Release Beta

So there's four major things that have happened with BlueMesh recently:

• Messages are now sent with headers describing their size, so the message size limit is as big as a 4 byte unsigned integer can get.
• We've switched to supporting only Android 4.x since the Bluetooth stack is significantly more reliable
• After some testing, we were satisfied that this release is stable enough to be released as a beta.
• We got an honorable mention at the RPI Undergraduate Research Symposium.

That's pretty much it. From here on out we will be focused on getting proper routing to work (as much as we can between classes).

This Week at BlueMesh

Hey guys,

So we are in our FINAL FINAL stages before releasing an official Beta! (seriously this time)  BlueMesh has preformed better than ever before!  We will have a release date announced next week around this time.  We are closing down on the rest of the blocking bugs and finishing up tweaking the code.

We are do however have one BIG change that we need to announce.  We are dropping official support for 2.X devices.  This DOESN'T mean that you won't be able to use BlueMesh with a 2.X device as we are still targeting API level 7, it just means that it may not work exactly as you expect it to.  We at BlueMesh recommend that you target your BlueMesh apps to Android 4.X devices in order to avoid weird behavior from some 2.X devices.

Here is what has happened over the past week.

Bugs fixed:

• ClientThread appears to die upon first connection
• Once device disconnects it will not reconnect
• Sockets do not get closed immediately when BlueMesh is stopped

Bugs found:

• FatalException on closing BlueMesh in Android Runtime

The goals for next week will be the following.

Jerry:

• Fix FatalException in Android Runtime
• Address TODOs in code comments
• Final testing for first beta release

Zach:

• Update WIKI to reflect new API
• Final testing for first beta release
• Propose implementation for new routing protocol for Beta 2

This Week at BlueMesh

This week Zach and I worked on fixing bugs related to connectivity issues and threading issues.

Bugs fixed:

• Runaway threads on exit
• Crash on deconstruction BlueMeshService object

Bugs found:

• ClientThread appears to die upon first connection
• Once device disconnects it will not reconnect

The goals for next week will be the following.

Jerry:

• Fix newly found connectivity bugs
• Final testing for first beta release

Zach:

• Propose implementation for new routing protocol
• Final testing for first beta release

Almost ready for another release.

Hey guys,

Thanks to Doug helping us create a test app, we were able to verify that BlueMesh is working as expected after the code refactor.  We are going to do another week or two of testing before we go ahead and release our next alpha version just to ensure that everything is working as we want it to.

There are still a few small features we are going to implement (mostly optional arguments when building bms) that will be in the new release that we will be doing this week.

Support for Windows, Linux, and OS X will most likely not make it into this alpha, but we will have another alpha release soon after this one with all those features included.

Stay posted for exciting mesh networking news on BlueMesh!

Jerry

BlueMesh Test App

Hello,

As Jerry mentioned last week, I've been working on an application to test the basic functionality of BlueMesh. I'm still learning the Android API and the BlueMesh code base, so my confidence in my work is not astoundingly high. However, I have a first draft of something which is at least a good step towards working. I'll be spending the next couple of days making sure that it does what it needs to.

As of right now, I have the test results simply displayed as a Toast message. Ideally, I would like to set up a full graphical interface of some sort, with a list of the tests performed and checkboxes (or something) indicating whether each was successful. I'll also be looking to expand the set of tests as I get more familiar with what the service is capable of, and as the features themselves are expanded.

-Doug

New Developers

Hey Guys,

As you may know, BlueMesh has been in development for just over a year!  It began with a lonely group of one (me) and remained as such for about 4 months.  For the past 9 months Sean joined the team and we were two.  As of a few weeks ago BlueMesh has attained 2 new developers: Doug and Zach!

Over the next few weeks...

Doug will be working on writing a test application for BlueMesh that we will use to ensure that our master and dev branches are in a working state.

Zach will be working on updating our wiki to reflect our new API (sorry) and all of the new features that we are implementing.

Sean and I will be working on BlueMesh core functionality.  First we will be adding support for Windows and maybe Linux and OS X.

