Develop Reference

AWS SSM parameter store not fetching all key/values

Could someone let me know why the below code only fetching few entries from the parameter store ?
GetParametersByPathRequest getParametersByPathRequest = new GetParametersByPathRequest();
getParametersByPathRequest.withPath("/").setRecursive(true);
getParametersByPathRequest.setWithDecryption(true);
GetParametersByPathResult result = client.getParametersByPath(getParametersByPathRequest);
result.getParameters().forEach(parameter -> {
System.out.println(parameter.getName() + " - > " + parameter.getValue());
});

GetParametersByPath is a paged operation. After each call you must retrieve NextToken from the result object, and if it's not null and not empty you must make another call with it added to the request.
Here's an example using DescribeParameters, which has the same behavior:
DescribeParametersRequest request = new DescribeParametersRequest();
DescribeParametersResult response;
do
{
response = client.describeParameters(request);
for (ParameterMetadata param : response.getParameters())
{
// do something with metadata
}
request.setNextToken(response.getNextToken());
}
while ((response.getNextToken() != null) && ! respose.getNextToken.isEmpty());

Here is the code, based on the code above, for the new 2.0 version of AWS SSM manager. Notice I have set the maxResults to 1 to prove out the loop. You will want to remove that. AWS has mentioned that in the new code they wanted to emphasize immutability.
Using this dependency:
<dependency>
<groupId>software.amazon.awssdk</groupId>
<artifactId>ssm</artifactId>
<version>2.10.32</version>
</dependency>
I came up with this code:
private void refreshCache() {
StopWatch sw = StopWatch.createStarted();
GetParametersByPathRequest request = GetParametersByPathRequest.builder()
.path(prefix)
.withDecryption(useDecryption)
.maxResults(1)
.build();
GetParametersByPathResponse response;
do {
response = ssm.getParametersByPath(request);
for (Parameter p : response.parameters()) {
//do something with the values.
}
request = GetParametersByPathRequest.builder()
.path(prefix)
.withDecryption(useDecryption)
.nextToken(response.nextToken())
.maxResults(1)
.build();
}
while (StringUtils.isNotBlank(response.nextToken()));
LOG.trace("Refreshed parameters in {}ms", sw.getTime());
}

private void getSsmParams() {
AWSSimpleSystemsManagement client = AWSSimpleSystemsManagementClientBuilder.defaultClient();
GetParametersByPathRequest request = new GetParametersByPathRequest();
request.withRecursive(true);
request.withPath('/your/path/parameterName').setWithDecryption(true);
GetParametersByPathResult response;
do {
response = client.getParametersByPath(request);
for (Parameter p : response.parameters()) {
//do something with the values. maybe add to a list
}
request.setNextToken(response.getNextToken())
}
while (StringUtils.isNotBlank(response.getNextToken()));
}
Above piece of code worked for me .ssm only sends 10 parameters at a time, so if you want to fetch more than 10 parameters from ssm parameter store programatically you will have to use multiple calls to fetch them. here the token is important , if there are more values in the path (request.withPath('/your/path/parameterName')) you have given, it will send a token indicating that there are more values in the given path ,and you will have to make the following request with the token received from the previous request in order to get the rest of the values.

