I am an OPC-UA newbie integrating a non-OPC-UA system to an OPC-UA server using the Milo stack. Part of this includes writing values to Nodes in the OPC-UA server. One of my problems is that values from the other system comes in the form of a Java String and thus needs to be converted to the Node's proper data type. My first brute force proof-of-concept uses the below code in order to create a Variant that I can use to write to the Node (as in the WriteExample.java). The variable value is the Java String containing the data to write, e.g. "123" for an Integer or "32.3" for a Double. The solution now includes hard-coding the "types" from the Identifiers class (org.eclipse.milo.opcua.stack.core, see the switch statement) which is not pretty and I am sure there is a better way to do this?
Also, how do I proceed if I want to convert and write "123" to a node that is, for example,
UInt64?
try {
VariableNode node = client.getAddressSpace().createVariableNode(nodeId);
Object val = new Object();
Object identifier = node.getDataType().get().getIdentifier();
UInteger id = UInteger.valueOf(0);
if(identifier instanceof UInteger) {
id = (UInteger) identifier;
}
System.out.println("getIdentifier: " + node.getDataType().get().getIdentifier());
switch (id.intValue()) {
// Based on the Identifiers class in org.eclipse.milo.opcua.stack.core;
case 11: // Double
val = Double.valueOf(value);
break;
case 6: //Int32
val = Integer.valueOf(value);
break;
}
DataValue data = new DataValue(new Variant(val),StatusCode.GOOD, null);
StatusCode status = client.writeValue(nodeId, data).get();
System.out.println("Wrote DataValue: " + data + " status: " + status);
returnString = status.toString();
} catch (Exception e) {
System.out.println("ERROR: " + e.toString());
}
I've looked at Kevin's response to this thread: How do I reliably write to a OPC UA server? But I'm still a bit lost... Some small code example would really be helpful.
You're not that far off. Every sizable codebase eventually has one or more "TypeUtilities" classes, and you're going to need one here.
There's no getting around that fact that you need to be able to map types in your system to OPC UA types and vice versa.
For unsigned types you'll use the UShort, UInteger, and ULong classes from the org.eclipse.milo.opcua.stack.core.types.builtin.unsigned package. There are convenient static factory methods that make their use a little less verbose:
UShort us = ushort(foo);
UInteger ui = uint(foo);
ULong ul = ulong(foo);
I'll explore that idea of including some kind of type conversion utility for an upcoming release, but even with that, the way OPC UA works you have to know the DataType of a Node to write to it, and in most cases you want to know the ValueRank and ArrayDimensions as well.
You either know these attribute values a priori, obtain them via some other out of band mechanism, or you read them from the server.
Related
when interacting with a rest api using Angular 2. Is it worth creating typescript classes for each object (eg. employee, company, project, user ...). the other option is getting json object and working with it on the fly ?
i suggest using models because :
your code will be more readable for yourself after a while coming back to change it, every one else also can easily understand what you've done
making changes in project will be more easily for example obj[0] does not have any special meaning but obj['username'] is more obvious
you will get intellinsense in you IDE
you can put logic in model for example so your controller will be more thin
name: string
age: number
sayInfo(): string {
return `name is ${this.name} and age is ${this.age}`
}
generally managing you app will be without headache (or at least less headache) :D
just remember that fat models thin controllers
don't forget that passing more than five arguments to a function is not a good practice use an object instead for example :
constructor(file) {
this.id = file['id']
this.fileName = file['fileName']
this.extention = file['extention']
this.fileSize = file['fileSize']
this.permission = file['permission']
this.description = file['description']
this.password = file['password']
this.isFolder = file['isFolder']
this.parent = file['parent']
this.banStat = file['banStat']
this.tinyLink = file['tinyLink']
}
getName(): string {
return `${this.fileName}${(this.isFolder) ? '' : '.'}${this.extention}`
}
getIcon(): string {
return this.isFolder ? 'fa-folder' : 'fa-music'
}
I have a requirement to convert the output of cypher into JSON.
Here is my code snippet.
RestCypherQueryEngine rcqer=new RestCypherQueryEngine(restapi);
String nodeN = "MATCH n=(Company) WITH COLLECT(n) AS paths RETURN EXTRACT(k IN paths | LAST(nodes(k))) as lastNode";
final QueryResult<Map<String,Object>> queryResult = rcqer.query(searchQuery);
for(Map<String,Object> row:queryResult)
{
System.out.println((ArrayList)row.get("lastNode"));
}
Output:
[http://XXX.YY6.192.103:7474/db/data/node/445, http://XXX.YY6.192.103:7474/db/data/node/446, http://XXX.YY6.192.103:7474/db/data/node/447, http://XXX.YY6.192.103:7474/db/data/node/448, http://XXX.YY6.192.103:7474/db/data/node/449, http://XXX.YY6.192.103:7474/db/data/node/450, http://XXX.YY6.192.103:7474/db/data/node/451, http://XXX.YY6.192.103:7474/db/data/node/452, http://XXX.YY6.192.103:7474/db/data/node/453]
I am not able to see the actual data (I am getting URL's). I am pretty sure I am missing something here.
