​A new configuration file parameter showed up in Oracle REST Data Services (ORDS) version 18.3. The parameter is called ‘procedure.rest.preHook’. Whilst this may seem like a pretty innocuous change, I believe it opens up a number of new possibilities for ORDS, which I will explore in this post.

​The parameter essentially allows you to identify a PL/SQL procedure which is called by ORDS prior to every web service call in a particular connection pool. This includes GET, POST, PUT and DELETE services. This gives you a spot where you can execute any code you want just before (and in the same database session as) every web service. ORDS expects the function to return a Boolean, and it will automatically return a HTTP status of 403 ‘forbidden’ and stop the execution of the handler code if the function returns a value of false.
 
Per the documentation, the parameter ‘procedure.rest.preHook’ : “Specifies the function to be invoked prior to dispatching each Oracle REST Data Services based REST Service. The function can perform configuration of the database session, perform additional validation or authorization of the request. If the function returns true, then processing of the request continues. If the function returns false, then processing of the request is aborted and an HTTP 403 Forbidden status is returned.”

Adding the parameter to the ORDS parameter file is pretty straight forward. Add the following entry to your defaults.xml (or add it to a specific connection pool if applicable):
<entry key="procedure.rest.preHook">xxrest.rest_utl.pre_hook</entry>
 
Note: The above entry assumes I have a package called rest_utl with a function called pre_hook, which I created in the schema xxords. Here is the package specification for the above example:

​Grants
The procedure needs to be executable from all schemas that your ORDS services are run from. For example, if you create a Prehook function called REST_UTL_PK.PRE_HOOK in the schema XXORDS, and you are running ORDS services from schemas XXORDS and XXREST, then you must grant execute on XXORDS.REST_UTL_PK.PRE_HOOK to the schema XXREST. If you do not, you will get the following error when running services from XXREST:

​Logging ORDS activity to a database table is probably the subject of a longer post. In short, there are two primary reasons you may want to log invocations of your ORDS services. The first is to track usage. Knowing what methods and resources are being utilized is extremely helpful. You can keep track of which services are and are not being used, which clients are using which services etc.
 
The second reason is to track, and trouble shoot errors that occur during web service execution. Obviously, the Prehook function won’t help us with logging errors raised by our web services because at the time it is called, the service has not yet run. It can, however, be used to perform all of our usage logging.
 
In some cases, we could already do this, by adding the log table insert to our handler logic. This did not, however, work for GET services where our handler was a SQL statement.
 
Let’s look at how we could go about adding table usage logging for all our ORDS services using the Prehook function.

​First you will need to create a logging table with columns that can capture information about the service invocation. Let’s consider the following table called rest_log:

​This table is by no means comprehensive but serves the purpose for this example. Our Prehook function to populate this table could look something like this:

​That’s not a lot of code to log every ORDS web service call!
 
You may notice in the above example that I am tracking a custom HTTP Header ‘X_USER_NAME’. This is to illustrate that you may want to introduce custom http headers so that you can track additional attributes about the client.

​Setting database session context is a particularly good use of this parameter. Let’s say you are operating in an Oracle e-Business Suite (EBS) environment. Each call to a web service needs to set the EBS session context based on the user and responsibility. This ensures the correct user and operating unit is used when querying data or calling EBS public APIs to create and update records. This is typically performed using the EBS API fnd_global.apps_initialize.
 
Before now, we could do this for POST services by including a call to fnd_global.apps_initialize at the start of the handler logic. This was not possible, however, for a GET based on a SELECT statement. This meant we had to build GET services using a PL/SQL block and emit the JSON manually using APEX_JSON.
 
The Prehook function allows us to call fnd_global.apps_initialize at the start of the session and have that context applied when the web service is called. This is much cleaner.

Of course, there are use cases outside of the EBS world where you need to set session information especially if you are using VPD (Virtual Private Database) or something similar to perform row-based security on your data.

