JSON Interface – examples

We have several ways of using the JSON interfaces. I will give few examples with the required C/AL code. I will be using Advania’s Online Banking solution interfaces for examples.

The Advania’s Online Banking solution is split into several different modules. The main module has the general framework. Then we have communication modules and functionality modules.

On/Off Question

A communication module should not work if the general framework does not exist or is not enabled for the current company. Hence, I need to ask the On/Off question

This is triggered by calling the solution enabled Codeunit.

The interface function will search for the Codeunit, check for execution permissions and call the Codeunit with an empty request BLOB.

The “Enabled” Codeunit must respond with a “Success” variable of true or false.

The “Enabled” Codeunit will test for Setup table read permission and if the “Enabled” flag has been set in the default record.

This is how we can make sure that a module is installed and enabled before we start using it or any of the dependent modules.

Table Access Interface

The main module has a standard response table. We map some of the communication responses to this table via Data Exchange Definition. From other modules we like to be able to read the response from the response table.

The response table uses a GUID value for a primary key and has an integer field for the “Data Exchange Entry No.”. From the sub module we ask if a response exists for the current “Data Exchange Entry No.” by calling the interface.

The Interface Codeunit for the response table will filter on the “Data Exchange Entry No.” and return the RecordID for that record if found.

If the response is found we can ask for the value of any field from that record by calling

Processing Interface

Some processes can be both automatically and manually executed. For manual execution we like to display a request page on a Report. On that request page we can ask for variables, settings and verify before executing the process.

For automatic processing we have default settings and logic to find the correct variables before starting the process. And since one module should be able to start a process in the other then we use the JSON interface pattern for the processing Codeunit.

We also like to include the “Method” variable to add flexibility to the interface. Even if there is only one method in the current implementation.

Reading through the code above we can see that we are also using the JSON interface to pass settings to the Data Exchange Framework. We put the JSON configuration into the “Table Filters” BLOB field in the Data Exchange where we can use it later in the data processing.

From the Report we start the process using the JSON interface.

The ExecuteInterfaceCodeunitIfExists will also verify that the Interface Codeunit exists and also verify the permissions before executing.

Extensible Interface

For some tasks it might be simple to have a single endpoint (Interface Codeunit) for multiple functionality. This can be achieved by combining Events and Interfaces.

We start by reading the required parameters from the JSON and then we raise an event for anyone to respond to the request.

We can also pass the JSON Interface Codeunit, as that will contain the full JSON and will contain the full JSON for the response.

One of the subscribers could look like this

Registration Interface

This pattern is similar to the discovery pattern, where an Event is raised to register possible modules into a temporary table. Example of that is the “OnRegisterServiceConnection” event in Table 1400, Service Connection.

Since we can’t have Event Subscriber in one module listening to an Event Publisher in another, without having compile dependencies, we have come up with a different solution.

We register functionality from the functionality module and the list of modules in stored in a database table. The table uses a GUID and the Language ID for a primary key, and then the view is filtered by the Language ID to only show one entry for each module.

This pattern gives me a list of possible modules for that given functionality. I can open the Setup Page for that module and I can execute the Interface Codeunit for that module as well. Both the Setup Page ID and the Interface Codeunit ID are object names.

The registration interface uses the Method variable to select the functionality. It can either register a new module or it can execute the method in the modules.

In the “ExecuteMethodInApps” function I use the filters to make sure to only execute each Interface Codeunit once.

The registration is executed from the Setup & Configuration in the other module.

Extend functionality using the Registered Modules.

As we have been taught we should open our functionality for other modules. This is done by adding Integration Events to our code.

Where the Subscriber that needs to respond to this Publisher is in another module we need to extend the functionality using JSON interfaces.

First, we create a Codeunit within the Publisher module with Subscribers. The parameters in the Subscribers are converted to JSON and passed to the possible subscriber modules using the “ExecuteMethodInApps” function above.

The module that is extending this functionality will be able to answer to these request and supply the required response.

