HTTPClient Component

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The HTTPClient component implements client-side functionality of HTTP and HTTPS protocols.

Syntax

TsbxHTTPClient

Remarks

HTTPClient provides means of exchanging HTTP messages with HTTP servers. Both plain (HTTP) and secure (HTTPS) connection types are supported.

Features supported

• All standard request types (GET, POST, PUT etc.), plus custom VERBs
• TLS 1.2 and 1.3 (and earlier versions for older servers)
• Strong client and server authentication on TLS and HTTP levels
• Flexible custom header adjustment
• A variety of proxy server types

Configuring the component

HTTPClient is very easy to configure. In some cases, like in the example given below, you do not need any special tuneups whatsoever: client.Get("http://www.mywebserver.com/"); if (client.StatusCode == 200) { string response = client.OutputString; } You may need to adjust the component settings if you plan to connect to endpoints secured with TLS. By default, HTTPClient relies on the system settings when validating server certificates. If you would prefer to ignore the system trust and implement customized chain validation procedures - such as certificate pinning - in your code instead, set TLSSettings.AutoValidateCertificates to false, and subscribe to CertificateValidate event. This event will fire whenever a server certificate validation needs to be performed.

Use ClientChain collection to provide your certificates for client authentication. Make sure the provided certificate contains a private key; otherwise it will be unable to authenticate.

To provide custom HTTP headers, subscribe to HeadersPrepared event. HTTPClient fires this event right before sending the request out to the server, giving you an opportunity to alter the headers or add your own. The list of headers can be accessed via the RequestHeaders collection. Note: the headers can only be modified from the HeadersPrepared event handler. Setting them earlier or later in your code won't provide the expected effect.

Having set up the component, use the appropriate variant of the request method (such as: Get, GetBytes, or GetFile) to obtain the response in the desired format (string, memory buffer, or file).

Property List

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The following is the full list of the properties of the component with short descriptions. Click on the links for further details.

Method List

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The following is the full list of the methods of the component with short descriptions. Click on the links for further details.

Event List

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The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.

Config Settings

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The following is a list of config settings for the component with short descriptions. Click on the links for further details.

BlockedCertificates Property (HTTPClient Component)

The certificates that must be rejected as trust anchors.

Syntax

property BlockedCertificates: TsbxCertificateList read get_BlockedCertificates write set_BlockedCertificates;

Remarks

Use this property to provide a list of compromised or blocked certificates. Any chain containing a blocked certificate will fail validation.

This property is not available at design time.

Please refer to the Certificate type for a complete list of fields.

ClientChain Property (HTTPClient Component)

The TLS client certificate chain.

Syntax

property ClientChain: TsbxCertificateList read get_ClientChain write set_ClientChain;

Remarks

Assign a certificate chain to this property to enable TLS client authentication in the component. Note that the client's end-entity certificate should have a private key associated with it.

Use CertificateStorage or CertificateManager components to import the certificate from a file, system store, or PKCS11 device.

This property is not available at design time.

Please refer to the Certificate type for a complete list of fields.

ConnectionInfo Property (HTTPClient Component)

Returns the details of the underlying network connection.

Syntax

property ConnectionInfo: TsbxConnectionInfo read get_ConnectionInfo;

Remarks

Use this property to learn about the connection setup, such as the protocol security details and amounts of data transferred each way.

This property is read-only and not available at design time.

Please refer to the ConnectionInfo type for a complete list of fields.

CustomRequest Property (HTTPClient Component)

Specifies a custom request verb.

Syntax

property CustomRequest: String read get_CustomRequest write set_CustomRequest;

Default Value

''

Remarks

Use this property to specify a custom HTTP method verb to use instead of the original method. PATCH is one of the commonly used custom verbs.

This property is not available at design time.

DynamicData Property (HTTPClient Component)

Takes a piece of data to be sent to the server within a dynamic POST or PUT request.

