Posts Tagged ‘jquery’

I’ve written several times about the development of a client-server Interactive Fiction platform. Parts of this system are called FyreVM, Zifmia, and other parts are just plain old web application development. FyreVM was created years ago and is a very stable implementation of the Glulx virtual machine. Zifmia is a state-machine wrapper that allows FyreVM games to run on a web server with all of the commands coming through AJAX calls and output returned as JSON. I wanted to provide a more detailed view of the new Textfyre system’s construction.

I spent a good portion of my spare time last summer working through the technical issues of a client-server implementation of FyreVM/Glulx. I’d had a very rough prototype, but last summer I sanded down the rough edges and came away with something solid. There were still major issues to resolve, including the design and persistence, but eventually I was able to send commands into the server-side engine and receive story data and display it on a web page. The next step was to turn it all into something “enterprise” ready. Something that initially could handle hundreds of users, but also be able to scale.

The first thing I worked on is making a reasonably clean “library” of JavaScript and jQuery code that was layered and maintainable. I then took all of that code and implemented an ASP.NET MVC 3 website. This allowed me to implement Clean URL’s, but also has a built-in capability for creating RESTful web services. It also allows me to continue using C#, since that’s how FyreVM and Zifmia were coded.

An additional benefit to using RESTful web services for all game play is that other types of clients can be developed later (iPad, Android, Windows 8 Metro).

One of the primary differences in this approach is that all of the game data is stored on the Textfyre servers. You might call it Cloud-IF since the player could conceivably play the same game from many computers and devices without any concern for saving, restoring, or managing files. The system stores the results of every turn and provides a user-interface that lets the player “jump” to any historical turn. The user interface even tracks branches, so the player can see where they jumped and where they changes paths.

This is done using Eloquera, an object-oriented database. It allows for very simple storage and retrieval of session data.

Not to stress this too much, but designing a modern user interface for Interactive Fiction is very difficult. Juhana Leinonen set the standard with his Vorple demonstration a year ago at PAX East. Jon Ingold and his partner Joseph Humfrey are doing some amazing things at Inkle Studios (Note: Jon Ingold is the co-designer and writer of Textfyre’s The Shadow in the Cathedral). I’d like Textfyre’s offering to be capable of similar results.

With that in mind, I’ve left all of the styling capability of this system to external resources. I considered adding a bunch of CSS capability to an Inform 7 extension and asking the author to work under those constraints. After a few passes, this was simply tiresome and very much the wrong direction. I designed the IO of FyreVM to be design neutral for a reason. I believe firmly that content should not know about how it is formatted; outside of emphasizing text with boldface, italics, or similar in-line styles. Any placement or styling beyond that should be handled by the content type. Since FyreVM allows the author to channel output to different content types, this is easily handled in the “interpreter”. In this case, the browser is our interpreter. We simply take content types and associate them to browser placement and styling.

The next assumption I made was that whatever template I designed was only going to be the default or standard template. There are a set of guidelines for authors or anyone interest to develop their own template. It may be daunting for an author and certainly a non-programmer to develop a template using HTML5, but it’s certainly not impossible or even improbable. I think the results of Vorple and Inkle Studios is confirmation that the IF world has the talent.

The standard template is very similar to a standard desktop interpreter with a few changes. Images can be identified by the game by filename and embedded in-game play, a map can be identified, and a few other visual elements allow interaction with the game, including displaying the player’s current inventory.

It would not be difficult to modify the standard template to move things around. Swapping in a new CSS file could change the entire design, similar to the way CSS Zen Garden works.

Web Services
I mentioned that game play is implemented using RESTful web services. Each service is called with a Clean URL and returns JSON (JavaScript Object Notation). HEre is a list of all of the possible web service calls (all executed through HttpWebRequest, always from a jQuery command):
Register player – /Register/{username}/{password}/{nickName}/{emailAddress}
Player login – /Login/{username}/{password}
Is Authorized – /IsAuthorized/{authKey}
Validate Player – /ValidatePlayer/{validationId}
Session Start – /SessionStart/{authKey}/{gameKey}
Session Get – /SessionGet/{authKey}/{sessionKey}
Session History – /SessionHistory/{authKey}/{sessionKey}/{branchid}/{turn}
Session Command – /SessionCommand/{authKey}/{sessionKey}/{branchId}/{turn}/{command}
User Session List – /UserSessionList/{authKey}
List all installed games – /Games

Game Data
When the player enters a command, it’s sent to the Session Command web service. This service executes the command and gathers all of the data. This data has always been called “Channels”, but you could also call it labelling. When the author is emitting text in a game, there are different kinds of text. FyreVM automatically determines most of the types and labels them accordingly. So the room title and description get labelled “Main”. The room title also is labelled “Location”, the score is labelled “Score”, time “Time”, turn “Turn”, and so on. The list of standard labels includes:

Prompt This is the text that precedes the prompt. In a standard IF game, this has always been “>”, but in our system, it can be any normal text.
Main This is the main text of the game, which includes any ‘before’ text, the location title and description, any object lists, and ‘after’ text.
Time This is the time of day within the game. It’s not always implemented or used, so the standard template looks at the Settings text to see if it should be displayed or not.
Location This is the location name.
Chapter If a game implements chapter titles, this is that text.
Credits This is the list of credits for the game.
Hints This is the current list of hints for the game. This data has to coordinate with the browser properly, so modifications to the standard template are required.
Score This contains the current score, if one is offered. The Settings text will identify if a score is displayed or not.
Title This is the game title.
Prologue This is the text displayed in the ‘When play begins’ rule of the game.
Turn This is the current turn number.
Tips This is a tip for the player.
Version This is version of the game.
Verb This contains the verb in the last command.
Tutorial This contains tutorial text.
Maps This contains a map image filename or some other text to show a map to the user. The standard template uses images (that change throughout the game).
Dead This is the text emitted when the game has ended.
Settings This text contains information on whether other types of text should be displayed or not.

Authors can dynamically label alternative content, which can in turn be displayed in the browser based on author preferences.

All of this data is returned in JSON and looks like this (this is an excerpt from a running version of Cloak of Darkness):

"Channels": [
{"Name": "PLOG", "Content": "Hurrying through the rain-swept November night, you\u0027re glad to see the bright lights of the Opera House. It\u0027s surprising that there aren\u0027t more people about but, hey, what do you expect in a cheap demo game...?"},
{"Name": "CRED", "Content": "Cloak of Darkness by David Cornelson\nGame Engine (FyreVM) by Jesse McGrew\nZifmia by David Cornelson\nInform 7 Programming by Emily Short and Graham Nelson, with Channel IO updates by David Cornelson.\nSpecial thanks to Graham Nelson and Emily Short for all of their hard work on Inform 7."},
{ "Name": "SCOR", "Content": "0"},
{ "Name": "TUTR", "Content": "You might try going WEST from the Foyer of the Opera House"},
{ "Name": "TIME", "Content": "540"},
{ "Name": "LOCN", "Content": "Foyer of the Opera House"},
{ "Name": "PRPT", "Content": "What do you want to do next?"},
{ "Name": "MAPS", "Content": "cloakmap-dark.png"},
{ "Name": "MAIN", "Content": "You are standing in a spacious hall, splendidly decorated in red and gold, with glittering chandeliers overhead. The entrance from the street is to the north, and there are doorways south and west."},
{ "Name": "TURN", "Content": "1"},
{ "Name": "TITL", "Content": "Cloak of Darkness"}

There’s a framework in place to convert the JSON data into a known JavaScript class, so “PLOG” becomes game.Prologue and “LOCN” becomes game.Location. This can then be displayed by updating the web page through a jQuery command, like this:


The new Textfyre website is nearly completed and in coordination with several eReader publications, is due out soon. It’s taken a long time to work through all of the technical details, but I think the results will be very attractive to Interactive Fiction game players as well as authors, teachers, and educational content providers.


As announced on, I’m running a mini-competition with a very specific style of game in mind. I call it the Ten Room Web IF Game Mini-Competition. The idea is to get people focused specifically on the art and design of a small game whose map fits on screen while balancing story and puzzle for such a construct. I have a web page site up for the mini-comp at
The rules are summarized below.

  1. Create a new and original Interactive Fiction game.
  2. The game must have exactly ten rooms.
  3. The map of all ten rooms must be visually accessible in 2D format or if you’re a snappy graphic artist, some sort of 3D imagery is acceptable. You must provide a graphical map.
  4. Use any tools you wish, but see #5.
  5. Game must be playable in a browser.
  6. Hosting Requirement *** REMOVED ***. You can send your games to me to host on Linux or Windows Server 2008 (IIS), or you can host them yourself. I’d still like to authenticate players completing each game somehow, possibly through an AJAX call with a game-embedded password or something.
  7. Bug fixes will be allowed at all times after games are “released”.
  • Competition Deadlines: February 1, 2012 – Sign up deadline. This gives you time to think about it, play around with some ideas, and decide if you want to proceed.
  • March 15, 2012 – Beta submissions.
  • April 30, 2012 – Final submissions, voting begins.
  • May 15, 2012 – Voting Ends, winner announced.
Competition Voting: Open web voting from people proven to have played through all of the games. Since all of the games need to be playable online, I’ll rig up an authentication system to allow voting once a user has completed all of the games.
Competition Prizes: I’m not sure what anyone will be interested in as a prize, so I’m open to suggestions. Textfyre will donate $100 to the best game based on my own judging (since the intended judging criteria are suspect and may not work out – if we can get that straightened out and there are more than a couple of submissions, the $100 will go to the judged winner).