Azure Function

The last example we will show is the Azure Function. Some functionality requires execution in an Azure Function.

By making sure that our Azure Function understands the same JSON format used in our JSON Interface Codeunit we can easily prepare the request and read the response using the same methods.

We have the Azure Function Execution in that same JSON Codeunit. Hence, easily prepare the request and call the function in a similar way as for other interfaces.

The request JSON is posted to the Azure Function and the result read with a single function.

We use the “OnBeforeExecuteAzureFunction” event with a manual binding for our Unit Tests.

In the Azure Function we read the request with standard JSON functions

Then based on the Method we call each functionality with the request and write the response to the response JSON.

Conclusion

Having standard ways of talking between modules and solutions has opened up for a lot of flexibility. We like to keep our solutions as small as possible.

We could mix “Methods” and “Versions” if we at later time need to be able to extend some of the interfaces. We need to honor the contract we have made for the interfaces. We must not make breaking changes to the interfaces, but we sure can extend them without any problems.

By attaching the JSON Interface Codeunit to the post I hope that you will use this pattern in your solutions. Use the Code freely. It is supplies as-is and without any responsibility, obligations or requirements.

JSON Interface – prerequisites

There are two objects we use in all JSON interfaces. We use the TempBlob table and our custom JSON Interface Codeunit.

Abstract

JSON interface uses the same concept as a web service. The endpoint is defined by the Codeunit Name and the caller always supplies a form of request data (JSON) and expects a response data (JSON).

These interface calls therefore are only internal to the Business Central (NAV) server and are very fast. All the data is handled in memory only.

We define these interfaces by Endpoints. Some Endpoints have Methods. We call these Endpoints with a JSON. The JSON structure is predefined and every interface respects the same structure.

We have a single Codeunit that knows how to handle this JSON structure. Passing JSON to an interface requires a data container.

Interface Data

TempBlob is table 99008535. The table is simple but is has a lot of useful procedures.

Wikipedia says: A Binary Large OBject (BLOB) is a collection of binary data stored as a single entity in a database management system. Blobs are typically imagesaudio or other multimedia objects, though sometimes binary executable code is stored as a blob. Database support for blobs is not universal.

We use this BLOB for our JSON data when we send a request to an interface and the interface response is also JSON in that same BLOB field.

For people that have been working with web requests we can say that TempBlob.Blob is used both for RequestStream and for ResponseStream.

TempBlob is only used as a form of Stream. We never use TempBlob to store data. We never do TempBlob.Get() or TempBlob.Insert(). And, even if the name indicates that this is a temporary record, we don’t define the TempBlob Record variable as temporary. There is no need for that since we never do any database call for this record.

Interface Helper Codeunit

We use a single Codeunit in all our solutions to prepare both request and response JSON and also to read from the request on the other end.

We have created a Codeunit that includes all the required procedures for the interface communication.

We have three functions to handle the basics;

  • procedure Initialize()
  • procedure InitializeFromTempBlob(TempBlob: Record TempBlob)
  • procedure GetAsTempBlob(var TempBlob: Record TempBlob)

A typical flow of executions is to start by initializing the JSON. Then we add data to that JSON. Before we execute the interface Codeunit we use GetAsTempBlob to write the JSON into TempBlob.Blob. Every Interface Codeunit expects a TempBlob record to be passed to the OnRun() trigger.

Inside the Interface Codeunit we initialize the JSON from the passed TempBlob record. At this stage we have access to all the data that was added to the JSON on the request side.

And, since the interface Codeunit will return TempBlob as well, we must make sure to put the response JSON in there before the execution ends.

JSON structure

The JSON is an array that contains one or more objects. An JSON array is represented with square brackets.

The first object in the JSON array is the variable storage. This is an example of a JSON that passes two variables to the interface Codeunit.

All variables are stored in the XML format, using FORMAT(<variable>,0,9) and evaluated back using EVALUATE(<variable>,<json text value>,9). The JSON can then have multiple record related objects after the variable storage.

