Early experiences from migrating to the hla evolved C++ and java APIs
Paper i proceeding, 2009
Several previous papers have described a number of new concepts and services in the HLA Evolved (IEEE 1516-2009) standard, such as fault tolerance, update rate reduction and modular FOMs. This paper focuses on the particulars of the updated C++ and Java APIs. One reason for updating the APIs is to support the new or extended HLA functionality. Another reason is to make it easier to switch between different RTI implementations by simply replacing an RTI library file. This paper describes some early experiences from migrating from HLA 1.3 and HLA 1516-2000 to the new C++ and Java APIs for some commonly used HLA functionality. It is based on migration work done both for some basic federates as well as some general-purpose HLA tools. Both the C++ and Java APIs have seen an evolution in the data types used for handles, which will affect every migration effort. For the C++ API there are also changes in the memory management schemes. The way that optional arguments are handled in the APIs has also evolved. All federates will need to introduce the new connect/join sequence. Otherwise the majority of the HLA service functionality is very similar to earlier HLA versions or even simplified. Federates still using HLA 1.3 DDM may however need a major revision. A few basic examples of using the new Encoding helpers are also given. This paper also shows how the new standardized time types are used. Some properties of the HLA Evolved Dynamic Link Compatibility API (EDLC API) based on the earlier SISO DLC standard (SISO-STD-004.1-2004) are explained in detail. One particular feature here is the ability to dynamically choose between different RTI implementations at runtime. The relationship between the link compatibility, standardized time types and extendable transportation types is also explained. This paper isn't a complete migration cookbook. Still it is intended to give developers some insights that are useful for planning their HLA Evolved migration efforts.