COMP 310 Spring 2017	Lec40: Mixed Data  Dictionaries, WWJ Mapping Library and the map package

Final Project Issues:

• How restrictive is the API?    Does it rule out certain system architectures, e.g. only client-server topologies are allowed?    Remember, that this assignment is not at all about games but rather about enterprise communications architectures that are connecting arbitrary systems together, so is it reasonable to make such restrictions?
  • Focus on what the fundamental behaviors and data are needed for message-based communications across an enterprise, not on what is "easiest to code" or "makes it easy to create a particular type of system".    The communications subsystem is one of the most invariant parts of an enterprise system and what it is asked to do today may not look anything like what it will be asked to do tomorrow.   Don't base your decisions on whether or not you think that the implementation will be "too hard"--do  the right thing, not the easy thing.
• Can an externally-sourced command send a message to
  • The sender of the datapacket that it is processing?  ==> Does the command have access to the local entity that would be defined as the "sender" of the message?
  • The chatroom in which the user of the command is located?   ==> Does the command have access to an ability to send a message directly to the containing chatroom?   
    • If sending to the chatroom is done by relaying the message back through the original sender of the data packet being processed, what implications does this have about the commands that are being used on that machine vs. other machines?
  • Other chatrooms?  ==> Does the command have access to services that enable this type of communications?
    • Once again, if sending to the chatroom is done by relaying the message back through the original sender of the data packet being processed, what implications does this have about the commands that are being used on that machine vs. other machines?
  • Does the API encourage the respecting of the local system's encapsulation of its communications subsystem?
    • At the level of the internal workings of a command, what can be said about how messages are transported between computers, e.g. does the command actually know how messages are transported?   Should it know anything about the message transport mechanism? 
• In client-server or other game architectures where different machines are not equivalent, what are the implications about what commands are being used to process the same message on different machines?
  • Are different "rooms" on the same machine even required to process the same message identically?
• Is there a semantic difference between the process used to initially connect the game clients and game server together and initialize the game vs. the actual in-game processes and is the API able to clearly express the differences and similarities?
  • Note that semantic differences can be expressed at many levels, e.g. at the receiver level, at the method level, at the message level or some combination of these techniques.
• Does an externally-sourced command have/need access to local system information, e.g. the name of the local user, the name of the room/team, IP address, etc?
• Does the GUI interactions enable the added components to be labeled?   This makes it a lot easier for the GUI to make a sensible presentation of the custom components.
  • Try to make your system maximally respectful of  the local system's MVC separations, including notions that code running under the command's (usually RMI) threads are not directly working with GUI threading.    This can be accomplished by having the command create a "mini-mini-MVC" where the command's "view" is installed into the local system's GUI.

Mixed Data Dictionaries

Please see the Java Resources page on Mixed Data Dictionaries and Inter-Module Communications.

WWJ Mapping Library

Please use a message-passing architecture for game server to game client communications -- one of the main points of the final project is to practice thinking in these terms.

Today we will discuss the new World Wind Java mapping library as well as any design issues that have come up over the break.   Here are some links to WWJ references and demos:

• Comp310 WWJ page
• WWJ library attachment instructions -- follow carefully!
• NASA WorldWind
  • World Wind Central
  • FAQ
  • Setup

A WWJ demo app is available: simply check out the following project:   https://svn.rice.edu/r/comp310/course/FinalProjec/FXX/WWJ_Demo   (FXX = F14 for Fall 2014, for example)

Word of advice:   Those who accomplish more, earlier, will have first dibs at suggesting and effecting common API changes that would naturally benefit their game the most!   Stragglers will be forced to modify their code to accomodate other people's desires.

map Package

The supplied map package provides some basic WWJ map capabilities such as

• Easy-to-use default annotation attributes
• Customizable right-click behavior for annotations
•  Simple map panel GUI component that shows the map that supports the adding and removing of map overlay layers.
• Map overlay layers onto which annotations can be placed.
• "Toggle Annotations" that will change their displayed text when clicked.
• A modified Position class that can have an altitude (hieght in the sky) different than its elevation (height of the ground at that point).

See the documentation for the map package.

© 2017 by Stephen Wong