Recent Posts
1
Programming / Re: merging PDFs
« Last post by Allen Miglore on March 28, 2023, 05:50:13 PM »We use Ghostscript. Not pvx, but just an invoke away, and available on both Windows and Linux.
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Programming / merging PDFs
« Last post by Cedric on March 28, 2023, 03:05:27 PM »Hi, I'm wondering if someone ever attempted to merge multiple PDF files into one via pvxplus? I have some PDFs saved on the server where my goal is to open them up on the client side at once. (not file by file). In some cases, there could be like 25 files to open at once.
I know there's some linux tools I could use, but wondering if it's doable in PVX?
I know there's some linux tools I could use, but wondering if it's doable in PVX?
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Programming / Re: Reading simple data from a TCP channel
« Last post by martinp on March 23, 2023, 03:37:34 PM »Thank you Mike this is great. Much appreciated!
In this case these are scanners. What's neat is I can set the scanner to send the length of the data as part of the data stream, so I can use that as well to parse if needed.
In this case these are scanners. What's neat is I can set the scanner to send the length of the data as part of the data stream, so I can use that as well to parse if needed.
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Programming / Re: Reading simple data from a TCP channel
« Last post by Mike King on March 23, 2023, 02:44:00 PM »Yes -- since its a streaming interface and since TCP/IP itself breaks up transmissions then reassembles them when they are received there is never a 100% clean way to assure you got all the data unless you issue something like a READ RECORD (nn, SIZ=xx) R$ where you know you are expecting fixed size data chunks.
BTW: If you notice on the last PNG you posted the time stamp for the split transmission was identical. Basically something in the TCP/IP protocol simply caused the blocks of data to arrive independently thus part of the transmission was received and passed to your program with the remainder arriving probably milliseconds later.
This streaming of TCP data is generally why TCP transmissions normally are designed to provide length information (e.g. the Content-Length header on web requests) or have a signal (e.g. the empty line between web page headers and contents) that can be used to detected end of transmission.
BTW: If you notice on the last PNG you posted the time stamp for the split transmission was identical. Basically something in the TCP/IP protocol simply caused the blocks of data to arrive independently thus part of the transmission was received and passed to your program with the remainder arriving probably milliseconds later.
This streaming of TCP data is generally why TCP transmissions normally are designed to provide length information (e.g. the Content-Length header on web requests) or have a signal (e.g. the empty line between web page headers and contents) that can be used to detected end of transmission.
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Programming / Re: Reading simple data from a TCP channel
« Last post by martinp on March 23, 2023, 02:11:48 PM »Just thinking about this again. Are you saying I should always concatenate the receiving data from [tcp] and then check for a starting/termination string in order to qualify the received data. I see. I was just surprised the nc data was just perfectly clean so I was not sure.
Not used to reading data directly from TCP streams so this is very helpful.
Not used to reading data directly from TCP streams so this is very helpful.
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Programming / Re: Reading simple data from a TCP channel
« Last post by martinp on March 23, 2023, 01:59:20 PM »Let me try the NODELAY I was thinking about that as well.
I don't think the comma will work because that output you were seeing was from a separate echo to a text file which I was just logging. I didnt want to post a bunch of messy code
Its clear its hitting a second READ
0100 let TEMP$="echo '"+TIME$+" "+A$+"' >> /tmp/ima2_out.txt"
Thanks for your rapid responses
I don't think the comma will work because that output you were seeing was from a separate echo to a text file which I was just logging. I didnt want to post a bunch of messy code
Its clear its hitting a second READ
0100 let TEMP$="echo '"+TIME$+" "+A$+"' >> /tmp/ima2_out.txt"
Thanks for your rapid responses
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Programming / Re: Reading simple data from a TCP channel
« Last post by Mike King on March 23, 2023, 01:55:10 PM »Yes but TCP is a streaming transmission so arrival times are never assured. A transmission error somewhere along the stream can cause a delay/small packet at any time.
Also, if you receiving small intermittent packets I would suggest you add the option NODELAY to disable the Nagles algorithm on the connection, it is normally enabled on TCP. (See Nagles Algorithm at https://en.wikipedia.org/wiki/Nagle%27s_algorithm). It also possible the sender may need to disable the algorithm to provide an even flow of data.
All that being said, did the example I posted with the trailing comma resolve what you seeing?
Also, if you receiving small intermittent packets I would suggest you add the option NODELAY to disable the Nagles algorithm on the connection, it is normally enabled on TCP. (See Nagles Algorithm at https://en.wikipedia.org/wiki/Nagle%27s_algorithm). It also possible the sender may need to disable the algorithm to provide an even flow of data.
All that being said, did the example I posted with the trailing comma resolve what you seeing?
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Programming / Re: Reading simple data from a TCP channel
« Last post by martinp on March 23, 2023, 01:51:37 PM »Let me resend with this picture I had this code with my time stamp
0040 let TCP=unt; open (TCP,bsz=4096,err=ERR_PORT)"[tcp];9004;KEEPALIVE"
0050 read record (TCP,err=ERR_READ)A$
0060 let TIME$=dte(0:%DATTIM_MSK$)
0070 print TIME$+" Got: ",A$
0040 let TCP=unt; open (TCP,bsz=4096,err=ERR_PORT)"[tcp];9004;KEEPALIVE"
0050 read record (TCP,err=ERR_READ)A$
0060 let TIME$=dte(0:%DATTIM_MSK$)
0070 print TIME$+" Got: ",A$
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Programming / Re: Reading simple data from a TCP channel
« Last post by martinp on March 23, 2023, 01:48:11 PM »Thanks Mike but this data is coming in very slow like as you can see by the time stamp. Every few seconds very small data chunks?
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Programming / Re: Reading simple data from a TCP channel
« Last post by Mike King on March 23, 2023, 01:44:52 PM »You have specified a blocking factor of 4K so every time you read the most you will get back is 4K regardless of how much has been received.
Your PRINT command will then insert a visible line break on the output -- the line feed is not in the data but simply a result of the PRINT statement not having a trailing comma..
Try:
Your PRINT command will then insert a visible line break on the output -- the line feed is not in the data but simply a result of the PRINT statement not having a trailing comma..
Try:
Code: [Select]
let TCP=unt; open (TCP,bsz=4096,err=ERR_PORT)"[tcp];9004;KEEPALIVE"
READ_NEXT:
read record (TCP,err=ERR_READ)A$
print A$,
goto READ_NEXT