Hi folks,Just a thought on this one quickly (Neil I'd like your opinion especially). Why not place a schedule method in the AltingChannelInput abstract class, or even Guard, with protected level visibility. This would allow all derived classes of Guard to call schedule, but remove the restriction that it must be in jcsp.lang. This would solve Anne's problem, but still not expose Alternative to the outside world too much, only via Guards. Personally I've never had a call to implement a new Guard, all my new channels extend NetAltingChannelInput, and are therefore automatically Guards without much hassle. However, it does seem a necessary feature by the looks of things.
On another note, I am getting pretty close to having our .NET CSP library ready for a release. Sorry for the delay. After the poor results (solved by Ruth) I was going to scrap it, but after the interest I have been working on it when I can. Really, all I need to do is finish off the documentation. I initially was going to write it all myself, but I am now getting lazy and cutting and altering from JCSP documentation to speed up the process. Any interest let me know. I will post again when I'm ready (hopefully in a week or two).
Regards Kevin Chalmers Research Student School of Computing Napier University Edinburgh Anne van Rossum wrote:
Hi Kevin, Thanks for your response. The code from One2OneChannelImpl can not be copied, because it uses the method .schedule() from the Alternative class in the .util package that is not visible outside that package. I want to have different classes of components. Let I use the following terminology: * CodeBlocks: implement CSProcess but send and receive "normal" data over their channel inputs and outputs; * Interpreters: implement CSProcess and may send and receive CodeBlock's over their channel inputs and outputs. Interpreters therefore are able to schedule, manipulate CodeBlock's. In this way e.g. different scheduling techniques can be tried in parallel. Or interpreters may only understand CodeBlock's in a certain programming language. They function as virtual machines; * Universal Interpreters: implement (in Java) CSProcess and may send and receive Interpreters over their channel inputs and outputs. Channel's should cross-language and cross-platform in the sense of pipes, CORBA, tcp/ip. Transporting an interpreter to another machine corresponds with e.g. downloading a JRE to that machine. They are a kind of "universal" virtual machines. CodeBlock's have certain restrictions on their channel inputs that Iaddress explicitely.I will temporarily remove the extension of the AltingChannelInput class. That channel endpoints are separate entities is indeed useful. They are in other Java libraries modelled as InputPipe and OutputPipe (JXTA), as SourceChannel and SinkChannel (java.nio.channels), as Puttable and Takable (java.util.concurrent). Kind regards, Anne On Tue, 2007-01-09 at 17:16 +0000, Kevin Chalmers wrote:Hi Anne,In Peter Welch's original JCSP library, the channel objects where much more accessible. This does however lead to problems. As an example, consider I receive an object from a channel and then need to check if it is either a ChannelInput or ChannelOutput object. In Peter's library, both of these where the case, and this led to problems in the usage on the JCSP.net library, so Quickstone modified the model somewhat. Therefore the channel ends are each distinct objects from the channel itself.Now, as for your problem, I suggest simply copying the One2OneChannelImpl code into a new class (One2OneProcChannel) and then use it instead. Ensure the channel extends AltingChannelInput (is therefore guarded and can be used in an Alternative), ChannelOutput and One2OneChannel. This class will therefore be a One2OneChannel as the original, but will allow you to do your modifications. The interface model in JCSP is sufficiently strong to allow this to be fairly routine.As for the requirement of what you want to do, I am not clear. Normal channels will quite happily carry a CSProcess (everything in Java is an object except primitive data), and the in() and out() methods of One2OneChannelImpl already return this as a result, the channel being both an input and output. If you could clear up the major difference I may be able to help further.Regards Kevin Chalmers Research Student Napier University Edinburgh Anne van Rossum wrote:Dear list members, The JCSP library is nice. However, for my purposes there is too muchpackage protected. Is this for some reason?I am creating a special CSProcess, let I call it an Interpreter. The Interpreter is decoupled from the application functionality (e.g. it does have several processes in an array). The Interpreter may take care of other non-functional aspects: * Scheduling: The ParallelInterpreter does have a run() method that calls all its processes in a Parallel construct. Other interpreters may implement all kind of pool policies. The Interpreter can be