Unexpected error in notifyUser

rvkvino

Can you please help me on this how to add log in my adapter.
@Override
public void subscribe(String itemName) throws SubscriptionException, FailureException {
logger.debug("Subscribing to " + itemName);
}
Is this okay or I add some other things. But when I check in my log file I couldn't find the Subscribing to in my log file.

Dario Crivelli

The log you perform in your code should be entirely managed by your code, without Lightstreamer involvement
(although the java remote SDK also provides a very simple logging interface).
For instance if your "logger" object is obtained with slf4j, you should provide a suitable slf4j implementation and configuration.

However, Giuseppe's advise was to log the startup phase of the process, when the process tries to establish a connection with Lightstreamer Server, since there is no evidence of such connection.
As log as the remote adapter process fails to connect, it won't receive any invocation of "subscribe", hence it is correct that you can't see this log.

rvkvino

Hello,
Finally find out the issue, I have modified my shell script as like below,

cpath="/home/postnammauzhavan/Lightstreamer/adapters/WINLITERemoteStockList/classes/ls-adapter-remote.jar:/home/postnammauzhavan/Lightstreamer/adapters/WINLITERemoteStockList/classes/jedis.jar:/home/postnammauzhavan/Lightstreamer/adapters/WINLITERemoteStockList/classes/gson.jar:/home/postnammauzhavan/Lightstreamer/adapters/WINLITERemoteStockList/classes/LS_quote_feed_simulator.jar"
class="stocklist.server.ServerMain"

command="java -cp $cpath $class -host localhost -metadata_rrport 6722 -data_rrport 6720 -data_notifport 6721"
exec $command $

It seems need to give values within double quote.

Now I have an issue on getting update from redis and serve this data to subscribed items.
I have used redis instance on ExternalFeedSimulator java class. Can you please on this where I need to create instance and where to close the redis exactly. Because of this I'm facing the issue like

Exception in thread "Timer-0" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 12

My code looks like below,
import com.google.gson.Gson;
import com.google.gson.annotations.SerializedName;
import redis.clients.jedis.Jedis;

public class ExternalFeedSimulator {
private static Jedis jedis;
private static final String redisHost = "localhost";
private static final Integer redisPort = 6379;
private static Gson gson = new Gson();

public void start() {
try {
jedis = new Jedis(redisHost, redisPort);
getJSON();
long waitTime = 500;
bidaskratescheduleGenerator(bidaskrates, waitTime);
} catch (Exception e) { System.out.println(e);
}
}

public static String getJSON() {
try {
liveratesnew.clear(); ClientsRateRow[] craterows = gson.fromJson(jedis.get("WLallclientsrates"), ClientsRateRow[].class);
for (ClientsRateRow raterow : craterows) {
liveratesnew.put(raterow.client_com_id, raterow);
curclientrates.add(raterow);
}
RateRow[] cbaserates = gson.fromJson(jedis.get("WLBaseRates"), RateRow[].class);
for (RateRow raterow : cbaserates) {
bidaskrates.add(raterow);
}
} catch (IllegalStateException ex) {
ex.printStackTrace();
} finally {
jedis.close();
}
return null;

}

private void bidaskratescheduleGenerator(final ArrayList<RateRow> displayrates, long waitTime) {
dispatcher.schedule(new TimerTask() {
@Override
public void run() {
long nextWaitTime;
synchronized (displayrates) {
if (listener != null) {
for (RateRow curbidaskrates : displayrates) {
final HashMap<String, String> bidaskevent = new HashMap<String, String>();
bidaskevent.put("desc", curbidaskrates.getGold1_symbol());
bidaskevent.put("bid", curbidaskrates.getGold1_bid());
bidaskevent.put("ask", curbidaskrates.getGold1_ask());
bidaskevent.put("high", curbidaskrates.getGold1_high());
bidaskevent.put("low", curbidaskrates.getGold1_low());
bidaskevent.put("ltp", curbidaskrates.getGold1_ltp());
listener.onEvent(curbidaskrates.getGold1_symbol(), bidaskevent, false);
}
}
displayrates.clear();
nextWaitTime = 500;
}
getJSON();
bidaskratescheduleGenerator(bidaskrates, nextWaitTime);
}
}, waitTime);
}

}

In my php service every second will update the stock market rates into redis key as json string. In my java adapter for every 500 milliseconds i need to read and update to subscribed clients. Could you please help me on this how to do this in my adapter.

Giuseppe Corti

Hi,

The error message seems not pertaining to redis but to the json parser.
Please have a look at this https://stackoverflow.com/questions/28418662/expected-begin-object-but-was-string-at-line-1-column-1, maybe can help with your issue.

Regards,
Giuseppe

rvkvino

I have referred this link already,
My actual issue comes like this first time after that only I'm facing issue on json string. If I handle this issue the above json issue not comes.

redis.clients.jedis.exceptions.JedisConnectionException: java.net.SocketException: Connection reset by peer: socket write error
at redis.clients.jedis.Connection.flush(Connection.java:334)
at redis.clients.jedis.Connection.getBinaryBulkReply(Connection.java:257)
at redis.clients.jedis.Connection.getBulkReply(Connection.java:248)
at redis.clients.jedis.Jedis.get(Jedis.java:153)
at stocklist.feed_simulator.ExternalFeedSimulator.getJSON(ExternalFeedSimulator.java:78)
at stocklist.feed_simulator.ExternalFeedSimulator$1.run(ExternalFeedSimulator.java:128)
at java.util.TimerThread.mainLoop(Unknown Source)
at java.util.TimerThread.run(Unknown Source)
Caused by: java.net.SocketException: Connection reset by peer: socket write error
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(Unknown Source)
at java.net.SocketOutputStream.write(Unknown Source)
at redis.clients.util.RedisOutputStream.flushBuffer(RedisOutputStream.java:52)
at redis.clients.util.RedisOutputStream.flush(RedisOutputStream.java:216)
at redis.clients.jedis.Connection.flush(Connection.java:331)
.

