I set up an OLE Automation Server and an OLE Client in Delphi XE2. My two Methods are the following:
function TMyCom2.Get_Text() : IStrings;
begin
GetOleStrings(unit1.Form1.Memo1.Lines, Result);
end;
and:
procedure TMyCom2.Set_Text(const value: IStrings);
begin
SetOleStrings(unit1.Form1.Memo1.Lines, value);
end;
Now I tried to call both by the client.
The second Method(Set_Text) was working perfectly fine.
But the first one(Get_Text) wich should gather the content of the memo of the server and write it into the memo of the client, caused this exception:
Exception error of the server!
To get the Ole information I wrote this on the client side:
procedure TForm1.Button1Click(Sender: TObject);
var
aStrings : IStrings;
begin
aStrings.Add(Server.Get_Text);
SetOleStrings(Memo1.Lines, aStrings);
end;
I have no idea what could be wrong and I was incredibly grateful if somebody could take a look at this code and tell me what the hell is going wrong;D
PS: I already tested it with Integers and it worked so the Problem has to do something with Strings
I uploaded the two projects on Dropbox so feel free to download them:
Client: here
Server: here
Related
I created a very simple ISAPI DLL with the following code on the default handler:
procedure TWebModule1.WebModule1DefaultHandlerAction(Sender: TObject;
Request: TWebRequest; Response: TWebResponse; var Handled: Boolean);
var
DevHandle : THandle;
begin
Printer.PrinterIndex := 0;
DevHandle := Printer.Handle;
end;
The second line always fails with "Printer Selected is not Valid." I originally thought this might be a rights issue, but have tried identities with adequate rights. Additionally, the Printer class does return the correct list of printers/drivers matching those installed on my machine.
Is there a way around this error so the default printer can be selected and I can retrieve the printer handle?
I am not sure it is safe to print from ISAPI dll , it may hang and several client can try to access at the same time.
what i have done :
ISAPI request write on local database what it wanted to print , then display an animation at client side while it waits for an external software to finish the job.
not sure it helps ..
I'm using Delphi 10.1 Berlin Update 2 Enterprise and the DataSnap client/server REST framework.
If I run the app without debugging and invoke a method the user isn't authorized to invoke, the code runs without any exception and the method returns a null response.
When interactively debugging a call on the client to a DataSnap server method, I get two popup exceptions regarding "unauthorized".
The first bubbles up and is replaced by the second.
The second exception gets "eaten" and the session/connection simply closed and then the method returns a blank result (e.g. a zero if the return type is integer, and an empty string for a string return type).
This is happening in the following section of code near the end of the ExecuteRequest method in the Datasnap.DSClientRest unit:
except
on E: TDSRestProtocolException do
LSessionExpired;
end;
Why are these exceptions (e.g. TDSRestProtocolException) not reaching my code?
I kind of think this is new to Update 2, and I remember seeing those exceptions bubble up to my code prior to Update 2.
Attached is a skeleton example (standard example generated by Delphi wizards) that demonstrates the issue - click the button and you get "" instead of "4321" because the user isn't authorized - but no runtime exception.
I'm new to DataSnap, so bear with me :-)
Thanks in advance for helpful responses =)
This is happening due to DSAuthenticationManager1 component added to webmodule of the server and client side is failing to authenticate.
Please go through this to check how to work with authentication
Adding Authentication and Authorization
Well..I'm not sure but try providing username and password to DSRestConnection1 component before the instance of server methods gets created
procedure TClientModule1.TestCon(aUsername, aPassword: string);
var
lServerMethodsClient : TServerMethodsClient;
begin
DSRestConnection1.UserName := aUsername;
DSRestConnection1.Password := aPassword;
lServerMethodsClient:=TServerMethodsClient.Create(DSRestConnection1);
end;
and try to call this functn from ur clientform
procedure TF_ClientForm.Button1Click(Sender: TObject);
begin
ClientModule1.TestCon(EdtUsername.Text, EdtPassword.Text);
end;
Maybe a little late but this morning I've had a deep dive into this because, after upgrading from Delphi XE6 to Tokyo 10.2, applications where I used the TDSRestConnection component got broken. Although I supplied the correct username and password, they did not appear in the TDSAuthenticationManager.OnUserAuthenticate event.
