MongoIterable.forEach requires a Block which is very similar to Java 8 Consumer.
They are similar enough to cause problems, for example, the following doesn't compile:
MongoIterable<Document> result = collection.find(...);
result.forEach(System.out::println);
because the compiler can't decide between Iterable.forEach( Consumer ) and MongoIterable.forEach( Block ). Fixing this requires workarounds like explicitly typing the parameter:
Block<Document> printer = System.out::println;
result.forEach(printer);
or alternatively, treating MongoIterable as a plain Stream:
StreamSupport.stream(result.spliterator(), false).forEach(System.out::println);
Why is MongoIterable.forEach not defined using the Consumer interface, something like: MongoIterable.forEach(Consumer<? super TResult> consumer)? Even better - why have forEach in MongoIterable at all?
The Java driver still supports Java 6 as a target. So while the attempts were made to make the 3.0 driver Java 8 and lambda friendly, we couldn't use actual Java 8 interfaces.
Related
I am tryint to reuse the code in following documentation : https://geode.apache.org/docs/guide/11/developing/region_options/dynamic_region_creation.html
The first problem that i met is that
Cache cache = CacheFactory.getAnyInstance();
Region<String,RegionAttributes<?,?>> regionAttributesMetadataRegion = createRegionAttributesMetadataRegion(cache);
should not be executed in constructor. In case it is , the code is executed in client instance , it is failed on not server error.When this fixed i receive
[fatal 2021/02/15 16:38:24.915 EET <ServerConnection on port 40527 Thread 1> tid=81] Serialization filter is rejecting class org.restcomm.cache.geode.CreateRegionFunction
java.lang.Exception:
at org.apache.geode.internal.ObjectInputStreamFilterWrapper.lambda$createSerializationFilter$0(ObjectInputStreamFilterWrapper.java:233)
The problem is that code is getting executed on dunit MemberVM and the required class is actually the part of the package under which the test is getting executed.
So i guess i should somehow register the classes ( or may be jar ) separately to dunit MemberVM. How it can be done?
Another question is: currently the code is checking if the region exists and if not it calls the method. In both cases it also tries to create the clientRegion. The question is whether this is a correct approach?
Region<?,?> cache = instance.getRegion(name);
if(cache==null) {
Execution execution = FunctionService.onServers(instance);
ArrayList argList = new ArrayList();
argList.add(name);
Function function = new CreateRegionFunction();
execution.setArguments(argList).execute(function).getResult();
}
ClientRegionFactory<Object, Object> cf=this.instance.createClientRegionFactory(ClientRegionShortcut.CACHING_PROXY).addCacheListener(new ExtendedCacheListener());
this.cache = cf.create(name);
BR
Yulian Oifa
The first problem that i met is that
Cache cache = CacheFactory.getAnyInstance();
should not be executed in constructor. In case it is , the code is executed in client instance , it is failed on not server error.When this fixed i receive
Once the Function is registered on server side, you can execute it by ID instead of sending the object across the wire (so you won't need to instantiate the function on the client), in which case you'll also avoid the Serialization filter error. As an example, FunctionService.onServers(instance).execute(CreateRegionFunction.ID).
The problem is that code is getting executed on dunit MemberVM and the required class is actually the part of the package under which the test is getting executed. So i guess i should somehow register the classes ( or may be jar ) separately to dunit MemberVM. How it can be done?
Indeed, for security reasons Geode doesn't allow serializing / deserializing arbitrary classes. Internal Geode distributed tests use the MemberVM and set a special property (serializable-object-filter) to circumvent this problem. Here's an example of how you can achieve that within your own tests.
Another question is: currently the code is checking if the region exists and if not it calls the method. In both cases it also tries to create the clientRegion. The question is whether this is a correct approach?
If the dynamically created region is used by the client application then yes, you should create it, otherwise you won't be able to use it.