​As the documentation suggests, the primary use for the Prehook function is to perform custom authorization. All you have to do is have the function return false, and ORDS will automatically return a 403 ‘Forbidden’ HTTP response code to the caller. If you use a custom token for authorization, you can use this function to verify the token, user name and password etc.

For example, you may want client X to have access to the GET and POST handler for a resource but not the DELETE handler. In this example, you can use the ‘REQUEST_METHOD’ CGI environment variable to determine the method (GET, POST, PUT or DELETE) and a combination of ‘PATH_INFO’ and ‘SCRIPT_NAME’ to determine the resource. Assuming you pass an identifier for the client in a http header, based on these values you can then decide if the call should be allowed or not.
 
I still recommend you use ORDS standard OAUTH token security as your primary method of authorization. If, however, the client cannot support OAUTH, or you need to supplement standard OAUTH with some additional checks, the Prehook function is a great option.

​I would also like to see a postHook function parameter, this would hopefully give developers access to the resultant http status and allow us to log the final status of each web service call. Ideally, it would also have access to the :body_text and response payloads. This would allow developers to implement a complete table logging solution for ORDS.

​The Prehook function capability is a well thought out feature that will be a big help to ORDS web service developers. Hopefully this post gave you some ideas on how it could be used, although I have no doubt there are many more uses cases out there.

There is an entire section of the ORDS documentation dedicated to this feature which includes examples.
 
P.S. It will be interesting to see if and how the ORDS development team plans to expose parameters like these to multi-tenant PaaS offerings such as Exadata Express. This may prove a challenge given the parameter is currently set in the parameter file on the server. 

​REST enabled SQL was first introduced in ORDS 17.4. It is an important feature in the continued evolution of ORDS as a product. REST enabled SQL fits very well into Oracle’s Cloud mantra, in that it enables functionality much akin to a database link but without incurring the resource overhead and the security shortfalls of database links. It essentially provides developers to run Queries, DML, DDL and PL/SQL  statements against an Oracle database via a REST interface.

GraphQL is a relatively new open-source technology, introduced by Facebook. GraphQL is a data query and manipulation language for APIs, and a runtime for fulfilling queries with existing data.

​While the relationship between GraphQL and REST enabled SQL may not be immediately obvious, I believe there are many similarities and plan to describe them in this post.

From Wikipedia: “GraphQL is an open-source data query and manipulation language for APIs, and a runtime for fulfilling queries with existing data. GraphQL was developed internally by Facebook in 2012 before being publicly released in 2015. On 7 November 2018, the GraphQL project was moved from Facebook to the newly-established GraphQL foundation, hosted by the non-profit Linux Foundation”.
 
Essentially, GraphQL allows a front-end developer to generate a dynamic data query without needing to know the underlying database technology. Much like REST services therefore, GraphQL abstracts the developer from the underlying database. Because of its dynamic nature, however, GraphQL removes the need to build a REST end-point to cover every resource and data element. Instead, you build one back end end-point to handle all requests. You then dynamically build your query on the front end (using a special JSON format) and submit your query to the server for execution. This avoids the overhead of calling multiple REST resources and then consolidating the responses.
 
GraphQL is not a database, it is a query language that allows you to inquire on data. It requires a backend (think middleware server) that handles the query and dispatches the query to the appropriate database(s) to get the actual data. These databases could be MySQL, Oracle, Postgress etc. An example of a GraphQL API server is an open source product called Prisma.

​GraphQL allows the client to decide exactly what data it wants. If you are just looking for the customer name and number, you can limit your GraphQL query to just those fields. Most REST services would force you to retrieve all attributes of a customer this bloating the payload.
 
GraphQL is strongly typed and each type describes a set of available fields. This not only facilitates descriptive error messages but also allows you to inquire on the types that are supported by the database.
 
So, what does a GraphQL query look like?

​You can see that the query itself defines the shape of the data that should be returned.
 
