Overview
Scope and Goals
Getting started
Configuration ** Topics ** Projects
Code Generator ** Generate an app stub ** Generate example app
Style Guide

Overview

sDDS is a DDS implementation for sensor networks.

Scope and Goals

sDDS has these goals:

API compatible to DDS implementation
Run on embedded devices as low as 8-bit micro controllers
...

Getting started

To get started with your first app add it to the 'example/examples.xml':

<examples>
    ...
    <example name = "my_example" os = "myos">My sDDS example</example>
    ...
</examples>

Then run the 'example/generate_examples.sh' to create the stub for your app.

Configuration

Topics

Topics are grouped by profiles and are configured in a xml file. By convention these files are placed into 'example/topics' to avoid topic and profile duplication as well as copy&paste madness. The following example is taken from sdds/example/topics/alphabet.xml:

<profile name = "alphabet">

    <topic name = "alpha" domain = "1" id = "A">
        Alpha messung topic.
        <attribute name = "value" type = "DDS_char">Any char value</attribute>
        <attribute name = "variant" type = "variant"></attribute>
        <attribute name = "parent" type = "parent"></attribute>
        <attribute name = "child" type = "child"></attribute>
    </topic>

    <topic name = "beta" domain = "1" id = "B">
        Beta messung topic.
        <attribute name = "value" type = "DDS_char">Any char value</attribute>
    </topic>

    <topic name = "gamma" domain = "1" id = "C">
        Gamma messung topic.
        <attribute name = "value" type = "DDS_char">Any char value</attribute>
    </topic>

    <topic name = "delta" domain = "1" id = "D">
        Delta messung topic.
        <attribute name = "value" type = "DDS_char">Any char value</attribute>
    </topic>

    <!-- Enums have a mandatory name and a optional namespace. You can have as
         many literals as an uint64 can hold. -->
    <enum name = "variant" namespace = "greek">
        Letter variants can be upper or lower case.
        <literal name = "upper" />
        <literal name = "lower" />
    </enum>

    <enum name = "parent" namespace = "greek">
        Parent systems of the greek alphabet
        <literal name = "egyptian" />
        <literal name = "proto sinaitic" />
        <literal name = "phoenician" />
    </enum>

    <!-- Enums can be further customized by assigning a unsigned integer. The
         largest value determines the data type (uint8 - uint64). -->
    <enum name = "child" namespace = "greek">
        Child systems of the greek alphabet
        <literal name = "coptic" value = "200" />
        <literal name = "gothic" value = "350" />
        <literal name = "glagolitic" value = "862" />
        <literal name = "cyrillic" value = "940" />
        <literal name = "armenian" value = "405" />
        <literal name = "old italic" value = "1000" />
        <literal name = "latin" value = "100" />
        <literal name = "georgian" value = "430" />
    </enum>
</profile>

Projects

To configure the example project use the generated sdds.xml and change it to your needs.

<project
    name = "my_example"
    script = "sdds.gsl"
    endian = "little"
    os = "myos"
    ip = "fe80::12:13ff:fe14:1516"
    iface = "eth0"
    >
    <!--
        Include your topic files here. You can include topics from multiple files.
        Only those topics will be generated that have at least one matching role.
    -->
    <include filename = "../topics/messung.xml" />

    <!--
        Add defines to enable/disable features.
    -->
    <define name = "FEATURE_SDDS_MULTICAST_ENABLED" />
    <define name = "FEATURE_SDDS_BUILTIN_TOPICS_ENABLED" />
    <define name = "FEATURE_SDDS_DISCOVERY_ENABLED" />
    <define name = "SDDS_NET_MAX_BUF_SIZE" value = "1024"/>
    <define name = "SDDS_NET_MAX_LOCATOR_COUNT" value = "20"/>
    <define name = "SDDS_DISCOVERY_RECEIVE_TIMER" value = "1"/>
    <define name = "SDDS_DISCOVERY_PARTICIPANT_TIMER" value = "1"/>
    <define name = "SDDS_DISCOVERY_PUBLICATION_TIMER" value = "5"/>
    <define name = "SDDS_DISCOVERY_TOPIC_TIMER" value = "0"/>
    <define name = "SDDS_QOS_LATENCYBUDGET"/>
    <define name = "SDDS_QOS_DW_LATBUD" value = "5000"/>
    <define name = "SDDS_QOS_DW_COMM" value = "1000"/>
    <define name = "SDDS_QOS_DW_READ" value = "1000"/>

    <!--
        Roles are bound to one topic and are either a publisher or subscriber.
        Publisher can have a list of subscriber to whom the should send data.
        If there's no subscriber for a publisher sDDS will automatically use
        discovery.
    -->
    <role topic = "alpha" type = "publisher"/>

    <!--
		 static topic subscriptions
		if a subcription should be static, it can be set here. This
        should only be set, if the role is publisher
		<subscription topic = "mytopic">
			<subscriber ip = "fe80::20"/>
			<subscriber ip = "fe80::30"/>
		</subscription>
	-->
	<subscription topic = "alpha">
		<subscriber ip = "fe80::12:13ff:fe14:1516"/>
	</subscription>
	
</project>

Once you're done configuring your example run 'generate.sh' to create the Makefile after that you can you 'make' and 'make clean' to build your example.

NOTE: The first time you're running 'generate.sh' it will download and install the code generator which will take some time!

Code Generator

The sDDS Code Generator is responsible for generating DDS topic and DDS participant dependent code. It uses GSL/4.1 as code construction tool.

The sDDS Code Generator has these primary goals:

generate topic files
generate topic implementations
generate Makefiles
generate skeletons for new apps

Makefile generation is currently supported for:

Linux
Contiki

The code generator is split into two distinct generation processes:

Generate an app stub

This is done by 'sdds_examples.gsl'.

Generate example app

The entry point is 'sdds.gsl':

sdds_topic.gsl - Generate the topics
sdds_impl.gsl - Generate the implementation of the topics
sdds_constants.gsl - Generate the default constants for sDDS
sdds_make_.gsl - Generates the Makefiles for the different operating systems
sdds_skeleton - Generates a skeleton for new examples dependent on topics and roles

Style Guide

sDDS uses uCLASS guild for code style.

bendst / sdds

Contents