I would also like to convert the output to JSON.
The cypher works in my browser interface.
I looked at various articles around this:
Java neo4j, REST and memory
Neo4j Cypher: How to iterate over ExecutionResult result
Converting ExecutionResult object to json
The last 2 make use of EmbeddedDatabase which may not be possible in my scenario (as the Neo is hosted in another cloud, hence the usage of REST).
Thanks.
Try to understand what you're doing? Your query does not make sense at all.
Perhaps you should re-visit the online course for Cypher: http://neo4j.com/online-course
MATCH n=(Company) WITH COLLECT(n) AS paths RETURN EXTRACT(k IN paths | LAST(nodes(k))) as lastNode
you can just do:
MATCH (c:Company) RETURN c
RestCypherQueryEngine rcqer=new RestCypherQueryEngine(restapi);
final QueryResult<Map<String,Object>> queryResult = rcqer.query(query);
for(Node node : queryResult.to(Node.class))
{
for (String prop : node.getPropertyKeys()) {
System.out.println(prop+" "+node.getProperty(prop));
}
}
I think it's better to use the JDBC driver for what you try to do, and also actually return the properties you're trying to convert to JSON.
I am very comfortable with UIMA, but my new work require me to use GATE
So, I started learning GATE. My question is regarding how to calculate performance of my tagging engines (java based).
With UIMA, I generally dump all my system annotation into a xmi file and, then using a Java code compare that with a human annotated (gold standard) annotations to calculate Precision/Recall and F-score.
But, I am still struggling to find something similar with GATE.
After going through Gate Annotation-Diff and other info on that page, I can feel there has to be an easy way to do it in JAVA. But, I am not able to figure out how to do it using JAVA. Thought to put this question here, someone might have already figured this out.
How to store system annotation into a xmi or any format file programmatically.
How to create one time gold standard data (i.e. human annotated data) for performance calculation.
Let me know if you need more specific or details.
This code seems helpful in writing the annotations to a xml file.
http://gate.ac.uk/wiki/code-repository/src/sheffield/examples/BatchProcessApp.java
String docXMLString = null;
// if we want to just write out specific annotation types, we must
// extract the annotations into a Set
if(annotTypesToWrite != null) {
// Create a temporary Set to hold the annotations we wish to write out
Set annotationsToWrite = new HashSet();
// we only extract annotations from the default (unnamed) AnnotationSet
// in this example
AnnotationSet defaultAnnots = doc.getAnnotations();
Iterator annotTypesIt = annotTypesToWrite.iterator();
while(annotTypesIt.hasNext()) {
// extract all the annotations of each requested type and add them to
// the temporary set
AnnotationSet annotsOfThisType =
defaultAnnots.get((String)annotTypesIt.next());
if(annotsOfThisType != null) {
annotationsToWrite.addAll(annotsOfThisType);
}
}
// create the XML string using these annotations
docXMLString = doc.toXml(annotationsToWrite);
}
// otherwise, just write out the whole document as GateXML
else {
docXMLString = doc.toXml();
}
// Release the document, as it is no longer needed
Factory.deleteResource(doc);
// output the XML to <inputFile>.out.xml
String outputFileName = docFile.getName() + ".out.xml";
File outputFile = new File(docFile.getParentFile(), outputFileName);
// Write output files using the same encoding as the original
FileOutputStream fos = new FileOutputStream(outputFile);
BufferedOutputStream bos = new BufferedOutputStream(fos);
OutputStreamWriter out;
if(encoding == null) {
out = new OutputStreamWriter(bos);
}
else {
out = new OutputStreamWriter(bos, encoding);
}
out.write(docXMLString);
out.close();
System.out.println("done");
From what I understood here, "V8 has a generational garbage collector. Moves objects aound randomly. Node can’t get a pointer to raw string data to write to socket." so I shouldn't store data that comes from a TCP stream in a string, specially if that string becomes bigger than Math.pow(2,16) bytes. (hope I'm right till now..)
What is then the best way to handle all the data that's comming from a TCP socket ? So far I've been trying to use _:_:_ as a delimiter because I think it's somehow unique and won't mess around other things.
A sample of the data that would come would be something_:_:_maybe a large text_:_:_ maybe tons of lines_:_:_more and more data
This is what I tried to do:
net = require('net');
var server = net.createServer(function (socket) {
socket.on('connect',function() {
console.log('someone connected');
buf = new Buffer(Math.pow(2,16)); //new buffer with size 2^16
socket.on('data',function(data) {
if (data.toString().search('_:_:_') === -1) { // If there's no separator in the data that just arrived...
buf.write(data.toString()); // ... write it on the buffer. it's part of another message that will come.