Adding data to the JSON

We have the following procedures for adding data to the JSON;

  • procedure AddRecordID(Variant: Variant)
  • procedure AddTempTable(TableName: Text; Variant: Variant)
  • procedure AddFilteredTable(TableName: Text; FieldNameFilter: Text; Variant: Variant)
  • procedure AddRecordFields(Variant: Variant)
  • procedure AddVariable(VariableName: Text; Value: Variant)
  • procedure AddEncryptedVariable(VariableName: Text; Value: Text)

I will write a more detailed blog about each of these methods and give examples of how we use them, but for now I will just do a short explanation of their usage.

If we need to pass a reference to a database table we pass the Record ID. Inside the interface Codeunit we can get the database record based on that record. Each Record ID that we add to the JSON is stored with the Table Name and we use either of these two procedures to retrieve the record.

  • procedure GetRecord(var RecRef: RecordRef): Boolean
  • procedure GetRecordByTableName(TableName: Text; var RecRef: RecordRef): Boolean

If we need to pass more than one record we can use pass all records inside the current filter and retrieve the result with

  • procedure UpdateFilteredTable(TableName: Text; KeyFieldName: Text; var RecRef: RecordRef): Boolean

A fully populated temporary table with table view and table filters can be passed to the interface Codeunit by adding it to the JSON by name. When we use

  • procedure GetTempTable(TableName: Text; var RecRef: RecordRef): Boolean

in the interface Codeunit to retrieve the temporary table we will get the whole table, not just the filtered content.

We sometimes need to give interface Codeunits access to the record that we are creating. Similar to the OnBeforeInsert() system event. If we add the record fields to the JSON we can use

  • procedure GetRecordFields(var RecRef: RecordRef): Boolean

on the other end to retrieve the record and add or alter any field content before returning it back to the caller.

We have several procedures available to retrieve the variable values that we pass to the interface Codeunit.

  • procedure GetVariableValue(var Value: Variant; VariableName: Text): Boolean
  • procedure GetVariableTextValue(var TextValue: Text; VariableName: Text): Boolean
  • procedure GetVariableBooleanValue(var BooleanValue: Boolean; VariableName: Text): Boolean
  • procedure GetVariableDateValue(var DateValue: Date; VariableName: Text): Boolean
  • procedure GetVariableDateTimeValue(var DateTimeValue: DateTime; VariableName: Text): Boolean
  • procedure GetVariableDecimalValue(var DecimalValue: Decimal; VariableName: Text): Boolean
  • procedure GetVariableIntegerValue(var IntegerValue: Integer; VariableName: Text): Boolean
  • procedure GetVariableGUIDValue(var GuidValue: Guid; VariableName: Text): Boolean
  • procedure GetVariableBLOBValue(var TempBlob: Record TempBlob; VariableName: Text): Boolean
  • procedure GetVariableBLOBValueBase64String(var TempBlob: Record TempBlob; VariableName: Text): Boolean
  • procedure GetEncryptedVariableTextValue(var TextValue: Text; VariableName: Text): Boolean

We use Base 64 methods in the JSON. By passing the BLOB to TempBlob.Blob we can use

and then

on the other end to pass a binary content, like images or PDFs.

Finally, we have the possibility to add and encrypt values that we place in the JSON. On the other end we can then decrypt the data to be used. This we use extensively when we pass sensitive data to and from our Azure Function.

Calling an interface Codeunit

As promised I will write more detailed blogs with examples. This is the current list of procedures we use to call interfaces;

  • procedure ExecuteInterfaceCodeunitIfExists(CodeunitName: Text; var TempBlob: Record TempBlob; ErrorIfNotFound: Text)
  • procedure TryExecuteInterfaceCodeunitIfExists(CodeunitName: Text; var TempBlob: Record TempBlob; ErrorIfNotFound: Text): Boolean
  • procedure TryExecuteCodeunitIfExists(CodeunitName: Text; ErrorIfNotFound: Text) Success: Boolean
  • procedure ExecuteAzureFunction() Success: Boolean

The first two expect a JSON to be passed using TempBlob. The third one we use to check for a simple true/false. We have no request data but we read the ‘Success’ variable from the response JSON.