Syntax

property DynamicData: TBytes read get_DynamicData write set_DynamicData;

Remarks

Assign the next chunk of data to this property from your DynamicDataNeeded event handler to pass it to the server. Leave it empty to tell the component that no more data is available.

This property is not available at design time.

ExternalCrypto Property (HTTPClient Component)

Provides access to external signing and DC parameters.

Syntax

property ExternalCrypto: TsbxExternalCrypto read get_ExternalCrypto;

Remarks

Use this property to tune-up remote cryptography settings. SecureBlackbox supports two independent types of external cryptography: synchronous (based on the ExternalSign event) and asynchronous (based on the DC protocol and the DCAuth signing component).

This property is read-only.

Please refer to the ExternalCrypto type for a complete list of fields.

FIPSMode Property (HTTPClient Component)

Reserved.

Syntax

property FIPSMode: Boolean read get_FIPSMode write set_FIPSMode;

Default Value

false

Remarks

This property is reserved for future use.

KeepAlivePolicy Property (HTTPClient Component)

Defines the keep-alive handling policy.

Syntax

property KeepAlivePolicy: TsbxKeepAlivePolicyTypes read get_KeepAlivePolicy write set_KeepAlivePolicy;

TsbxKeepAlivePolicyTypes = (
  ckapStandardDefined,
  ckapPreferKeepAlive,
  ckapRelyOnServer,
  ckapKeepAlivesDisabled
);

Default Value

ckapStandardDefined

Remarks

Use this property to tune-up the keep-alive mechanism as per the needs of your application.

KnownCertificates Property (HTTPClient Component)

Additional certificates for chain validation.

Syntax

property KnownCertificates: TsbxCertificateList read get_KnownCertificates write set_KnownCertificates;

Remarks

Use this property to supply a list of additional certificates that might be needed for chain validation. An example of a scenario where you might want to do that is when intermediary CA certificates are absent from the standard system locations (or when there are no standard system locations), and therefore should be supplied to the component manually.

The purpose of the certificates to be added to this collection is roughly equivalent to that of the Intermediate Certification Authorities system store in Windows.

Do not add trust anchors or root certificates to this collection: add them to TrustedCertificates instead.

This property is not available at design time.

Please refer to the Certificate type for a complete list of fields.

KnownCRLs Property (HTTPClient Component)

Additional CRLs for chain validation.

Syntax

property KnownCRLs: TsbxCRLList read get_KnownCRLs write set_KnownCRLs;

Remarks

Use this property to supply additional CRLs that might be needed for chain validation. This property may be helpful when a chain is validated in offline mode, and the associated CRLs are stored separately from the signed message or document.

This property is not available at design time.

Please refer to the CRL type for a complete list of fields.

KnownOCSPs Property (HTTPClient Component)

Additional OCSP responses for chain validation.

Syntax

property KnownOCSPs: TsbxOCSPResponseList read get_KnownOCSPs write set_KnownOCSPs;

Remarks

Use this property to supply additional OCSP responses that might be needed for chain validation. This property may be helpful when a chain is validated in offline mode, and the associated OCSP responses are stored separately from the signed message or document.

This property is not available at design time.

Please refer to the OCSPResponse type for a complete list of fields.

OutputBytes Property (HTTPClient Component)

Contains the response content.

Syntax

property OutputBytes: TBytes read get_OutputBytes;

Remarks

Use this property to access the content received from the server in response to a prior request.

This property is read-only and not available at design time.

OutputString Property (HTTPClient Component)

Contains the response content.

Syntax

property OutputString: String read get_OutputString;

Default Value

''

Remarks

Use this property to access the content received from the server in response to a prior request, as a string.

This property is read-only and not available at design time.

Proxy Property (HTTPClient Component)

The proxy server settings.

Syntax

property Proxy: TsbxProxySettings read get_Proxy;

Remarks

Use this property to tune up the proxy server settings.

This property is read-only.

Please refer to the ProxySettings type for a complete list of fields.

