjectCacheService {
   }
 
   /**
-   * Add operations to a the existing list of operations for an ObjectCacheEntry
+   * Add operations to the existing list of operations for an ObjectCacheEntry
+   * Makes sure the ServerSyncBuffer for this ObjectCacheEntry is updated
    * @param {string} uuid
    *     the uuid of the ObjectCacheEntry
    * @param {Operation[]} patch
    *     list of operations to perform
    */
-  private addOperations(uuid: string, patch: Operation[]) {
-    this.store.dispatch(new PatchObjectCacheAction(uuid, patch));
+  private addPatch(uuid: string, patch: Operation[]) {
+    this.store.dispatch(new AddPatchObjectCacheAction(uuid, patch));
+    this.store.dispatch(new AddToSSBAction(uuid, RestRequestMethod.Patch));
   }
 
   /**
@@ -224,6 +232,17 @@ export class ObjectCacheService {
    *    false if the entry is there are no operations left in the ObjectCacheEntry, true otherwise
    */
   private isDirty(entry: ObjectCacheEntry): boolean {
-    return isNotEmpty(entry.operations);
+    return isNotEmpty(entry.patches);
   }
+
+  /**
+   * Apply the existing operations on an ObjectCacheEntry in the store
+   * NB: this does not make any server side changes
+   * @param {string} uuid
+   *     the uuid of the ObjectCacheEntry
+   */
+  private applyPatchesToCachedObject(uuid: string) {
+    this.store.dispatch(new ApplyPatchObjectCacheAction(uuid));
+  }
+
 }

src/app/core/cache/response-cache.service.ts

@@ -12,7 +12,7 @@ import { coreSelector, CoreState } from '../core.reducers';
 import { pathSelector } from '../shared/selectors';
 
 function entryFromKeySelector(key: string): MemoizedSelector<CoreState, ResponseCacheEntry> {
-  return pathSelector<CoreState, ResponseCacheEntry>(coreSelector, 'data/response', key);
+  return pathSelector<CoreState, ResponseCacheEntry>(coreSelector, 'cache/response', key);
 }
 
 /**

src/app/core/cache/server-sync-buffer.actions.ts

@@ -0,0 +1,83 @@
+import { Action } from '@ngrx/store';
+
+import { type } from '../../shared/ngrx/type';
+import { CacheableObject } from './object-cache.reducer';
+import { Operation } from 'fast-json-patch';
+import { RestRequest, RestRequestMethod } from '../data/request.models';
+
+/**
+ * The list of ServerSyncBufferAction type definitions
+ */
+export const ServerSyncBufferActionTypes = {
+  ADD: type('dspace/core/cache/syncbuffer/ADD'),
+  COMMIT: type('dspace/core/cache/syncbuffer/COMMIT'),
+  EMPTY: type('dspace/core/cache/syncbuffer/EMPTY'),
+};
+
+/* tslint:disable:max-classes-per-file */
+
+/**
+ * An ngrx action to add a new cached object to the server's sync buffer
+ */
+export class AddToSSBAction implements Action {
+  type = ServerSyncBufferActionTypes.ADD;
+  payload: {
+    href: string,
+    method: RestRequestMethod
+  };
+
+  /**
+   * Create a new AddToSSBAction
+   *
+   * @param href
+   *    the unique href of the cached object entry that should be updated
+   */
+  constructor(href: string, method: RestRequestMethod) {
+    this.payload = { href, method };
+  }
+}
+
+/**
+ * An ngrx action to commit everything (for a certain method, when specified) in the ServerSyncBuffer to the server
+ */
+export class CommitSSBAction implements Action {
+  type = ServerSyncBufferActionTypes.COMMIT;
+  payload?: RestRequestMethod;
+
+  /**
+   * Create a new CommitSSBAction
+   *
+   * @param method
+   *    an optional method for which the ServerSyncBuffer should send its entries to the server
+   */
+  constructor(method?: RestRequestMethod) {
+    this.payload = method;
+  }
+}
+/**
+ * An ngrx action to remove everything (for a certain method, when specified) from the ServerSyncBuffer to the server
+ */
+export class EmptySSBAction implements Action {
+  type = ServerSyncBufferActionTypes.EMPTY;
+  payload?: RestRequestMethod;
+
+  /**
+   * Create a new EmptySSBAction
+   *
+   * @param method
+   *    an optional method for which the ServerSyncBuffer should remove its entries
+   */
+  constructor(method?: RestRequestMethod) {
+    this.payload = method;
+  }
+}
+
+/* tslint:enable:max-classes-per-file */
+
+/**
+ * A type to encompass all ServerSyncBufferActions
+ */
+export type ServerSyncBufferAction
+  = AddToSSBAction
+  | CommitSSBAction
+  | EmptySSBAction