Contact us with any questions you may have,
Jerry

Builder Pattern

Hey guys,

I recently change BlueMesh so that when constructing BlueMeshService objects, rather than using a constructor method you now use a builder.  This makes it a lot easier to add new features to BlueMesh such as support for WIFI or other operating systems.  In addition, it is now a lot easier to configure BlueMesh to exactly how you want it.  Here is a short example of how it works:

BlueMeshService bms;
BlueMeshServiceBuilder bmsb = new BlueMeshServiceBuilder();
bms = bmsb.uuid(UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66"))
          .bluetooth(true)
          .build();
We will be updating the documentation to reflect these new changes soon and also have some new tutorials about how to use BlueMesh.

-Jerry

Another Code Restructure!

Hey Guys,

Over the next week I will be working on a code restructure of the entire project.  I will be abstracting all classes that are currently dependent of Android APIs so that they can be implemented for different wireless communication stacks.  I will also be making some of the larger and more complicated methods smaller and more readable.

After the restructure is done we will be adding support for the Windows Bluetooth stack and maybe another form of wireless communication.  In addition, we will be developing some new apps that use BlueMesh to demonstrate its capabilities.

Stay tuned for more updates!

-Jerry

Addition of Routing in BlueMesh

The traditional Android-only BlueMesh now has functionality to route messages to certain devices on the network. The "write" method now has two versions. The first takes only the byte array as before. The second takes the byte array and a RemoteDevice of some target, and sends the byte array only to that target, if connected at the time.

The routing done is similar to how messages are sent normally, only a targeted message will be ignored by all but the target. This allows for information to be routed only to one device on the network through other, unrelated devices.

The message packet is constructed in a different way depending on whether or not it is a targeted message or not. The old packet construction was allocated so that byte 0 was the message level, bytes 1-4 were a message ID, and bytes 5-1028 are the message itself. Targeted messages are now laid out so that byte 0 is the message level, bytes 1-4 are a message ID, bytes 5-12 are the target, and bytes 13-1036 are the message. Keep in mind these distinctions are controlled by the Constants file and can be changed if necessary. Specifially, the MESSAGE_ID_LEN controls the number of bytes long the message ID is. TARGET_ID_LEN is the length of the target identification, which is a byte array representing the Bluetooth address of the device. MAX_MESSAGE_LEN controls the maximum length of a message, currently set to 1024 bytes.

Message chunking has not been implemented and may not be, since the heuristics to making sure that all of the pieces get where they need to in order are difficult. Instead, increasing MAX_MESSAGE_LEN can be used for reasonable values. I do plan on doing some testing to find what is reasonable for this purpose.

The Agnostic project has been started, but I've run into difficulties in determining what exactly the interface should supply and/or be required to supply. Since different versions of Bluetooth work so drastically differently, it may be better to simply rewrite BlueMesh for a different device. Included here and below is the pertinent information for writing BlueMesh for J2ME, and I'm unsure as to whether or not that will be my next project or not. If anyone is using BlueMesh and is in need of it for a different platform, that may be my next project instead.

Until then, I may just continue testing and debugging.

Bluetooth Client and Server Information

In J2ME, the client in Bluetooth works through the DiscoveryListener interface. This means that the client-side must have some object that extends the DiscoveryListener interface. Meanwhile, the server has a DiscoveryAgent and does some things (as detailed in my last blog) to create an input-output stream between the server and client. However, the method for picking up the other (client) end of the steam was unknown. Below is a tutorial on how the J2ME client should look simply to get an input and output stream.

Note: Something followed by "()" is used to define it as a function in the API, but does not necessarily mean it has no arguments.

An action on the DiscoveryAgent on the client's side causes the four triggers in the DiscoveryListener, also on the client's side. To start, the startInquiry() method on the DiscoveryAgent will eventually call the deviceDiscovered() method in the DiscoveryListener whenever a server device is discovered. Then, the searchServices() method on the DiscoveryAgent finds services from the server and calls the servicesDiscovered() method once it has completed. This will return a ServiceRecord, which contains all the services that the server contains. To summarize, DiscoveryAgent.startInquiry() eventually calls DiscoveryListener.deviceDiscovered(), while DiscoveryAgent.searchServices() eventually calls DiscoveryListener.servicesDiscovered(), which contains as an argument a ServiceRecord.