As a side note, there's a lot of internal logic implemented by Geode when creating a Region so I wouldn't advice to dynamically create regions on your own. Instead, it would be advisable to use the gfsh create region command directly, or look at how it works internally (see here) and try to re-use that.
I just started using the driver org.apache.hive.jdbc.HiveDriver (Version
1.2.1 for spark2) with a Spark Thrift Server (STS) (reference here)
java.sql.ResultSet defines the method absolute() (JavaDoc here)
but HiveBaseResultSet seems to have chosen not to implement the method (source code here)
So now my application (built on top of SmartGWT) was doing a simple operation and I got the following error message:
=== 2017-05-13 18:06:16,980 [3-47] WARN RequestContext - dsRequest.execute() failed:
java.sql.SQLException: Method not supported
at org.apache.hive.jdbc.HiveBaseResultSet.absolute(HiveBaseResultSet.java:70)
at org.apache.commons.dbcp.DelegatingResultSet.absolute(DelegatingResultSet.java:373)
at com.isomorphic.sql.SQLDataSource.executeWindowedSelect(SQLDataSource.java:2970)
at com.isomorphic.sql.SQLDataSource.SQLExecute(SQLDataSource.java:2024)
What is the reason that the driver chose not to implement absolute()?
Are there any workaround for the limitation?
Thanks for the hint from Mark Rotteveel. Now I understand better and let me post an answer to my own question.
Implementation of absolute() is optional
As specified by the Interface of ResultSet#absolute() (link), the implementation for absolute() is optional -- especially when the result set type is TYPE_FORWARD_ONLY.
Workaround
In my case, the result set comes from a Spark Thrift Server (STS) so I guess it is indeed forward-only. So the question became how to instruct my application to NOT making a call to absolute(), which is basically for cursor movement.
SmartGWT-specific answer
For SmartGWT, this is controlled by a property called sqlPaging, which we can specified for an OperationBinding. The right value to use seems to be dropAtServer (more reference here). So I set my SmartGWT DataSource XML file to something like this
<operationBindings>
<operationBinding operationType="fetch" progressiveLoading="false"
sqlPaging="dropAtServer"
>
After that I saw another error, which is now related to HiveConnection#commit():
java.sql.SQLException: Method not supported
at org.apache.hive.jdbc.HiveConnection.commit(HiveConnection.java:742)
at org.apache.commons.dbcp.DelegatingConnection.commit(DelegatingConnection.java:334)
at com.isomorphic.sql.SQLTransaction.commitTransaction(SQLTransaction.java:307)
at com.isomorphic.sql.SQLDataSource.commit(SQLDataSource.java:4673)
After more digging, I realized that the right property for SmartGWT to control the commit behavior is autoJoinTransactions and I should set it to false (more reference here). After these two changes, I could get may application to talk to STS via jdbc.HiveDriver
For anyone out there who are also trying this, here is my full settings for the driver in SmartGWT's server.properties (more reference here)
sql.defaultDatabase: perf2 # this name is picked by me, but it can be anyname
sql.perf2.driver.networkProtocol: tcp
sql.perf2.driver: org.apache.hive.jdbc.HiveDriver # important
sql.perf2.database.type: generic # important
sql.perf2.autoJoinTransactions: false # important
sql.perf2.interface.type: driverManager # important
sql.perf2.driver.url: jdbc:hive2://host:port # important -- pick your host:port
sql.perf2.driver.user: someuser # important -- pick your username
sql.perf2.interface.credentialsInURL: true
sql.perf2.driver.databaseName: someDb
sql.perf2.driver.context:
I'm using hibernate-validator with a JAX-RS service to validate query parameters using #NotNull:
#GET
public Response doSomething(#NotNull #QueryParam("myParam") String myParam) {...}
This works as expected and throws a ConstraintViolationException if myParam is null. I'd like to extract the param name which is associated to the violation (e.g. myParam), and return that in the response message to the client but there does not appear to be an obvious way of extracting this from the exception. Can someone provide some insight?