ReasonPhrase Property (HTTPClient Component)

Contains the Reason Phrase element of the server's response.

Syntax

property ReasonPhrase: String read get_ReasonPhrase;

Default Value

''

Remarks

Use this property to access the reason phrase supplied by the server in its response (such as OK in HTTP 200 OK).

This property is read-only and not available at design time.

RequestHeaders Property (HTTPClient Component)

Contains HTTP request headers.

Syntax

property RequestHeaders: TsbxStringNameValuePairList read get_RequestHeaders;

Remarks

Use this property to check and/or adjust the HTTP request headers from your HeadersPrepared event handler.

This property is read-only and not available at design time.

Please refer to the StringNameValuePair type for a complete list of fields.

RequestParameters Property (HTTPClient Component)

Provides access to common HTTP request properties.

Syntax

property RequestParameters: TsbxHTTPRequestParameters read get_RequestParameters write set_RequestParameters;

Remarks

Use this property to configure the HTTP request properties.

This property is not available at design time.

Please refer to the HTTPRequestParameters type for a complete list of fields.

ResponseHeaders Property (HTTPClient Component)

Contains the HTTP server's response headers.

Syntax

property ResponseHeaders: TsbxStringNameValuePairList read get_ResponseHeaders;

Remarks

Use this property to check the headers of the HTTP response received from the server. The headers become available as soon as HeadersReceived event is fired.

This property is read-only and not available at design time.

Please refer to the StringNameValuePair type for a complete list of fields.

ResponseParameters Property (HTTPClient Component)

Contains the HTTP server's response parameters.

Syntax

property ResponseParameters: TsbxHTTPResponseParameters read get_ResponseParameters;

Remarks

Use this property to access the properties of the received HTTP response.

This property is read-only and not available at design time.

Please refer to the HTTPResponseParameters type for a complete list of fields.

ServerChain Property (HTTPClient Component)

The TLS server's certificate chain.

Syntax

property ServerChain: TsbxCertificateList read get_ServerChain;

Remarks

Use this property to access the certificate chain sent by the TLS server. This property is ready to read when OnCertificateValidate event is fired by the client component.

This property is read-only and not available at design time.

Please refer to the Certificate type for a complete list of fields.

SocketSettings Property (HTTPClient Component)

Manages network connection settings.

Syntax

property SocketSettings: TsbxSocketSettings read get_SocketSettings;

Remarks

Use this property to tune up network connection parameters.

This property is read-only.

Please refer to the SocketSettings type for a complete list of fields.

StatusCode Property (HTTPClient Component)

Contains the Status Code element of the server's response.

Syntax

property StatusCode: Integer read get_StatusCode;

Default Value

0

Remarks

Use this property to access the status code supplied by the server in its response (such as 200 in HTTP 200 OK).

This property is read-only and not available at design time.

TLSSettings Property (HTTPClient Component)

Manages TLS layer settings.

Syntax

property TLSSettings: TsbxTLSSettings read get_TLSSettings;

Remarks

Use this property to tune up the TLS layer parameters.

This property is read-only.

Please refer to the TLSSettings type for a complete list of fields.

TrustedCertificates Property (HTTPClient Component)

A list of trusted certificates for chain validation.

Syntax

property TrustedCertificates: TsbxCertificateList read get_TrustedCertificates write set_TrustedCertificates;

Remarks

Use this property to supply a list of trusted certificates that might be needed for chain validation. An example of a scenario where you might want to do that is when root CA certificates are absent from the standard system locations (or when there are no standard system locations), and therefore should be supplied to the component manually.

The purpose of this certificate collection is largely the same as that of the Windows Trusted Root Certification Authorities system store.

Use this property with extreme care as it directly affects chain verifiability; a wrong certificate added to the trusted list may result in bad chains being accepted, and forfeited signatures being recognized as genuine. Only add certificates that originate from the parties that you know and trust.

This property is not available at design time.