my json looks like this only

[
{
"com_id": "33",
"com_name": "GOLD BAR",
"selling_rate": "5001",
"buying_rate": "-",
"delivery": "03-07-2020",
"retail_rate": "-",
"com_weight": "1.000",
"com_order": "1",
"client": "lmxtrade",
"client_com_id": "lmxtrade_33",
"high_rate": "5002",
"low_rate": "4980"
},
{
"com_id": "36",
"com_name": "GOLD FT",
"selling_rate": "5001",
"buying_rate": "4800",
"delivery": "03-07-2020",
"retail_rate": "-",
"com_weight": "1.000",
"com_order": "2",
"client": "lmxtrade",
"client_com_id": "lmxtrade_36",
"high_rate": "5002",
"low_rate": "4980"
},
{
"com_id": "37",
"com_name": "GOLD RTGS",
"selling_rate": "4901",
"buying_rate": "-",
"delivery": "03-07-2020",
"retail_rate": "-",
"com_weight": "1.000",
"com_order": "3",
"client": "lmxtrade",
"client_com_id": "lmxtrade_37",
"high_rate": "4902",
"low_rate": "4880"
},
{
"com_id": "38",
"com_name": "SILVER",
"selling_rate": "49190",
"buying_rate": "48463",
"delivery": "03-07-2020",
"retail_rate": "-",
"com_weight": "1000.000",
"com_order": "4",
"client": "lmxtrade",
"client_com_id": "lmxtrade_38",
"high_rate": "49190",
"low_rate": "49190"
},
{
"com_id": "33",
"com_name": "GOLD CBE RTGS ",
"selling_rate": "5001",
"buying_rate": "4890",
"delivery": "07-07-2020",
"retail_rate": "-",
"com_weight": "1.000",
"com_order": "1",
"client": "kkvtrade",
"client_com_id": "kkvtrade_33",
"high_rate": "5002",
"low_rate": "4980"
},
{
"com_id": "36",
"com_name": "GOLD FT",
"selling_rate": "5001",
"buying_rate": "4900",
"delivery": "07-07-2020",
"retail_rate": "-",
"com_weight": "1.000",
"com_order": "2",
"client": "kkvtrade",
"client_com_id": "kkvtrade_36",
"high_rate": "5002",
"low_rate": "4980"
},
{
"com_id": "37",
"com_name": "GOLD RTGS",
"selling_rate": "4901",
"buying_rate": "5000",
"delivery": "07-07-2020",
"retail_rate": "-",
"com_weight": "1.000",
"com_order": "3",
"client": "kkvtrade",
"client_com_id": "kkvtrade_37",
"high_rate": "4902",
"low_rate": "4880"
},
{
"com_id": "38",
"com_name": "SILVER",
"selling_rate": "50369",
"buying_rate": "50354",
"delivery": "07-07-2020",
"retail_rate": "-",
"com_weight": "1000.000",
"com_order": "4",
"client": "kkvtrade",
"client_com_id": "kkvtrade_38",
"high_rate": "50400",
"low_rate": "50008"
}
]

This above json i'm parsing using the class,(Array of object)
ClientsRateRow[] craterows = gson.fromJson(jedis.get("WLallclientsrates"), ClientsRateRow[].class);

Giuseppe Corti

Have you tried to approach all redis operations in the getJSON method (open the connection, retrieve the json and close)?

rvkvino

Yes this helped me. I have open and close all the places wherever I have used Redis and then closed. Now working fine my adapter. My problem is solved in website. Now I need to know whether is there any LS client library is available for dart language. I'm developing app in Flutter, now I need to show market rates in app also which I done in website.

Giuseppe Corti

A flutter/dart client is in our roadmap, but not in the very short term.
But in the past we have suggested a workaround to those interested in the Flutter/Dart platform which consists of leverage our Android/iOS SDK and write a thin compatibility layer calling the Android/iOS Client API from Dart (see here for details).

As an extreme alternative if you are comfortable with the Dart language, you could directly implement the TLCP protocol at least for the functionality necessary for your app (https://www.lightstreamer.com/repo/distros/Lightstreamer_7_1_1_20200527.zip%23/Lightstreamer/DOCS-SDKs/sdk_client_generic/doc/TLCP%20Specifications.pdf).

Please let us know if you need any further clarifications.

Regards,
Giuseppe

rvkvino

Is this possible my same LS server can serve to TLCP protocol subscription clients. Or I need to do any changes on LS server also to connect TLCP. And also any sample code available for this concept to bind stock market data. If it is available means it will be helpful to me.

Giuseppe Corti

From a technical point of view you should only be sure that the version of TLCP you implement is compatible with the version of the server in use. For example TLCP version 2.2.0 targets Lightstreamer Server v. 7.1.1 or greater.

Then you should consider that TLCP explicit support is an optional feature so you need to verify your license and in case upgrade it.

rvkvino

I'm using SERVER VERSION: Lightstreamer Server version 7.1.1 using COMMUNITY edition. Is this possible by using this version and edition to use TLCP

Giuseppe Corti

Yes I confirm that you can use a client directly implementing the TLCP protocol with COMMUNITY edition by leveraging the parameter:

<enabled_client_api>generic_client</enabled_client_api>

of section community_edition_details in the lightstreamer_edition_conf.xml.

But in this case I confirm that a server can only support clients of only the specified type: so if you enable Generic Client, the normal web clients cannot be handled by the same server.

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