Implement basic functionalities for workflow control.
- Manage join/leave of clients
- All clients communicate via socket.io
- Probes emit events
- Managers register workflows (by using a workflow essence)
- Send kickstart request to Managers to launch workflows
- Route events to workflow runs
- Queue events to not lose events between workflow tasks
- Fixed some issues found while working on testcases
- Set to perform coverage and unittest and generate outputs to files

Change-Id: I678723edc20df9247d63a4bf6380785ab8b2b221
diff --git a/src/workflows/loader.js b/src/workflows/loader.js
new file mode 100644
index 0000000..a7bc275
--- /dev/null
+++ b/src/workflows/loader.js
@@ -0,0 +1,131 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+
+ * http://www.apache.org/licenses/LICENSE-2.0
+
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+(function () {
+    'use strict';
+
+    const path = require('path');
+    const fs = require('fs');
+    const _ = require('lodash');
+    const Workflow = require('../types/workflow.js');
+    const logger = require('../config/logger.js');
+
+    const loadEssence = (essenceFilename, absPath=false) => {
+        let filepath;
+        if(!absPath) {
+            filepath = path.join(__dirname, essenceFilename);
+        }
+        else {
+            filepath = essenceFilename;
+        }
+
+        try {
+            if (fs.existsSync(filepath)) {
+                logger.log('debug', `Loading an essence - ${filepath}`);
+                let rawdata = fs.readFileSync(filepath);
+                let essence = null;
+                try {
+                    essence = JSON.parse(rawdata);
+                }
+                catch (objError) {
+                    if (objError instanceof SyntaxError) {
+                        logger.log('warn', `failed to parse a json data (syntax error) - ${rawdata}`);
+                    }
+                    else {
+                        logger.log('warn', `failed to parse a json data - ${rawdata}`);
+                    }
+                }
+                return essence;
+            }
+            else {
+                logger.log('warn', `No ${filepath} found`);
+                return null;
+            }
+        }
+        catch(e) {
+            logger.log('warn', `Cannot read ${filepath} - ${e}`);
+            return null;
+        }
+    };
+
+    const loadWorkflows = (essenceFilename) => {
+        let filepath = path.join(__dirname, essenceFilename);
+
+        try {
+            if (fs.existsSync(filepath)) {
+                logger.log('debug', `Loading an essence - ${filepath}`);
+                let rawdata = fs.readFileSync(filepath);
+                let workflows = [];
+
+                try {
+                    let essence = JSON.parse(rawdata);
+
+                    // an essence can have multiple workflows
+                    _.forOwn(essence, (workflowEssence, workflowId) => {
+                        let workflow = Workflow.Workflow.fromEssence(workflowEssence);
+                        if(workflow) {
+                            workflows.push(workflow);
+                            logger.log('debug', `Loaded workflow: ${workflowId}`);
+                        }
+                    });
+                }
+                catch (objError) {
+                    if (objError instanceof SyntaxError) {
+                        logger.log('warn', `failed to parse a json data (syntax error) - ${rawdata}`);
+                    }
+                    else {
+                        logger.log('warn', `failed to parse a json data - ${rawdata}`);
+                    }
+                }
+
+                return workflows
+            }
+            else {
+                logger.log('warn', `No ${filepath} found`);
+                return null;
+            }
+        }
+        catch(e) {
+            logger.log('warn', `Cannot read ${filepath} - ${e}`);
+            return null;
+        }
+    };
+
+    const loadAllWorkflows = () => {
+        let dirpath = __dirname;
+
+        let allWorkflows = [];
+        let dirEntries = fs.readdirSync(dirpath);
+        dirEntries.forEach((dirEntry) => {
+            if(dirEntry.endsWith('.json')) {
+                // found workflow essence file in json format
+                let workflows = loadWorkflows(dirEntry);
+                if(workflows) {
+                    for(let workflow in workflows) {
+                        allWorkflows.push[workflow];
+                    }
+                }
+            }
+        });
+        return allWorkflows;
+    };
+
+    module.exports = {
+        loadEssence: loadEssence,
+        loadAllWorkflows: loadAllWorkflows,
+        loadWorkflows: loadWorkflows
+    };
+})();
\ No newline at end of file