Conversation ID leads to unkown path in graph-api

I have a code that fetches conversations and the messages inside them (a specific number of pages). It works most of the time, but for certain conversations it throws an exception, such as:
Exception in thread "main" com.restfb.exception.FacebookOAuthException: Received Facebook error response of type OAuthException: Unknown path components: /[id of the message]/messages (code 2500, subcode null)
at com.restfb.DefaultFacebookClient$DefaultGraphFacebookExceptionMapper.exceptionForTypeAndMessage(DefaultFacebookClient.java:1192)
at com.restfb.DefaultFacebookClient.throwFacebookResponseStatusExceptionIfNecessary(DefaultFacebookClient.java:1118)
at com.restfb.DefaultFacebookClient.makeRequestAndProcessResponse(DefaultFacebookClient.java:1059)
at com.restfb.DefaultFacebookClient.makeRequest(DefaultFacebookClient.java:970)
at com.restfb.DefaultFacebookClient.makeRequest(DefaultFacebookClient.java:932)
at com.restfb.DefaultFacebookClient.fetchConnection(DefaultFacebookClient.java:356)
at test.Test.main(Test.java:40)
After debugging I found the ID that doesn't work and tried to access it from graph-api, which results in an "unknown path components" error. I also attempted to manually find the conversation in me/conversations and click the next page link in the graph api explorer which also lead to the same error.
Is there a different way to retrieve a conversation than by ID? And if not, could someone show me an example to verify first if the conversation ID is valid, so if there are conversations I can't retrieve I could skip them instead of getting an error. Here's my current code:
Connection<Conversation> fetchedConversations = fbClient.fetchConnection("me/Conversations", Conversation.class);
int pageCnt = 2;
for (List<Conversation> conversationPage : fetchedConversations) {
for (Conversation aConversation : conversationPage) {
String id = aConversation.getId();
//The line of code which causes the exception
Connection<Message> messages = fbClient.fetchConnection(id + "/messages", Message.class, Parameter.with("fields", "message,created_time,from,id"));
int tempCnt = 0;
for (List<Message> messagePage : messages) {
for (Message msg : messagePage) {
System.out.println(msg.getFrom().getName());
System.out.println(msg.getMessage());
}
if (tempCnt == pageCnt) {
break;
}
tempCnt++;
}
}
}
Thanks in advance!
Update: Surrounded the problematic part with a try catch as a temporary solution, also counted the number of occurrences and it only effects 3 out of 53 conversations. I also printed all the IDs, and it seems that these 3 IDs are the only ones that contain a "/" symbol, I'm guessing it has something to do with the exception.
The IDs that work look something like this: t_[text] (sometimes a "." or a ":" symbol) and the ones that cause an exception are always t_[text]/[text]

conv_id/messages is not a valid graph api call.
messages is a field of conversation.
Here is what you do (single call to api):
Connection<Conversation> conversations = facebookClient.fetchConnection("me/conversations", Conversation.class);
for (Conversation conv : conversations.getData()) {
// To get list of messages for given conversation
LinkedList<Message> allConvMessagesStorage = new LinkedList<Message>();
Connection<Message> messages25 = facebookClient.fetchConnection(conv.getId()+"/messages", Message.class);
//Add messages returned
allConvMessagesStorage.addAll(messages25.getData());
//Check if there is next page to fetch
boolean progress = messages25.hasNext();
while(progress){
messages25 = facebookClient.fetchConnectionPage(messages25.getNextPageUrl(), Message.class);
//Append next page of messages
allConvMessagesStorage.addAll(messages25.getData());
progress = messages25.hasNext();
}
}

How to synchronize / limit certain async http calls in android

I am making use of the Android Async Http Library in my app to make async http requests.
I have come into a situation in my android app where the following happens. My web api makes use of an access token and a refresh token. On every request that I make I check if the access token is still valid. If it is not I then issue a http post to go get a new access token using the refresh token.
Now i have noticed the following situation.
user of my app leaves their phone inactive for enough time for the access token to expire. When they wake the phone up. In my onResume() function I fire off two separate http requests.
Request 1 checks the access token and determines its not valid. it then issues a refreshAccessToken request.
While Request 1 is waiting for the response, Request 2 also checks the access token and determines its not valid. And it also issues a refreshAccessToken request.
Request 1 returns successfully and updates the access token and refresh token values.
Request 2, then gets a 401 response from the api as the refresh token which it provided has already been used. My application then thinks that there is an error with the refreshToken and logs the user out.
This is obviously incorrect and I would like to avoid it. I have in the mean time, done a double check in the refreshAccessToken onFailed() method. To see if the accessToken is maybe valid again. However this is inefficient as I am still sedning two requests over the air, and my API has to handle the failed refresh attempt.
Question:
Now my issue is that i cant use any locks or synchronization as you cannot block the main UI thread in android. And Android Async Http Library handles all of the different threads etc.

