MB-820 Microsoft Dynamics 365 Business Central Developer Questions and Answers

 Verbosity::Critical: This ensures that the telemetry logs the failure as a critical event.

 DataClassification::CustomerContent: This helps classify the error as related to customer data.

 TelemetryScope::All: This ensures that the error is visible across all relevant telemetry scopes, making it easier to monitor the issue in real-time.

https://api.businesscentral.dynamics.com/v2.6/myTenant/myEnvironment/api/alpine/integration/rooms

Read Scale-Out:

Read scale-out is a feature in Business Central that allows you to improve performance by distributing read-only queries (such as the ones from the ticketAPI) across multiple read replicas in the cloud database. This reduces the load on the primary database and helps improve the response time for read-intensive operations, like analyzing POS data through the ticketAPI.

Data Access Intent - ReadOnly:

When enabling read scale-out, you can configure the DataAccessIntent property of APIs to be ReadOnly. This directs the system to use read replicas to handle read-only queries, which enhances performance by offloading such queries from the primary database.

Why Not Other Options?

Option A (ODataReadonlyGetEnabled): This parameter is unrelated to read scale-out and primarily affects OData services behavior, not API performance tuning.

Option B (AccessByPermission): Setting the permission to Read does not directly affect the performance. It only controls access based on user permissions.

Option D (DataAccessIntent ReadOnly): While setting this property to ReadOnly helps in read-only operations, enabling read scale-out (option C) ensures the underlying infrastructure is optimized to handle such read operations, which is the fundamental action required.

Reference Documentation:

Read Scale-Out in Business Central

Data Access Intent in AL

codeunit 52102 "POS API Management"

{

Access = Public;

Permissions = TableData "POS Information" = rwdx;

trigger OnRun()

begin

readAPI();

end;

procedure readAPI()

begin

// Your code here to read from the POS API

end;

}

API Publishing for Extensions:

In Business Central, when creating custom APIs like RoomsAPI, it is important to ensure that they are automatically published during the installation or upgrade of the extension.

To achieve this, you can include a codeunit of type Install in the extension that explicitly publishes the custom API (RoomsAPI) as a web service. This ensures that it is available for use immediately after the extension is deployed without requiring manual intervention.

Codeunit Type:

A codeunit of type Install runs when the extension is installed or upgraded. This type of codeunit can be used to perform setup tasks such as publishing web services or APIs like RoomsAPI.

Why Not Other Options?

Option A (default API configuration): This would not automatically publish the RoomsAPI. Default APIs do not cover custom APIs.

Option B (enable APIs for the environment): Enabling APIs in Business Central allows the standard APIs to be used, but custom APIs still need to be manually published.

Option C (publish via Web Services page): This would work but requires manual intervention to publish RoomsAPI, which does not fulfill the requirement of automatic publishing during installation.

Reference Documentation:

Publishing APIs in Extensions

Codeunit Types in Business Central

In the context provided by the case study, when calling an API action from a mobile application, the correct format for a POST request to an action in Business Central typically involves specifying the entity (/issues), the ID of the entity (88122e0e-5796-ec11-bb87-000d3a392eb5), and the action to be called (/Copy). The action name should match the exact name as defined in the AL code, which is case-sensitive.

Option A is incorrect because it uses a non-standard format for the action call.

Option B uses the PATCH method, which is generally used for update operations, not for calling actions.

Option C is correct as it uses the POST method, which is appropriate for calling actions, and correctly specifies the entity, ID, and action name.

Option D is incorrect because the action name /copy is in lowercase, while AL is case-sensitive, and it should match the case exactly as defined in the code.

Option E incorrectly adds 'MicrosoftNAV' before the action name, which is not standard for calling actions in Business Central APIs.

Hence, the correct action to use when calling the Issue API action from the mobile application is given in Option C.

In Business Central development using AL (the language for Business Central extensions), the use of access modifiers defines how variables and procedures are accessed within and outside of an object or codeunit.

Access Modifiers in AL:

Public: A public variable can be accessed from any object or codeunit within the same module or extension.

