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AccessVersion

Started by May 21, 2013 08:11 PM
0 comments, last by WitchLord 11 years, 6 months ago

I really enjoy the flexibility that comes with Access masks and Dynamic Configurations, but I have a need that doesn't quite fit well into either paradigm.

It would be nice if functions (whether global or methods) could be registered with a version. Working just like the access mask, except the logic would restrict access to the function to that version or higher.

It looks like a "asDWORD accessVersion" variable could be added to "asCModule" and all of the entities that currently support access masks to accomplish this. An additional logical test wherever the access mask is tested should suffice. A value of DWORD_MAX could be the default, so that all version tests would pass unless the user sets a specific version.

I apologize for the length and complexity of what follows, but I would like to explain my situation.

My application consists of two processes, a client and a server. Several clients can connect to a server, and the clients are backward compatible (they can connect to a lower-version server). Some scripts run on the client, and some scripts run on the server. The client compiles and validates all scripts, and all scripts are stored on the server. Any client can access and run the scripts of any other client.

My application interface exposes new functionality with every version. I impose a rule that a client can only use the functionality available to the server's version. This is so if a newer client connects to an older server it cannot create a script that an older client (matching the server's version) would not be able to run.

To complicate things more, one client can be connected to several servers at the same time. I thought I could create a dynamic configuration for each version and remove them as needed, but if a version 5 client is connected to a version 5 server and running version 5 scripts I would not be able to remove the version 5 configuration when the client connects to a version 4 server. I could use an access mask, but then I would be limited to 32 versions, and I have other uses for the access mask.

I could solve the problem by creating one engine for each version or one engine which supports several versions through an access mask, then more engines if I use up all the bits of the mask. I prefer to use one AngelScript engine per process though, and I wouldn't really want to manage such a complicated version system.

Do you have any ideas for how I might accomplish this special versioning requirement in the existing construct, or do you think an "AccessVersion" member could be appropriate? I am open to suggestion.

Thank you.

I'll think about this suggestion of having a version alongside the access mask.

With the current implementation I believe I would solve your dilemma the following way:

1. Set up a main script engine with the full interface, i.e. with the latest version. This will be the script engine used for all script execution, but it will not be used for compiling scripts. Instead the scripts will be loaded from pre-compiled bytecode into this engine.

2. When compiling a script for a specific version, set up a separate engine with only the interface available for that particular version. Compile the script, then save the bytecode to memory, and finally load the bytecode into the main script engine where it will be executed.

Assuming each version only adds to the interface and never removes anything this will work well. You shouldn't see a noticeable delay with the saving and loading of the bytecode either as this is much much faster than the actual compilation.

The separate engine doesn't need to have access to the actual interface methods as it will never call them, so you'll be able to register this interface with dummy functions. You can even perform the compilation to bytecode in an offline compiler that can be completely separate from the rest of the game engine.

I suggest you take a look at the sample asbuild. It implements a generic offline compiler that can compile scripts for any application, assuming the interface is known in the form of a configuration file. (The configuration file can be created automatically from the application with a call to the helper function WriteConfigToFile)

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