Thursday, June 22, 2017

Managing Credential Sets and Parameters: A Simple Delphi Value List Editor Component

The Problem

I am frequently called on to develop a solution that accesses a database or cloud service. During development the best practice is to develop using a test bed or "sandbox" to avoid potentially devastating real client data. This necessarily implies at least two sets of credentials to access the needed information: test and production. Sometimes, there are more than two, depending on the project requirements.

Additionally, some of the tools I develop have a general applicability, which is to say I may be able to employ the same solution for more than one client. This means even more sets of credentials as the tool is applied to additional client data.

Add to this some of the complexity inherent in credentials—and I'm thinking specifically of something like OAuth2 that has numerous data items from client IDs, to secret keys, redirection endpoints and so forth—and just managing multiple sets of credentials becomes tedious and error prone.

Further, it would be nice if changes to credential sets (or parameters sets or any other kind of set that might be fluid) could be made a run time rather than having to modify source code and recompile an application. 

The Solution

The first thing that comes to mind is to use a Value List Editor component to make it easy to manage credential sets. This is a good start, but something more is needed to make it truly convenient to implement as well as run-time friendly.

The solution I came up with is a simple Delphi component called TGetCredentials, that displays a dialog that permits management of credential sets stored in a .ini file and allows their creation, retrieval, update and deletion (CRUD) using a set of intuitive buttons.

TGetCredentials Component

The dialog GUI looks like this example, that might be used to manage credentials for accessing a Google API:


The desired set is chosen from the Drop-down Combo Box that retrieves the set from a .ini file and displays the contents. The set can then be modified or in other ways manipulated if desired. Finally, the user may cancel the retrieval (the dialog returns mrCancel) or elect to use the current values (the dialog returns the newly selected credentials along with mrOK).

.ini File

The .ini file is a standard .ini file; i.e., a text file divided into a number of sections that are named by a section header enclosed in brackets and followed by any number of name=value pairs.

The full path and filename of the .ini file is specified by associated component properties. The file must be manually created in the specified location and it must be populated with at least one section named *model. *model is used to create new credential sets; whatever the contents of *model, those are copied to the new credential set. By basing the credential sets on a programmer specified model section you may specify any items in the set as desired.

Using the Component

The TGetCredentials component can be downloaded from GitHub:

Documentation

More extensive documentation on using the component is available in the Doc folder of the project. The contents of the .chm file (MS Help) and the .pdf are identical; either may be selected.

Download the Component

You may either download a .zip file with the project or clone the project using one of the several available Git tools. If you download the .zip file, you must unzip the project to use the contents (which require compilation and installation.)

Using the Component

More comprehensive documentation about using the component is contained in either of the two documentation files in the Doc folder. In general:
  • Compile the .bpl projects.
  • Install the design time project.
  • Launch your own project that will utilize the component.
  • Drop the TGetCredentials component on a form.
  • Configure the TGetCredentials component appropriately.
  • Create the .ini file (including the *model section) to match the specification you made in the TGetCredentials component properties.
  • Use the appropriate methods in the TGetCredentials component to display the dialog, retrieve the desired credential sets, and incorporate the retrieved values into your own code.

Disclaimer

The TGetCredentials component is offered at no charge and has no guarantees. You are responsible for ensuring correct results and I offer no guarantees of any kind.

Feel free to leave comments and corrections here.

Thanks for visiting.