src/app/core/cache/server-sync-buffer.effects.ts

@@ -0,0 +1,55 @@
+import { delay, exhaustMap, filter, first, map } from 'rxjs/operators';
+import { Inject, Injectable } from '@angular/core';
+import { Actions, Effect, ofType } from '@ngrx/effects';
+import {
+  AddToSSBAction,
+  CommitSSBAction,
+  EmptySSBAction,
+  ServerSyncBufferActionTypes
+} from './server-sync-buffer.actions';
+import { GLOBAL_CONFIG } from '../../../config';
+import { GlobalConfig } from '../../../config/global-config.interface';
+import { CoreState } from '../core.reducers';
+import { select, Store } from '@ngrx/store';
+import { ServerSyncBufferEntry, ServerSyncBufferState } from './server-sync-buffer.reducer';
+import { of as observableOf } from 'rxjs';
+import { RequestService } from '../data/request.service';
+import { PutRequest } from '../data/request.models';
+
+@Injectable()
+export class ObjectCacheEffects {
+  @Effect() setTimeoutForServerSync = this.actions$
+    .pipe(ofType(ServerSyncBufferActionTypes.ADD),
+      exhaustMap((action: AddToSSBAction) => {
+        const autoSyncConfig = this.EnvConfig.cache.autoSync;
+        const timeoutInSeconds = autoSyncConfig.timePerMethod[action.type] || autoSyncConfig.defaultTime;
+        return observableOf(new CommitSSBAction(action.payload.method)).pipe(delay( timeoutInSeconds * 1000))
+      })
+    );
+
+  @Effect() commitServerSyncBuffer = this.actions$
+    .pipe(ofType(ServerSyncBufferActionTypes.COMMIT),
+      map((action: CommitSSBAction) => {
+        this.store.pipe(
+          select(serverSyncBufferSelector),
+          first()
+        ).subscribe((bufferState: ServerSyncBufferState) => {
+            bufferState.buffer
+            .filter((entry: ServerSyncBufferEntry) => entry.method === action.payload)
+            .forEach((entry: ServerSyncBufferEntry) => {
+              this.requestService.configure(new PutRequest(this.requestService.generateRequestId(), ,))
+            })
+        });
+        return new EmptySSBAction(action.payload);
+      })
+    );
+
+  constructor(private actions$: Actions,
+              private store: Store<CoreState>,
+              private requestService: RequestService,
+              @Inject(GLOBAL_CONFIG) private EnvConfig: GlobalConfig) {
+
+  }
+}
+
+export const serverSyncBufferSelector = (state: CoreState) => state['cache/syncbuffer'];

