Event-Driven Integration with OCI Events, ORDS, & APEX

Event-Driven Integration with OCI Events, ORDS, & APEX

Jon Dixon
·Jul 29, 2022·

8 min read

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Table of contents

Introduction

There are several providers, including Oracle, that sell comprehensive integration solutions. Sometimes, these are necessary, but they can be overkill (and expensive) in many cases. In this post, I will describe an event-driven file-based integration approach using APEX, ORDS, OCI Object Store, and OCI Events. This approach allows us to create a fully automated no-touch file integration using products available on the OCI Cloud Free Tier.

Integration Architecture

The diagram below describes the high-level architecture for this approach: Oracle OCI Object Store Events Integration

  1. The source system generates export files
  2. The source system posts files to OCI Object Store
  3. OCI Object Store raises an event when each file is created in OCI Object Store
  4. ORDS receives JSON documents from the OCI events
  5. The ORDS POST Handler PL/SQL parses the event JSON and fetches the file from OCI Object Store. The file is parsed and loaded into local tables
  6. APEX can now access the data in the local tables

Example Use Case

One real-world example of this approach is the integration of General Ledger Journal entries from Oracle ERP Cloud to a SaaS Oracle Database. This involved configuring ERP Cloud Business Intelligence Cloud Connector (BICC) to bulk export journal entries to an OCI Bucket. An OCI Event was configured to trigger when the files hit Object Store and call an ORDS Web Service to fetch the newly generated files and import them into a local table. This integration was capable of importing five and a half million ERP Cloud Journal Entry records in five minutes.

Creating the Integration

There are several pieces and parts to the integration approach. I will describe each of them in this section.

ORDS Template and Handler

We need to create an ORDS Template and Handler to receive a JSON payload from the OCI Event and process it.

ORDS Template

Screenshot of ORDS Template

ORDS Handler

Screenshot of ORDS Handler Screenshot of ORDS Handler Parameters

ORDS Handler PL/SQL Code

The PL/SQL package/procedure below can be used as a starting point. i.e., it is not production-ready. The code does the following:

  • Parse the OCI Event JSON
  • Check to see if the payload contains the initial Confirmation URL (see below for details)
  • If it does, then capture and log the Confirmation URL
  • If it does not, then capture the file name, bucket name, and file extension from the Create Object Event JSON
  • 🚧 I have not included the code to fetch the file from OCI Object Store and process it. We will discuss options for achieving this later in the post
CREATE OR REPLACE EDITIONABLE PACKAGE BODY blog_oci_pk AS

  -- Scope prefix used for Logger
  GC_SCOPE_PREFIX    CONSTANT VARCHAR2(60)   := LOWER($$plsql_unit) || '.';

-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
PROCEDURE oci_object_created
  (p_payload      IN CLOB,
   x_http_status OUT NUMBER) IS

  l_logger_scope    logger_logs.SCOPE%TYPE := GC_SCOPE_PREFIX || utl_call_stack.subprogram(1)(2);
  l_logger_params   logger.tab_param;
  l_json_object     JSON_OBJECT_T;
  l_bucket_name     VARCHAR2(500);
  l_file_name       VARCHAR2(500);
  l_file_extension  VARCHAR2(10);
  l_confirm_url     VARCHAR2(1000);

BEGIN

  -- Assume Success
  x_http_status := 201;

  logger.append_param(l_logger_params, 'payload', p_payload);
  logger.log('Start', l_logger_scope, NULL, l_logger_params);

  -- Parse The OCI Notification JSON Payload.
  BEGIN
    l_json_object    := JSON_OBJECT_T.PARSE(p_payload);

    -- When you first establish a Notification in OCI, it Sends a URL to the EndPoint to confirm
    --   you are who you say you are. Check to See if this is that Initial Callback and log the URL to the log file.
    IF l_json_object.has('ConfirmationURL') THEN
      l_confirm_url  := l_json_object.get_String('ConfirmationURL');
      logger.append_param(l_logger_params, 'confirm_url', l_confirm_url);
      logger.log_info('First Call, Confirm URL', l_logger_scope, NULL, l_logger_params);
    ELSE
      -- Get information about the file that was received.
      l_file_name      := l_json_object.get_Object('data').get_String('resourceName');
      l_bucket_name    := l_json_object.get_Object('data').get_Object('additionalDetails').get_String('bucketName');
      l_file_extension := apex_string_util.find_file_extension(p_filename => l_file_name);
      logger.append_param(l_logger_params, 'file_name', l_file_name);
      logger.append_param(l_logger_params, 'bucket_name', l_bucket_name);
      logger.append_param(l_logger_params, 'file_extension', l_file_extension);
      logger.log('File Info Captured', l_logger_scope, NULL, l_logger_params);

       -- TBD - Fetch file from Object Store and Process it.