The 'problem' has to do with the new System.Net.HttpClient implementation.
To make a long story short (or a little bit less long):
The client component does not send the credentials until the receiving server demands one by sending a 401 response. After receiving this (properly formatted) response the client looks at de TDSConnection credentials en tries again. At the client side a complete list of urls with credential requirements is maintaned so repetitive calls to the same url go 'smoother'.
I added this code to the server's WebModule (where the TDSRESTWebDispatcher resides) which solved my problems:
procedure TwbmMain.WebModuleBeforeDispatch(Sender: TObject; Request: TWebRequest; Response: TWebResponse; var Handled: Boolean);
var
LAuthorization: string;
begin
inherited;
if Request.PathInfo.StartsWith('/datasnap/') then
begin
LAuthorization := TNetEncoding.Base64.Decode(Request.Authorization.Replace('Basic ', ''));
if LAuthorization.IsEmpty then
begin
Response.StatusCode := 401;
Response.WWWAuthenticate := 'Basic';
Handled := True;
end;
end;
end;
Because my applications provides some downloadable items like a logo etc., I limited the check to just those URLs that have anything to do with datasnap.
Hope this is useful to others!
I'm trying to make a Delphi application to work with AlwaysOn solution. I found on Google that I have to use MultiSubnetFailover=True in the connection string.
Application is compiled in Delphi XE3 and uses TADOConnection.
If I use Provider=SQLOLEDB in the connection string, application starts but it looks like MultiSubnetFailover=True has no effect.
If I use Provider=SQLNCLI11 (I found on Google that OLEDB doesn't support AlwaysOn solution and I have to use SQL Native client) I get invalid attribute when trying to open the connection.
The connection string is:
Provider=SQLOLEDB.1;Password="password here";Persist Security Info=True;User ID=sa;Initial Catalog="DB here";Data Source="SQL Instance here";MultiSubnetFailover=True
Do I have to upgrade to a newer version on Delphi to use this failover solution or is something that I'm missing in the connection string?
I am currently using XE2 with SQL Server AlwaysOn. If you read the documentation you will see that AlwaysOn resilience events will cause your database connection to fail and you need to initiate a new one.
If a SqlClient application is connected to an AlwaysOn database that
fails over, the original connection is broken and the application must
open a new connection to continue work after the failover.
I've dealt with this via the simple expedient of overriding the TAdoQuery component with my own version which retries the connection after getting a connection failure. This may not be the proper way to do this but it certainly works. What it does is override the methods invoked for opening (if the query returns a result set) or executes the SQL (otherwise) and if there is a failure due to connection loss error tries again (but only once). I have heavily tested this against AlwaysOn switch overs and it works reliably for our configuration. It will also react to any other connection loss events and hence deals with some other causes of queries failing. If you are using a component other than TAdoQuery you would need to create similar overrides for that component.
It is possible this can be dealt with in other ways but I stopped looking for alternatives once I found something that worked. You may want to tidy up the uses statement as it clearly includes some stuff that isn't needed. (Just looking at this code makes me want to go away and refactor the code duplication as well)
unit sptADOQuery;
interface
uses
Windows, Messages, SysUtils, Classes, Db, ADODB;
type
TsptADOQuery = class(TADOQuery)
protected
procedure SetActive(Value: Boolean); override;
public
function ExecSQL: Integer; // static override
published
end;
procedure Register;
implementation
uses ComObj;
procedure Register;
begin
RegisterComponents('dbGo', [TsptADOQuery]);
end;
procedure TsptADOQuery.SetActive(Value: Boolean);
begin
try
inherited SetActive(Value);
except
on e: EOleException do
begin
if (EOleException(e).ErrorCode = HRESULT($80004005)) then
begin
if Assigned(Connection) then
begin
Connection.Close;
Connection.Open;
end;
inherited SetActive(Value); // try again
end
else raise;
end
else raise;
end;
end;
function TsptADOQuery.ExecSQL: Integer;
begin
try
Result := inherited ExecSQL;
except
on e: EOleException do
begin
if (EOleException(e).ErrorCode = HRESULT($80004005)) then
begin
if Assigned(Connection) then
begin
Connection.Close;
Connection.Open;
end;
Result := inherited ExecSQL; // try again
end
else raise;
end
else raise;
end;
end;
end.
