Initial VES for DANOS vRouter

1. Create vpp_measurement_reporter that use DANOS configd query
   to retrieve statistics and libevel to transmit
2. Copy VES evel library to build a debian package under
   vpp_measurement_report
3. Add debian files to create a vpp_measurement_reporter + libevel
   debian package
4. Add debian install and systemctl start files
5. Add instruction to build VES reporter debian package (that will
   include libevel.so)
6. Add instructions to build DANOS ISO with VES reporter debian
   package and creating glance image

Issue-ID: INT-1566
Change-Id: If18f16525f07f1b6bae0fc105e0452263b4bf661
Signed-off-by: Brian Freeman <bf1936@att.com>

1 files changed, 1664 insertions, 0 deletions

diff --git a/vnfs/VESreporting_vFW5.0_DANOS/evel/evel-library/code/evel_library/evel_event_mgr.c b/vnfs/VESreporting_vFW5.0_DANOS/evel/evel-library/code/evel_library/evel_event_mgr.c
new file mode 100644
index 00000000..cc676a6f
--- /dev/null
+++ b/vnfs/VESreporting_vFW5.0_DANOS/evel/evel-library/code/evel_library/evel_event_mgr.c
@@ -0,0 +1,1664 @@
+/*************************************************************************//**
+ *
+ * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
+ *
+ * Unless otherwise specified, all software contained herein is
+ * 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.
+ * ECOMP is a trademark and service mark of AT&T Intellectual Property.
+ ****************************************************************************/
+
+/**************************************************************************//**
+ * @file
+ * Event Manager
+ *
+ * Simple event manager that is responsible for taking events (Heartbeats,
+ * Faults and Measurements) from the ring-buffer and posting them to the API.
+ *
+ ****************************************************************************/
+
+#include <string.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+#include <curl/curl.h>
+
+#include "evel.h"
+#include "evel_internal.h"
+#include "ring_buffer.h"
+#include "evel_throttle.h"
+
+/**************************************************************************//**
+ * How long we're prepared to wait for the API service to respond in
+ * seconds.
+ *****************************************************************************/
+static const int EVEL_API_TIMEOUT = 5;
+
+/**************************************************************************//**
+ * Wait time if both the collectors are not responding
+ *****************************************************************************/
+static const int EVEL_COLLECTOR_RECONNECTION_WAIT_TIME = 120;
+
+/*****************************************************************************/
+/* Prototypes of locally scoped functions.                                   */
+/*****************************************************************************/
+static size_t read_callback(void *ptr, size_t size, size_t nmemb, void *userp);
+static void * event_handler(void *arg);
+static bool evel_handle_response_tokens(const MEMORY_CHUNK * const chunk,
+                                        const jsmntok_t * const json_tokens,
+                                        const int num_tokens,
+                                        MEMORY_CHUNK * const post);
+static bool evel_tokens_match_command_list(const MEMORY_CHUNK * const chunk,
+                                           const jsmntok_t * const json_token,
+                                           const int num_tokens);
+static bool evel_token_equals_string(const MEMORY_CHUNK * const chunk,
+                                     const jsmntok_t * const json_token,
+                                     const char * check_string);
+static EVEL_ERR_CODES evel_setup_curl();
+static EVEL_ERR_CODES evel_send_to_another_collector(const EVEL_EVENT_DOMAINS evel_domain, char * json_body, size_t json_size);
+
+/**************************************************************************//**
+ * Buffers for error strings from libcurl.
+ *****************************************************************************/
+static char curl_err_string[CURL_ERROR_SIZE] = "<NULL>";
+
+/**************************************************************************//**
+ * Handle for the API into libcurl.
+ *****************************************************************************/
+static CURL * curl_handle = NULL;
+int curr_global_handles = 0;
+
+/**************************************************************************//**
+ * Special headers that we send.
+ *****************************************************************************/
+static struct curl_slist * hdr_chunk = NULL;
+
+/**************************************************************************//**
+ * Message queue for sending events to the API.
+ *****************************************************************************/
+static ring_buffer event_buffer;
+
+/**************************************************************************//**
+ * Single pending priority post, which can be generated as a result of a
+ * response to an event.  Currently only used to respond to a commandList.
+ *****************************************************************************/
+static MEMORY_CHUNK priority_post;
+
+/**************************************************************************//**
+ * The thread which is responsible for handling events off of the ring-buffer
+ * and posting them to the Event Handler API.
+ *****************************************************************************/
+static pthread_t evt_handler_thread;
+
+/**************************************************************************//**
+ * Variable to convey to the event handler thread what the foreground wants it
+ * to do.
+ *****************************************************************************/
+static EVT_HANDLER_STATE evt_handler_state = EVT_HANDLER_UNINITIALIZED;
+
+/**************************************************************************//**
+ * The configured API URL for event and throttling.
+ *****************************************************************************/
+static char * evel_event_api_url;
+static char * evel_throt_api_url;
+static char * evel_batch_api_url;
+
+static char * evel_bevent_api_url;
+static char * evel_bthrot_api_url;
+static char * evel_bbatch_api_url;
+
+/**************************************************************************//**
+ * Storage for other CURL related parameters
+ *****************************************************************************/
+int evel_secure = -1;
+int evel_verbosity = -1;
+
+long evel_verify_peer = 0;
+long evel_verify_host = 0;
+
+static char * evel_source_ip = NULL;
+static char * evel_source_ip_bakup = NULL;
+static char * evel_cert_file_path = NULL;
+static char * evel_key_file_path = NULL;
+static char * evel_ca_info = NULL;
+static char * evel_ca_file_path = NULL;
+static char * evel_username = NULL;
+static char * evel_password = NULL;
+static char * evel_username2 = NULL;
+static char * evel_password2 = NULL;
+
+static long http_response_code = 0;
+static int evel_collector_id = 1;
+/**************************************************************************//**
+ * Initialize the event handler.
+ *
+ * Primarily responsible for getting CURL ready for use.
+ *
+ * @param[in] event_api_url
+ *                      The URL where the Vendor Event Listener API is expected
+ *                      to be.
+ * @param[in] throt_api_url
+ *                      The URL where the Throttling API is expected to be.
+ * @param[in] source_ip  Source IP of VES Agent
+ * @param[in] ring_buf_size     Initial size of ring buffer
+ * @param[in] secure     Whether Using http or https
+ * @param[in] cert_file_path  Path to Client Certificate file
+ * @param[in] key_file_path   Path to Client key file
+ * @param[in] ca_info         Path to CA info file
+ * @param[in] ca_file_path    Path to CA file 
+ * @param[in] verify_peer     Using peer verification or not 0 or 1
+ * @param[in] verify_host     Using host verification or not 0 or 1
+ * @param[in] username  The username for the Basic Authentication of requests.