As of BeanValidation 1.1 there is a ParameterNameProvider contract which makes parameter name extraction configurable. As mentioned in the other answer, with Java 8 you can get the parameter names in the byte code provided you compile with the -parameters flag. Use the ReflectionParameterNameProvider in this case. However, even with Java 7 you can get parameter names, for example by using the ParanamerParameterNameProvider. This parameter name provider is based on Paranamer and there are several ways to set it up.
This only works if you're using Java 8, as prior to Java 8 the actual parameter name was lost at compile time. Its now retained, assuming you compile and run at Java 8. See also http://docs.jboss.org/hibernate/validator/5.2/reference/en-US/html_single/#_java_8_support
Problem:
Attempting to use the JYTHON command below and I cannot retrieve the id of my active specification defined at a node-server level in Websphere. I believe its a syntax issue but I'm not sure what.
Code:
AdminConfig.getid('/Cell:mycell/Node:mynode/Server:myserver/J2CActivationSpec:myActiveSpecName/')
Problem Notes:
I do not get a invalid object error so I believe I have the syntax right but it just cannot find the resource even though it exists.
I am using the AdminConfig.getid() as a way to check if the resource already exists in order to do a modify or a create.
If I use the following code: AdminConfig.getid('/J2CActivationSpec:myActiveSpecName/') it will find it but not if I use a more specific path listed above.
Reference Material:
IBM Documentation
Containment paths are always a little tricky. In my (limited) experience, even if you can trace the path by AdminConfig.parents, you may not always be able to use getid.
Are you restricted to using getid? If not, here are some alternatives that will get you an ActivationSpec at the /Cell/Node/Server level:
Querying using AdminConfig.list
This approach will list the Activation Specifications at the specified scope (in our case, the server), and grab the one that has it's name attribute equal to 'myActiveSpecName'.
server = AdminConfig.getid('/Cell:mycell/Node:mynode/Server:myserver')
activationSpec = ''
for as in AdminConfig.list('J2CActivationSpec', server).splitlines():
if AdminConfig.showAttribute(as, 'name') == 'myActiveSpecName'
activationSpec = as
print 'found it :)'
Using Wildcards
This approah uses AdminConfig.list as well, but with a pattern to narrow down your list. If you know your activation spec's configuration begins with myActiveSpecName, then you can do the following:
activationSpec = AdminConfig.list('J2CActivationSpec', 'myActiveSpecName*')
I'm looking to integrate the Barcode2 class in the EDMK 2.6 library into our existing Barcode scanning interface.
I've wired the example code up to our interface method StartScan() and always get E_SCN_READTIMEOUT as the result even though the code seems to be responding to the scan. (the breakpoint at if (scan.Result == Results.SUCCESS) is hit in response to the scan
public void StartScan()
{
if (!barcode.IsScanPending)
{
ScanData scan = barcode.ScanWait(2000); // 2 second timeout
if (scan.Result == Results.SUCCESS)
{
if (scan.IsText)
{
textbox1.Text = scan.Text;
}
}
}
}
The result is always E_SCN_READTIMEOUT, I suspect this may be a conflict with DataWedge 3.4 running on the device, but the functionality of the scanner and triggers seem to be dependent on it.
Getting barcode scans to the clipboard using DataWedge is not an option for us, is there a way to get the library to function despite DataWedge(assuming that is causing the read timeouts)?
The DataWedge application did need to be disabled, (this can be done programmatically via the datawedge API from Motorola, Thanks Abdel for the hint here!).
https://docs.symbol.com/ReleaseNotes/Release%20Notes%20-%20DataWedge_3.3.htm
A little background on our Windows Mobile application for reference, we have a hardware singleton that contains interfaces for all hardware components and loads related types and assemblies via reflection. If we referenced types directly the code above worked.
The end solution ended up being to use the Symbol.Barcode library instead of Symbol.Barcode2.