Please refer to the Certificate type for a complete list of fields.

UseDigestAuth Property (HTTPClient Component)

Enables or disables the HTTP Digest authentication.

Syntax

property UseDigestAuth: Boolean read get_UseDigestAuth write set_UseDigestAuth;

Default Value

false

Remarks

Digest authentication is more advanced than the Basic scheme, as it does not send the username and password in plain text and is immune to replay attacks.

Digest authentication is standardized in RFC 2617.

UseKerberosAuth Property (HTTPClient Component)

Enables Kerberos authentication mechanism.

Syntax

property UseKerberosAuth: Boolean read get_UseKerberosAuth write set_UseKerberosAuth;

Default Value

false

Remarks

Set this property to true to enable Kerberos (Negotiate) authentication mechanism.

UseNTLMAuth Property (HTTPClient Component)

Enables or disables NTLM authentication.

Syntax

property UseNTLMAuth: Boolean read get_UseNTLMAuth write set_UseNTLMAuth;

Default Value

false

Remarks

NT LAN Manager (NTLM) authentication relies on Windows credentials to authenticate the user, and requires multiple exchanges between the client and server. Generally it is considered more secure and SSO-friendly than the Digest authentication.

Config Method (HTTPClient Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): String;

Remarks

Config is a generic method available in every component. It is used to set and retrieve configuration settings for the component.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Delete Method (HTTPClient Component)

Sends a DELETE request to the server.

Syntax

procedure Delete(Url: String);

Remarks

Use this method to send a DELETE request to server. In response to this request, the server may (without any guarantees) delete the resource specified in Url. Most of the servers disable DELETE requests.

If this request fails, an exception will be thrown, and the error details published in StatusCode and ReasonPhrase properties.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

DoAction Method (HTTPClient Component)

Performs an additional action.

Syntax

function DoAction(ActionID: String; ActionParams: String): String;

Remarks

DoAction is a generic method available in every component. It is used to perform an additional action introduced after the product major release. The list of actions is not fixed, and may be flexibly extended over time.

The unique identifier (case insensitive) of the action is provided in the ActionID parameter.

ActionParams contains the value of a single parameter, or a list of multiple parameters for the action in the form of PARAM1=VALUE1;PARAM2=VALUE2;....

Get Method (HTTPClient Component)

Sends a GET request to the server.

Syntax

procedure Get(Url: String);

Remarks

GET is one of the most widely used HTTP requests. The server responds with the content of the resource specified in Url.

If the request is successful, the received content will be available in OutputBytes and OutputString properties. Otherwise an exception will be thrown, and the error details published in StatusCode and ReasonPhrase properties.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

GetBytes Method (HTTPClient Component)

Sends a GET request to the server and returns the output.

Syntax

function GetBytes(Url: String): TBytes;

Remarks

GET is one of the most widely used HTTP requests. The server responds with the content of the resource specified in Url.

If the request is successful, the method returns the received content. Otherwise, an exception will be thrown, and the error details published in StatusCode and ReasonPhrase properties.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

GetFile Method (HTTPClient Component)

Sends a GET request to the server and saves the output to a file.

Syntax

procedure GetFile(Url: String; Filename: String);

Remarks

GET is one of the most widely used HTTP requests. The server responds with the content of the resource specified in Url.

If the request is successful, the received content will be saved to Filename. Otherwise, an exception will be thrown, and the error details published in StatusCode and ReasonPhrase properties.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

GetStream Method (HTTPClient Component)

Sends a GET request to the server and saves the output in a stream.

Syntax

procedure GetStream(Url: String; OutputStream: TStream);

Remarks

GET is one of the most widely used HTTP requests. The server responds with the content of the resource specified in Url.

If the request is successful, the method saves the received content to OutputStream. Otherwise, an exception will be thrown, and the error details published in StatusCode and ReasonPhrase properties.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

Head Method (HTTPClient Component)

Sends a HEAD request to the server.

