Switching between remote and local proxy at runtime

[kobi-shanti]

Hi,

We just wanted to know if it is possible to switch between remote and local proxy at runtime? Using CSLA5 specifically.

Thanks in advance for any help.

[hurcane]

We might need more information regarding the context in which you ask this question. The data portal can be defined via a configuration file, which is read when the runtime process starts. The RunLocal allows specific methods to always run locally, regardless of the default data portal configuration.

In what scenario would you want to be able to change the location of the data portal call?

[rockfordlhotka]

@kobi-shanti it doesn't sound like you need to dynamically change as the app is running? But rather that you want the option to run local or remote as the app starts up?

To dynamically change, you need to determine the dynamic conditions under which you'd change - like the Internet going offline - and then switch the current data portal proxy to another one. There are different ways to do this, but it doesn't sound like you need this level of complexity.

To switch for a given launch of the application, it used to be that you'd probably change the config file. These days the choice of configuration is normally done within Program.cs where you set up your DI services.

CSLA 5 was in the awkward spot where we partially supported/used DI and hadn't yet fully committed to DI. Which is to say that the most common way to configure CSLA 5 was to use the fluent configuration API.

      CslaConfiguration.Configure()
        .DataPortal().DefaultProxy(typeof(Csla.DataPortalClient.HttpProxy), "https://localhost:44332/api/dataportal");

      Csla.ApplicationContext.User = new Csla.Security.UnauthenticatedPrincipal();

As long as that DataPortal configuration occurs before any use of the data portal, that line of code can be invoked at any time.

In other words, you could pop up a dialog as the app starts, asking the user if they want to run in 2-tier or 3-tier mode, and set the proxy accordingly.

I think you might be able to use that code to change the default proxy later too - I just don't remember. I know we did enable that at some point.

[kobi-shanti]

Ideally, we were hoping to dynamically change the data portal proxy after startup, when the app is running. This would mean we as developers could quickly compare performance of 2-tier vs 3-tier without needing to change our config files and restart the application. It would also allow some of our users to run in 2-tier, and others in 3-tier, based on a saved user setting.

Based on what you've both said and some tests, it doesn't look like it is possible to implement both, at least without some effort (e.g. separate RunLocal methods or custom data portal classes). From what I can tell when using the fluent configuration API as above, once a call is made to the data portal, it appears to be locked into whatever proxy was used first. We can probably get around this for the user setting component by making a non-CSLA call directly to the database to get the preferred mode (2-tier vs 3-tier), then setting the proxy in our Program.cs based on the result.

Thanks @hurcane and @rockfordlhotka for the responses.

[rockfordlhotka]

See if there's a static method on the DataPortal type to update the current proxy.

[rockfordlhotka]

@kobi-shanti

I finally had some time to look through the CSLA 5 codebase.

The secret in CSLA 5 is to change the ApplicationContext.DataPortalProxy value:

  ApplicationContext.DataPortalProxy = typeof(your proxy type).AssemblyQualifiedName;

or

  ApplicationContext.DataPortalProxy = "Local";

Here's a link to the code in ApplicationContext.

[kobi-shanti]

@rockfordlhotka thanks for coming back and especially for the follow up. I had a brief look following your initial response regarding a static method with no luck. We'll have a go with the ApplicationContext value approach.