Once you have Subversion set up properly you can update the construct codebase as a new project in your Eclipse workspace. It is important that you do this as a new project, since we commit our project settings, which include the plugin settings for our static checkers - the main point of this blog post

So, without further ado, here are the list of static checkers we use on the eclipse codebase:

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Provided my bag doesn’t get stolen there will be more to follow.

Part 2

And here it is. On Monday (8/9) I deployed Construct 0.8a to Machu Picchu in Peru. The Inkas love it. When I left the Inka chief was in deep discussion about named graph support and php-based web mashups over a hot cup of coca tea:

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• The first 3 bytes correspond to the message type identifier (see below).

The next 10 bytes correspond to the length of the message payload in bytes. For example, a message with a 64 byte payload would be written as 0000000064.

• Finally, the message payload consists of a number of bytes indicated by the previous part of the message. The contents of the payload are protocol specific.

The message identifier codes used are as follows:

When most service send a response to the client, the payload also takes the form of a code:

Working with the discovery service

Open a connection to the host/port given in the bonjour resolution (there is no need to send any data). You will be sent an XML descriptor file of the form -

This provides you with all the information required to open a connection to the data port or query service directly.

Working with the data port

Use the protocol described above. This is an example of adding a single line:

• 1000000000043<http://hello> <http://construct> "world" .

NOTE: The data RDF Triple must have the trailing full stop . Example responses might be:

• 1100000000003600 (OK)
• 1100000000003610 (ERROR)
• 1100000000003650 (UNKNOWN)

Working with the query service

The point of contact for application developers to Construct is the Query Service. It takes a SPARQL query as an input. This query is run on the data store (a list of RDF triples). If the query is valid and answerable, a string of data will be returned. This section will try to help you write a SPARQL query, and make sense of the returned information.

Writing a SPARQL query

The presence of a query service implies that there must be something to query. The data in Construct is stored in the data store. All the data is represented in RDF triples. Here’s a few examples of these: For readability, we will replace the URIs with the prefixes “sighting:” and “person:”. NOTE: The prefixes in the query(below) is valid SPARQL syntax.

These four statements represent a sighting from a computer activity sensor.

The Query

To retrieve information from construct, a query must be written in the SPARQL format. This has a similar “Select X From Y Where Z” form to an SQL query. Here is an example query which relates to the RDF Triples above. It finds all the times of sightings of Waldo(note the time triple above).

For a more comprehensive tutorial on SPARQL, visit the website at: http://www.w3.org/TR/rdf-sparql-query/

In order to send a query to the query service we must use the protocol described above. Below is an example.

• 200[payload length][SPARQL QUERY]

The Response

You will be sent back a string of the form

• 210[payload length][SPARQL result set in RDF form]
• OR 2100000000003610 (if an error occured)

This String is a SPARQL ResultSet. This is a valid RDF string, represented in N-TRIPLE format. This means that way in which it is processed is dependent on the RDF parsing capabilities of the language used. For example, in java, a new Jena model (or indeed a ResultSet object) can be created from it, and it can be then easily traversed.

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As part of his leaving presents we made up this rather fetching (even if we do say so ourselves) T-Shirt, so that he can spread the word of Construct to the world.

Good luck Steve - Bon Voyage!

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Following on from last year’s workshop in Innsbruck, USE ‘08 aims to bring together practitioners from a wide range of disciplines to discuss best practice and challenges in the evaluation of ubiquitous systems. Recognised evaluation strategies are essential in order that the contribution of new techniques can be quantified objectively. Experience has shown that evaluating ubiquitous systems is extremely difficult; approaches tend to be subjective, piecemeal or both. Individual approaches to evaluation risk being incomplete and comparisons between systems can be difficult.

The submission deadline for USE ‘08 is July 07, 2008. Please visit http://www.useworkshop.org for further details.

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When querying named graphs in Construct using SPARQL and the QueryService you need to add the GRAPH keyword to pattern match against graphs in the dataset. Lets start with the easiest example, selecting all the graphs and all the statements…

So now your resultset is going to be able to return four pieces of info for every statement.

