Xin Li

A update for my progress. I have been able to write the calls the web service received to a queue and found out the web service is able to receive all the calls. The reason for SQLite to fail to write is because I used a time stamp as input for a variable that need to be unique, but with the simultaneous calls, that time stamp is the same. Thanks for everyone's help here!

Thanks so much for sharing, I will look at these next week!

Hi Lipko, I think our task priority is not exactly the same but the way how you handle the web service through queues could be helpful to me. I feel the labview web service modules' help manual not very helpful and examples lacking. I think the web service will need to deal with hand-shaking between client and server automatically. But if I am handling the request through my own queues, I am not sure how to implement in labview and make sure the request data is send to the right client. I am still very new to Labview, so if you could give me some hint in more details how I can implement this or share this part of the code, it could be very helpful.

Thanks, JKSH. I am trying to write the web service request to a queue, but having issues of SSE2 error. Disabling SSE2 does not resolve it. I am still trying to solve the issue. I will update once I succeed.

Thanks. When my web service is not reentrant, I can see error produced from "EXEC SQL" call. However, when web service vi is reentrant, I don't see error.

Thanks for sharing your experience. Our situations are similar. We have concurrent writes and reads. I would like all reads to be executed immediately and simultaneously and all writes line up. The writes don't have to be executed immediately but I want to make sure they are all executed properly. So it will be nice if I can forward all web service calls to SQLite and use SQlite to handle concurrency and queuing automatically. If I cannot make this work, I will try what you suggested to handle the queue and priority myself. Could you share more how you do it? If you could share some of your code, it will be great. Not sure how to make sure the read results are returned to the right client. Thanks!

Thanks. I followed https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019QK9SAM&l=en-US and see no errors of web service. Because I want to handle simultaneous web calls, I am making the web service vi reentrant. Not sure how to log all the queries when it is reentrant. Could you give me a hint how?

I would like multiple process to write to SQLite database at the same time through web service. How do I insure all the write queries queue up and all of them get executed? In the web service VI, I am now opening the database and set a long enough busy timeout and then pass the query from web service calls to SQLite EXEC SQL. But my test showed some queries are not executed. So SQLite is not automatically queuing the writing queries? What is the proper way to ensure all queries queue up and get executed?