Request 2 also checks the access token and determines its not valid.
This is wrong. Since Request 1 may have already issued refreshAccessToken request, then the state of the access token cannot be determined by consulting the server.
So you need a combined operation getAccessToken() which checks access token, issues refreshAccessToken when needed, and, when called in parallel, only waits for previously called getAccessToken() operation.
UPDATE. refreshAccessToken is a part of a class which serves as a gatekeeper and allows requests to run only if access token is refreshed. If token is not refreshed, gatekeeper sends single request to refresh the token. Meantime, input requests are saved in a queue. When the token is refreshed, the gatekeeper lets saved requests to run.

I found the solution with authenticator, the id is the number of the request, only for identification. Comments are in Spanish
private final static Lock locks = new ReentrantLock();
httpClient.authenticator(new Authenticator() {
#Override
public Request authenticate(#NonNull Route route,#NonNull Response response) throws IOException {
Log.e("Error" , "Se encontro un 401 no autorizado y soy el numero : " + id);
//Obteniendo token de DB
SharedPreferences prefs = mContext.getSharedPreferences(
BuildConfig.APPLICATION_ID, Context.MODE_PRIVATE);
String token_db = prefs.getString("refresh_token","");
//Comparando tokens
if(mToken.getRefreshToken().equals(token_db)){
locks.lock();
try{
//Obteniendo token de DB
prefs = mContext.getSharedPreferences(
BuildConfig.APPLICATION_ID, Context.MODE_PRIVATE);
String token_db2 = prefs.getString("refresh_token","");
//Comparando tokens
if(mToken.getRefreshToken().equals(token_db2)){
//Refresh token
APIClient tokenClient = createService(APIClient.class);
Call<AccessToken> call = tokenClient.getRefreshAccessToken(API_OAUTH_CLIENTID,API_OAUTH_CLIENTSECRET, "refresh_token", mToken.getRefreshToken());
retrofit2.Response<AccessToken> res = call.execute();
AccessToken newToken = res.body();
// do we have an access token to refresh?
if(newToken!=null && res.isSuccessful()){
String refreshToken = newToken.getRefreshToken();
Log.e("Entra", "Token actualizado y soy el numero : " + id + " : " + refreshToken);
prefs = mContext.getSharedPreferences(BuildConfig.APPLICATION_ID, Context.MODE_PRIVATE);
prefs.edit().putBoolean("log_in", true).apply();
prefs.edit().putString("access_token", newToken.getAccessToken()).apply();
prefs.edit().putString("refresh_token", refreshToken).apply();
prefs.edit().putString("token_type", newToken.getTokenType()).apply();
locks.unlock();
return response.request().newBuilder()
.header("Authorization", newToken.getTokenType() + " " + newToken.getAccessToken())
.build();
}else{
//Dirigir a login
Log.e("redirigir", "DIRIGIENDO LOGOUT");
locks.unlock();
return null;
}
}else{
//Ya se actualizo tokens
Log.e("Entra", "El token se actualizo anteriormente, y soy el no : " + id );
prefs = mContext.getSharedPreferences(BuildConfig.APPLICATION_ID, Context.MODE_PRIVATE);
String type = prefs.getString("token_type","");
String access = prefs.getString("access_token","");
locks.unlock();
return response.request().newBuilder()
.header("Authorization", type + " " + access)
.build();
}
}catch (Exception e){
locks.unlock();
e.printStackTrace();
return null;
}
}
return null;
}
});