Syntax

procedure Head(Url: String);

Remarks

HEAD is very similar to GET, with the only difference being that only the headers (but not the content) is returned.

HEAD is often use to retrieve the parameters of the resource, such as its size and modification date. If the request is successful, those details will be available via ResponseParameters and ResponseHeaders properties. Otherwise, an exception will be thrown, and the error details published in StatusCode and ReasonPhrase properties.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

Options Method (HTTPClient Component)

Sends an OPTIONS request to the server.

Syntax

procedure Options(Url: String);

Remarks

This request gets various information about the server such as supported HTTP methods. No content is included in the response.

Post Method (HTTPClient Component)

Sends a POST request to the server.

Syntax

procedure Post(Url: String; Content: String);

Remarks

POST is used to send data to the remote HTTP endpoint/script.

Provide the data you need to send via the Content parameter. If Content is omitted, and only Url is set, the data will be streamed dynamically using the DynamicDataNeeded event.

To post a web form's data (including file attachments to the form) use PostWebForm method.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

PostBytes Method (HTTPClient Component)

Sends a POST request to the server.

Syntax

procedure PostBytes(Url: String; ContentBytes: TBytes);

Remarks

POST is used to send data to the remote HTTP endpoint/script.

Provide the data you need to send via the ContentBytes parameter. If content is omitted, and only Url is set, the data will be streamed dynamically using the DynamicDataNeeded event.

To post a web form's data (including file attachments to the form) use PostWebForm method.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

PostFile Method (HTTPClient Component)

Sends a file to the server using a POST request.

Syntax

procedure PostFile(Url: String; Filename: String);

Remarks

POST is used to send data to the remote HTTP endpoint/script. The content to send will be taken from Filename.

To post a web form's data (including file attachments to the form) use PostWebForm method.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

PostStream Method (HTTPClient Component)

Sends a POST request to the server.

Syntax

procedure PostStream(Url: String; InputStream: TStream);

Remarks

POST is used to send data to the remote HTTP endpoint/script.

Provide the data you need to send via the InputStream parameter.

To post a web form data (including file attachments to the form) use PostWebForm method.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

PostWebForm Method (HTTPClient Component)

Posts a web form data to the server.

Syntax

procedure PostWebForm(Url: String; Fields: String; FileField: String; FileName: String; ContentType: String);

Remarks

This variant of the POST method provides means to submit a form (as in a web browser) with an optional file attachment. Fields are expected to contain a list of field names and values in "Name=Value" format separated with EOLs. This list can be empty.

If including a file with your request, use the FileField and FileName properties to specify the file field name and the local filename for the uploaded file. Use ContentType to override the default content type chosen by the client, e.g., "application/x-www-form-urlencoded".

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

Put Method (HTTPClient Component)

Sends a PUT request to the server.

Syntax

procedure Put(Url: String; Content: String);

Remarks

PUT method is used to write data to the server. This method is optional to support and is disabled on most of HTTP servers.

If Content is not present, and only Url is set, the data will be streamed dynamically using the DynamicDataNeeded event. Note that some servers do not support streaming.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

PutBytes Method (HTTPClient Component)

Sends a PUT request to the server.

Syntax

procedure PutBytes(Url: String; ContentBytes: TBytes);

Remarks

PUT method is used to write data to the server. This method is optional to support and is disabled on most of HTTP servers.

If ContentBytes is not present, and only Url is set, the data will be streamed dynamically using the DynamicDataNeeded event. Note that some servers do not support streaming.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

PutFile Method (HTTPClient Component)

Sends a file to the server using a PUT request.

Syntax

procedure PutFile(Url: String; Filename: String);

Remarks

PUT is an alternative to POST and is used to send data to the remote HTTP endpoint/script. Many servers have this method switched off. The content to send will be taken from Filename.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

PutStream Method (HTTPClient Component)

Sends a PUT request to the server.