This all sounds great but the GraphQL server does not come for free. It obviously needs to understand everything about the underlying databases. Forgetting the infrastructure requirements, the work of mapping all of that data can be a big hurdle.
 
So how can Oracle RAD stack developers achieve some of the benefits of GraphQL using the software they already own? ORDS and REST enabled SQL to the rescue.

REST enabled SQL allows a client to send any SQL statement to an Oracle database and have the database execute that statement.
These statements can include:

• SELECT, UPDATE, DELETE
• PL/SQL Blocks
• SQL*Plus and SQLCL Commands

​Attributes of REST Enabled SQL that are similar to Graph include:

• The client can inquire on what tables and views are available in the database by inquiring on the data dictionary.
• The client can inquire on the structure of specific tables and views and receive detailed information on each column (i.e. columnName, jsonColumnName, type, precision, scale and isNullable)
• The client can request exactly what data it wants by defining it in the SQL statement.
• REST enabled SQL uses a single end-point “https://<HOST>/ords/<SchemaAlias>/_/sql“ for all inquiries (not multiple separate REST services).
• Because it is using the Oracle database, the data is strongly typed.
• You can join multiple tables (an or use views) to consolidate data into one request that would otherwise have required you to call multiple REST resources and then merge the data together.

 
​An interesting point to note here is that much like with GraphQL, a ‘smart’ client can navigate an inquire on a database with no pre-programmed knowledge of the structure of the database.
 
Other attributes of REST Enabled SQL:

• Queries can be expressed as a simple select statement ‘SELECT SYSDATE FROM DUAL’ or by passing a structured JSON document.
• REST enabled SQL can be secured by:
  • Schema Authentication (the database schema user name and password).
  • OAuth 2 Client Credentials (client gets a token and then uses that token for subsequent calls)
  • First Party Authentication (Basic Authentication). Utilize a user and password created in Oracle REST Data Services with the SQL Developer role.

 
Probably the biggest mismatch between GraphQL and REST Enabled SQL is that REST enabled SQL assumes the client/developer knows the Oracle database. While this may sound like heresy to the open source world, in the RAD stack world this is not a bad thing. In fact, embracing the power of the Oracle database is something every RAD stack developer should be looking to do.

​To enable REST enabled SQL for your instance, you need to add the following entry to the ORDS parameter file on your server (typically defaults.xml):
<entry key="restEnabledSql.active">true</entry>
 
In order to use REST enabled SQL for a specific schema, you also need to REST enable the schema, just like you would to allow creation of any ORDS services in a schema.

• Connect to the Schema
• Run the command: exec ords.enable_schema;

 
Important Note: As mentioned in the documentation “Enabling the REST- Enabled SQL service enables authentication against the Oracle REST Data Service enabled database schemas. This makes the database schemas accessible over HTTPS, using the database password. Oracle highly recommends that you provide strong secure database passwords”.

In view of this warning described above, I advise that you create an entirely separate schema for use with REST enabled SQL (and make the schema password very complex). This at least limits your exposure to that one schema. Added to that, you should also avoid using Schema Authentication (i.e. use schema name and password) whenever possible and instead use OAUTH2 Client Credentials Authentication.
 
If a third party needs to access your database using REST enabled SQL, setup OAUTH2 Client Credentials Authentication by performing the following steps:

• Create a new schema e.g. SYSTEMX
• Login as SYSTEMX and run ords.enable_schema to enable ORDS in the schema
• Create the appropriate grants to the schema SYSTEMX for the tables and views you want to provide access to.
• Create an OAUTH client and assign the role ‘SQL Developer’
• Provide the client with the client_id and client_secret values from the table ORDS_METADATA.OAUTH_CLIENTS.
• The client would then use the client id and secret to get a token and use that and would never know the schema password.

​Unfortunately, even when you configure OAUTH2 Client Credentials Authentication you can still use Schema Authentication. I would like to see a way of turning Schema Authentication off for a schema that has OAUTH2 Client Credentials Authentication.