This ServiceRecord can be used to be accessed all of the services, but the connection URL can be obtained with one line of code (Where servRecord is the instance of ServiceRecord):

String connectionURL = servRecord.getConnectionURL(0,false);

The URL returned is the RFCOMM URL that connects to this device. With this, a StreamConnection can be created with another line of code, which connects the devices and opens the stream between them:

StreamConnection con = (StreamConnection)Connector.open(connectionURL);

This StreamConnection can be broken down into an input and output stream, as in the server. These input-output stream pairs should communicate with each other, and will allow BlueMesh to pass data using the RFCOMM between the devices.

I am still uncertain as to whether the RemoteDevice's Bluetooth address or name should be used as a universal identifier to be passed to the router in BlueMesh. Both are easily accessible from the RemoteDevice. I am leaning towards the address, as the name can be duplicated, but I am unsure as to whether or not it is something that all API's (or at least the Android API) can also deliver.

Bluetooth ServerThread Interface Design

I've managed to work out BlueCove sufficiently enough to use it. Its syntax is identical to that of J2ME. J2ME is a version of Java that is designed to work with small devices, hence its built-in API support of Bluetooth. BlueCove, however, lets us use these same commands with J2SE (Standard Edition) and your basic computer running Windows or OSX.

I have also learned how to use these commands to write client-side and server-side algorithms to get devices to communicate. A useful, if slightly unclear, example can be found on CodeGuru.com. This gives us an input and output stream to work with. Since BlueMesh ultimately uses just an input & an output stream, this should be fine. However, BlueMesh's ServerThread currently passes a "BluetoothSocket" object instead, and that object is deconstructed to an input and output portion in the ReadWriteThread. So, BlueMesh is going to require a back-end redesign.

The ServerThread-like Interface will need to export an input and output stream. This is because the input and output streams are the lowest common denominator in the Android API and the J2ME API. The J2ME API gets these streams from the StreamConnection object, while the Android API gets them from the BluetoothAdapter object. Each object is specific to its own API, and cannot be included in an agnostic BlueMesh. So, the ServerThread will have to send only the input-output stream and some sort of device-identifying data (Device Name? Random Serial Number?) to the RouterObject. It will then be the RouterObject's job to find out if that device is already connected and to set up the ReadWriteThread for it.

Further, the way that J2ME handles clients is unusual. Specifically, it does not generate a BluetoothSocket object, so ClientThread will have to be reworked as well. The J2ME client is implemented with a virtual class, "DiscoveryListener", with four purely-virtual functions that are called when certain things happen, such as discovering a device. I am unsure as to whether or not this class is automatically a thread or really much about clients in J2ME at all. More research will have to be done.

Hopefully, I will just be able to extract from one of these functions/objects the input and output streams, so that the overall design of BlueMesh can be preserved. Otherwise, the ServerThread may be the only object able to set up communication and pass it to the router, meaning the client-side ClientThread will have to invoke the ServerThread to create two-way communication. I want to avoid this, so hopefully it won't be necessary.

Interfacing with others!

Hello, All! As detailed in the last post, BlueMesh will be trying to make the move towards greater compatibility. Specifically, we're looking towards creating a Java interface that will encapsulate all of the proprietary portions of Bluetooth. So, if you are willing to write an interface class for your platform, then BlueMesh will work on it.

That's the vision. Practically, BlueMesh will have to come with a couple of common interfaces. Luckily, I found another open-source project, BlueCove, that will allow Microsoft, OS X, and a few other platforms to do just that. Specifically, I no longer have to write code for these machines specifically; I can use this program as a bridge. More importantly, I hope that BlueCove will give me some insight as to what exactly the BlueMesh interface should expect and contain, so that any interfaces can be written easily.

This task, as large as it is, is one of my greater priorities, for two reasons.
1) It will give BlueMesh greater compatibility and intercommunication
2) It will allow for testing with the library itself to be done one any one platform, and it can be a platform of choice. The Android SDK is nice enough, but doesn't allow for easy debugging. If this interface is successfully written, then BlueMesh can be tested, and eventually operated, between any two Bluetooth-enabled devices.

Over the summer

Hey guys,

I just wanted to write a quick post about what will be going on with BlueMesh this summer.  Sean will be working on the project with RCOS at RPI and he has a lot of really awesome things that he plans to do.  I will be working up by Boston this summer, but I will still try to help out as much as possible.