For some of our functionality we use an Azure Function. We have created our function to read the same JSON structure we use internally. We also expect our Azure Function to respond with the sames JSON structure. By doing it that way, we can use the same functions to prepare the request and to read from the response as we do for our internal interfaces.

My Soap Service Proxy Codeunit

Up to now we in Advania have been using the method described here on my blog to connect to most of the Soap web services that we needed to integrate with.

The problem with this method is that we have to manage a lot of DLLs.  This has caused some issues and problems.

Another thing is that we are moving to AL.  And in AL we can’t just throw in a custom DLL to do all the work.

In C/AL We can do this with standard dotnet objects

AL code to do the same with the built in AL objects but that code is not much shorter.

With a custom proxy DLL the code would be

With this example we can easily see why we have chosen to create a proxy DLL for most of the Soap services.

I wanted to find a way to make things easier in AL and I remembered having dealt with C/AL objects by Vjeko from some time ago.  I took another look and that code helped me to get started.

The result is a Soap Proxy Client Mgt. Codeunit in C/AL that I have sent to Microsoft’s cal-open-library project asking to have this code put into the standard C/AL library.

Using this Codeunit the code will be like this.

What about AL?

For now this C/AL Codeunit is not in the standard CRONUS database.  I need to import the C/AL code and make sure that AL will be able to use that Codeunit.  You can see how to do this in my last blog post.

This C/AL Code will directly convert to AL and is ready to use.

More examples on how to use this Proxy Codeunit will follow.  Stay tuned…

Using AdvaniaGIT in Visual Studio Code

It has become obvious that the future of AL programming is in Visual Studio Code.

Microsoft has made a decision to ship all their releases as Docker Containers.

The result of this is a development machine that does not have any NAV version installed.  I wanted to go through the installation and configuration of a new NAV on Docker development machine.

Here is what I did.

I installed Windows Server 2016 with Containers.  The other option was to use Windows 10 and install Docker as explained here.

After installing and fully updating the operating system I downloaded and installed Visual Studo Code.

After installation Visual Studio Code detects that I need to install Git.

I selected Download Git and was taken to the Git download page.

I downloaded and installed Git with default settings.

To be able to run NAV Development and NAV Client I need to install prerequisite components.  I copied the Prerequisite Components folder from my NAV 2018 DVD and installed some of them…

Let’s hook Visual Studio Code to our NAV 2018 repository and install AdvaniaGIT.  I first make sure to always run Visual Studio Code with administrative privileges.

Now that we have our AdvaniaGIT installed and configured we can start our development.  Let’s start our C/AL classic development.  Where this video ends you can continue development as described in my previous posts on AdvaniaGIT.  AdvaniaGIT also supports NAV 2016 and NAV 2017.

Since we are running NAV 2018 we can and should be using AL language and the Extension 2.0 model.  Let’s see how to use our repository structure, our already build Docker container and Visual Studio Code to start our first AL project.

So as you can see by watching these short videos it is easy to start developing both in C/AL and AL using AdvaniaGIT and Visual Studio Code.

My next task is to update my G/L Source Names extension to V2.  I will be using these tools for the job.  More to come soon…

Using AdvaniaGIT – FTP server for teams

So, you are not the only one in your company doing development, right?

Essential part of being able to develop C/AL is to have a starting point.  That starting point is usually where you left of last time you did some development.  If you are starting a task your starting point may just be the localized release from Microsoft.

A starting point in AdvaniaGIT is a database backup.  The database backup can contain data and it should.  Data to make sure that you as a developer can do some basic testing of the solution you are creating.

