Post Command Problem

Dave dave at looktowindward.com
Thu Nov 13 06:19:13 EST 2008


Hi,

I read records from a database, format them, and add them to a block  
of data. There is a blocking factor variable, it is set to 200, so I  
read 200 records from the database, block them into one big block and  
send it to the server via a "post" command. The Server then sends a  
response which can be variable in length, the response is in XML  
format. This process works well 99% of the time, but sometimes, (and  
this can be reproduced if the right data (or the wrong data in this  
case!) is present in the database). When this happens the response  
from the server is truncated in the middle of an XML node. As far as  
I can tell the difference is that by chance, a group of 200 records  
has caused the response to be over a certain size.

If I set the BlockingFactor to 50, the problem goes away, but this  
causes a major slowdown.

All the Best
Dave

On 11 Nov 2008, at 21:18, Dave Cragg wrote:

> Dave
>
> I'm not clear about the problem you are having.
>
> When you say you are "receiving blocks of data", is this as a  
> result of a series of post commands? (one block per post)
>
> If so, it seems some responses contain less data than expected. If  
> you are getting no error (the result is empty), I can think of 2  
> possible causes.
>
> 1.  The server is wrongly setting the Content-Length header
>
> 2.  The server is not using a Content-Length header and is not  
> using the "chunked" transfer-encoding. This is the case with some  
> servers. This forces the client (Rev app) to use the closing of the  
> connection as a signal that the transfer has ended. I've seen cases  
> (although not recently) where the connection is apparently closed  
> before all data is read.
>
> (I'm sure there are other possible causes.)
>
> I'd suspect the latter cause. But only because I've never seen the  
> first one occur.
>
> I don't know how ASP.NET works. But I remember having a problem  
> like this with Rev CGIs on an IIS server. One thing that helped was  
> to put a short wait (40 milliseconds) at the end of the CGI script.  
> This seemed to prevent the server from closing the connection  
> prematurely (from the Rev client's point of view.)
>
> If I've misunderstood your problem, sorry.
>
> Dave
>
>
>
>>>
>>>
>>> On Mon, Nov 10, 2008 at 1:27 PM, Dave <dave at looktowindward.com>  
>>> wrote:
>>>> Hi All,
>>>>
>>>> I'm getting a weird error when receiving data with the "post"  
>>>> command. I am
>>>> receiving blocks of data from a server and some blocks seem to get
>>>> truncated. Is this a limit on the size of a data block received  
>>>> with the
>>>> "post" command? If there is, how can I set it bigger?
>>>>
>>>> Thanks a lot
>>>> All the Best
>>>> Dave
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