+ * @param[in] password  The password for the Basic Authentication of requests.
+ * @param     verbosity 0 for normal operation, positive values for chattier
+ *                        logs.
+ *****************************************************************************/
+EVEL_ERR_CODES event_handler_initialize(const char * const event_api_url,
+                                        const char * const bakup_api_url,
+                                        const char * const throt_api_url,
+                                        const char * const source_ip,
+                                        const char * const source_ip_bakup,
+                                        int ring_buf_size,
+                                        int secure,
+                                        const char * const cert_file_path,
+                                        const char * const key_file_path,
+                                        const char * const ca_info,
+                                        const char * const ca_file_path,
+                                        long verify_peer,
+                                        long verify_host,
+                                        const char * const username,
+                                        const char * const password,
+                                        const char * const username2,
+                                        const char * const password2,
+                                        int verbosity)
+{
+  int rc = EVEL_SUCCESS;
+  char batch_api_url[EVEL_MAX_URL_LEN + 1] = {0};
+
+  EVEL_ENTER();
+
+  /***************************************************************************/
+  /* Check assumptions.                                                      */
+  /***************************************************************************/
+  assert(event_api_url != NULL);
+  assert(throt_api_url != NULL);
+  assert(username != NULL);
+  assert(password != NULL);
+  if( bakup_api_url != NULL )
+  {
+    assert(username2 != NULL);
+    assert(password2 != NULL);
+  }
+
+  /***************************************************************************/
+  /* Store the API URLs.                                                     */
+  /***************************************************************************/
+  evel_event_api_url = strdup(event_api_url);
+  assert(evel_event_api_url != NULL);
+  sprintf(batch_api_url,"%s/eventBatch",event_api_url);
+  evel_batch_api_url = strdup(batch_api_url);
+  assert(evel_batch_api_url != NULL);
+  evel_throt_api_url = strdup(throt_api_url);
+  assert(evel_throt_api_url != NULL);
+
+  curr_global_handles = 1;
+
+  if( bakup_api_url != NULL )
+  {
+    evel_bevent_api_url = strdup(bakup_api_url);
+    assert(evel_bevent_api_url != NULL);
+    sprintf(batch_api_url,"%s/eventBatch",bakup_api_url);
+    evel_bbatch_api_url = strdup(batch_api_url);
+    assert(evel_bbatch_api_url != NULL);
+    evel_bthrot_api_url = strdup(throt_api_url);
+    assert(evel_bthrot_api_url != NULL);
+    curr_global_handles = 2;
+  }
+
+  /***************************************************************************/
+  /* Store other parameters                                                  */
+  /***************************************************************************/
+  evel_secure = secure;
+  evel_verbosity = verbosity;
+
+  evel_verify_peer = verify_peer;
+  evel_verify_host = verify_host;
+
+  evel_source_ip = NULL;
+  if (source_ip != NULL)
+  {
+    evel_source_ip = strdup(source_ip);
+    assert(evel_source_ip != NULL);
+  }
+
+  evel_source_ip_bakup = NULL;
+  if (source_ip_bakup != NULL)
+  {
+    evel_source_ip_bakup = strdup(source_ip_bakup);
+    assert(evel_source_ip_bakup != NULL);
+  }
+
+  evel_cert_file_path = NULL;
+  if (cert_file_path != NULL)
+  {
+    evel_cert_file_path = strdup(cert_file_path);
+    assert(evel_cert_file_path != NULL);
+  }
+
+  evel_key_file_path = NULL;
+  if (key_file_path != NULL)
+  {
+    evel_key_file_path = strdup(key_file_path);
+    assert(evel_key_file_path != NULL);
+  }
+
+  evel_ca_info = NULL;
+  if (ca_info != NULL)
+  {
+    evel_ca_info = strdup(ca_info);
+    assert(evel_ca_info != NULL);
+  }
+
+  evel_ca_file_path = NULL;
+  if (ca_file_path != NULL)
+  {
+    evel_ca_file_path = strdup(ca_file_path);
+    assert(evel_ca_file_path != NULL);
+  }
+
+  evel_username = NULL;
+  if (username != NULL)
+  {
+    evel_username = strdup(username);
+    assert(evel_username != NULL);
+  }
+
+  evel_password = NULL;
+  if (password != NULL)
+  {
+    evel_password = strdup(password);
+    assert(evel_password != NULL);
+  }
+
+  evel_username2 = NULL;
+  if (username2 != NULL)
+  {
+    evel_username2 = strdup(username2);
+    assert(evel_username2 != NULL);
+  }
+
+  evel_password2 = NULL;
+  if (password2 != NULL)
+  {
+    evel_password2 = strdup(password2);
+    assert(evel_password2 != NULL);
+  }
+
+  curl_version_info_data *d = curl_version_info(CURLVERSION_NOW);
+  /* compare with the 24 bit hex number in 8 bit fields */
+  if(d->version_num >= 0x072100) {
+     /* this is libcurl 7.33.0 or later */
+     EVEL_INFO("7.33 or later Curl version %x.",d->version_num);
+  }
+  else {
+     EVEL_INFO("Old Curl version.");
+  }
+
+  /***************************************************************************/
+  /* Initialize a message ring-buffer to be used between the foreground and  */
+  /* the thread which sends the messages.  This can't fail.                  */
+  /***************************************************************************/
+  if( ring_buf_size < EVEL_EVENT_BUFFER_DEPTH )
+  {
+    log_error_state("Warning: Failed to initialize Ring buffer size to %d. ",
+                    ring_buf_size);
+    goto exit_label;
+  }
+  ring_buffer_initialize(&event_buffer, EVEL_EVENT_BUFFER_DEPTH);
+
+exit_label:
+
+  EVEL_EXIT();
+
+  return rc;
+
+}
+/**************************************************************************//**
+ * Setup the curl connection to collector
+ *
+ * Primarily responsible for getting CURL ready to send message. Also it would
+ * be used to swithch over to other collector 
+ *****************************************************************************/
+static EVEL_ERR_CODES evel_setup_curl()
+{
+  int rc = EVEL_SUCCESS;
+  CURLcode curl_rc = CURLE_OK;
+  char local_address[64];
+  char * api_url = NULL;
+  char * username = NULL;
+  char * password = NULL;
+  char * source_ip = NULL;
+
+  EVEL_ENTER();
+
+  if (evel_collector_id > 2)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Wrong evel_collector- value > 2");
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* Initialize the local variable with proper global variables that are     */
+  /* required to setup the connection                                        */
+  /***************************************************************************/
+  if (evel_collector_id == 1)
+  {
+     api_url = evel_event_api_url;
+     source_ip = evel_source_ip;
+     username = evel_username;
+     password = evel_password;
+  }
+  else if (evel_collector_id == 2)
+  {
+     api_url = evel_bevent_api_url;
+     source_ip = evel_source_ip_bakup;
+     username = evel_username2;
+     password = evel_password2;
+  }
+  /***************************************************************************/
+  /* Clean-up the cURL library.                                              */
+  /***************************************************************************/
+  if (curl_handle != NULL)
+  {
+    curl_easy_cleanup(curl_handle);
+    curl_handle = NULL;
+  }
+  if (hdr_chunk != NULL)
+  {
+    curl_slist_free_all(hdr_chunk);
+    hdr_chunk = NULL;
+  }
+
+  /***************************************************************************/
+  /* Start the CURL library. Note that this initialization is not threadsafe */
+  /* which imposes a constraint that the EVEL library is initialized before  */
+  /* any threads are started.                                                */
+  /***************************************************************************/
+  curl_rc = curl_global_init(CURL_GLOBAL_SSL);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL. Error code=%d", curl_rc);
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* Get a curl handle which we'll use for all of our output.                */
+  /***************************************************************************/
+  curl_handle = curl_easy_init();
+  if (curl_handle == NULL)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to get libCURL handle");