In many tutorials i read how to select data from a database in a datasnap client, p.e. to complete a dbgrid.
But i need now to know how to insert or update a row, p.e "new client". Can everybody recommends me a book or tutorial?
I have an sqlconnection on a clientdatamodule on the clientside apart from clientclassesunit. I was prooving wuth an SQLQuery with an insert SQL Statement but it doen't function.
On the other han i have on the server side:
procedure TServerMethods1.nuevocheque(idcliente,numero,cuenta,idbanco : integer; fr,fc, titular:string ;importe:Double;cobrado:Boolean);
var
ucheque:integer;
begin
with qicheque do
begin
Open;
ParamByName('idcliente').AsInteger:=idcliente;
ParamByName('numero').AsInteger:=numero;
ParamByName('fr').AsDate:=StrToDate(fr);
ParamByName('fc').AsDate:=StrToDate(fc);
ParamByName('importe').AsFloat:=importe;
ParamByName('titular').AsString:=titular;
ParamByName('cobrado').AsBoolean:=cobrado;
ParamByName('cuenta').AsInteger:=cuenta;
ExecSQL();
end;
end;
With this method i try to insert, the statement is into SQL property of the component.
On the client side, i have a TSQLServerMethod wich calls "nuevocheque":
procedure TForm4.BGuardarClick(Sender: TObject);
var
idcliente,numero,cuenta,idbanco:integer;
titular:string;
cobrado:Boolean;
fr,fc:string;
importe:Double;
begin
ClientModule1.nuevocheque.Create(nil);
with ClientModule1.nuevocheque do
begin
idcliente:=1;
numero:=StrToInt(ENumero.Text);
cuenta:=StrToInt(Ecuenta.Text);
idbanco:=1;
titular:=ENombre.Text;
cobrado:=False;
importe:=StrToFloat(EMonto.Text);
fr:=EFechaEmision.Text;
fc:=EFechacobro.Text;
end;
end;
But it doesn´t function.
Thank for your help
Well, i achieve inserting data into mysql database i had desgined.
This is te code in delphi into a button:
procedure TForm4.BGuardarClick(Sender: TObject);
var
idcliente,numero,cuenta,idbanco:integer;
titular:string;
cobrado:Boolean;
fr,fc:string;
importe:Double;
a:TServerMethods1Client;
interes:Double;
begin
a:=TServerMethods1Client.Create(ClientModule1.SQLConnection1.DBXConnection);
begin
idcliente:=Unit3.id;
numero:=StrToInt(ENumero.Text);
cuenta:=StrToInt(Ecuenta.Text);
idbanco:=lcbbanco.KeyValue;
titular:=ENombre.Text;
cobrado:=False;
if (EP.Text<>'') then
begin
importe:=StrToFloat(EHC.Text);
end
else
begin
importe:=StrToFloat(EMonto.Text);
end;
fr:=EFechaEmision.Text;
fc:=EFechacobro.Text;
end;
a.nuevocheque(idcliente,numero,cuenta, idbanco,fr,fc,titular,importe,cobrado);
end;
I've called to method create() with the SQL component such as M Diwo said me.
Im too hapy. Thanks to all
I don't know what you use as database connection, for my own convenience I have slightly modified for dbGO (parameters passed by variant).