Graphs in Construct probably don’t confer too much useful information on their own however, as they are just unique ids, created by the data store.

It is useful though to know what graph(s) a statement or set of statements appears in. You could use something like this…

Now you’ve got the graph(s) that your statement(s) appears in, suppose you wanted to find all the metadata associated with those statements. All you have to do is add the following query…

where $GRAPH_URI corresponds to the name of the graph(s) returned by the previous query. Now you’ve got all the metadata associated with your statement(s). This is only a small example of what kind of SPARQL queries can get the most out of the new data storage technique - all that’s left is to have a go!

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*** WARNING *** The programme ‘java’ uses the Apple Bonjour compatiblity layer of Avahi.

*** WARNING *** Please fix your application to use the native API of Avahi!

*** WARNING *** For more information see

*** WARNING *** The programme ‘java’ called ‘DNSServiceQueryRecord()’ which is not supported (or only supported partially) in the Apple Bonjour compatiblity layer of Avahi.

*** WARNING *** Please fix your application to use the native API of Avahi!

*** WARNING *** For more information see

One way to address this is just to turn off the Avahi warning. Set an environmental variable list this export AVAHI_COMPAT_NOWARN=1 This isn’t a fix though it is just hiding the warning.

The best I have figured out so far is just to reinstall Bonjour:

Instructions for Installing Apple’s Bonjour on *nix

1. Download the latest version of the Bonjour source code here.
2. Decompress the downloaded archive
3. cd to the mDNSPosix directory below the mDNSResponder-xxx directory (where xxx is the Bonjour version number).
4. Edit Makefile and change line JDK = /usr/jdk to make it point at your Java installation (e.g., /usr/lib/jvm/java-6-sun)
5. Type sudo make os=linux Java

6. Type sudo make os=linux install — if you have problems with this, see below. Most likely you will need to install a specific version of gcc
   
7. Copy the java specific files to your jre lib’s ext directory (cp build/prod/* /path/to/jre/lib/ext/)
8. Open up /etc/nsswitch.conf and ensure that the ‘mdns’ switch appears on the “hosts:” line. My “hosts:” line looks like this:

hosts:          files dns mdns

Remember, whenever you use a new jre, make sure to include dns_sd.jar (Bonjour JAR file) in your jre/lib/ext directory

Problems with the install

Problems with stdlib.h

Lorcan had some problems with this install on Ubuntu (Edgy). He says: when running sudo make os=linux Java I got a lot of errors, starting with ../mDNSShared/dnssd_clientlib.c:71:20: error: stdlib.h: No such file or directory.

I installed the libc6-dev package. When I tried again everything worked fine

Problems with __stack_chk_fail_local

I had some major problems with this install on Ubuntu (Edgy), specifically when using gcc4.1 (to find out which version of gcc you are using type gcc --version).

lorcan@comp:~/Desktop/mDNSResponder-107.6/mDNSPosix$ sudo make os=linux install
Stopping Apple Darwin Multicast DNS / DNS Service Discovery daemon: mdnsd.
cp build/prod/mdnsd /usr/sbin/mdnsd
/usr/sbin/mdnsd installed
cp mdnsd.sh /etc/init.d/mdns
chmod ugo+x /etc/init.d/mdns
/etc/init.d/mdns start
Starting Apple Darwin Multicast DNS / DNS Service Discovery daemon: mdnsd.
ln -s -f /etc/init.d/mdns /etc/rc2.d/S52mdns
ln -s -f /etc/init.d/mdns /etc/rc3.d/S52mdns
ln -s -f /etc/init.d/mdns /etc/rc4.d/S52mdns
ln -s -f /etc/init.d/mdns /etc/rc5.d/S52mdns
ln -s -f /etc/init.d/mdns /etc/rc0.d/K16mdns
ln -s -f /etc/init.d/mdns /etc/rc6.d/K16mdns
/etc/init.d/mdns installed
cp build/prod/libdns_sd.so /usr/lib/libdns_sd.so.1
ln -s -f /usr/lib/libdns_sd.so.1 /usr/lib/libdns_sd.so
/usr/lib/libdns_sd.so.1 /usr/include/dns_sd.h installed
/usr/share/man/man8/mdnsd.8 installed
make[1]: Entering directory `/home/lorcan/Desktop/mDNSResponder-107.6/Clients’
mkdir build
cc dns-sd.c -L../mDNSPosix/build/prod/ -ldns_sd -I../mDNSShared -o build/dns-sd
/usr/bin/ld: build/dns-sd: hidden symbol `__stack_chk_fail_local’ in /usr/lib/libc_nonshared.a(stack_chk_fail_local.oS) is referenced by DSO
/usr/bin/ld: final link failed: Nonrepresentable section on output
collect2: ld returned 1 exit status
make[1]: *** [build/dns-sd] Error 1
make[1]: Leaving directory `/home/lorcan/Desktop/mDNSResponder-107.6/Clients’