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* Prime the library to give friendly error codes.                         */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_ERRORBUFFER,
+                             curl_err_string);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL to provide friendly errors. "
+                    "Error code=%d", curl_rc);
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* If running in verbose mode generate more output.                        */
+  /***************************************************************************/
+  if (evel_verbosity > 0)
+  {
+    curl_rc = curl_easy_setopt(curl_handle, CURLOPT_VERBOSE, 1L);
+    if (curl_rc != CURLE_OK)
+    {
+      rc = EVEL_CURL_LIBRARY_FAIL;
+      log_error_state("Failed to initialize libCURL to be verbose. "
+                      "Error code=%d", curl_rc);
+      goto exit_label;
+    }
+  }
+
+  /***************************************************************************/
+  /* Set the URL for the API.                                                */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, api_url);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL with the API URL. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+  EVEL_INFO("Initializing CURL to send events to: %s", api_url);
+
+  /***************************************************************************/
+  /* send all data to this function.                                         */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_WRITEFUNCTION,
+                             evel_write_callback);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL with the write callback. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* configure local ip address if provided */
+  /* Default ip if NULL */
+  /***************************************************************************/
+  if( source_ip != NULL )
+  {
+    snprintf(local_address,sizeof(local_address),source_ip);
+    if( local_address[0] != '\0' )
+    {
+      curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_INTERFACE,
+                             local_address);
+      if (curl_rc != CURLE_OK)
+      {
+        rc = EVEL_CURL_LIBRARY_FAIL;
+        log_error_state("Failed to initialize libCURL with the local address. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+        goto exit_label;
+      }
+    }
+  }
+
+  /***************************************************************************/
+  /* configure SSL options for HTTPS transfers */
+  /***************************************************************************/
+  if( evel_secure )
+  {
+    if( evel_cert_file_path != NULL )
+    {
+      curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_SSLCERT,
+                             evel_cert_file_path);
+      if (curl_rc != CURLE_OK)
+      {
+        rc = EVEL_CURL_LIBRARY_FAIL;
+        log_error_state("Failed to initialize libCURL with the client cert. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+        goto exit_label;
+      }
+    }
+
+    if( evel_key_file_path != NULL )
+    {
+      curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_SSLKEY,
+                             evel_key_file_path);
+      if (curl_rc != CURLE_OK)
+      {
+        rc = EVEL_CURL_LIBRARY_FAIL;
+        log_error_state("Failed to initialize libCURL with the client key. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+        goto exit_label;
+      }
+    }
+
+    if( evel_ca_info != NULL )
+    {
+      curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_CAINFO,
+                             evel_ca_info);
+      if (curl_rc != CURLE_OK)
+      {
+        rc = EVEL_CURL_LIBRARY_FAIL;
+        log_error_state("Failed to initialize libCURL with the CA cert file. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+        goto exit_label;
+      }
+    }
+
+    if( evel_ca_file_path != NULL )
+    {
+      curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_CAPATH,
+                             evel_ca_file_path);
+      if (curl_rc != CURLE_OK)
+      {
+        rc = EVEL_CURL_LIBRARY_FAIL;
+        log_error_state("Failed to initialize libCURL with the CA cert path. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+        goto exit_label;
+      }
+    }
+
+      curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_SSL_VERIFYPEER,
+                             evel_verify_peer);
+      if (curl_rc != CURLE_OK)
+      {
+        rc = EVEL_CURL_LIBRARY_FAIL;
+        log_error_state("Failed to initialize libCURL with SSL Server verification. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+        goto exit_label;
+      }
+      curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_SSL_VERIFYHOST,
+                             evel_verify_host);
+      if (curl_rc != CURLE_OK)
+      {
+        rc = EVEL_CURL_LIBRARY_FAIL;
+        log_error_state("Failed to initialize libCURL with Client host verification. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+        goto exit_label;
+      }
+
+  }
+
+
+
+  /***************************************************************************/
+  /* some servers don't like requests that are made without a user-agent     */
+  /* field, so we provide one.                                               */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_USERAGENT,
+                             "libcurl-agent/1.0");
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL to upload. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* Specify that we are going to POST data.                                 */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle, CURLOPT_POST, 1L);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL to upload. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* we want to use our own read function.                                   */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle, CURLOPT_READFUNCTION, read_callback);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL to upload using read "
+                    "function. Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* All of our events are JSON encoded.  We also suppress the               */
+  /* Expect: 100-continue   header that we would otherwise get since it      */
+  /* confuses some servers.                                                  */
+  /*                                                                         */
+  /* @TODO: do AT&T want this behavior?                                      */
+  /***************************************************************************/
+  hdr_chunk = curl_slist_append(hdr_chunk, "Content-type: application/json");
+  hdr_chunk = curl_slist_append(hdr_chunk, "Expect:");
+
+  /***************************************************************************/
+  /* set our custom set of headers.                                         */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle, CURLOPT_HTTPHEADER, hdr_chunk);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL to use custom headers. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* Set the timeout for the operation.                                      */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_TIMEOUT,
+                             EVEL_API_TIMEOUT);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL for API timeout. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* Set that we want Basic authentication with username:password Base-64    */
+  /* encoded for the operation.                                              */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL for Basic Authentication. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+  curl_rc = curl_easy_setopt(curl_handle, CURLOPT_USERNAME, username);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL with username. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+  curl_rc = curl_easy_setopt(curl_handle, CURLOPT_PASSWORD, password);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL with password. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* Initialize the priority post buffer to empty.                           */
+  /***************************************************************************/
+  priority_post.memory = NULL;
+
+exit_label:
+  EVEL_EXIT();
+
+  return(rc);
+}
+
+/**************************************************************************//**
+ * Run the event handler.