Syntax

procedure PutStream(Url: String; InputStream: TStream);

Remarks

PUT is an alternative to POST, and is used to send data to the remote HTTP endpoint/script. Many servers have this method switched off.

Provide the data you need to send via the InputStream parameter.

Note that any parameters you intend to pass to this method should be properly encoded before this method is called.

Trace Method (HTTPClient Component)

Sends a TRACE request to the server.

Syntax

procedure Trace(Url: String);

Remarks

TRACE is a debug command and is typically switched off and/or not supported by web servers.

Cookie Event (HTTPClient Component)

Fired to report a received cookie.

Syntax

type TCookieEvent = procedure (
  Sender: TObject;
  const CookieText: String
) of Object;

property OnCookie: TCookieEvent read FOnCookie write FOnCookie;

Remarks

The CookieText parameter contains the text of the cookie.

DocumentBegin Event (HTTPClient Component)

Marks the start of the incoming HTML document or file.

Syntax

type TDocumentBeginEvent = procedure (
  Sender: TObject
) of Object;

property OnDocumentBegin: TDocumentBeginEvent read FOnDocumentBegin write FOnDocumentBegin;

Remarks

This event is followed by one or more Progress calls. When the document has been received in full, the DocumentEnd event is fired.

DocumentEnd Event (HTTPClient Component)

Marks the successful receipt of the incoming HTML document or file.

Syntax

type TDocumentEndEvent = procedure (
  Sender: TObject
) of Object;

property OnDocumentEnd: TDocumentEndEvent read FOnDocumentEnd write FOnDocumentEnd;

Remarks

This event fires when the document has been received in full.

DynamicDataNeeded Event (HTTPClient Component)

Requests a portion of data to be uploaded from the application.

Syntax

type TDynamicDataNeededEvent = procedure (
  Sender: TObject;
  BytesNeeded: Integer
) of Object;

property OnDynamicDataNeeded: TDynamicDataNeededEvent read FOnDynamicDataNeeded write FOnDynamicDataNeeded;

Remarks

If dynamic ('streaming') variants of PUT or POST methods are used, this event is fired periodically to request portions of data to be sent to the server.

When handling this event, assign the next portion of data of BytesNeeded length (or less) to DynamicData. If no more data is available to upload (the whole document has been sent), leave DynamicData empty.

Error Event (HTTPClient Component)

Information about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

The event is fired in case of exceptional conditions during message processing.

ErrorCode contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the HTTPS section.

ExternalSign Event (HTTPClient Component)

Handles remote or external signing initiated by the SignExternal method or other source.

Syntax

type TExternalSignEvent = procedure (
  Sender: TObject;
  const OperationId: String;
  const HashAlgorithm: String;
  const Pars: String;
  const Data: String;
  var SignedData: String
) of Object;

property OnExternalSign: TExternalSignEvent read FOnExternalSign write FOnExternalSign;

Remarks

Assign a handler to this event if you need to delegate a low-level signing operation to an external, remote, or custom signing engine. Depending on the settings, the handler will receive a hashed or unhashed value to be signed.

The event handler must pass the value of Data to the signer, obtain the signature, and pass it back to the component via the SignedData parameter.

OperationId provides a comment about the operation and its origin. It depends on the exact component being used, and may be empty. HashAlgorithm specifies the hash algorithm being used for the operation, and Pars contains algorithm-dependent parameters.

The component uses base16 (hex) encoding for the Data, SignedData, and Pars parameters. If your signing engine uses a different input and output encoding, you may need to decode and/or encode the data before and/or after the signing.