src/app/core/cache/server-sync-buffer.reducer.ts

@@ -0,0 +1,92 @@
+import { RestRequestMethod } from '../data/request.models';
+import { hasNoValue, hasValue } from '../../shared/empty.util';
+import {
+  AddToSSBAction,
+  EmptySSBAction,
+  ServerSyncBufferAction,
+  ServerSyncBufferActionTypes
+} from './server-sync-buffer.actions';
+
+/**
+ * An entry in the ServerSyncBufferState
+ * href: unique href of an ObjectCacheEntry
+ * method: RestRequestMethod type
+ */
+export class ServerSyncBufferEntry {
+  href: string;
+  method: RestRequestMethod;
+}
+
+/**
+ * The ServerSyncBuffer State
+ *
+ * Consists list of ServerSyncBufferState
+ */
+export interface ServerSyncBufferState {
+  buffer: ServerSyncBufferEntry[];
+}
+
+// Object.create(null) ensures the object has no default js properties (e.g. `__proto__`)
+const initialState: ServerSyncBufferState = { buffer: [] };
+
+/**
+ * The ServerSyncBuffer Reducer
+ *
+ * @param state
+ *    the current state
+ * @param action
+ *    the action to perform on the state
+ * @return ServerSyncBufferState
+ *    the new state
+ */
+export function serverSyncBufferReducer(state = initialState, action: ServerSyncBufferAction): ServerSyncBufferState {
+  switch (action.type) {
+
+    case ServerSyncBufferActionTypes.ADD: {
+      return addToServerSyncQueue(state, action as AddToSSBAction)
+    }
+
+    case ServerSyncBufferActionTypes.EMPTY: {
+      return emptyServerSyncQueue(state, action as EmptySSBAction);
+    }
+    default: {
+      return state;
+    }
+  }
+}
+
+/**
+ * Add a new entry to the buffer with a specified method
+ *
+ * @param state
+ *    the current state
+ * @param action
+ *    an AddToSSBAction
+ * @return ServerSyncBufferState
+ *    the new state, with a new entry added to the buffer
+ */
+function addToServerSyncQueue(state: ServerSyncBufferState, action: AddToSSBAction): ServerSyncBufferState {
+  const actionEntry = action.payload as ServerSyncBufferEntry;
+  if (hasNoValue(state.buffer.find((entry) => entry.href === actionEntry.href && entry.method === actionEntry.method))) {
+    return Object.assign({}, state, { buffer: state.buffer.concat(actionEntry) });
+  }
+}
+
+/**
+ * Remove all ServerSyncBuffers entry from the buffer with a specified method
+ * If no method is specified, empty the whole buffer
+ *
+ * @param state
+ *    the current state
+ * @param action
+ *    an AddToSSBAction
+ * @return ServerSyncBufferState
+ *    the new state, with a new entry added to the buffer
+ */
+function emptyServerSyncQueue(state: ServerSyncBufferState, action: EmptySSBAction): ServerSyncBufferState {
+    let newBuffer = [];
+    if (hasValue(action.payload)) {
+      newBuffer = state.buffer.filter((entry) => entry.method !== action.payload);
+    }
+    return Object.assign({}, state, { buffer: newBuffer });
+}

src/app/core/core.reducers.ts

@@ -5,18 +5,21 @@ import { objectCacheReducer, ObjectCacheState } from './cache/object-cache.reduc
 import { indexReducer, IndexState } from './index/index.reducer';
 import { requestReducer, RequestState } from './data/request.reducer';
 import { authReducer, AuthState } from './auth/auth.reducer';
+import { serverSyncBufferReducer, ServerSyncBufferState } from './cache/server-sync-buffer.reducer';
 
 export interface CoreState {
-  'data/object': ObjectCacheState,
-  'data/response': ResponseCacheState,
+  'cache/object': ObjectCacheState,
+  'cache/response': ResponseCacheState,
+  'cache/syncbuffer': ServerSyncBufferState,
   'data/request': RequestState,
   'index': IndexState,
   'auth': AuthState,
 }
 
 export const coreReducers: ActionReducerMap<CoreState> = {
-  'data/object': objectCacheReducer,
-  'data/response': responseCacheReducer,
+  'cache/object': objectCacheReducer,
+  'cache/response': responseCacheReducer,
+  'cache/syncbuffer': serverSyncBufferReducer,
   'data/request': requestReducer,
   'index': indexReducer,
   'auth': authReducer

src/config/auto-sync-config.interface.ts

@@ -0,0 +1,12 @@
+import { RestRequestMethod } from '../app/core/data/request.models';
+
+/* enum indices  */
+type TimePerMethod = {
+  [method in RestRequestMethod]: number;
+};
+
+export interface AutoSyncConfig {
+  defaultTime: number;
+  timePerMethod: TimePerMethod;
+  maxBufferSize: number;
+};

src/config/cache-config.interface.ts

@@ -1,6 +1,8 @@
 import { Config } from './config.interface';
+import { AutoSyncConfig } from './auto-sync-config.interface';
 
 export interface CacheConfig extends Config {
   msToLive: number,
-  control: string
+  control: string,
+  autoSync: AutoSyncConfig
 }