+ *
+ * Spawns the thread responsible for handling events and sending them to the
+ * API.
+ *
+ *  @return Status code.
+ *  @retval ::EVEL_SUCCESS if everything OK.
+ *  @retval One of ::EVEL_ERR_CODES if there was a problem.
+ *****************************************************************************/
+EVEL_ERR_CODES event_handler_run()
+{
+  EVEL_ERR_CODES rc = EVEL_SUCCESS;
+  int pthread_rc = 0;
+
+  EVEL_ENTER();
+
+  /***************************************************************************/
+  /* Start the event handler thread.                                         */
+  /***************************************************************************/
+  evt_handler_state = EVT_HANDLER_INACTIVE;
+  pthread_rc = pthread_create(&evt_handler_thread, NULL, event_handler, NULL);
+  if (pthread_rc != 0)
+  {
+    rc = EVEL_PTHREAD_LIBRARY_FAIL;
+    log_error_state("Failed to start event handler thread. "
+                    "Error code=%d", pthread_rc);
+  }
+
+  EVEL_EXIT()
+  return rc;
+}
+
+/**************************************************************************//**
+ * Terminate the event handler.
+ *
+ * Shuts down the event handler thread in as clean a way as possible. Sets the
+ * global exit flag and then signals the thread to interrupt it since it's
+ * most likely waiting on the ring-buffer.
+ *
+ * Having achieved an orderly shutdown of the event handler thread, clean up
+ * the cURL library's resources cleanly.
+ *
+ *  @return Status code.
+ *  @retval ::EVEL_SUCCESS if everything OK.
+ *  @retval One of ::EVEL_ERR_CODES if there was a problem.
+ *****************************************************************************/
+EVEL_ERR_CODES event_handler_terminate()
+{
+  EVEL_ERR_CODES rc = EVEL_SUCCESS;
+
+  EVEL_ENTER();
+  EVENT_INTERNAL *event = NULL;
+
+  /***************************************************************************/
+  /* Make sure that we were initialized before trying to terminate the       */
+  /* event handler thread.                                                   */
+  /***************************************************************************/
+  if (evt_handler_state != EVT_HANDLER_UNINITIALIZED)
+  {
+    /*************************************************************************/
+    /* Make sure that the event handler knows it's time to die.              */
+    /*************************************************************************/
+    event = evel_new_internal_event(EVT_CMD_TERMINATE,"EVELinternal","EVELid");
+    if (event == NULL)
+    {
+      /***********************************************************************/
+      /* We failed to get an event, but we don't bail out - we will just     */
+      /* clean up what we can and continue on our way, since we're exiting   */
+      /* anyway.                                                             */
+      /***********************************************************************/
+      EVEL_ERROR("Failed to get internal event - perform dirty exit instead!");
+    }
+    else
+    {
+      /***********************************************************************/
+      /* Post the event then wait for the Event Handler to exit.  Set the    */
+      /* global command, too, in case the ring-buffer is full.               */
+      /***********************************************************************/
+      EVEL_DEBUG("Sending event to Event Hander to request it to exit.");
+      evt_handler_state = EVT_HANDLER_REQUEST_TERMINATE;
+      evel_post_event((EVENT_HEADER *) event);
+      pthread_join(evt_handler_thread, NULL);
+      EVEL_DEBUG("Event Handler thread has exited.");
+    }
+  }
+  else
+  {
+    EVEL_DEBUG("Event handler was not initialized, so no need to kill it");
+  }
+
+  /***************************************************************************/
+  /* Clean-up the cURL library.                                              */
+  /***************************************************************************/
+  if (curl_handle != NULL)
+  {
+    curl_easy_cleanup(curl_handle);
+    curl_handle = NULL;
+  }
+  if (hdr_chunk != NULL)
+  {
+    curl_slist_free_all(hdr_chunk);
+    hdr_chunk = NULL;
+  }
+
+  /***************************************************************************/
+  /* Free off the stored API URL strings.                                    */
+  /***************************************************************************/
+  if (evel_event_api_url != NULL)
+  {
+    free(evel_event_api_url);
+    evel_event_api_url = NULL;
+  }
+  if (evel_batch_api_url != NULL)
+  {
+    free(evel_batch_api_url);
+    evel_batch_api_url = NULL;
+  }
+  if (evel_throt_api_url != NULL)
+  {
+    free(evel_throt_api_url);
+    evel_throt_api_url = NULL;
+  }
+
+  EVEL_EXIT();
+  return rc;
+}
+
+/**************************************************************************//**
+ * Post an event.
+ *
+ * @note  So far as the caller is concerned, successfully posting the event
+ * relinquishes all responsibility for the event - the library will take care
+ * of freeing the event in due course.
+
+ * @param event   The event to be posted.
+ *
+ * @returns Status code
+ * @retval  EVEL_SUCCESS On success
+ * @retval  "One of ::EVEL_ERR_CODES" On failure.
+ *****************************************************************************/
+EVEL_ERR_CODES evel_post_event(EVENT_HEADER * event)
+{
+  int rc = EVEL_SUCCESS;
+
+  EVEL_ENTER();
+
+  /***************************************************************************/
+  /* Check preconditions.                                                    */
+  /***************************************************************************/
+  assert(event != NULL);
+
+  /***************************************************************************/
+  /* We need to make sure that we are either initializing or running         */
+  /* normally before writing the event into the buffer so that we can        */
+  /* guarantee that the ring-buffer empties  properly on exit.               */
+  /***************************************************************************/
+  if ((evt_handler_state == EVT_HANDLER_ACTIVE) ||
+      (evt_handler_state == EVT_HANDLER_INACTIVE) ||
+      (evt_handler_state == EVT_HANDLER_REQUEST_TERMINATE))
+  {
+    if (ring_buffer_write(&event_buffer, event) == 0)
+    {
+      log_error_state("Failed to write event to buffer - event dropped!");
+      rc = EVEL_EVENT_BUFFER_FULL;
+      evel_free_event(event);
+    }
+  }
+  else
+  {
+    /*************************************************************************/
+    /* System is not in active operation, so reject the event.               */
+    /*************************************************************************/
+    log_error_state("Event Handler system not active - event dropped!");
+    rc = EVEL_EVENT_HANDLER_INACTIVE;
+    evel_free_event(event);
+  }
+
+  EVEL_EXIT();
+  return (rc);
+}
+
+/**************************************************************************//**
+ * Post an event to the Vendor Event Listener API.