Protected: This restricts access to the current object and objects that inherit from the current object. However, in AL (at least in versions used for Business Central), the Protected access modifier is used with methods but not variables.

Internal: This modifier restricts the visibility to the current extension. This means that variables or methods declared as internal can only be accessed from within the same extension. This is appropriate when you want to provide functionality that is shared within the extension but not exposed externally.

Local: This restricts the variable or method to the current object or method where it is declared. It cannot be accessed from anywhere else, even within the same extension.

Scenario Justification:

In the scenario for Contoso, Ltd., IssueTotal is a global variable in the ISSUE BASE extension, and the ISSUE EXT extension needs to access it. Therefore, the variable cannot be declared as Local, because this would restrict access to just the current object (or method).

Using Public would expose the variable outside of the extension, which is unnecessary because you only want other parts of the extension (specifically the ISSUE EXT extension) to have access.

The best choice in this case is Internal because it restricts access to the variable to within the same extension, which includes the base extension and any dependent extensions like ISSUE EXT. It strikes the right balance between visibility and encapsulation.

Microsoft Dynamics 365 Business Central Developer References:

Access Modifiers in AL: Microsoft's documentation on AL provides the details on access modifiers, where it is specified that internal variables can be accessed within the extension, and the public variable is accessible across all extensions【source: Microsoft Learn on AL Programming】.

Best Practices for AL Development: Business Central development best practices suggest keeping variables internal unless they need to be accessed outside of the current extension【source: Microsoft Learn on AL development guidelines】.

Here is the most logical sequence of actions for implementing the Issue Management module in Business Central and exposing the PostIssue method:

Correct Order:

Create a codeunit named "Issue Management Impl." and set the value of Access property to Internal.

This is the first step because Issue Management Impl. is the implementation layer where the actual business logic resides, and setting it to Internal ensures that it is only accessible from within the module, following best practices in encapsulation.

Create a local procedure named PostIssueImpl in the "Issue Management Impl." codeunit.

This step adds the actual PostIssueImpl method, which contains the core logic of posting an issue.

Create a codeunit named "Issue Management" and set the value of Access property to Public.

After defining the implementation logic, you need to create a public-facing Issue Management codeunit to expose the service externally.

Create a PostIssue procedure in the "Issue Management" codeunit, and in it call the PostIssueImpl method.

Lastly, expose the PostIssue method in the Issue Management codeunit, which will internally call the PostIssueImpl method, completing the chain.

The task is to identify unwanted incoming web service calls during the last seven days. To do this, we need to look at KQL (Kusto Query Language) queries that would filter out web service calls based on the timestamp (to ensure the calls are within the last seven days) and by certain characteristics that would indicate they are unwanted, such as the wrong type of protocol (SOAP in this case, as Contoso Ltd. plans to dismiss using it).

Looking at the options:

Option A: This query selects all traces where the timestamp is within the last 7 days and where the custom dimension has a value of 'RT0008', and where the category is either 'ODataV4', 'ODataV3', or 'Api'. This query would show all API calls except SOAP, so it does not directly answer the question about unwanted calls.

Option B: This query filters for traces with a timestamp within the last 7 days, where 'RT0008' is present, and specifically looks for the category 'SOAP'. This query is correct because it directly targets SOAP calls, which are the unwanted calls according to Contoso Ltd.'s plans.

Option C: Similar to option B, this query filters for traces within the last 7 days and looks for 'RT0008' but uses the equality operator for the category 'SOAP'. This would also correctly return the unwanted SOAP calls.

Option D: This query also filters for traces within the last 7 days, but it excludes the 'ODataV4' category, which doesn't necessarily target the unwanted SOAP calls.

Option E: This query selects traces where the timestamp is within the last 7 days and the custom dimension has 'RT0008'. However, it filters out categories 'ODataV4' and 'Api', which does not directly help in identifying the unwanted SOAP calls.