Some of the changes we hope to implement are as follows:

1)  Port BlueMesh to Java.  Currently BlueMesh only works on Android devices, we plan to port it to Java so it will run on PCs as well.  This will make development much easier and quicker.  Once we have a working version in Java it should be quick and painless to port it back to Android.

2)  Implement message chunking.  Message chunking will allow us to determine the optimum maximum size of a message and allow us to chunk messages into this maximum size in order to allow for maximum throughput.

3)  Implement routing algorithm.  This will allow for point to point communication rather than flooding the network with every write.

There are other changes that are also in speculation right now in addition to these three.  I'm sure Sean will be updating us with his progress often and I look forward to seeing BlueMesh progress.

-Jerry

So close to our first release!

Currently we are one bug fix away from our first release of BlueMesh!

This week I added in an argument to the BlueMeshService constructor so that you can specify a UUID for your program.  This is important because you probably don't want your BlueMesh program to interact with other BlueMesh programs.

This is how you can call the constructor now:
bms = new BlueMeshService(UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66"));



A UUID is specified by hex digits in the following format 8-4-4-4-12.  The UUID can also be used to enable or disable backwards compatibility of your app!  If you would like a new version of your app to be able to talk to an older one, simply do not change the UUID between versions, however if your network protocol changes between versions you can specify a new UUID so that a new version will not communicate with an older version.

The bug we are still trying to fix involves not properly detecting a disconnection and deleting information about that device so that a re-connection will be attempted and successfully completed.  I hope we will have this fixed within the next few weeks and we will try to keep you updated on what we think might be causing it.

WebViewTest Bug fixes

This weekend I fixed a minor bug in WebViewTest (can be found at http://scrambledeggs.myrpi.org/APKs/WebViewTest.apk): The app no longer crashes on start if Bluetooth is not enabled.  I also added more comments to the source so it will be easier to follow.

Please try out the tutorial and try to make your own app using BlueMesh!

How to use BlueMesh Tutorial

This post is a basic tutorial on how to use BlueMesh in your own android project.  Source code for this tutorial was taken from WebViewHost and WebViewTest.

To begin, you can consider the BlueMeshService object both a device for input and output.  This object provides functionality for both reading data from all devices on the BlueMesh network and writing data to all devices on the BlueMesh network.

As a prerequisite to using BlueMesh, a device should enable Bluetooth and pair with other devices.  It is not necessary to be paired with all devices that are going to be on the network, but there should be a path from every device to every other device via Bluetooth pairs.

The first thing that needs to be done when using BlueMesh is create a BlueMeshService object.
try{ bms = new BlueMeshService(); } catch(NullPointerException e){ Log.e(TAG, "Bluetooth not enabeled"); return; }

It is important to note that the BlueMeshService() constructor throws a NullPointerException if Bluetooth is not enabled.  If this happens it means that the constructor failed and you should not proceed, rather you should either end the program, or attempt to enable Bluetooth and try again.

If the constructor completes successfully, it is then time to call launch().  launch begins the Bluetooth communications (listening for other devices running the same app to connect to) and allows you to use the IO functions.
bms.launch();

Now that BlueMesh is running it is time to use the IO functions.  Remember that the UI thread must complete in order to render any graphical display, so it is recommended that BlueMesh IO is preformed in a separate thread.

The following code block shows how to set up a button to send data over BlueMesh.  The write(byte[]) function takes one argument, a byte array, and sends it to all devices on the network.  In this example slides is an ArrayList of Strings.
//button listener send final Button buttonSend = (Button) findViewById(R.id.btnSend); buttonSend.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { if( bluetoothWorking ){ bms.write(slides.get(currentSlide).getBytes()); } } });

In order to read data, use the byte[] pull() function.  This function will return a byte array containing a received message on success and null if there is no message to receive.  This call is non-blocking and will return immediately, please note that it is not recommended that this function be called instantly over and over again in a read loop without a small sleep between attempts.