+ *
+ * @returns Status code
+ * @retval  EVEL_SUCCESS On success
+ * @retval  "One of ::EVEL_ERR_CODES" On failure.
+ *****************************************************************************/
+static EVEL_ERR_CODES evel_post_api(char * msg, size_t size)
+{
+  int rc = EVEL_SUCCESS;
+  CURLcode curl_rc = CURLE_OK;
+  MEMORY_CHUNK rx_chunk;
+  MEMORY_CHUNK tx_chunk;
+
+  EVEL_ENTER();
+
+  /***************************************************************************/
+  /* Create the memory chunk to be used for the response to the post.  The   */
+  /* will be realloced.                                                      */
+  /***************************************************************************/
+  rx_chunk.memory = malloc(1);
+  assert(rx_chunk.memory != NULL);
+  rx_chunk.size = 0;
+
+  /***************************************************************************/
+  /* Create the memory chunk to be sent as the body of the post.             */
+  /***************************************************************************/
+  tx_chunk.memory = msg;
+  tx_chunk.size = size;
+  EVEL_DEBUG("Sending chunk of size %d", tx_chunk.size);
+
+  /***************************************************************************/
+  /* Point to the data to be received.                                       */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, &rx_chunk);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to initialize libCURL to upload. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+  EVEL_DEBUG("Initialized data to receive");
+
+  /***************************************************************************/
+  /* Pointer to pass to our read function                                    */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle, CURLOPT_READDATA, &tx_chunk);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to set upload data for libCURL to upload. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+  EVEL_DEBUG("Initialized data to send");
+
+  /***************************************************************************/
+  /* Size of the data to transmit.                                           */
+  /***************************************************************************/
+  curl_rc = curl_easy_setopt(curl_handle,
+                             CURLOPT_POSTFIELDSIZE,
+                             tx_chunk.size);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to set length of upload data for libCURL to "
+                    "upload.  Error code=%d (%s)", curl_rc, curl_err_string);
+    goto exit_label;
+  }
+  EVEL_DEBUG("Initialized length of data to send");
+
+  /***************************************************************************/
+  /* Now run off and do what you've been told!                               */
+  /***************************************************************************/
+  http_response_code = 0;
+
+  curl_rc = curl_easy_perform(curl_handle);
+  if (curl_rc != CURLE_OK)
+  {
+    rc = EVEL_CURL_LIBRARY_FAIL;
+    log_error_state("Failed to transfer an event to Vendor Event Listener! "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+    EVEL_ERROR("Dropped event: %s", msg);
+    goto exit_label;
+  }
+
+  /***************************************************************************/
+  /* See what response we got - any 2XX response is good.                    */
+  /***************************************************************************/
+  curl_easy_getinfo(curl_handle, CURLINFO_RESPONSE_CODE, &http_response_code);
+  EVEL_DEBUG("HTTP response code: %d", http_response_code);
+  if ((http_response_code / 100) == 2)
+  {
+    /*************************************************************************/
+    /* If the server responded with data it may be interesting but not a     */
+    /* problem.                                                              */
+    /*************************************************************************/
+    if ((rx_chunk.size > 0) && (rx_chunk.memory != NULL))
+    {
+      EVEL_DEBUG("Server returned data = %d (%s)",
+                 rx_chunk.size,
+                 rx_chunk.memory);
+
+      /***********************************************************************/
+      /* If this is a response to priority post, then we're not interested.  */
+      /***********************************************************************/
+      if (priority_post.memory != NULL)
+      {
+        EVEL_ERROR("Ignoring priority post response");
+      }
+      else
+      {
+        evel_handle_event_response(&rx_chunk, &priority_post);
+      }
+    }
+  }
+  else
+  {
+    EVEL_ERROR("Unexpected HTTP response code: %d with data size %d (%s)",
+                http_response_code,
+                rx_chunk.size,
+                rx_chunk.size > 0 ? rx_chunk.memory : "NONE");
+    EVEL_ERROR("Potentially dropped event: %s", msg);
+  }
+
+exit_label:
+  free(rx_chunk.memory);
+  EVEL_EXIT();
+  return(rc);
+}
+
+/**************************************************************************//**
+ * Send event to another collector
+ *
+ * Identify the next collector and try sending the event to that collector
+ ****************************************************************************/
+static EVEL_ERR_CODES evel_send_to_another_collector(
+                        const EVEL_EVENT_DOMAINS evel_domain, 
+                        char * json_body, 
+                        size_t json_size)
+{
+  int rc = EVEL_SUCCESS;
+  CURLcode curl_rc;
+
+  EVEL_ENTER();
+
+  if ((evel_collector_id == 1) && (curr_global_handles == 2))
+  {
+     evel_collector_id =2;
+  }
+  else if (evel_collector_id == 2)
+  {
+     evel_collector_id =1;
+  }
+
+  rc = evel_setup_curl();
+
+  if ( rc == EVEL_SUCCESS)
+  {
+     if (evel_collector_id == 1)
+     {
+        if (evel_domain == EVEL_DOMAIN_BATCH)
+           curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, evel_batch_api_url);
+        else
+           curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, evel_event_api_url);
+     }
+     else if (evel_collector_id == 2)
+     {
+        if (evel_domain == EVEL_DOMAIN_BATCH)
+           curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, evel_bbatch_api_url);
+        else
+           curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, evel_bevent_api_url);
+     }
+
+     rc = evel_post_api(json_body, json_size);
+  }
+
+  EVEL_EXIT();
+
+  return rc;
+}
+
+/**************************************************************************//**
+ * Callback function to provide data to send.
+ *
+ * Copy data into the supplied buffer, read_callback::ptr, checking size
+ * limits.
+ *
+ * @returns   Number of bytes placed into read_callback::ptr. 0 for EOF.
+ *****************************************************************************/
+static size_t read_callback(void *ptr, size_t size, size_t nmemb, void *userp)
+{
+  size_t rtn = 0;
+  size_t bytes_to_write = 0;
+  MEMORY_CHUNK *tx_chunk = (MEMORY_CHUNK *)userp;
+
+  EVEL_ENTER();
+
+  bytes_to_write = min(size*nmemb, tx_chunk->size);
+
+  if (bytes_to_write > 0)
+  {
+    EVEL_DEBUG("Going to try to write %d bytes", bytes_to_write);
+    strncpy((char *)ptr, tx_chunk->memory, bytes_to_write);
+    tx_chunk->memory += bytes_to_write;
+    tx_chunk->size -= bytes_to_write;
+    rtn = bytes_to_write;
+  }
+  else
+  {
+    EVEL_DEBUG("Reached EOF");
+  }
+
+  EVEL_EXIT();
+  return rtn;
+}
+
+/**************************************************************************//**
+ * Callback function to provide returned data.