Since getting the service layer running for Zifmia, I’m now focused on the client side look and feel and getting a first iteration completed by PAX for the IF Demo Fair. To that end, I’ve come up with a first draft of the wireframe layout.

As you can see, this is very different from previous Interactive Fiction UI designs. There are tabs on the right for different types of content. Popup menus that can auto-enter commands relative to a word in the text, a history of commands and recommended commands, a movement panel with all of the common directional verbs for auto-entering, a list of users (the lamp represents who is in charge of entering commands, everyone else is a watcher), an achievement panel, and a description panel (which will show the results of examine, search, and similar commands without using a turn – everything in-scope is known for every turn).

I’ve tried to keep the focus on words and reading as opposed to images, but this the first foray into developing a Zifmia web client and I wanted to try to stay somewhat generic. Future, game-specific user interfaces could have clickable maps, and other features. Eventually, Zifmia will allow a UI package to be uploaded that contains javascript, css, html, and images and tie the package to a game. Then when someone starts that game, the game UI package is used to display the game.

There is still one piece missing and I’m still pondering the implementation. The user can review previous turns. This data is stored on the server. So if the user has played 100 turns, how do we show this and how can we make it easy to select a previous turn or allow paging? This is a purely UI question. Technically, retrieving any turn is a simple AJAX call.

Since we’re using jQuery to design pages, we should be able to offer jQuery themes too.

I will also be adding oAuth to protect the service and offer pay games, web chat, and more.

I’m hoping to have the bulk of this design ready for PAX.

So I have a working version of Zifmia, a client/server implementation of FyreVM. Basically, this is FyreVM with a state management wrapper where state is stored on the server. The wrapper and engine are hosted in a web service. I started developing the client web behavior with very basic html controls and it’s now time to design and create something interesting.

I was wondering if anyone with mad jQuery/CSS/HTML skills might want to help out and that’s not even a request to actually write code. Even ideas on how to translate an IF game onto a web page would be great. For instance, I don’t plan to implement a running scrollable textbox with game transcript text. I want to develop a paging mechanism and use jQuery to make it fluid within the browser, so keystrokes will allow movement to previous turn output and returning to the latest “page”. I’d like to implement a CSS based compass rose that shows available visited exits and possible unvisited exits (I’ve recently implemented a new channel that reports, in XML, what the visted and unvisted exits are).

I’m not much of a designer and defintely not a jQuery/CSS developer. I also have many other tasks on my plate.

The result of any work is open source and will be documented and shared with the IF community.

So I had set aside a lot of IF work in the past month for work and health reasons. I found myself with a very bad case of whiplash after several wild rollercoaster rides at Six Flags which uncovered high blood pressure, which led to me to get a stress test, a physical, and to see a foot doctor. The neck pain and dizziness are gone, the new orthopedic shoe inserts are wonderful, and the blood work all came back normal. I feel better. Relieved.

I had left Zifmia in a nearly working state, outside of details like security and the client aspects. The server was very close to being completed. So I’ve spent the last three days working through the issues and it’s now running perfectly. Here’s what I did.

I’ve developed FyreVM in a new WCF web service. For newcomers, WCF is a framework from Microsoft that allows you to easily build web services. The service has a single interface, GetResponse:

    public interface IZifmia
        ZifmiaResponse GetResponse(ZifmiaCommand zCommand);

The ZifmiaCommand is parameter class:

    public class ZifmiaCommand
        public string SiteKey { get; set; }
        public string GameKey { get; set; }
        public string UserKey { get; set; }
        public string Command { get; set; }

The main parts we’re interested in today are GameKey, UserKey, and Command. The GameKey is a reference to a server-side game file. The UserKey is a user’s identity. The Command is whatever the user has typed into the game window.

WCF has a built in test client that helps us test:

In the first frame, we’ve opened up our test client. We click on the GetResponse interface, which displays our available zCommand interface. Then we add in our start up arguments and invoke. You can see the results in the third image. Each channel has a value or is blank. Then we add a command and invoke a second time. This shows the channels again with different data. In the final image there is a couple of files that represent the state of the game. The main file is the save data and the numbered XML files are the channel data saved for each turn. We can re-use this data to display previous turns in the browser (or any application that consumes the Zifmia service).

It all works and is very fast.

Next up, the client with fancy jQuery controls to display our channel data.