|
Mark Salsbery wrote: I prefer a class that represents/wraps a connection (e.g. a socket) and handles
its own asynchronous I/O.
I never really got a grasp of how to asynchronous I/O with operations that may need to time out or be aborted; I've read that there isn't really good support for that. I think the concern by the socket implementors was that if an application times out or otherwise decides to abort an operation with a TCP socket, there's no guarantee as to what data may or may not be 'in transit'. Certainly such an issue is reasonable, but in some cases it may be easier and cheaper to recover from the 'unknown data' scenario than to close and reopen the socket. For example, if the remote system includes an 'echo' command, the PC can ask the remote machine to echo back a GUID, repeating the request until the proper GUID is echoed(*). Once the proper echo is received, the PC will know that the only thing that could possibly be in the transmit pipe would be more copies of the 'echo' command, and the only thing that could possibly be in the receive pipe would be more copies of the echoed GUID.
(*) If both endpoints were running TCP natively, there would be no point in retransmitting the data. On the other hand, many embedded systems use a TCP-to-serial gateway, and there is a possibility of data loss on the serial link.
What would be the best way to set up an application if it has to be able to exchange data via the following three methods, interchangeably:
-1- TCP socket
-2- Serial port
-3- Thread which polls a custom USB device each millisecond to see if there's any data
Are there any good example programs showing how best to do such things?
|
|
|
|
|
supercat9 wrote: asynchronous I/O with operations that may need to time out or be aborted; I've read that there isn't really good support for that. I think the concern by the socket implementors was that if an application times out or otherwise decides to abort an operation with a TCP socket, there's no guarantee as to what data may or may not be 'in transit'.
Is it really an issue in practice with TCP? If you implement a timeout or abort you run the risk of data loss
regardless - there's no way for an endpoint to know what the other endpoint is about to do.
supercat9 wrote: What would be the best way to set up an application if it has to be able to exchange data via the following three methods, interchangeably
I don't know, beyond making a base common interface then implementing three derived
implementations that implement the interface for the given communication type.
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/coffee.gif)
|
|
|
|
|
Mark Salsbery wrote: Is it really an issue in practice with TCP? If you implement a timeout or abort you run the risk of data loss
regardless - there's no way for an endpoint to know what the other endpoint is about to do.
Is there any practical way to abort an asynchronous TCP operation without closing a connection, if one is willing to accept the loss or late arrival of data prior to the abort, but one wants to avoid memory or resource leaks, weird crashes, etc.? I know that in many of the applications for which TCP is designed, dropping a connection would be preferable to losing data while keeping a connection, but when dealing with embedded systems that isn't always true.
Also, btw, is it safe to have one thread write to a socket while a different thread reads it? I know that having two threads writing or two threads reading would likely be problematical at best, but the write/read case would seem common enough I would hope the implementors would have handled it correctly.
|
|
|
|
|
supercat9 wrote: is it safe to have one thread write to a socket while a different thread reads it?
I've never seen it documented, and may never, but it works on Windows and I rely on it working 
Mark Salsbery
Microsoft MVP - Visual C++
|
|
|
|
|
Thanks for your help. I think I have a workable approach for the handoff (at least my simple test apps work fine). As for aborting an asynchronous operation, I've decided the best approach is probably to have the asynchronous receive handler call a delegate for the incoming data. That way, if I give up on receiving one type of data and want to start looking for another type, I don't need to abort the pending receive--I can simply leave it pending; when data comes in, it will go to the new delegate.
|
|
|
|
|
supercat9 wrote: What would be the preferred method of handing off a socket to an application which isn't yet launched
I would prefer not to do that. So I would want to have zero other choices before adopting that approach. Keep it simple by just having the new process start a new connection and design session and application protocol for aligning the data that is transmitted. Passing sockets across applications just sounds like a bad idea. Of course I don't have your complete requirements, I'm just saying I would think that is a last resort.
|
|
|
|
|
I agree. And using TCP and sockets, the session IS the connected socket
so it's not very complex to implement.
Mark Salsbery
Microsoft MVP - Visual C++
|
|
|
|
|
I have a reserved TCP port for a class of applications which generally involve an electronic device (not a PC) connecting to a server. The first line of data sent from a device will identify the device type and serial number. Different devices will need to be handled by different applications. It is necessary to keep the remote end as simple as possible, since it's a relatively unsophisticated microcontroller.
While it might be possible to build a mega-application which would handle everything internally (indeed, that's what I have now) splitting things off into different applications should improve system reliability and extensibility.
|
|
|
|
|
|
Hi All.........
I know very well how to create crystal reports using Access and I am trying same method for sql server but its not working.
Is there any different method for creating a crystal report while working with sql server?
If any........suggest me.
Thanks.
-Neeta
|
|
|
|
|
hi...
I am working with sql server and vb.net.