In this example, I am going to be using the ‘application/sql’ Content-Type. This indicates to ORDS that it should expect a SQL statement in the payload. You can also use ‘application/json’ and pass a structured JSON document. You may notice that I am using OAUTH2 Client Credentials security and passing a token with each call.
 
I have created a table called atx_ev_charging_stations which contains a list of the electric vehicle charging stations in Austin. The first think I need to do is get a definition of the table. REST enabled SQL will always return a metadata array in the response, this describes the columns in the SELECT statement. All I need to do is pass a SQL statement that I know will return no rows and I can get the metadata e.g. 'select * from  atx_ev_charging_stations where 1=2'

​I have just shown the first column in the metadata array, but you can see from this the metadata information that is returned about each column.
 
Now I understand the table structure I can form a query to get the charging station name and first line of the address for charging stations at apartments in the zip code 78704.

​Notice I am only asking for two columns from the table. An equivalent REST resource would need to contain all of the columns in order to fulfill the requirements of all inquiries on this resource:

​In this post, I provided some insight into what GraphQL is and how it can be compared to ORDS and REST enabled SQL. I also provided a high-level overview of REST enabled SQL along with a basic example. From this, I hope to convey what a powerful feature REST enabled SQL is and how you may be able to use it in your applications.

​I have been working with Oracle e-Business Suite (EBS) since version 9.4 (that’s character mode!). Although EBS has come a long way since then, even the newer releases are starting to look long in the tooth. In this post I will explore a number of use cases where Oracle APEX was used to bring the joy back to ERP without spending a whole lot of money.

​Although many companies are moving their ERP to the cloud, many cannot because cloud ERPs offerings do not yet provide all of the features, they need to run their business. This leaves companies running on-premise ERP systems like EBS version 12.1.3 in limbo. Do they try and upgrade to version 12.2 for an incremental improvement in UX or do they wait until key cloud features are available and then move to the cloud? If they wait, how do they explain to their users that the technical acrobatics required to run Java from a browser these days is worth the effort? The user base for such companies are in full revolt and they won’t stand for it any more. This is especially challenging for companies that have introduced edge application such as HR in Workday. Users now know what is possible and want more of it.

So, how can an IT department provide a significant improvement in UX to EBS users for zero additional software cost? Oracle APEX is a no cost option of the Oracle database. APEX provides you with all the tools you need to build beautiful, scalable apps in a single, extensible platform, which runs as a part of Oracle Database. In this case it will run in the same database as EBS, providing zero latency data access.
 
What you will need

• An application server (or VM) to run Tomcat and ORDS (e.g. 25GB Disk 4GB Memory, 1 CPU)
• Install the latest version of APEX on the EBS Oracle Database
• Install Tomcat and ORDS on the Tomcat/ORDS server

Note: There is no additional cost for any of the software mentioned above.
 
I am not advocating re-writing EBS in APEX, far from it. What I am advocating is taking a few key processes that have high visibility and high impact to your organization and using APEX to provide a modern easy to use interface.

I have found that using APEX to extend EBS makes it easier to introduce other technologies that can also transform the way users interact with EBS. For example:

• Voice interfaces to EBS with Alexa.
• Utilizing SMS to communicate with your employees (and process responses).
• Introducing PaaS products like Exadata Express to extend EBS outside of your firewall.
• Leveraging AWS S3 for document storage.
  
• Provide custom mobile interfaces for users to interact with EBS.

​In all likelihood, your organization has an annual review and performance management process. If you do then it is also likely that most people in your organization participate, making it a highly visible process. Oracle EBS has a performance management module that is fully functional and integrates well with Oracle Human Resources. The User Experience, however, is not something you can be proud of. In addition, you are probably spending a significant amount of time managing issues related to this poor UX.
 