+ *
+ * Copy data into the supplied buffer, write_callback::ptr, checking size
+ * limits.
+ *
+ * @returns   Number of bytes placed into write_callback::ptr. 0 for EOF.
+ *****************************************************************************/
+size_t evel_write_callback(void *contents,
+                             size_t size,
+                             size_t nmemb,
+                             void *userp)
+{
+  size_t realsize = size * nmemb;
+  MEMORY_CHUNK * rx_chunk = (MEMORY_CHUNK *)userp;
+
+  EVEL_ENTER();
+
+  EVEL_DEBUG("Called with %d chunks of %d size = %d", nmemb, size, realsize);
+  EVEL_DEBUG("rx chunk size is %d", rx_chunk->size);
+
+  rx_chunk->memory = realloc(rx_chunk->memory, rx_chunk->size + realsize + 1);
+  if(rx_chunk->memory == NULL) {
+    /* out of memory! */
+    printf("not enough memory (realloc returned NULL)\n");
+    return 0;
+  }
+
+  memcpy(&(rx_chunk->memory[rx_chunk->size]), contents, realsize);
+  rx_chunk->size += realsize;
+  rx_chunk->memory[rx_chunk->size] = 0;
+
+  EVEL_DEBUG("Rx data: %s", rx_chunk->memory);
+  EVEL_DEBUG("Returning: %d", realsize);
+
+  EVEL_EXIT();
+  return realsize;
+}
+
+/**************************************************************************//**
+ * Event Handler.
+ *
+ * Watch for messages coming on the internal queue and send them to the
+ * listener.
+ *
+ * param[in]  arg  Argument - unused.
+ *****************************************************************************/
+static void * event_handler(void * arg __attribute__ ((unused)))
+{
+  int old_type = 0;
+  EVENT_HEADER * msg = NULL;
+  EVENT_INTERNAL * internal_msg = NULL;
+  int json_size = 0;
+  char json_body[EVEL_MAX_JSON_BODY];
+  int rc = EVEL_SUCCESS;
+  CURLcode curl_rc;
+  int collector_down_count = 0;
+  int switch_coll = 0;
+
+  EVEL_INFO("Event handler thread started");
+
+  /***************************************************************************/
+  /* Set this thread to be cancellable immediately.                          */
+  /***************************************************************************/
+  pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &old_type);
+
+  /***************************************************************************/
+  /* Set the handler as active, defending against weird situations like      */
+  /* immediately shutting down after initializing the library so the         */
+  /* handler never gets started up properly.                                 */
+  /***************************************************************************/
+  if (evt_handler_state == EVT_HANDLER_INACTIVE)
+  {
+    evt_handler_state = EVT_HANDLER_ACTIVE;
+  }
+  else
+  {
+    EVEL_ERROR("Event Handler State was not INACTIVE at start-up - "
+               "Handler will exit immediately!");
+  }
+  /***************************************************************************/
+  /* Set the connection to collector                                         */
+  /***************************************************************************/
+  while (true)
+  {
+     evel_collector_id = 1;
+     rc = evel_setup_curl();
+
+     if ( rc != EVEL_SUCCESS)
+     {
+        EVEL_ERROR("Failed to setup the first collector. Error code=%d", rc);
+        if (curr_global_handles == 2)
+        {
+           EVEL_DEBUG("Switching to other collector");
+
+           evel_collector_id = 2;
+
+           rc = evel_setup_curl();
+           if ( rc != EVEL_SUCCESS)
+           {
+              EVEL_ERROR("Failed to setup the connection to second collector also, Error code%d", rc);
+              sleep(EVEL_COLLECTOR_RECONNECTION_WAIT_TIME);
+              collector_down_count = collector_down_count + 1;
+              EVEL_ERROR("Collectors setup issue- retry count=%d", collector_down_count);
+           }
+           else
+           {
+              collector_down_count = 0;
+              break;
+           }
+        }
+        else
+        {
+           sleep(EVEL_COLLECTOR_RECONNECTION_WAIT_TIME);
+           collector_down_count = collector_down_count + 1;
+           EVEL_ERROR("Collector setup issue-retry count=%d", collector_down_count);
+         }
+     }
+     else
+     {
+        collector_down_count = 0;
+        break;
+     }
+  }
+
+  while (evt_handler_state == EVT_HANDLER_ACTIVE)
+  {
+    /*************************************************************************/
+    /* Wait for a message to be received.                                    */
+    /*************************************************************************/
+    EVEL_DEBUG("Event handler getting any messages");
+    msg = ring_buffer_read(&event_buffer);
+
+    /*************************************************************************/
+    /* Internal events get special treatment while regular events get posted */
+    /* to the far side.                                                      */
+    /*************************************************************************/
+    if (msg->event_domain == EVEL_DOMAIN_BATCH )
+    {
+      EVEL_DEBUG("Batch event received");
+
+      /***********************************************************************/
+      /* Encode the event in JSON.                                           */
+      /***********************************************************************/
+      json_size = evel_json_encode_batch_event(json_body, EVEL_MAX_JSON_BODY, msg);
+
+      /***************************************************************************/
+      /* Set the URL for the API.                                                */
+      /***************************************************************************/
+      if (evel_collector_id == 1)
+      {
+         curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, evel_batch_api_url);
+      }
+      else
+      {
+         curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, evel_bbatch_api_url);
+      }
+
+      if (curl_rc != CURLE_OK)
+      {
+        rc = EVEL_CURL_LIBRARY_FAIL;
+        log_error_state("Failed to initialize libCURL with the Batch API URL. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+      }
+
+      /***********************************************************************/
+      /* Send the JSON across the API.                                       */
+      /***********************************************************************/
+      EVEL_DEBUG("Sending Batch JSON of size %d is: %s", json_size, json_body);
+      rc = evel_post_api(json_body, json_size);
+
+      switch_coll = 0;
+      if ((rc == EVEL_SUCCESS) && ((http_response_code / 100) != 2))
+      {
+         switch_coll = 1;
+         if (http_response_code == 400) // 400 - Bad JSON related return code
+            switch_coll = 0;
+      }
+
+      if ((rc != EVEL_SUCCESS)  || (switch_coll == 1))
+      {
+        EVEL_ERROR("Failed to transfer the data. Error code=%d", rc);
+        EVEL_DEBUG("Switching to other collector if any");
+
+        while (true)
+        {
+           if (curr_global_handles == 2)
+           {
+              rc = evel_send_to_another_collector(msg->event_domain, json_body, json_size);
+
+              switch_coll = 0;
+              if ((rc == EVEL_SUCCESS) && ((http_response_code / 100) != 2))
+              {
+                 switch_coll = 1;
+                 if (http_response_code == 400) // 400 - Bad JSON related return code
+                    switch_coll = 0;
+              }
+              if ((rc != EVEL_SUCCESS)  || (switch_coll == 1))
+              {
+                 sleep(EVEL_COLLECTOR_RECONNECTION_WAIT_TIME);
+                 collector_down_count = collector_down_count + 1;
+                 EVEL_ERROR("Collector setup issue-retry count=%d", collector_down_count);
+              }
+              else
+              {
+                 break;
+              }
+           }
+           else
+           {
+              sleep(EVEL_COLLECTOR_RECONNECTION_WAIT_TIME);
+              collector_down_count = collector_down_count + 1;
+              EVEL_ERROR("Collector setup issue-retry count=%d", collector_down_count);
+           }
+
+           rc = evel_send_to_another_collector(msg->event_domain, json_body, json_size);
+
+           switch_coll = 0;
+           if ((rc == EVEL_SUCCESS) && ((http_response_code / 100) != 2))
