the 'Freiburg' project is an replacement for shared libraries on Unix, Windows and Mac OS X ...
goals
usability study 1
I maintain an application based on REMEDY-Ars running a workflow application. The application is running on a SUN server using a local SYBASE database. To monitor the server I wrote an ARS module to check the health status of ARS and the workflow application. The module was developed on SUN Solaris using a gcc compiler and a non free REMEDY-Ars api. To monitor the server I'm using moods as front-end and the module as data provider. The moods application is using a graphic and a text based output devices. The quality of information provided combined with the easiness of using moods created a killer application with a strong request for additional installations. To minimize the installation requirements and maximize the support quality I decided to run the module on a ULTRA SPARC 10 and only ship a generic moods application for different kind of UNIX and WINDOWS environments. With using the module technology I do not need to port the data provider to different environments and was able to support environments with no api support by the REMEDY-Ars supplier.
RHS It sounds like an implementation of a Service Oriented Architecture. While each module can provide functionality, they're not libraries per se, so much as services that other modules or programs can then use.
the 'Freiburg' project and the 'command line'
the traditional unix command line was developed to create complex filters based on simple tools:
tool1 | tool2 | tool3
|-tool2 tool1-| |-tool3-|-tool4 |-tool5
more information will be available
escargo 21 Aug 2004 - Couldn't the distinction between step one and step two also be described as using objects with string-based serializations being sent between your modules? As long as all communicating modules agree on the mechanisms for encoding and decoding, it does not matter if your serialization mechanism is XML, YAML, or anything else. (In fact, if it's properly layered, you could even be going through an ssh tunnel.) -> YES
the 'Freiburg' project and 'Tcl'
this is an example-link between 'Freiburg' and 'Tcl'
package require TestOnFreiburg set FH [TestOnFreiburg::Start -name TclTestOnFreiburg -tcp -inetd -host myserver -port myapp] set RET [TestOnFreiburg::Echo2 $FH -int2 12345] puts "Answer: $RET" rename $FH ""
description: start test based on 'Freiburg' using the module on server myserver using port myport and call procedure Echo2 with a 2-byte integer 12345 as argument
the communication between application and module is based on different data-types
INT2 .... 2 byte integer INT4 .... 4 byte integer INT8 .... 8 byte integer FLT4 .... 4 byte float FLT8 .... 8 byte float PTR ..... pointer STR ..... \0 terminated string BIN ..... binary LST ..... list can contain all types
RHS Given the rename $FH "", it seems like $FH is a command. If so, why not make it so that you can call it directly to get results, ie:
set RET [$FH Echo2 -int2 12345]
because it is just an wrapper for:
proc TestOnFreiburg::Echo2 { Ctx args } { return [$Ctx send -wait -type ECO2 $args] }
description:
the 'Freiburg' project and 'C'
The 'Freiburg' project was written in 'C' an 'C' is the native interface:
int main(int argc, char **argv) { ContextS *context; // the initial context BufferLS *largv = BufferLCreateArgv(NULL, --argc, ++argv); MsgqueS *a_msgque; INT2 ret; // create the ContextS ErrorCheck(ContextCreate(largv, &context)); // call Echo2 struct SendS * const send = context->msgque->send; SendSTART(send); SendTOKEN(send, "ECO2", NULL, NULL /* transaction not needed */); Send2(send, 12345); ErrorCheck(SendEND(send)); // do some work .... // read the result ErrorCheck(ReadHDR(context->msgque->read, &a_msgque)); ErrorCheck(Read2(a_msgque->read, &ret)); printf("Answer:%i\n", ret); error: ErrorSSend(CONTEXT_SAVE_ERROR(context), __func__); ContextDelete(&context); exit(EXIT_SUCCESS); return 0; }
Lars H: One great obstacle this kind of project faces is how to make different modules communicate rather than just send data to each other, i.e., how does one module do to understand the data another module is sending to it? One could declare that the project only bothers with getting the binary data across ungarbled and leave it at that, but that just leaves a huge amount of work for the writer of a module to take care of. Unix pipes wouldn't have been of much use had not most of the tools in the pipe at least had the text file format in common. It is likely that Freiburg will similarly need a common basic format.
From list of data-types above, it seems to me that the developers might find it interesting to compare their work with that which has been done on the Multi Protocol (MP). The official home for that is http://www.symbolicnet.org/areas/protocols/mp.html but unfortunately many of the links on that page to papers are now broken. I have however been able to find some copies via CiteSeer; [L1 ] has links to many of the relevant papers. An interesting feature of MP is the way that one can mix data with an explicit type specification for each datum with long blocks of data that do not have individual type specifications, to reduce communication overhead.
Communication formats is very much a Catch 22. If it is too hard to encode and decode messages, then programmers will not bother. If messages are not properly encoded, then they cannot be interchanged.
FAQ
1. how to make different modules communicate
both sites using the same communication library libfreiburg which implement the protocoll. Application software only using the freiburg API (e.g. SendI2).
2. what exactly does 'libfreiburg'
3. how does one module do to understand the data another module is sending to it?
4. It is likely that 'Freiburg' will similarly need a common basic format?
the common format is:
[PACKAGE]=[HEADER]+[BODY] [HEADER]=HDR+BinaryFlag|StatisticFlag|DebuggingFlag|VerboseFlag+ MyContext+RemoteContext+BodySize+Token+TokenPtr+TransactionPtr [BODY]=[BODYItem]+[BODYItem]+ ... [BODYItem]=ItemSize+ItemType+ItemValue
reading and writing the format is done by the libfreiburg library
5. What does 'Freiburg' not do?
6. What is the overhad of 'Freiburg'