} else { // if there is a separator in the data that arrived
parts = data.toString().split('_:_:_'); // the first part is the end of a previous message, the last part is the start of a message to be completed in the future. Parts between separators are independent messages
if (parts.length == 2) {
msg = buf.toString('utf-8',0,4) + parts[0];
console.log('MSG: '+ msg);
buf = (new Buffer(Math.pow(2,16))).write(parts[1]);
} else {
msg = buf.toString() + parts[0];
for (var i = 1; i <= parts.length -1; i++) {
if (i !== parts.length-1) {
msg = parts[i];
console.log('MSG: '+msg);
} else {
buf.write(parts[i]);
}
}
}
}
});
});
});
server.listen(9999);
Whenever I try to console.log('MSG' + msg), it will print out the whole buffer, so it's useless to see if something worked.
How can I handle this data the proper way ? Would the lazy module work, even if this data is not line oriented ? Is there some other module to handle streams that are not line oriented ?
It has indeed been said that there's extra work going on because Node has to take that buffer and then push it into v8/cast it to a string. However, doing a toString() on the buffer isn't any better. There's no good solution to this right now, as far as I know, especially if your end goal is to get a string and fool around with it. Its one of the things Ryan mentioned # nodeconf as an area where work needs to be done.
As for delimiter, you can choose whatever you want. A lot of binary protocols choose to include a fixed header, such that you can put things in a normal structure, which a lot of times includes a length. In this way, you slice apart a known header and get information about the rest of the data without having to iterate over the entire buffer. With a scheme like that, one can use a tool like:
node-buffer - https://github.com/substack/node-binary
node-ctype - https://github.com/rmustacc/node-ctype
As an aside, buffers can be accessed via array syntax, and they can also be sliced apart with .slice().
Lastly, check here: https://github.com/joyent/node/wiki/modules -- find a module that parses a simple tcp protocol and seems to do it well, and read some code.
You should use the new stream2 api. http://nodejs.org/api/stream.html
Here are some very useful examples: https://github.com/substack/stream-handbook
https://github.com/lvgithub/stick
I'm trying to read weight from Sartorius Weighing Scale model No BS2202S using the following code in C#.net 2.0 on a Windows XP machine:
public string readWeight()
{
string lastError = "";
string weightData = "";
SerialPort port = new SerialPort();
port.PortName = "COM1";
port.BaudRate = 9600;
port.Parity = Parity.Even;
port.DataBits = 7;
port.StopBits = StopBits.One;
port.Handshake = Handshake.RequestToSend;
try {
port.Open();
weightData = port.ReadExisting();
if(weightData == null || weightData.Length == 0) {
lastError = "Unable to read weight. The data returned form weighing machine is empty or null.";
return lastError;
}
}
catch(TimeoutException) {
lastError = "Operation timed out while reading weight";
return lastError;
}
catch(Exception ex) {
lastError = "The following exception occurred while reading data." + Environment.NewLine + ex.Message;
return lastError;
}
finally {
if(port.IsOpen == true) {
port.Close();
port.Dispose();
}
}
return weightData;
}
I'm able to read the weight using Hyperterminal application (supplied with Windows XP) with the same serial port parameters given above for opening the port. But from the above code snippet, I can open the port and each time it is returning empty data.
I tried opening port using the code given this Stack Overflow thread, still it returns empty data.
Kindly assist me.
I know this is probably old now ... but for future reference ...
Look at the handshaking. There is both hardware handshaking and software handshaking. Your problem could be either - so you need to try both.
For hardware handshaking you can try:
mySerialPort.DtrEnable = True
mySerialPort.RtsEnable = True
Note that
mySerialPort.Handshake = Handshake.RequestToSend
I do not think sets the DTR line which some serial devices might require
Software handshaking is also known as XON/XOFF and can be set with
mySerialPort.Handshake = Handshake.XOnXOff
OR
mySerialPort.Handshake = Handshake.RequestToSendXOnXOff
You may still need to enable DTR
When all else fails - dont forget to check all of these combinations of handshaking.
Since someone else will probably have trouble with this in the future, hand shaking is a selectable option.
In most of the balances you will see the options for Software, Hardware 2 char, Hardware 1 char. The default setting for the Sartorius balances is Hardware 2 Char. I usually recommend changing to Software.
Also if it stops working all together it can often be fixed by defaulting the unit using the 9 1 1 parameter. And then resetting the communication settings.
An example of how to change the settings can be found on the manual on this page:
http://www.dataweigh.com/products/sartorius/cpa-analytical-balances/