+           {
+              switch_coll = 1;
+              if (http_response_code == 400) // 400 - Bad JSON related return code
+                 switch_coll = 0;
+           }
+           if ((rc != EVEL_SUCCESS)  || (switch_coll == 1))
+           {
+              collector_down_count = collector_down_count + 1;
+              EVEL_ERROR("Collector setup issue-retry count=%d", collector_down_count);
+           }
+           else
+           {
+              break;
+           }
+        }
+      }
+    }
+    else if (msg->event_domain != EVEL_DOMAIN_INTERNAL )
+    {
+      EVEL_DEBUG("External event received");
+
+      /***********************************************************************/
+      /* Encode the event in JSON.                                           */
+      /***********************************************************************/
+      json_size = evel_json_encode_event(json_body, EVEL_MAX_JSON_BODY, msg);
+
+      /***************************************************************************/
+      /* Set the URL for the API.                                                */
+      /***************************************************************************/
+      if (evel_collector_id == 1)
+         curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, evel_event_api_url);
+      else
+         curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, evel_bevent_api_url);
+      if (curl_rc != CURLE_OK)
+      {
+        rc = EVEL_CURL_LIBRARY_FAIL;
+        log_error_state("Failed to initialize libCURL with the API URL. "
+                    "Error code=%d (%s)", curl_rc, curl_err_string);
+      }
+
+      /***********************************************************************/
+      /* Send the JSON across the API.                                       */
+      /***********************************************************************/
+      EVEL_DEBUG("Sending JSON of size %d is: %s", json_size, json_body);
+      rc = evel_post_api(json_body, json_size);
+
+      switch_coll = 0;
+      if ((rc == EVEL_SUCCESS) && ((http_response_code / 100) != 2))
+      {
+         switch_coll = 1;
+         if (http_response_code == 400) // 400 - Bad JSON related return code
+            switch_coll = 0;
+      }
+
+      if ((rc != EVEL_SUCCESS)  || (switch_coll == 1))
+      {
+        EVEL_ERROR("Failed to transfer the data. Error code=%d", rc);
+        EVEL_DEBUG("Switching to other collector if any");
+
+        while (true)
+        {
+           if (curr_global_handles == 2)
+           {
+              rc = evel_send_to_another_collector(msg->event_domain, json_body, json_size);
+
+              switch_coll = 0;
+              if ((rc == EVEL_SUCCESS) && ((http_response_code / 100) != 2))
+              {
+                 switch_coll = 1;
+                 if (http_response_code == 400) // 400 - Bad JSON related return code
+                    switch_coll = 0;
+              }
+              if ((rc != EVEL_SUCCESS)  || (switch_coll == 1))
+              {
+                 sleep(EVEL_COLLECTOR_RECONNECTION_WAIT_TIME);
+                 collector_down_count = collector_down_count + 1;
+                 EVEL_ERROR("Collector setup issue-retry count=%d", collector_down_count);
+              }
+              else
+              {
+                 break;
+              }
+           }
+           else
+           {
+              sleep(EVEL_COLLECTOR_RECONNECTION_WAIT_TIME);
+              collector_down_count = collector_down_count + 1;
+              EVEL_ERROR("Collector setup issue-retry count=%d", collector_down_count);
+           }
+
+           rc = evel_send_to_another_collector(msg->event_domain, json_body, json_size);
+
+           switch_coll = 0;
+           if ((rc == EVEL_SUCCESS) && ((http_response_code / 100) != 2))
+           {
+              switch_coll = 1;
+              if (http_response_code == 400) // 400 - Bad JSON related return code
+                 switch_coll = 0;
+           }
+           if ((rc != EVEL_SUCCESS)  || (switch_coll == 1))
+           {
+              collector_down_count = collector_down_count + 1;
+              EVEL_ERROR("Collector setup issue-retry count=%d", collector_down_count);
+           }
+           else
+           {
+              break;
+           }
+        }
+      }
+    }
+    else
+    {
+      EVEL_DEBUG("Internal event received");
+      internal_msg = (EVENT_INTERNAL *) msg;
+      assert(internal_msg->command == EVT_CMD_TERMINATE);
+      evt_handler_state = EVT_HANDLER_TERMINATING;
+    }
+
+    /*************************************************************************/
+    /* We are responsible for freeing the memory.                            */
+    /*************************************************************************/
+    evel_free_event(msg);
+    msg = NULL;
+
+    /*************************************************************************/
+    /* There may be a single priority post to be sent.                       */
+    /*************************************************************************/
+    if (priority_post.memory != NULL)
+    {
+      EVEL_DEBUG("Priority Post");
+
+      /***********************************************************************/
+      /* Set the URL for the throttling API.                                 */
+      /***********************************************************************/
+      curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, evel_throt_api_url);
+      if (curl_rc != CURLE_OK)
+      {
+        /*********************************************************************/
+        /* This is only likely to happen with CURLE_OUT_OF_MEMORY, in which  */
+        /* case we carry on regardless.                                      */
+        /*********************************************************************/
+        EVEL_ERROR("Failed to set throttling URL. Error code=%d", rc);
+      }
+      else
+      {
+        rc = evel_post_api(priority_post.memory, priority_post.size);
+        if (rc != EVEL_SUCCESS)
+        {
+          EVEL_ERROR("Failed to transfer priority post. Error code=%d", rc);
+        }
+      }
+
+      /***********************************************************************/
+      /* Reinstate the URL for the event API.                                */
+      /***********************************************************************/
+      curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, evel_event_api_url);
+      if (curl_rc != CURLE_OK)
+      {
+        /*********************************************************************/
+        /* This is only likely to happen with CURLE_OUT_OF_MEMORY, in which  */
+        /* case we carry on regardless.                                      */
+        /*********************************************************************/
+        EVEL_ERROR("Failed to reinstate events URL. Error code=%d", rc);
+      }
+
+      /***********************************************************************/
+      /* We are responsible for freeing the memory.                          */
+      /***********************************************************************/
+      free(priority_post.memory);
+      priority_post.memory = NULL;
+    }
+  }
+
+  /***************************************************************************/
+  /* The event handler is now exiting. The ring-buffer could contain events  */
+  /* which have not been processed, so deplete those.  Because we've been    */
+  /* asked to exit we can be confident that the foreground will have stopped */
+  /* sending events in so we know that this process will conclude!           */
+  /***************************************************************************/
+  evt_handler_state = EVT_HANDLER_TERMINATING;
+  while (!ring_buffer_is_empty(&event_buffer))
+  {
+    EVEL_DEBUG("Reading event from buffer");
+    msg = ring_buffer_read(&event_buffer);
+    evel_free_event(msg);
+  }
+  evt_handler_state = EVT_HANDLER_TERMINATED;
+  EVEL_INFO("Event handler thread stopped");
+
+  return (NULL);
+}
+
+/**************************************************************************//**
+ * Handle a JSON response from the listener, contained in a ::MEMORY_CHUNK.