I have a table with two fields i.e. serial number (SrNo) and Department Name (dept).
for ex:
SrNo dept
1 Finance
2 Hr
3 Production
when i am deleting any single row from the database then serial_number's sequence changed because of deleting a row.
Such as:
SrNo dept
1 Finance
3 Production
I want a help so that serial_number sequence should be arranged in a sequence automatically after deleting a row.
such as:
SrNo dept
1 Finance
2 Production
-Neeta
|
|
|
|
|
That goes against 'proper design'. See, those numbers are usually used to make a "connection" with another table.
SrNo dept
1 Finance
3 Production
Employee StationOnDept
Johnny 1
Neeta 1
Bill 3
We can use a query to determine who works where. Bill works at production, in the above example. Now, if you change the "3" that belongs with the "Production" to a "2", then Bill will still work at dept 3, even though it doesn't exist anymore.
You're likely to break your database as soon as you start messing with them numbers.
I are troll
|
|
|
|
|
Though it is possible todo, this also introduces performance and scalibility problems. Since you'll have to rewrite every record in the database to resqeuence the numbers, the more data you have in the table, the longer it takes to resequence them. Now, since you can't have people reading or writing to the database during this time, to (partially!!) maintain data integtry, noone can access the database at all until this resequence is done.
Now, AFTER the resequence, the data that everyone is looking at in their copy of the application is now obsolete, and if they make any changes to the database using this obsolete data, you've just destroyed the database. Everyone is going to have to reload the data they're using after every resequence.
What you want IS possible, but it's a HORRIBLE idea.
|
|
|
|
|
I think it would be helpful to know why you want to do this. As others have pointed out, it is not generally regarded as good practice but in rare circumstances I suppose you could make a case for it. Depending on how large your table is and how frequent or infrequent the deletions are, it may be feasible to resequence on every delete but we'd need more information in order to be able to judge. (If you only delete a department once a year you could get away with it, if you're doing it many times a day then probably not.)
Is there a specific reason why you do not want to have gaps in the sequence numbers in your table? Also, is serial number the unique key to your table, or is it just a sequence number that gets displayed to the user, or is it used for alternate sort sequences or something like that?
Also, there is a database forum here. If you have a question relating to databases, you might get a better answer there.
|
|
|
|
|
I have several variables tagged with a DescriptionAttribute, like so:
<Description("String 1")> Public Str1 As String = "One"
<Description("String 2")> Public Str2 As String = "Two"I want to retrieve the text of the description off of both Str1 and Str2. I can find examples of how to get attribute information off of classes and members of an enumeration, but nothing at all on how to get metadata that was applied to an instance of a class. I assume it is possible, but how can it be done?
|
|
|
|
|
The answer seems to be that metadata is attached only to type objects, not to instances. My examples above serve as documentation in the source and nothing more. By the time the code is running, only static objects still have metadata. 
|
|
|
|
|
Hi,
I got problem with sample code provided by the FedEx Services i need to access FedEx Rates based on Zip code while running sample code getting error like "Requested package detail type is missing or invalid." Can any one help me its very urgent.
Code used by me:
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
RateRequest request = CreateRateRequest();
RateService rst = new RateService();
RateReply reply = rst.getRates(request);
if (reply.HighestSeverity == NotificationSeverityType.SUCCESS || reply.HighestSeverity == NotificationSeverityType.WARNING)
{
//showReply(reply);
Response.Write("SUCCESS");
}
else
{
Response.Write(reply.Notifications[0].Message);
}
}
private static RateRequest CreateRateRequest()
{
// Build the RateRequest
RateRequest request = new RateRequest();
//
request.WebAuthenticationDetail = new WebAuthenticationDetail();
request.WebAuthenticationDetail.UserCredential = new WebAuthenticationCredential();
request.WebAuthenticationDetail.UserCredential.Key = "Key"; // Replace "XXX" with the Key
request.WebAuthenticationDetail.UserCredential.Password = "Password"; // Replace "XXX" with the Password
//
request.ClientDetail = new ClientDetail();
request.ClientDetail.AccountNumber = "AccountNumber"; // Replace "XXX" with client's account number
request.ClientDetail.MeterNumber = "MeterNumber"; // Replace "XXX" with client's meter number
//
request.TransactionDetail = new TransactionDetail();
request.TransactionDetail.CustomerTransactionId = "TEST"; // This is a reference field for the customer. Any value can be used and will be provided in the response.