Therefore, the queries that should be used to determine if there are unwanted incoming web service calls (SOAP calls) in the tenant during the last seven days are Options B and C. These queries are specific to identifying SOAP protocol usage, which is what Contoso Ltd. considers unwanted.

 Upgrade codeunit trigger: OnValidateUpgradePerDatabase

Since the question specifies that you are handling data upgrades, and you need to use validation before upgrading at the database level, the correct choice is OnValidateUpgradePerDatabase. This method ensures that the upgrade process is validated before applying to the entire database, making it more efficient when data affects multiple companies or structures.

 DataTransfer method to use: CopyRows

CopyRows is the appropriate method when you are handling large data transfers between tables, especially in an upgrade scenario where you are migrating or transferring data from one table to another. It copies entire rows of data and is optimal for bulk data operations during upgrades.

In Microsoft Dynamics 365 Business Central, when configuring snapshot debugging, it is crucial that the parameters in the configuration file are correctly set. From the options provided, the issue with the debugger not starting correctly is most likely due to an incorrect "userId" parameter.

Option A is the cause of the problem. The "userId" parameter must be the GUID of the user, not the username. The snapshot debugger needs the exact GUID to attach to the right session for debugging.

Option B is incorrect because "breakOnNext" set to "WebClient" is a valid setting. This tells the debugger to break on the next client action in the web client, which is a typical scenario.

Option C is not the cause of the problem. The "userId" parameter is meant to specify which user session to debug, and this works in conjunction with the "breakOnNext" parameter.

Option D is incorrect as the "executionContext" parameter does not need to be set to "Debug" for snapshot debugging to work. "DebugAndProfile" is a valid value for the "executionContext" parameter, as it allows for debugging and collecting performance information.

Therefore, the reason why the debugger does not start correctly is due to Option A: The "userId" parameter must have the GUID of the user specified, not the username.

 Add Clear(PurchaseLine); as a line before line 01 of the code: No

 Add PurchaseLine.SetFilter("Line No."; '>0') as a line after line 06: Yes

 Change the filter on line 06 from a "No." field to a "Document No." field: No

 Remove "not" in line 07: No

 Add Clear(PurchaseLine); as a line before line 01 of the code.

No

You do not need to clear the PurchaseLine record before running the query, because the SetRange filters will take care of setting the correct context.

 Add PurchaseLine.SetFilter("Line No."; '>0') as a line after line 06.

Yes

Adding a SetFilter on the "Line No." field ensures that you're checking for actual purchase lines greater than 0, which are valid lines. This would fix the issue where the check might return false even when lines exist.

 Change the filter on line 06 from a "No." field to a "Document No." field.

No

The filter on the No. field is correct, as it's filtering based on the purchase order number. Changing this to Document No. is unnecessary.

 Remove "not" in line 07.

No

The not in line 07 is necessary because IsEmpty() returns true when no lines are found. To correctly return a boolean indicating whether the purchase order has lines, you need to negate the result of IsEmpty().

To create a query that assigns vendors to items in Business Central, use the following code blocks in sequence:

dataitem(Vendor; Vendor)

dataitem(Item; Item)

DataItemLink = "Vendor No." = Item.Vendor_No;

Creating a query:In Business Central, a query object is used to combine data from multiple tables. You start by specifying each table as a data item. In this case, you would start with the Vendor table and then the Item table. After specifying the data items, you need to link them together. The DataItemLink property is used to establish a relationship between two data items based on a common field. Here, you are linking the Vendor and Item tables on the "Vendor No." field, which is present in both tables. This link ensures that the query will return a dataset that includes related records from both tables based on the vendor number. The order of the code blocks ensures the logical flow and relationships between tables as required for the query.

When creating a page with the PageType property set to RoleCenter in Microsoft Dynamics 365 Business Central, it's essential to organize the functionalities and actions in a manner that enhances user experience and efficiency. The best practice is to define actions in the area (reporting) before actions in the area (creation) (A). This organization allows users to access reporting and analytical features quickly, which are commonly used in Role Centers for overview and insight purposes, before moving on to creation or transactional tasks. This logical flow aligns with typical user workflows, where analysis and review precede the creation of new records or transactions. The other options, such as defining the navigation menu in the area(processing) (B), defining the navigation bar in the area (embedding) (C), or adding a source table on the Role Center page (D), do not directly address the need to add functionalities to the Role Center page in a user-friendly manner.