Neo4j ExecutionEngine does not return valid results

Trying to use a similar example from the sample code found here
My sample function is:
void query()
{
String nodeResult = "";
String rows = "";
String resultString;
String columnsString;
System.out.println("In query");
// START SNIPPET: execute
ExecutionEngine engine = new ExecutionEngine( graphDb );
ExecutionResult result;
try ( Transaction ignored = graphDb.beginTx() )
{
result = engine.execute( "start n=node(*) where n.Name =~ '.*79.*' return n, n.Name" );
// END SNIPPET: execute
// START SNIPPET: items
Iterator<Node> n_column = result.columnAs( "n" );
for ( Node node : IteratorUtil.asIterable( n_column ) )
{
// note: we're grabbing the name property from the node,
// not from the n.name in this case.
nodeResult = node + ": " + node.getProperty( "Name" );
System.out.println("In for loop");
System.out.println(nodeResult);
}
// END SNIPPET: items
// START SNIPPET: columns
List<String> columns = result.columns();
// END SNIPPET: columns
// the result is now empty, get a new one
result = engine.execute( "start n=node(*) where n.Name =~ '.*79.*' return n, n.Name" );
// START SNIPPET: rows
for ( Map<String, Object> row : result )
{
for ( Entry<String, Object> column : row.entrySet() )
{
rows += column.getKey() + ": " + column.getValue() + "; ";
System.out.println("nested");
}
rows += "\n";
}
// END SNIPPET: rows
resultString = engine.execute( "start n=node(*) where n.Name =~ '.*79.*' return n.Name" ).dumpToString();
columnsString = columns.toString();
System.out.println(rows);
System.out.println(resultString);
System.out.println(columnsString);
System.out.println("leaving");
}
}
When I run this in the web console I get many results (as there are multiple nodes that have an attribute of Name that contains the pattern 79. Yet running this code returns no results. The debug print statements 'in loop' and 'nested' never print either. Thus this must mean there are not results found in the Iterator, yet that doesn't make sense.
And yes, I already checked and made sure that the graphDb variable is the same as the path for the web console. I have other code earlier that uses the same variable to write to the database.
EDIT - More info
If I place the contents of query in the same function that creates my data, I get the correct results. If I run the query by itself it returns nothing. It's almost as the query works only in the instance where I add the data and not if I come back to the database cold in a separate instance.
EDIT2 -
Here is a snippet of code that shows the bigger context of how it is being called and sharing the same DBHandle
package ContextEngine;
import ContextEngine.NeoHandle;
import java.util.LinkedList;
/*
* Class to handle streaming data from any coded source
*/
public class Streamer {
private NeoHandle myHandle;
private String contextType;
Streamer()
{
}
public void openStream(String contextType)
{
myHandle = new NeoHandle();
myHandle.createDb();
}
public void streamInput(String dataLine)
{
Context context = new Context();
/*
* get database instance
* write to database
* check for errors
* report errors & success
*/
System.out.println(dataLine);
//apply rules to data (make ContextRules do this, send type and string of data)
ContextRules contextRules = new ContextRules();
context = contextRules.processContextRules("Calls", dataLine);
//write data (using linked list from contextRules)
NeoProcessor processor = new NeoProcessor(myHandle);
processor.processContextData(context);
}
public void runQuery()
{
NeoProcessor processor = new NeoProcessor(myHandle);
processor.query();
}
public void closeStream()
{
/*
* close database instance
*/
myHandle.shutDown();
}
}
Now, if I call streamInput AND query in in the same instance (parent calls) the query returns results. If I only call query and do not enter ANY data in that instance (yet web console shows data for same query) I get nothing. Why would I have to create the Nodes and enter them into the database at runtime just to return a valid query. Shouldn't I ALWAYS get the same results with such a query?

You mention that you are using the Neo4j Browser, which comes with Neo4j. However, the example you posted is for Neo4j Embedded, which is the in-process version of Neo4j. Are you sure you are talking to the same database when you try your query in the Browser?
In order to talk to Neo4j Server from Java, I'd recommend looking at the Neo4j JDBC driver, which has good support for connecting to the Neo4j server from Java.
http://www.neo4j.org/develop/tools/jdbc
You can set up a simple connection by adding the Neo4j JDBC jar to your classpath, available here: https://github.com/neo4j-contrib/neo4j-jdbc/releases Then just use Neo4j as any JDBC driver:
Connection conn = DriverManager.getConnection("jdbc:neo4j://localhost:7474/");
ResultSet rs = conn.executeQuery("start n=node({id}) return id(n) as id", map("id", id));
while(rs.next()) {
System.out.println(rs.getLong("id"));
}
Refer to the JDBC documentation for more advanced usage.
To answer your question on why the data is not durably stored, it may be one of many reasons. I would attempt to incrementally scale back the complexity of the code to try and locate the culprit. For instance, until you've found your problem, do these one at a time:
Instead of looping through the result, print it using System.out.println(result.dumpToString());
Instead of the regex query, try just MATCH (n) RETURN n, to return all data in the database
Make sure the data you are seeing in the browser is not "old" data inserted earlier on, but really is an insert from your latest run of the Java program. You can verify this by deleting the data via the browser before running the Java program using MATCH (n) OPTIONAL MATCH (n)-[r]->() DELETE n,r;
Make sure you are actually working against the same database directories. You can verify this by leaving the server running. If you can still start your java program, unless your Java program is using the Neo4j REST Bindings, you are not using the same directory. Two Neo4j databases cannot run against the same database directory simultaneously.

