Socket Server

The Socket Server module provides a generic interface for Socket based (network) clients. The Socket Server module allows you to receive and send data from any network accessible client. Note that this is a generic module in that you will need to adhere to the data protocol of the external client.

More specialized communications (like HTTP) have their own modules but cannot be used in servers that are not known to RoboRealm or created as custom products. This module provides the underlying basic network server connection for remote clients but requires that you specify what and how data is transmitted and received.

Note that this module provides yet another way of integrating RoboRealm with external applications. For a more comprehensive overview please have a look at our Integration documentation.

Interface

Instructions

1. Settings - Specify the port number the server should listen on for connections.

2. Method - Specify what protocol you would like to use when sending information. Note that TCP/IP should work in most cases across the Internet as it is a standard protocol with built in error checking. UPD is quicker (has less overhead) than TCP but does NOT guarantee delivery of the information and should only be used on local networks as most routers will block UDP traffic.

3. Console - If a client connects to the server you will start to see a large amount of numbers scrolling by in the console. This shows the current values being read from the client and provides a log of the ongoing communication activities. The red text are characters received from the client while the green text are characters sent by RoboRealm to the client. To copy the log click on the Copy button, likewise to clear it click on the Clear button. Note that the console log only shows several lines at a time with older information being discarded.
You can switch the output to various formats for better viewing:

ASCII - shows new data as ASCII characters. Any character outside of printable characters will be represented with a \ followed by the actual integer data that was read

Decimal - shows new data as sets of single byte integer numbers

Hexadecimal - shows new data as sets of hexadecimal numbers (base 16 numbers, e.g. FF)

Short Binary - shows new data as binary numbers with prefix 0's removed

Binary - shows new data as sets of single byte binary numbers

4. Send Now - often you need to quickly test the client by sending a certain sequence of characters. To do so just type in the character sequence (using for carriage return, [image_count] for variables, etc.) and click on Send Now. The text will be parsed and sent to the server whose response will then appear in the console log. Note that this is different from the send sequence which will be sent each time the module is encountered in the processing pipeline. The Send Now button is a manual testing mechanism meant for debugging purposes. Also note that the returned text will be parsed by the Receive Sequence so that you can test your parsing code and see if the variables have been created. Use the Watch Variables module to see those variables being created.

5. Refresh Rate - to slow the scrolling of the numbers select a different refresh rate for the console. This will just slow down how quickly RoboRealm reads information from the server.

6. Initialization Sequence - The initialization data sequence sends the provided string to the client on initialization of communication. You may want to use this to command the receiving client into a specific mode ready for communication with RoboRealm. This initialization sequence is sent each time the communication is reset. This happens when you click on the "Stop" button in this interface or when the RoboRealm starts running for the first time. It is NOT sent when the Run button in the main RoboRealm interface is toggled.

7. Send sequence - Used to enter commands sent per pipeline loop (i.e. image processed) by RoboRealm. You can use this sequence to transmit variables created by other RoboRealm modules to the client. Each time an image is captured and processed the Socket Server module will interpret the Send Sequence text and send the result to the server. See the Text Formats page for additional information about the text string format.

8. Enable - Allows you to temporarily disable sending text to the server while performing edits. Note that the Send Sequence textarea will turn red to indicate this setting.

9. Send Rate - Some clients cannot handle rapid data streams. Use this dropdown to select how quickly you want the data to be sent. At AFAP (As Fast As Possible) the data will be sent out about 30 times a second (this assumes a camera running at 30 fps).

10. Send only on change - If your data does need to be sent out to your client every iteration through the processing pipeline loop this selection will prevent the same data from being sent to the client that was last sent. This is also an elegant way to reduce the data bandwidth to the client if your sequence does not change rapidly.

11. Receive sequence - used to receive and parse text send from the client. The text string is matched against the incoming bytes. When a match is found variables are added into RoboRealm for use in other modules. Reading into variables just requires adding in a variable at the appropriate spot within the receive string similar to the scanf routine in C/C++. The Receive sequence works similar to an expect string, i.e. you need to specify patterns that match the incoming text and substitute the areas that need to be fed into variables with the [ variable_nane ] format. Note that even if you are missing one space or newline the patter will not match and the variable will be zero or blank. See the Text Formats page for additional information about the text string format.

Example

1. Download the Sensor Data Streamer for your iPhone/iPad and enter in your PC ip address and port 9090.

2. Launch RoboRealm, click on the Search tab, and enter in Socket Server. Double Click on Socket_Server that will add this module to the pipeline.

3. Select UDP as the method

4. Enter in one line

FS\w[ver]\f[acc_x]\f[acc_y]\f[acc_z]\f[gyro_x]\f[gyro_y]\f[gyro_z]\F[tes_x]\F
[tes_y]\F[tes_z]\F[mag_head]\F[true_head]\F[latitude]\F[longitude]\F[altitude]

into the Receive Sequence text box and press the START button to start the module.

5. This example shows how external applications can send data to RoboRealm. The Sensor Data Streamer will send UDP packets of accelerometer, gyro, etc. information collected on the iPhone/iPad to the PC over the network. This data stream is then interpreted by RoboRealm given the receive sequence. This shows how RoboRealm can be configured to receive information from external applications that have their own data protocol.

Note, if you add a Watch module you can see the specific variables change when you move your device.

As the Sensor Data Streamer app uses UDP you MAY not be able to receive packets from your iPhone as UDP packets are often blocked in WIFI networks. Also note that UPD is NOT a guaranteed protocol and without a CRC (checksum) there is no guarantee that the data from the iPhone is correct. Its very possible that only half the message be received which may cause momentary corruption of the data. Care should be taken when using this technique to steer or control large machinery!

See Also

Socket Client
Serial
USB HID

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