To create the Approver field in the Item table using an AL extension, perform the following actions in sequence:

Create an enum object named Approver and include all options.

Create a table extension object for an Item table with an Approver field of enum type named Approver in the fields section.

Create a page extension object that extends the Item Card object. Add the field to the fields section.

Build and extend tables:To add a new field to an existing table in Business Central using AL extension, you need to define an enumeration (enum) with the possible values for the new field. Then, you create a table extension object where you add the new field and specify its type as the enum you created. This adds the field to the Item table. Finally, you modify the user interface to display the new field by creating a page extension for the Item Card page and adding the new field to it.

Assigning a SUPER permission set to all users would indeed resolve the permission errors and access issues reported by the users, as it grants full permissions across all objects and data in Business Central. However, this approach contradicts the principle of least privilege, which advocates for providing only the minimum levels of access necessary for users to perform their jobs. The SUPER permission set would excessively elevate user privileges, potentially leading to security risks and unintended modifications to critical data. Therefore, while assigning the SUPER permission set might technically resolve the immediate issues, it does not meet the goal of adhering to the principle of least privilege and is not a recommended solution.

When developing an app for Microsoft AppSource, it is essential to use an object range that is specifically designated by Microsoft to avoid conflicts with other apps and the base application. The correct object range to use is:

An object range within the range of 70000000 to 74999999 that is requested from Microsoft (D): This range is reserved for AppSource apps. Developers need to request this range from Microsoft to ensure that the objects used in their extension do not conflict with those used by other extensions or by the base application. Using this reserved range helps maintain the integrity and compatibility of extensions published on AppSource.

It's important to note that the other ranges mentioned (A, B, C, and E) are not suitable for apps intended for AppSource. Ranges 50000 to 59999 and 50000 to 99999 are typically reserved for per-tenant customizations or partner solutions, not for distribution on AppSource. The standard range 1 to 49999 is reserved for the base application objects, and using an object range divided by countries (C) is not a standard practice for AppSource apps.

When exporting a file from a client using the DownloadFromStream method in a Business Central online environment, you need to create an InStream data type to send the data. The solution is to use the CreateInStream method from codeunit "Temp Blob" (A). The Temp Blob codeunit provides temporary storage of BLOBs (Binary Large Objects) and is commonly used for handling files and streams in Business Central. By using the CreateInStream method on a Temp Blob, you create an InStream that can then be used with the DownloadFromStream method to send the file data to the client. This approach is efficient for file handling and transfer in Business Central, especially in scenarios involving data export or file manipulation.

Permission sets control access to objects (such as pages, tables, reports) in Business Central. By creating a new permission set that specifically excludes the critical table (or page) and assigning this permission set to the users in Department A, you can prevent them from accessing the page.

Option A (creating a different role center page) is incorrect because role centers control the user interface, but do not directly restrict access to specific pages or tables.

Option B and Option C (extending the base application permission set) are not the best options because extending permission sets typically involves adding permissions, not removing access. The question requires restricting access to a critical page, so simply including or excluding permission sets won’t solve the issue at the table or page level.

Option D (creating an entitlement object) is not relevant here, as entitlements are used in more complex licensing scenarios or environments.

Summary:

Creating a permission set object that specifically excludes access to the critical table or page and assigning it to the users will solve the problem effectively.

To enable debugging in an extension and allow the source code to be viewed, the allowDebugging property should be specified in the app.json file (C). The app.json file serves as the manifest for an AL project in Microsoft Dynamics 365 Business Central, defining the project's properties, dependencies, and features. By setting the allowDebugging property to true in this file, developers enable the debugging of the extension's source code, facilitating troubleshooting and development. This is essential for analyzing the behavior of the extension and identifying issues during the development process.