Retrieve multiple messages from SQS

I have multiple messages in SQS. The following code always returns only one, even if there are dozens visible (not in flight). setMaxNumberOfMessages I thought would allow multiple to be consumed at once .. have i misunderstood this?
CreateQueueRequest createQueueRequest = new CreateQueueRequest().withQueueName(queueName);
String queueUrl = sqs.createQueue(createQueueRequest).getQueueUrl();
ReceiveMessageRequest receiveMessageRequest = new ReceiveMessageRequest(queueUrl);
receiveMessageRequest.setMaxNumberOfMessages(10);
List<Message> messages = sqs.receiveMessage(receiveMessageRequest).getMessages();
for (Message message : messages) {
// i'm a message from SQS
}
I've also tried using withMaxNumberOfMessages without any such luck:
receiveMessageRequest.withMaxNumberOfMessages(10);
How do I know there are messages in the queue? More than 1?
Set<String> attrs = new HashSet<String>();
attrs.add("ApproximateNumberOfMessages");
CreateQueueRequest createQueueRequest = new CreateQueueRequest().withQueueName(queueName);
GetQueueAttributesRequest a = new GetQueueAttributesRequest().withQueueUrl(sqs.createQueue(createQueueRequest).getQueueUrl()).withAttributeNames(attrs);
Map<String,String> result = sqs.getQueueAttributes(a).getAttributes();
int num = Integer.parseInt(result.get("ApproximateNumberOfMessages"));
The above always is run prior and gives me an int that is >1
Thanks for your input

AWS API Reference Guide: Query/QueryReceiveMessage
Due to the distributed nature of the queue, a weighted random set of machines is sampled on a ReceiveMessage call. That means only the messages on the sampled machines are returned. If the number of messages in the queue is small (less than 1000), it is likely you will get fewer messages than you requested per ReceiveMessage call. If the number of messages in the queue is extremely small, you might not receive any messages in a particular ReceiveMessage response; in which case you should repeat the request.
and
MaxNumberOfMessages: Maximum number of messages to return. SQS never returns more messages than this value but might return fewer.

There is a comprehensive explanation for this (arguably rather idiosyncratic) behaviour in the SQS reference documentation.
SQS stores copies of messages on multiple servers and receive message requests are made to these servers with one of two possible strategies,
Short Polling : The default behaviour, only a subset of the servers (based on a weighted random distribution) are queried.
Long Polling : Enabled by setting the WaitTimeSeconds attribute to a non-zero value, all of the servers are queried.
In practice, for my limited tests, I always seem to get one message with short polling just as you did.

I had the same problem. What is your Receive Message Wait Time for your queue set to? When mine was at 0, it only returned 1 message even if there were 8 in the queue. When I increased the Receive Message Wait Time, then I got all of them. Seems kind of buggy to me.

I was just trying the same and with the help of these two attributes setMaxNumberOfMessages and setWaitTimeSeconds i was able to get 10 messages.
ReceiveMessageRequest receiveMessageRequest = new ReceiveMessageRequest(myQueueUrl);
receiveMessageRequest.setMaxNumberOfMessages(10);
receiveMessageRequest.setWaitTimeSeconds(20);
Snapshot of o/p:
Receiving messages from TestQueue.
Number of messages:10
Message
MessageId: 31a7c669-1f0c-4bf1-b18b-c7fa31f4e82d
...

receiveMessageRequest.withMaxNumberOfMessages(10);
Just to be clear, the more practical use of this would be to add to your constructor like this:
ReceiveMessageRequest receiveMessageRequest = new ReceiveMessageRequest(queueUrl).withMaxNumberOfMessages(10);
Otherwise, you might as well just do:
receiveMessageRequest.setMaxNumberOfMessages(10);
That being said, changing this won't help the original problem.