Also I have made a function from the server method, like this the client can be notified that there has been a problem (with the query, connection,...). Here is the server method:
//server
function TServerMethods1.NuevoCheque(idcliente, numero, cuenta,
idbanco: integer; fr, fc, titular: string; importe: Double;
cobrado: Boolean): Boolean;
begin
try
with qicheque, Parameters do
begin
Close;
ParamByName('idcliente').Value:=idcliente;
ParamByName('numero').Value:=numero;
ParamByName('fr').Value:=StrToDate(fr);
ParamByName('fc').Value:=StrToDate(fc);
ParamByName('importe').Value:=importe;
ParamByName('titular').Value:=titular;
ParamByName('cobrado').Value:=cobrado;
ParamByName('cuenta').Value:=cuenta;
ExecSQL();
end;
Result := true;
except
Result := false;
//raise; <-- uncomment if you want to handle this properly in your code
end;
end;
For the client I suppose you generated a proxy unit that generally creates an object called ServerMethods1 ?
You must pass the client dbx connection to this - I say this because I saw you put nil in your code.
// client
procedure TfrmClient.BGuardaClick(Sender: TObject);
var
sm : TServerMethods1Client; // <-- generated by proxy generator
idcliente,numero,cuenta,idbanco : integer;
fr,fc, titular : string ;
importe : Double;
cobrado : Boolean;
begin
sm := TServerMethods1Client.Create(SQL.DBXConnection);
if sm.nuevocheque(idcliente,numero,cuenta,idbanco, fr,fc, titular, importe, cobrado) then
// ok
else
// error
sm.Free;
end;
hth
You can use calls to remote methods, but they won't automatically update your data aware controls automatically. Datasnap is able to handle it. First, you need to add/update/remove data on the client. It happens in the local cache managed by the TClientDataset, even when you "Post".
When you're ready, you need to "apply" changes to the remote server calling the Apply() method.
When you call it, the provider component on the server receives a "delta" with the record to change from the client dataset, and will automatically generate the needed INSERT/UPDATED/DELETE SQL statements.
If you don't like them, or you need to perform more complex processing, you can use the provider events to perform the needed operations yourself for each changed record and then tell the provider you did it to avoid the automatic processing. Then the provider passes back the "delta" to the client, where it is used to updated the data aware controls. You can also modify the "delta" before it is passed back.
Read in the documentation the explanation of the Datasnap architecture - it's a multistep design where several components work to allow for a multi-tier implementation.
Im trying to code a basic irc client in Delphi 2010 using Indy components.
Im able to connect to my irc server (unrealircd) using sample A below.
After connecting I have many procedures that should perform actions when it receives a private message, ping, ctcp, channel modes etc. but they never react to any of these incoming events.
Sample A:
This connects to the IRC server when button4 is pressed.
It sucessfully joins the channel with the name specified.
procedure TForm1.Button4Click(Sender: TObject);
begin
IdIRC1.Host := '72.20.53.142';
IdIRC1.Port := 6667;
IdIRC1.Nickname := ssh.frmmain.Edit1.text;//insert your nickname here
try
idIRC1.Connect;
except
if not idIRC1.Connected then
begin
Memo2.Lines.add('Error Connecting to ' + idIRC1.Host);
Exit;
end;
end;
Memo2.Lines.add ('Connected to Auth Server');
idIRC1.Join(channel,key);
Memo2.Lines.add ('Auth Accepted');
end;
These events dont work at all and no errors are generated during a compile.
procedure TForm1.IdIRC1Connected(Sender: TObject);
begin
memo2.Lines.Clear;
memo2.Lines.add ('2Connected');
end;
procedure TForm1.IdIRC1ServerVersion(ASender: TIdContext; Version, Host, Comments: String);
begin
memo2.Lines.Add(Version +'Host '+Host+'Comments '+Comments);
end;
Ive had a few people look at this, and it just seems theres some unicode issues that destroyed my TClientSocket irc setup, and even when I moved to indy and used samples off the official site I was still unable to get anything to fire such as the onconnect event.
A friend had a copy of an application he wrote in Delphi 2010 using the same version of indy and I managed to import his project and it started working.
Not sure why