    END IF;
  EXCEPTION WHEN OTHERS THEN
    logger.log_error('Failed to Parse OCI File ['||SQLERRM||']', l_logger_scope, NULL, l_logger_params);
    x_http_status := 400;
    RETURN;
  END;

EXCEPTION WHEN OTHERS THEN
  logger.log_error('Unhandled Error ['||SQLERRM||']', l_logger_scope, NULL, l_logger_params);
  x_http_status := 400;
END oci_object_created;

END blog_oci_pk;

OCI Components

Let's turn now to the OCI components that make up this approach.

OCI Object Store Bucket

I already have an OCI compartment called DEV in which I will create a new bucket.

  • Login to the OCI Console
  • 🧭 Storage > Object Storage & Archive > Buckets > Click 'Create Bucket'
  • Enter a Bucket Name and check 'Emit Object Events'. This allows OCI to post bucket lifecycle events (e.g., create, delete object, etc.) to OCI Event Topics OCI Object Store Create Bucket
  • After Bucket creation Screenshot of OCI Object Store Bucket after Creation

OCI Notification Topic and Subscription

Next, we must tell OCI what to do when a file is created in our Bucket. We do this by creating a Notification Topic and then Subscribing the ORDS Web Service to the topic.

  • Login to the OCI Console
  • 🧭 Developer Services > Application Integration > Notifications > Click 'Create Topic'
  • Enter a name and description, then click 'Create' OCI Create Topic.png
  • Click on the Topic Name, then click 'Create Subscription'. Enter your ORDS Web Service URL in the URL field OCI Create Subscription.png
  • After creation, the subscription will be in 'Pending' status OCI Subscription Pending.png
  • OCI does not immediately activate the subscription. Instead, it sends JSON containing a Confirmation URL to your ORDS Web Service. The subscription will not be activated until you access the Confirmation URL
  • Because this initial Confirmation JSON will differ from the event JSON, you need to include code in your ORDS Handler to accept and store this confirmation URL JSON. I have included this logic in the sample PL/SQL procedure described above called oci_object_created
  • Example Confirmation URL JSON
    {"ConfirmationURL":"https://cell1.notification.us-ashburn-1.oci.oraclecloud.com/20181201/subscriptions/ocid1.onssubscription.oc1.iad.XXXX/confirmation?token=MDAwMHRhYUJOTWZTUjZic1NmUDdGYlN0bEVIbFdyRm45T092emJkemZySFdXM1picGkxVlXXXX==&protocol=CUSTOM_HTTPS"}
    
  • To complete confirmation, copy and paste the confirmation URL from the JSON into a browser address bar OCI Enter Confirmation URL

  • If you look at your subscription again, it should now be active OCI Subscription Confirmed.png

Create OCI Event Rule

Next, we need to create an Event Rule to post a message to the notification topic whenever a file is created in the OCI Bucket.

  • Login to the OCI Console
  • 🧭 Observability & Management > Events Services > Rules > Click 'Create Rule'
  • Enter a Display Name
  • Under Rule Conditions; Service Name = 'Object Storage', Event Type = 'Object -Create'
  • Under Actions; Action Type = 'Notifications', Topic = 'The Topic you Created Above' OCI Create Event Rule.png

Testing the Integration

We now have everything in place to test our integration. Let's upload a test file to make sure everything is working OK.