make: *** [../Clients/build/dns-sd] Error 2

Solution:
If the version of gcc is not 4.0.x Follow these instructions (EXACTLY!!!) to correct the problem:

1. Ensure that gcc version 4.0.x is installed. This is a little tricky as the synaptic package manager stopped supporting this version of gcc since edgy. You’ll have to download the following packages:  gcc-4.0-base, cpp-4.0 , gcc-4.0
2. Open the terminal and cd to where you saved the package.
3. Do the following for each of the three packages: dpkg -i PACKAGE.deb Install them in the same order the are above. gcc base first, then cpp, then gcc — This should put gcc-4.0 into your /usr/bin directory.
4. cd /usr/bin
5. sudo mv gcc gcc-backup
6. sudo ln -s gcc-4.0 gcc

Now completely rerun the instructions above (at the top of this page) to install Bonjour (you must completely rerun them from step 2). When installation is complete continue these instructions.

1. sudo cd /usr/bin
2. sudo rm gcc
3. sudo mv gcc-backup gcc

Now gcc should point to the original version of gcc (i.e. that version that you were using before you installed Bonjour).

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(Download Construct PHP Class)

The PHP Class has been tested on Windows versions of PHP (using XAMPP) and on Mac XServe (Darwin), it should work with any webserver running PHP 5, (possibly 4) with sockets support.

The Construct PHP Class also contains a file called constructmananger.php and example.php, the Construct Manager uses the Construct class to give an advanced web interface to Construct, and the Example shows a simple implementation of a sparql query using the Construct class.

Put the files in any web accessible directory, and edit the example.php file to point at the machine that is running Construct.

<?php

$host = "localhost";

// find the class

include_once('Construct.class.php');

// create a new construct object

$construct = new Construct($host);

?>

After importing the class and instatiating it (see above) it is then possible to query Construct as shown below

// prepare a query

$sparql_query = "SELECT ?subject ?predicate ?object WHERE {?subject ?predicate ?object}";

// execute query

try{

$results = $construct->query($sparql_query);

}Catch(Exception $e){

// catch any problems

echo $e->getMessage();

exit();

}

// output the results

print_r($results);

The results are returned as a PHP array by default, but can also be returned as JSON, XML or a Simple XML Object.

$construct->query($querystring, [$xsl=null, [$format=null, [&$error=null]]]) 

Where $querystring is the SPARQL query, $xsl is the xsl-stylesheet to apply (send null if not used), $format indicated the format of the returned data, and $error is an array into which errors should be placed. Values in [] are optional.

The values for format are:

JSON, XML, XMLOBJECT or ARRAY

It is also possible to insert data, the following gives an example

$timeout = "30000"; // Time in ms to keep data in store

try{

$success = $construct->insert($rdftriplets, $timeout);

}Catch(Exception $e){

echo $e-getMessage();

}

Where $rdftriplets are in valid n-triple format.

If links are unavailable, you can try here

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