//
request.Version = new VersionId(); // WSDL version information, value is automatically set from wsdl
//
// Origin information
request.ReturnTransitAndCommit = true;
request.ReturnTransitAndCommitSpecified = true;
request.CarrierCodes = new CarrierCodeType[1];
request.CarrierCodes[0] = CarrierCodeType.FDXE;
request.RequestedShipment = new RequestedShipment();
request.RequestedShipment.Shipper = new Party();
request.RequestedShipment.Shipper.Address = new Address();
request.RequestedShipment.Shipper.Address.StreetLines = new string[1] { "Sender Address Line 1" };
request.RequestedShipment.Shipper.Address.City = "tennessee";
request.RequestedShipment.Shipper.Address.StateOrProvinceCode = "TN";
request.RequestedShipment.Shipper.Address.PostalCode = "38115";
request.RequestedShipment.Shipper.Address.CountryCode = "US";
//
// Destination Information
request.RequestedShipment.Recipient = new Party();
request.RequestedShipment.Recipient.Address = new Address();
request.RequestedShipment.Recipient.Address.StreetLines = new string[1] { "Recipient Address Line 1" };
request.RequestedShipment.Recipient.Address.City = "Quebec";
request.RequestedShipment.Recipient.Address.StateOrProvinceCode = "PQ";
request.RequestedShipment.Recipient.Address.PostalCode = "H1E1A1";
request.RequestedShipment.Recipient.Address.CountryCode = "CA";
//
// Payment Information
request.RequestedShipment.ShippingChargesPayment = new Payment();
request.RequestedShipment.ShippingChargesPayment.PaymentType = PaymentType.SENDER; // Payment options are RECIPIENT, SENDER, THIRD_PARTY
request.RequestedShipment.ShippingChargesPayment.PaymentTypeSpecified = true;
request.RequestedShipment.ShippingChargesPayment.Payor = new Payor();
request.RequestedShipment.ShippingChargesPayment.Payor.AccountNumber = "AccountNumber"; // Replace "XXX" with client's account number
request.RequestedShipment.DropoffType = DropoffType.STATION; //Drop off types are BUSINESS_SERVICE_CENTER, DROP_BOX, REGULAR_PICKUP, REQUEST_COURIER, STATION
request.RequestedShipment.ServiceType = ServiceType.INTERNATIONAL_PRIORITY; // Service types are STANDARD_OVERNIGHT, PRIORITY_OVERNIGHT, FEDEX_GROUND ...
request.RequestedShipment.ServiceTypeSpecified = true;
request.RequestedShipment.PackagingType = PackagingType.FEDEX_BOX; // Packaging type FEDEX_BOK, FEDEX_PAK, FEDEX_TUBE, YOUR_PACKAGING, ...
request.RequestedShipment.PackagingTypeSpecified = true;
//
request.RequestedShipment.TotalInsuredValue = new Money();
request.RequestedShipment.TotalInsuredValue.Amount = 100;
request.RequestedShipment.TotalInsuredValue.Currency = "USD";
request.RequestedShipment.ShipTimestamp = DateTime.Now; // Shipping date and time
request.RequestedShipment.ShipTimestampSpecified = true;
request.RequestedShipment.RateRequestTypes = new RateRequestType[2];
request.RequestedShipment.RateRequestTypes[0] = RateRequestType.ACCOUNT;
request.RequestedShipment.RateRequestTypes[1] = RateRequestType.LIST;
//
// The RateRequest can be populated with one of the following:
//
// RequestedPackageSummary - Details of multi piece shipment rate request - Use this to rate a total piece total weight shipment.
// Array of RequestedPackage - Details of single piece shipment rate request or multiple packages with differing parameters.
bool bPassRateRequestPackageSummary = false;
if (bPassRateRequestPackageSummary)
{
// -----------------------------------------
// Passing multi piece shipment rate request
// -----------------------------------------
request.RequestedShipment.TotalWeight = new Weight();
request.RequestedShipment.TotalWeight.Value = 20.0M;
request.RequestedShipment.TotalWeight.Units = WeightUnits.LB;
//
request.RequestedShipment.PackageCount = "2";
request.RequestedShipment.PackageDetail = RequestedPackageDetailType.PACKAGE_SUMMARY;
//
request.RequestedShipment.RequestedPackageSummary = new RequestedPackageSummary();
request.RequestedShipment.RequestedPackageSummary.Dimensions = new Dimensions(); // package dimensions, applies to each package
request.RequestedShipment.RequestedPackageSummary.Dimensions.Length = "10";
request.RequestedShipment.RequestedPackageSummary.Dimensions.Width = "10";
request.RequestedShipment.RequestedPackageSummary.Dimensions.Height = "3";
request.RequestedShipment.RequestedPackageSummary.Dimensions.Units = LinearUnits.IN;
}
else
{
// ------------------------------------------
// Passing individual pieces rate request
// ------------------------------------------
request.RequestedShipment.PackageCount = "2";
request.RequestedShipment.PackageDetail = RequestedPackageDetailType.INDIVIDUAL_PACKAGES;
//
request.RequestedShipment.RequestedPackages = new RequestedPackage[2];
request.RequestedShipment.RequestedPackages[0] = new RequestedPackage();
request.RequestedShipment.RequestedPackages[0].SequenceNumber = "1"; // package sequence number
//