AdvaniaGIT has a dedicated folder (C:\AdvaniaGIT\Backup) for the database backups.  That is where you should put your backups.

If you are working in teams, and even if not you might not want to flood your local drive with database backups.  That is why we configure an FTP server in C:\AdvaniaGIT\Data\GITSetting.json.

When we start an action to build NAV development environment the AdvaniaGIT tools searches for a database backup.

The search is both on C:\AdvaniaGIT\Backup and also on the root of the FTP server.

Using the function Get-NAVBackupFilePath to locate the desired backup file it will search based on these patterns.

The navRelease is the year (2016,2017,…).  The navVersion is the build (9.0.46045.0,9.0.46290.0,10.0.17972.0,…)

The projectName and navSolution parameters are defined in Setup.json (settings file) in every GIT branch.

Combining these values we can see that the search will be done with these patterns.

And these file patterns are applied both to C:\AdvaniaGIT\Backup and to the FTP server root folder.  Here are screenshots from our FTP server.

Looking into the 2017 folder

And into one of the build folders

My local backup folder is simpler

This should give you some idea on where to store your SQL backup files.

 

 

Using AdvaniaGIT – Docker Containers

There is a new kid in town.  His name is Docker.

Microsoft is saying:

We are currently investigating how we can use Docker for deploying NAV. For test purposes we have created a Docker Container Image with the NAV Developer Preview, which you can try out.

Docker Containers is a technology where you, instead of virtualizing the entire machine, only virtualize the services and share resources from the host computer. Read more about it here: https://www.docker.com/what-docker

Read more about how to get started with Docker here: https://docs.docker.com/docker-for-windows/install/

So what does this mean?

We can install NAV environments as container both in Azure and on premise.  We can have multiple NAV versions to work with without having to install, so there is no conflict.  We can also get access to container images that are still in preview.

Note what Microsoft says, they are investigating.  The NAV Container Image service is not public yet.  You need authentication to get access.  This project has a place on GitHub.  To get access please contact Microsoft or send me a line and I will point you in the right direction.

The easiest way to get started is to try the NAV Developer Preview template on Azure,  http://aka.ms/navdeveloperpreview.  This will give you a full development environment for NAV Extension2.0 using VS Code.

It should be straight forward to install AdvaniaGIT on top of the NAV Developer Preview and start from there.  We can also start from Azure template called “Windows Server 2016 Datacenter – with Containers”.

The local option is to install Docker on our Windows laptop.  If you would like to use Docker on your laptop you need to change one setting after installation.  You need to switch to Windows containers.  Your laptop will most likely restart during installation and configuration of Docker so make sure to have your work saved.

If you are planning to run a Docker-Only environment you don’t need to install NAV.  Still there are prerequisite components that you must install.  These components can be found on the NAV DVD folder “Prerequisite Components”.  From the “Microsoft SQL Server” folder install sqlncli64.msi and ReportBuilder3.msi.  From the “Microsoft Visual C++ 2013” folder install vcredist_x64.exe.  From the “Microsoft Visual Studio 2010 Tools for Office Redist” install vstor_redist.exe.  From the “Microsoft Report Viewer” folder install both SQLSysClrTypes.msi and ReportViewer.msi.  You should now be ready for the next step.

So, let’s get started

In your C:\AdvaniaGIT\Data folder open DockerSettings.json

That’s all.  Your are now ready to use Docker with AdvaniaGIT.  Make sure to always have the latest version of AdvaniaGIT installed.

You can even use the “devpreview” build of NAV TENERIFE to do vNext development both in C/AL and AL.

Stay tuned, the AdvaniaGIT journey will continue…

Using AdvaniaGIT – How to configure licenses

When NAV environments are built a development license is uploaded to the development database.

Make sure to save your development licenses in your AdvaniaGIT license folder.

There are two ways to configure which license is used.  First with the “licenseFile” property of GITSettings.json in your AdvaniaGIT data folder.

Just specify the file name in the license folder.