A sample MD5 hash encoded in base16: a0dee2a0382afbb09120ffa7ccd8a152 - lower case base16 A0DEE2A0382AFBB09120FFA7CCD8A152 - upper case base16

A sample event handler that uses the .NET RSACryptoServiceProvider class may look like the following: signer.OnExternalSign += (s, e) => { var cert = new X509Certificate2("cert.pfx", "", X509KeyStorageFlags.Exportable); var key = (RSACryptoServiceProvider)cert.PrivateKey; var dataToSign = e.Data.FromBase16String(); var signedData = key.SignHash(dataToSign, "2.16.840.1.101.3.4.2.1"); e.SignedData = signedData.ToBase16String(); };

HeadersPrepared Event (HTTPClient Component)

Fires when the request headers have been formed and are about to be sent to the server.

Syntax

type THeadersPreparedEvent = procedure (
  Sender: TObject
) of Object;

property OnHeadersPrepared: THeadersPreparedEvent read FOnHeadersPrepared write FOnHeadersPrepared;

Remarks

The prepared headers are available in RequestHeaders property. This event provides you the last chance to review/alter them.

HeadersReceived Event (HTTPClient Component)

Fires when the HTTP response headers have just been received from the server.

Syntax

type THeadersReceivedEvent = procedure (
  Sender: TObject
) of Object;

property OnHeadersReceived: THeadersReceivedEvent read FOnHeadersReceived write FOnHeadersReceived;

Remarks

The received headers are available via the ResponseHeaders property.

Notification Event (HTTPClient Component)

This event notifies the application about an underlying control flow event.

Syntax

type TNotificationEvent = procedure (
  Sender: TObject;
  const EventID: String;
  const EventParam: String
) of Object;

property OnNotification: TNotificationEvent read FOnNotification write FOnNotification;

Remarks

The component fires this event to let the application know about some event, occurrence, or milestone in the component. For example, it may fire to report completion of the document processing. The list of events being reported is not fixed, and may be flexibly extended over time.

The unique identifier of the event is provided in the EventID parameter. EventParam contains any parameters accompanying the occurrence. Depending on the type of the component, the exact action it is performing, or the document being processed, one or both may be omitted.

Progress Event (HTTPClient Component)

Fires periodically during the data transfer.

Syntax

type TProgressEvent = procedure (
  Sender: TObject;
  Total: Int64;
  Current: Int64;
  var Cancel: Boolean
) of Object;

property OnProgress: TProgressEvent read FOnProgress write FOnProgress;

Remarks

Use this event to check the progress of an upload or download operation. Total indicates the total number of bytes to be transferred; Current specifies how much data has been transferred so far, and Cancel gives you a chance to cancel the operation.

Redirection Event (HTTPClient Component)

Fires when the server suggests a redirect.

Syntax

type TRedirectionEvent = procedure (
  Sender: TObject;
  const OldURL: String;
  var NewURL: String;
  var AllowRedirection: Boolean
) of Object;

property OnRedirection: TRedirectionEvent read FOnRedirection write FOnRedirection;

Remarks

This event is fired when the server suggests a redirection request (typically via a 301 or 302 response). OldURL indicates the 'from' page, and NewURL indicates the 'to' one. The destination page can be altered by the application if needed. Use AllowRedirection to block undesirable redirects.

Generally, this is a notification event: the component handles redirections automatically. Use the MaxRedirections config property to limit the number of redirection hops.

TLSCertNeeded Event (HTTPClient Component)

Fires when a remote TLS party requests a client certificate.

Syntax

type TTLSCertNeededEvent = procedure (
  Sender: TObject;
  const Host: String;
  const CANames: String
) of Object;

property OnTLSCertNeeded: TTLSCertNeededEvent read FOnTLSCertNeeded write FOnTLSCertNeeded;

Remarks

This event fires to notify the implementation that a remote TLS server has requested a client certificate. The Host parameter identifies the host that makes a request, and the CANames parameter (optional, according to the TLS spec) advises on the accepted issuing CAs.

Use the TLSClientChain property in response to this event to provide the requested certificate. Please make sure the client certificate includes the associated private key. Note that you may set the certificates before the connection without waiting for this event to fire.

This event is preceded by the TLSHandshake event for the given host and, if the certificate was accepted, succeeded by the TLSEstablished event.