request.RequestedShipment.RequestedPackages[0].Weight = new Weight(); // package weight
request.RequestedShipment.RequestedPackages[0].Weight.Units = WeightUnits.LB;
request.RequestedShipment.RequestedPackages[0].Weight.Value = 15.0M;
//
request.RequestedShipment.RequestedPackages[0].Dimensions = new Dimensions(); // package dimensions
request.RequestedShipment.RequestedPackages[0].Dimensions.Length = "10";
request.RequestedShipment.RequestedPackages[0].Dimensions.Width = "13";
request.RequestedShipment.RequestedPackages[0].Dimensions.Height = "4";
request.RequestedShipment.RequestedPackages[0].Dimensions.Units = LinearUnits.IN;
//
request.RequestedShipment.RequestedPackages[0].InsuredValue = new Money(); // insured value
request.RequestedShipment.RequestedPackages[0].InsuredValue.Amount = 100;
request.RequestedShipment.RequestedPackages[0].InsuredValue.Currency = "USD";
//
request.RequestedShipment.RequestedPackages[1] = new RequestedPackage();
request.RequestedShipment.RequestedPackages[1].SequenceNumber = "2"; // package sequence number
//
request.RequestedShipment.RequestedPackages[1].Weight = new Weight(); // package weight
request.RequestedShipment.RequestedPackages[1].Weight.Units = WeightUnits.LB;
request.RequestedShipment.RequestedPackages[1].Weight.Value = 25.0M;
//
request.RequestedShipment.RequestedPackages[1].Dimensions = new Dimensions(); // package dimensions
request.RequestedShipment.RequestedPackages[1].Dimensions.Length = "20";
request.RequestedShipment.RequestedPackages[1].Dimensions.Width = "13";
request.RequestedShipment.RequestedPackages[1].Dimensions.Height = "4";
request.RequestedShipment.RequestedPackages[1].Dimensions.Units = LinearUnits.IN;
//
request.RequestedShipment.RequestedPackages[1].InsuredValue = new Money(); // insured value
request.RequestedShipment.RequestedPackages[1].InsuredValue.Amount = 500;
request.RequestedShipment.RequestedPackages[1].InsuredValue.Currency = "USD";
}
return request;
}
}
modified on Monday, June 15, 2009 12:56 AM
|
|
|
|
|
If it's that urgent - call FedEx's developer support.
|
|
|
|
|
A tip: when you're using a web service that requires authentication, remove the key, password, account number, postal code and meter number
Between the idea
And the reality
Between the motion
And the act
Falls the Shadow
|
|
|
|
|
Whoops! The OP's client might want to get FedEx to change their credentials toot sweet (as the French are wont to say) before some hackery types start using them...
That was a bit of a fox paw (as the French etc. etc.)
There are three kinds of people in the world - those who can count and those who can't...
|
|
|
|
|
Just browsing the forums, and I'm surprised this is still here unedited.
saritha_codeproject wrote: request.WebAuthenticationDetail.UserCredential.Key = "eek!!!"; // Replace "XXX" with the Key
request.WebAuthenticationDetail.UserCredential.Password = "aaarghhh!"; // Replace "XXX"
request.ClientDetail.AccountNumber = "yikes!!"; // Replace "XXX" with client's account number
request.ClientDetail.MeterNumber = "crivens!!"; // Replace "XXX" with client's meter number
OP (Saritha) you really need to edit your post to remove the sensitive information. Also, if this is your company, or if this is a client you're doing work for, you need to let them know their account information may now be public, and get them to at least change their password, if not the whole account.
It may have just been a silly mistake, copying and pasting the code here, but it's very unprofessional to leave this exposed to anyone and everyone.
(I'll send this by PM as well, since the OP may not be reading replies to his post.)
There are three kinds of people in the world - those who can count and those who can't...
|
|
|
|
|
I have placed it mistakenly. Thank you for your valuable suggestion.
|
|
|
|
|
Can Anyone Help me regarding Natural Language Processing??
What I need is .....
I want to match the sentance with respect of its context meaning for example i search for a pharase 'Status of the given task is updated' so with Natural Language Processing all sentences in a file that are written in the context of informing about the status of the task should be searched by algo as May be sentence in the file is 'The status of the task is completed assigned to John'.
I want any open source language processing tool ar any web service for this purpose that i can include into my project as third party tool....
Plzzzz Help....
Thanks
|
|
|
|
|
Have a read of this[^] article. It was at the top of a simple google search.
"WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
|
|
|
|
|
I have already check and run the whole sharpNLP/openNLP Project but it only split sentences , Tokenize and find Names etc.Realy didinot fullfill my requirement of understanding the sentence with its context
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