The license configured in GITSettings.json will be used as default for all builds.  However, as mentioned earlier, every settings in GITSettings.json can be overwritten by the settings in each branch.

The settings file in each branch is named according to the “setupPath” parameter in GITSettings.json.  If we take a look at the setup.json file for my G/L Source Names solution.

Here I need to use another license file.  The one used when I applied for the object range for my extension.

Licenses are not to be stored in SQL backups used by AdvaniaGIT.  When using AdvaniaGIT to create SQL backups the license is removed before creating the backup and reinstalled afterwards.

The first function that is executed after SQL database restore is a database upgrade with the development environment.  This must be done to make sure that the database fits the service version being used.  For this database upgrade function to be successful, first either make sure that the database does not contain expired license, and make sure that you have a valid license in the master database.

There are a few ways of doing this.  First, there is an option when installing NAV to upload the license.

Secondly, in the development environment you can upload a license, going through Tools and License Information.

But make sure that the database your development environment is connected to does not have the “Save license in database” set like here, going through File, Database and Alter.

The third option is to use the server administrative shell.

Hope this helps.  More to come soon.  Stay tuned…

Using AdvaniaGIT – Bring your solution into SCM

Most of us are not just starting working with NAV.  But again not all of us have been able to apply Source Control Management (SCM) to our daily work.

In the previous posts we have installed and prepared our development environment and we are now ready to start working on our solution in the SCM way.

Our first step is to create a branch for our solution.

Now we should look at the options we have to import our solution into our branch.  We can have our solution in different formats.

All these file formats can be imported into our solution branch with the tools that AdvaniaGIT delivers.  Let’s start with the SQL backup, 2016-DAA_WineApp.bak.  AdvaniaGIT will search for backups using these patterns.

In this example the values are:

The module first searches the local drive (default = C:\AdvaniaGIT\Backup) and then the ftp server if one is defined in GITSettings.json.

When AdvaniaGIT creates a database backup it is named according to the first pattern, in this case 2016-WineSolution.bak and saved in the default backup location.

The rest of the file types require that the solution branch has already been built like shown in the first video.

Here we restore from bacpac.  Bacpac format is for example used by AzureSQL.

The Navdata format was created by the NAV development team.  To be able to import from a Navdata file we require an Navdata export with the application included.

Perhaps the most common way is to have a FOB export.

Text exported objects can be imported directly into out GIT branch.

And finally we can update the solution branch from delta files.

Out next task will be to do some development in our solution and commit the changes we make to our GIT server.  Stay tuned…

Using AdvaniaGIT – Create a localization branch

In our previous post we completed the installation of GIT, SourceTree, NAV and the AdvaniaGIT modules.  We also created a GIT repository in Bitbucket.  We selected to use BitBucket just because I already had a user configured there.  I also have a user configured in Visual Studio Online where I store many of my NAV solutions in a private GIT repository.  Public projects I put on GitHub.  As I stated before we must make sure not to push any of the NAV standard code to public repositories.

Advania has internal GIT servers where we host our solutions.

The choice is yours.  I don’t have any favorite GIT server solution.

In Advania we have created a branch structure.  We create repositories for each NAV version.  The master branch is always the W1 release.  Each commit to the W1 branch contains a CU update.  We always store all objects in every branch.  In solution branches we also store deltas and reverse deltas.

We can access any of the CU’s code from the GIT repository and we can see every code change made from one CU to the next.

We branch out master to each localization.  Each localization has the same rule as the master branch.  Every CU is available and every code change is traceable.

All the GIT servers have a nice web interface.  There we can easily see all commits, all code and all changes.  This is a list of commits for the master branch.

This is a list of code changes in NAV 2017 CU8.

Let’s go ahead and create our first localization branch.  In the following video I use the AdvaniaGIT functions to download and extract information from the latest CU.  I don’t have a function that will download all updates for a given version.

Our next step will be creating a solution branch based of our localization.  Stay tuned…