Last year JMJ developed an APEX application to replace the employee facing side of EBS performance management. This application acted as a skin on the underlying Oracle performance management module, utilizing standard Oracle APIs to create and update records in the EBS data model.

1. Employees logged in directly to the APEX App, using their EBS credentials. The App had a URL that was easy to remember and was not associated with EBS. The UX for the app was completely unlike EBS, in fact it more closely resembled a consumer application.
2. On the back end, the HR department used the standard EBS functionality for tasks such as moving appraisals to compensation workbench.

 
The overall impact was dramatic. People actually liked using the application, not only did this make employees feel good but it increased participation in the process.

My second example involves taking a critical business process and building a custom application to manage that process in a way that would not be possible with standard functionality. To some, this may sound like heresy. In fact, for the 18 years I worked for Oracle Consulting extending EBS and ERP Cloud, my mantra was always don’t customize unless you have to. The key here is the word ‘have to’. If you can save a million dollars a year (or make an additional million dollars a year) by building a product that costs 250 thousand dollars a year to maintain and upgrade, then you have to do it.
 
JMJ Cloud recently built an APEX application that managed the receipt and processing of material at over 40 manufacturing plants. In doing this, we built a whole new UI for plant staff to greatly simplify their interactions with EBS. Behind the scenes, however, were able to use significant pieces of EBS functionality to avoid having to re-invent the wheel.

1. Plant users’ gain access via either a native iOS mobile application or an APEX App. These users perform plant operations such as receiving material, creating sales orders, logging production etc.
2. Back office and corporate staff log directly into EBS to perform back office processing. e.g. pricing and booking orders, creating invoices etc.

 
Simplified overview of the business process:

• Material delivered by customer for processing:
  • User logs into APEX and created a new job.
  • The APEX UI for creating the job pulls customer information directly from EBS. When a job is created, an EBS Sales Order header is also created.
  • During the receiving process order lines are added to the EBS Sales Order via an APEX page. The receiver enters just 3 fields per order line in the APEX application making data entry simpler and faster.
• As material is processed production data is posted via the APEX App, to the associated sales order lines in EBS.
• Once the sales order is priced and booked, invoicing and collections is handled from standard EBS.

 
The APEX application in conjunction with a native iOS app that speaks to EBS using Oracle REST Data Services (ORDS), means the majority of users at the plant do not have to be concerned with EBS at all. In an environment with a high turnover of staff who have limited technical skills, having an easy to use and simplified UI is critical.

As I mentioned earlier, Oracle EBS is one of the most feature rich ERP platforms out there. This complexity can be both a blessing and a curse. A single Oracle module can take months of effort to implement and you may end up using less than 25% of the full functionality of that module. The problem is you are paying for 100% of the functionality. If you could build the pieces of the module that you really need and then integrate that with other aspects of EBS you could end up saving money and providing a more modern user experience at the same time.
 
One example of this is a Capital Expenses Tracking system which JMJ Cloud recently built for an EBS customer. This was a relatively simple 8-page (4 table) application that allows users to enter details of a Capital Expenditure request and then submit the request for approval. Having the new App build on the EBS database, allows us to leverage EBS for much of the heavy lifting.
For example:

• Authenticate users using Oracle EBS credentials
• Use EBS view, value sets and lookups as the source for List of Values to reduce dual maintenance and increase consistency. (e.g. List of GL account segments, List of GL periods)
• Utilize Oracle Workflow to handle notifications and approvals of submissions
• Provide list of Capital Project budgets (from Oracle Projects in EBS) to associate a CAPEX request with

​Oracle EBS is one of the most (if not the most) feature rich ERP application on the market. Often times, these features have come at the expense of UX and in 2018, the UI is showing its age more than ever. By using APEX to replace the UX of key processes in EBS, you can bring the joy back to ERP for your users. Applications that bring users joy are known to have higher adoption rates and bring more smiles. Using APEX to modernize your existing EBS implementation can buy the time you need for Cloud offerings to match the functionality that you need to run your business.