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Improved J661 support: Difference between revisions
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= Ideas = | = Ideas = | ||
** Handling multiple properties ** | |||
* One thing that would be great would maybe to be able to have more than one parameter to the output for the client in one telnet output (for example all the properties that have been requested), but even without that, performance should be far better than with polling I think. | * One thing that would be great would maybe to be able to have more than one parameter to the output for the client in one telnet output (for example all the properties that have been requested), but even without that, performance should be far better than with polling I think. | ||
* For your information, in the ARINC 661 protocol, the User Application concatenates several "commands" in the same buffer, denoting each specific command by its ID (and in the case of ARINC, also it's widget ID, but it's not relevant to our problem). In our User Application implementation (which happens to be coded in C++), a lot of parameters which are considered as cyclic are send regardless of their value change, because they change often. However the Server checks for their change, and in this case, it does not go further than their decoding. It turned out that the time the Server takes to decode a huge buffer and make its checks is negligible (of the order of 1 ms for example). | * For your information, in the ARINC 661 protocol, the User Application concatenates several "commands" in the same buffer, denoting each specific command by its ID (and in the case of ARINC, also it's widget ID, but it's not relevant to our problem). In our User Application implementation (which happens to be coded in C++), a lot of parameters which are considered as cyclic are send regardless of their value change, because they change often. However the Server checks for their change, and in this case, it does not go further than their decoding. It turned out that the time the Server takes to decode a huge buffer and make its checks is negligible (of the order of 1 ms for example). | ||
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* The list of CSVs sounds good to me. And I agree that having the timestamps could be useful in some usecases. | * The list of CSVs sounds good to me. And I agree that having the timestamps could be useful in some usecases. | ||
* supporting multiple values in one response (i.e. like CSV) will inevitably require server-side escaping and client-side "unescaping" of properties. | * supporting multiple values in one response (i.e. like CSV) will inevitably require server-side escaping and client-side "unescaping" of properties. | ||
== Hashing == | |||
* hashing is already supported by the property tree itself (see SimGear library), it is in fact used internally for storing properties, so one of the easiest ways to hashing support would be directly exposing and using the hashes computed by the property tree: http://simgear.sourceforge.net/doxygen/classSGPropertyNode.html It seems, the hash code is stored as an unsigned int (private storage), see line #01758 in http://simgear.sourceforge.net/doxygen/props_8hxx_source.html So it would just be a matter of adding the following to the public interface of the "bucket" class: inline unsigned int getHashcode() const {return hashcode;} And then add a corresponding wrapper to the top level SGPropertyNode class for accessing a node's hash. Either as a static method or as a member function using the "this" pointer. Something along these lines would then allow using hashes of properties internally, which would also reduce bandwidth requirements. | |||
= Patch prototype = | = Patch prototype = | ||