The following code block shows how to create a read thread the polls the BlueMeshService object for incoming messages.  In this example, the read thread passes messages to the UI thread via Handler mHandler.
private final Handler mHandler = new Handler(){ @Override public void handleMessage( Message msg ){ byte[] byteMessage = (byte[]) msg.obj; String stringMessage = byteMessage.toString(); //Here you can do UI with the message } }; private class ReadThread extends Thread { public void run(){ Looper.myLooper(); Looper.prepare(); while (true){ if( this.isInterrupted()){ Log.d(TAG, "readThread interrupted"); return; } byte bytes[] = null; bytes = bms.pull(); if( bytes == null){ //Sleep if nothing is received to avoid //pounding bms try { sleep(100); } catch (InterruptedException e) { Log.e(TAG, "sleep() failed", e); } } else{ mHandler.obtainMessage (0, bytes.length, -1, bytes) .sendToTarget(); //Here you could process the message //and send a response } } } }

Now that your program can read and write over BlueMesh the only thing that remains is shutting down communications.  This requires a simple call to disconnect() which can be run as the program shuts down.
@Override public void onDestroy(){ super.onDestroy(); readThread.interrupt(); bms.disconnect(); }

Hopefully you enjoyed this simple tutorial on BlueMesh and will be able to develop your own apps.  If you have any questions please email me at schnej7@rpi.edu.

Slideshow Presentations over BlueMesh

Our new test app works with BlueMesh now!  There are two new apps (that work together) developed for BlueMesh that are now in the repository in the WebView branch in the directory "WebViewTest" (the audience app) and "WebViewHost" (the presenter app).

WebViewHost:

The presenter app is fairly simple.  It simply takes strings consisting of html pages and sends them over BlueMesh when the "send" button is pushed.

WebViewTest:

The client app is slightly more complicated than the presenter app because the view needs to be updated during run-time as new slides come in.  This means that BlueMesh needs to be run in it's own thread and pass messages to a handler in the UI thread.  It is important to note that a looper must be prepared if BlueMesh is run in a separate thread than the UI thread.

Stay tuned for a more in depth blog post about how this app works and how to use BlueMesh.

Test Metric Redefined

As programming of our test programs goes on, some of our goals have changed.

The "Fastest Bounce" program works through the CLD, intermittently. We seemed to be getting a bounce time of roughly 1 to 2 milliseconds, though this varied greatly. Also, the program only gets through a few bounces before crashing. We believe that this is due to the CLD front-end, so we are currently trying to implement this test with a stripped-down front-end that will avoid tampering with test results.
Also, as a side note, our last entry didn't include that accuracy will also be tested, even though we haven't seen anything to even remotely suggest that accuracy has been an issue.

The "Largest Message" program will be a moot point initially, since BlueMesh has a maximum message size of 1024 bytes. This will be added to the API. The "Fastest Bounce" test will be repeated for max size, however, to try and obtain a max throughput. As a later goal, we may want to try editing this maximum, but that would require serious code rewrites and is being tabled.

Testing Metrics and BlueMesh

We have been working on developing a number of metric test programs to try and find the technical limitations and performance ability of BlueMesh. Hopefully, we'll be able to get some useful and important data concerning performance and limitations for developers.

Right now, the tests we're trying to create and the questions we have are:
- Fastest Bounce : How quickly can BlueMesh send a small message from device A to device B and back? How much does this time change with N intermediate devices?

- Largest Message: What's the largest message that can reliably be sent through BlueMesh? Does this result in a significant slowdown? What's the greatest data throughput we can achieve with BlueMesh, and what affects it?

I'm considering adding a "Proliferation" test, to see how quickly a message can be sent to a large number of devices, but due to a lack of testing devices, this will likely have to wait.

Fastest Bounce has already been written and is on the git's development branch. It has not yet been shown to work, nor has it been run for numbers. Since I need two phones at least to run a test, achieving this has been difficult, but should be accomplished soon.

A New Test App!

Hey Guys!

I've been thinking of new ways to use BlueMesh and I have come up with some great ideas.  I just posted a REALLY EARLY version of what will be a presentation app that uses BlueMesh to distribute slides between android devices.  The idea is that you will have a presentation and the app will be able to distribute additional notes to the audience.

"How will this work?" you might ask...

The slides will be created using HTML in order to make their distribution across BlueMesh fast and light-weight.  Once the slides are distributed, they will be rendered using Android's WebView object.  The viewer will then have the option to move freely in the slides he/she has received, or jump to the newest slide each time it is received.

If you have any other ideas about what this app should do, ideas for other apps using BlueMesh, or ideas for the BlueMesh API, please post comments on this blog, post on the github, or email me at schnej7@rpi.edu