  • Login to the OCI Console
  • 🧭 Storage > Object Storage > Buckets > Click the Newly Created Bucket Name
  • Click Upload and Upload a test file
  • Within a couple of seconds, you should see the event in the Event Metrics OCI Event Metrics.png
  • Here is a sample JSON document received by the ORDS Web Service from an Object Store Create Object event. The JSON contains everything we need to go and fetch the file from Object Storage
    {
    "eventType" : "com.oraclecloud.objectstorage.createobject",
    "cloudEventsVersion" : "0.1",
    "eventTypeVersion" : "2.0",
    "source" : "ObjectStorage",
    "eventTime" : "2022-06-29T18:34:43Z",
    "contentType" : "application/json",
    "data" : {
      "compartmentId" : "ocid1.compartment.oc1..XXXX",
      "compartmentName" : "DEV",
      "resourceName" : "Sample_File.json",
      "resourceId" : "/n/nueva/b/BLOG_FILES/o/Sample_File.json",
      "availabilityDomain" : "IAD-AD-3",
      "additionalDetails" : {
        "bucketName" : "BLOG_FILES",
        "versionId" : "25b08005-77b3-42c3-86cb-bcb32d2c8d4e",
        "archivalState" : "Available",
        "namespace" : "XXXX",
        "bucketId" : "ocid1.bucket.oc1.iad.XXXX",
        "eTag" : "03a5d98f-9dff-4ce6-bded-9047840c288d"
      }
    },
    "eventID" : "c6f0012a-a04d-3e92-bb02-24e6392e6639",
    "extensions" : {
      "compartmentId" : "ocid1.compartment.oc1..XXXX"
    }
    }
    

Completing the Integration

In the sample PL/SQL procedure oci_object_created, we stubbed out the code to fetch and parse the file. In this section, I'll discuss options for completing these steps.

Synchronous Vs. Asynchronous

We first have to decide if we want to process the file immediately when it is created or defer processing until a later time.

Synchronous Processing We could add code to fetch and process files inside our ORDS Handler procedure. This provides for real-time processing of files posted to OCI Object Store.

Asynchronous We could also change the ORDS Handler to log details of the newly created file in a local queue table. We can then create an APEX Automation to query the queue table and process the file at a later time.

Whichever option you choose, the approach for fetching and parsing the file will be the same.

Fetching the File

We can use the APEX_WEB_SERVICE PL/SQL API to fetch files from OCI Object Store.

Before we can do this, we need to create an APEX Web Credential that will authenticate any requests we make to the OCI Bucket. Read my post Setup Secure APEX Access to OCI Object Storage to find out how to do this.

We can now reference the APEX Web Credential to fetch files from OCI. The PL/SQL block below will fetch the test file from OCI into a BLOB variable.

DECLARE
   l_oci_url    VARCHAR2(500);
   l_file_blob  BLOB;
BEGIN
  -- Create an APEX Session (required to reference Web Credential in APEX_WEB_SERVICE)
  apex_session.create_session (p_app_id => 2000, p_page_id => 1, p_username => 'OCI');
  l_oci_url := 'https://objectstorage.us-ashburn-1.oraclecloud.com/n/XXXX/b/BLOG_FILES/o/Sample_File.json';
  l_file_blob := apex_web_service.make_rest_request_b
   (p_url                  => UTL_URL.ESCAPE(l_oci_url),
    p_http_method          => 'GET',
    p_credential_static_id => 'WEB_CREDENTIAL_STATIC_ID');
END;

The URL is made up of the following components:

  • The Object Store Region Endpoint e.g. https://objectstorage.us-ashburn-1.oraclecloud.com
  • The object storage name space e.g. /n/XXXX. You can get the Namespace from the OCI Console, by clicking the Profile Icon (top right), then click 'Tenancy'. Use the value hidden by the green highlight in the screenshot below OCI Tenancy Information.png
  • The bucket name e.g., /b/BLOG_FILES
  • The filename e.g., /o/Sample_File.json

The value for p_credential_static_id is the APEX Web Credential Static ID created above.

Parsing and Processing the File

Now that we have the file in a BLOB variable, we can parse it using the APEX_DATA_PARSER PL/SQL API. Read my post Easy file Parsing with the APEX_DATA_PARSER API for more details. You can use APEX_DATA_PARSER to parse CSV, XLSX, XML or JSON files.

With the data parsed, load it into local tables so that it can be used by your APEX Applications.

Conclusion

There are many ways any one integration can be implemented. I encourage you to consider using APEX and ORDS to see if you can implement an elegant solution using these no cost options of the Oracle Database.

In this post, I showed you how you can build such an elegant solution with some help from OCI Object Store and OCI Events.

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