called a Pool in this scenario; * Coupling: Instead of containing an CSProcess array, the interpreter may access a pool where processes swim around. It can take one that performs fast of about which it has positive experiences; * Process manipulation: An Interpreter may consider its processes and combine them too one new process, before running it: Transforming channels to (variable) assignments within the same namespace; To create an Interpreter I want to have ChannelInput's and ChannelOutput's that carry CSProcess instances. Let I call them ChannelProcInput's and ChannelProcOutput's. So, the One2OneProcChannelImpl should implement ChannelProcInput, ChannelProcOutput and One2OneProcChannel. The methods to overwrite areonly in() and out(): public ChannelProcInput in() { return this(); }public ChannelProcOutput out() { return this(); } //and read, write Regretfully One2OneChannelImpl is package-protected, so I can't extend it. Neither can I copy its code, because the method schedule of the Alternative class is not visible either. Can the visibility be adapted? Or should I create my adapted jcsp library? In that case I need at last the source code of the com.quickstone.jcsp.util library. Thanks in advance! Kind regards, Anne On Tue, 2007-01-02 at 10:38 +0100, Anne van Rossum wrote:Dear list members, Currently I am playing with the JCSP library. I wrote this code that has a Writer that writes values on channelA, an Incrementer that increments those values and a Reader that reads them and displays them at the console: Code: public static void main(String[] args) { ChannelFactory channelFactory = new StandardChannelFactory(); One2OneChannel channelA = channelFactory.createOne2One(); One2OneChannel channelB = channelFactory.createOne2One();Parallel processPool = new Parallel(new CSProcess[] { new Writer(channelA.out()),new Incrementer(channelA.in(), channelB.out()), new Reader(channelB.in())} ); processPool.run(); } Questions: I have the following questions regarding this example: * The CSProcesses run parallel, but it is unclear how each process gets its processing time. Maybe the Reader gets much more cycles than the Writer. Who knows? * The CSProcesses may be placed in any order. The Incrementer can not read a value from its input channel when it is not available. How is this implemented? Is the Incrementer polling channelA? Or send channelA an event to the Incrementer? * The nomenclature of channel.in() and channel.out() is confusing. Channel.out() should be the endpoint of the channel, not the output of the component where a channel starts. If a channel is a first-class entity, it should be treated like that. * The Parallel construct is rigid. Why is it not coupled to some kind of "parallel" thread pool (or actually a process pool)? The implementation of above gives all processes (supposedly) the same amount of processing time in parallel. An "alternative" construct is also allowed. And some implementing "priorities". That's it. How can I code other process pools with other policies? * On rewiring the network the One2OneChannel object has to be replaced by an Any2OneChannel object or One2AnyChannel object, etc. How can a process removed easily? There is a Parallel.removeProcess method that will be executed before a call to run(). The Reader process above reads continuously from channelB and never stops. How can I swap the Writer for another in that case? Code after processPool.run() will not be reached. * How many threads are there actually? Has every channel, or every "plug" of a channel their own thread? Or only the CSProcess objects? Background: What do I have in mind? I like to develop large-grain dataflow model where the large-grain processes are aggregations of small-grain processes (and have a better performance). If such a conversion (from small to large-grain processes) can be automated, software will automatically adjust to the amount and type of hardware processors(multiple CPUs, FPGAs, etc.) For that:* Different CSProcesses should be implemented; * Those should be swapped for each other easily; * Those should be compared w.r.t. performance; * Aggregations of CSProcesses should be compared with the distinct CSProcesses w.r.t. performance; * Channels should be plugged somewhere else easily. Etc. etc. Thanks a lot in advance for taking time! 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This message is intended for the addressee(s) only and should not be read, copied or disclosed to anyone else outwith the University without the permission of the sender. It is your responsibility to ensure that this message and any attachments are scanned for viruses or other defects. Napier University does not accept liability for any lossor damage which may result from this email or any attachment, or for errors or omissions arising after it was sent. Email is not a secure medium. Email entering the University's system is subject to routine monitoring and filtering by the University.