Thanks Caoilte!
I faced this issue also. Finally solved by using long polling follow the configuration here:
https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-configure-long-polling-for-queue.html
Unfortunately, to use long polling, you must create your queue as FIFO one. I tried standard queue with no luck.
And when receiving, need also set MaxNumberOfMessages. So my code is like:
ReceiveMessageRequest receive_request = new ReceiveMessageRequest()
.withQueueUrl(QUEUE_URL)
.withWaitTimeSeconds(20)
.withMaxNumberOfMessages(10);
Although solved, still feel too wired. AWS should definitely provide a more neat API for this kind of basic receiving operation.
From my point, AWS has many many cool features but not good APIs. Like those guys are rushing out all the time.

For small task list I use FIFO queue like stackoverflow.com/a/55149351/13678017
for example modified AWS tutorial
// Create a queue.
System.out.println("Creating a new Amazon SQS FIFO queue called " + "MyFifoQueue.fifo.\n");
final Map<String, String> attributes = new HashMap<>();
// A FIFO queue must have the FifoQueue attribute set to true.
attributes.put("FifoQueue", "true");
/*
* If the user doesn't provide a MessageDeduplicationId, generate a
* MessageDeduplicationId based on the content.
*/
attributes.put("ContentBasedDeduplication", "true");
// The FIFO queue name must end with the .fifo suffix.
final CreateQueueRequest createQueueRequest = new CreateQueueRequest("MyFifoQueue4.fifo")
.withAttributes(attributes);
final String myQueueUrl = sqs.createQueue(createQueueRequest).getQueueUrl();
// List all queues.
System.out.println("Listing all queues in your account.\n");
for (final String queueUrl : sqs.listQueues().getQueueUrls()) {
System.out.println(" QueueUrl: " + queueUrl);
}
System.out.println();
// Send a message.
System.out.println("Sending a message to MyQueue.\n");
for (int i = 0; i < 4; i++) {
var request = new SendMessageRequest()
.withQueueUrl(myQueueUrl)
.withMessageBody("message " + i)
.withMessageGroupId("userId1");
;
sqs.sendMessage(request);
}
for (int i = 0; i < 6; i++) {
var request = new SendMessageRequest()
.withQueueUrl(myQueueUrl)
.withMessageBody("message " + i)
.withMessageGroupId("userId2");
;
sqs.sendMessage(request);
}
// Receive messages.
System.out.println("Receiving messages from MyQueue.\n");
var receiveMessageRequest = new ReceiveMessageRequest(myQueueUrl);
receiveMessageRequest.setMaxNumberOfMessages(10);
receiveMessageRequest.setWaitTimeSeconds(20);
// what receive?
receiveMessageRequest.withMessageAttributeNames("userId2");
final List<Message> messages = sqs.receiveMessage(receiveMessageRequest).getMessages();
for (final Message message : messages) {
System.out.println("Message");
System.out.println(" MessageId: "
+ message.getMessageId());
System.out.println(" ReceiptHandle: "
+ message.getReceiptHandle());
System.out.println(" MD5OfBody: "
+ message.getMD5OfBody());
System.out.println(" Body: "
+ message.getBody());
for (final Entry<String, String> entry : message.getAttributes()
.entrySet()) {
System.out.println("Attribute");
System.out.println(" Name: " + entry
.getKey());
System.out.println(" Value: " + entry
.getValue());
}
}

Here's a workaround, you can call receiveMessageFromSQS method asynchronously.
bulkReceiveFromSQS (queueUrl, totalMessages, asyncLimit, batchSize, visibilityTimeout, waitTime, callback) {
batchSize = Math.min(batchSize, 10);
let self = this,
noOfIterations = Math.ceil(totalMessages / batchSize);
async.timesLimit(noOfIterations, asyncLimit, function(n, next) {
self.receiveMessageFromSQS(queueUrl, batchSize, visibilityTimeout, waitTime,
function(err, result) {
if (err) {
return next(err);
}
return next(null, _.get(result, 'Messages'));
});
}, function (err, listOfMessages) {
if (err) {
return callback(err);
}
listOfMessages = _.flatten(listOfMessages).filter(Boolean);
return callback(null, listOfMessages);
});
}
It will return you an array with a given number of messages