+ *
+ * Tokenize the response, and decode any tokens found.
+ *
+ * @param chunk         The memory chunk containing the response.
+ * @param post          The memory chunk in which to place any resulting POST.
+ *****************************************************************************/
+void evel_handle_event_response(const MEMORY_CHUNK * const chunk,
+                                MEMORY_CHUNK * const post)
+{
+  jsmn_parser json_parser;
+  jsmntok_t json_tokens[EVEL_MAX_RESPONSE_TOKENS];
+  int num_tokens = 0;
+
+  EVEL_ENTER();
+
+  /***************************************************************************/
+  /* Check preconditions.                                                    */
+  /***************************************************************************/
+  assert(chunk != NULL);
+  assert(priority_post.memory == NULL);
+
+  EVEL_DEBUG("Response size = %d", chunk->size);
+  EVEL_DEBUG("Response = %s", chunk->memory);
+
+  /***************************************************************************/
+  /* Initialize the parser and tokenize the response.                        */
+  /***************************************************************************/
+  jsmn_init(&json_parser);
+  num_tokens = jsmn_parse(&json_parser,
+                          chunk->memory,
+                          chunk->size,
+                          json_tokens,
+                          EVEL_MAX_RESPONSE_TOKENS);
+
+  if (num_tokens < 0)
+  {
+    EVEL_ERROR("Failed to parse JSON response.  "
+               "Error code=%d", num_tokens);
+  }
+  else if (num_tokens == 0)
+  {
+    EVEL_DEBUG("No tokens found in JSON response");
+  }
+  else
+  {
+    EVEL_DEBUG("Decode JSON response tokens");
+    if (!evel_handle_response_tokens(chunk, json_tokens, num_tokens, post))
+    {
+      EVEL_ERROR("Failed to handle JSON response.");
+    }
+  }
+
+  EVEL_EXIT();
+}
+
+/**************************************************************************//**
+ * Handle a JSON response from the listener, as a list of tokens from JSMN.
+ *
+ * @param chunk         Memory chunk containing the JSON buffer.
+ * @param json_tokens   Array of tokens to handle.
+ * @param num_tokens    The number of tokens to handle.
+ * @param post          The memory chunk in which to place any resulting POST.
+ * @return true if we handled the response, false otherwise.
+ *****************************************************************************/
+bool evel_handle_response_tokens(const MEMORY_CHUNK * const chunk,
+                                 const jsmntok_t * const json_tokens,
+                                 const int num_tokens,
+                                 MEMORY_CHUNK * const post)
+{
+  bool json_ok = true;
+
+  EVEL_ENTER();
+
+  /***************************************************************************/
+  /* Check preconditions.                                                    */
+  /***************************************************************************/
+  assert(chunk != NULL);
+  assert(json_tokens != NULL);
+  assert(num_tokens < EVEL_MAX_RESPONSE_TOKENS);
+
+  /***************************************************************************/
+  /* Peek at the tokens to decide what the response it, then call the        */
+  /* appropriate handler to handle it.  There is only one handler at this    */
+  /* point.                                                                  */
+  /***************************************************************************/
+  if (evel_tokens_match_command_list(chunk, json_tokens, num_tokens))
+  {
+    json_ok = evel_handle_command_list(chunk, json_tokens, num_tokens, post);
+  }
+
+  EVEL_EXIT();
+
+  return json_ok;
+}
+
+/**************************************************************************//**
+ * Determine whether a list of tokens looks like a "commandList" response.
+ *
+ * @param chunk         Memory chunk containing the JSON buffer.
+ * @param json_tokens   Token to check.
+ * @param num_tokens    The number of tokens to handle.
+ * @return true if the tokens look like a "commandList" match, or false.
+ *****************************************************************************/
+bool evel_tokens_match_command_list(const MEMORY_CHUNK * const chunk,
+                                    const jsmntok_t * const json_tokens,
+                                    const int num_tokens)
+{
+  bool result = false;
+
+  EVEL_ENTER();
+
+  /***************************************************************************/
+  /* Make some checks on the basic layout of the commandList.                */
+  /***************************************************************************/
+  if ((num_tokens > 3) &&
+      (json_tokens[0].type == JSMN_OBJECT) &&
+      (json_tokens[1].type == JSMN_STRING) &&
+      (json_tokens[2].type == JSMN_ARRAY) &&
+      (evel_token_equals_string(chunk, &json_tokens[1], "commandList")))
+  {
+    result = true;
+  }
+
+  EVEL_EXIT();
+
+  return result;
+}
+
+/**************************************************************************//**
+ * Check that a string token matches a given input string.
+ *
+ * @param chunk         Memory chunk containing the JSON buffer.
+ * @param json_token    Token to check.
+ * @param check_string  String to check it against.
+ * @return true if the strings match, or false.
+ *****************************************************************************/
+bool evel_token_equals_string(const MEMORY_CHUNK * const chunk,
+                              const jsmntok_t * json_token,
+                              const char * check_string)
+{
+  bool result = false;
+
+  EVEL_ENTER();
+
+  const int token_length = json_token->end - json_token->start;
+  const char * const token_string = chunk->memory + json_token->start;
+
+  if (token_length == (int)strlen(check_string))
+  {
+    result = (strncmp(token_string, check_string, token_length) == 0);
+  }
+
+  EVEL_EXIT();
+
+  return result;
+}