TLSCertValidate Event (HTTPClient Component)

This event is fired upon receipt of the TLS server's certificate, allowing the user to control its acceptance.

Syntax

type TTLSCertValidateEvent = procedure (
  Sender: TObject;
  const ServerHost: String;
  const ServerIP: String;
  var Accept: Boolean
) of Object;

property OnTLSCertValidate: TTLSCertValidateEvent read FOnTLSCertValidate write FOnTLSCertValidate;

Remarks

This event is fired during a TLS handshake. Use the TLSServerChain property to access the certificate chain. In general, components may contact a number of TLS endpoints during their work, depending on their configuration.

Accept is assigned in accordance with the outcome of the internal validation check performed by the component, and can be adjusted if needed.

TLSEstablished Event (HTTPClient Component)

Fires when a TLS handshake with Host successfully completes.

Syntax

type TTLSEstablishedEvent = procedure (
  Sender: TObject;
  const Host: String;
  const Version: String;
  const Ciphersuite: String;
  ConnectionId: TBytes;
  var Abort: Boolean
) of Object;

property OnTLSEstablished: TTLSEstablishedEvent read FOnTLSEstablished write FOnTLSEstablished;

Remarks

The component uses this event to notify the application about a successful completion of a TLS handshake.

The Version, Ciphersuite, and ConnectionId parameters indicate the security parameters of the new connection. Use the Abort parameter if you need to terminate the connection at this stage.

TLSHandshake Event (HTTPClient Component)

Fires when a new TLS handshake is initiated, before the handshake commences.

Syntax

type TTLSHandshakeEvent = procedure (
  Sender: TObject;
  const Host: String;
  var Abort: Boolean
) of Object;

property OnTLSHandshake: TTLSHandshakeEvent read FOnTLSHandshake write FOnTLSHandshake;

Remarks

The component uses this event to notify the application about the start of a new TLS handshake to Host. If the handshake is successful, this event will be followed by the TLSEstablished event. If the server chooses to request a client certificate, the TLSCertNeeded event will also be fired.

TLSPSK Event (HTTPClient Component)

Notifies the application about the PSK key exchange.

Syntax

type TTLSPSKEvent = procedure (
  Sender: TObject;
  const Host: String;
  const Hint: String
) of Object;

property OnTLSPSK: TTLSPSKEvent read FOnTLSPSK write FOnTLSPSK;

Remarks

The component fires this event to notify the application about the beginning of TLS-PSK key exchange with Host. The Hint parameter may be used by the server to identify the key or service to use. Use the PreSharedKey field of TLSSettings to provide the pre-shared key to the component.

TLSShutdown Event (HTTPClient Component)

Reports the graceful closure of a TLS connection.

Syntax

type TTLSShutdownEvent = procedure (
  Sender: TObject;
  const Host: String
) of Object;

property OnTLSShutdown: TTLSShutdownEvent read FOnTLSShutdown write FOnTLSShutdown;

Remarks

This event notifies the application about the closure of an earlier established TLS connection. Note that only graceful connection closures are reported.

Certificate Type

Provides details of an individual X.509 certificate.

Remarks

This type provides access to X.509 certificate details.

Fields

Constructors

>

constructor Create();

Creates a new object with default field values.

ConnectionInfo Type

Contains information about a network connection.

Remarks

Use this property to check various details of the network connection. These include the total amounts of data transferred, the availability of TLS, and its parameters.

Fields

Constructors

>

constructor Create();

Creates a new ConnectionInfo object.

CRL Type

Represents a Certificate Revocation List.

Remarks

CRLs store information about revoked certificates, i.e., certificates that have been identified as invalid by their issuing certificate authority (CA) for any number of reasons.

Each CRL object lists certificates from a single CA and identifies them by their serial numbers. A CA may or may not publish a CRL, may publish several CRLs, or may publish the same CRL in multiple locations.

Unlike OCSP responses, CRLs only list certificates that have been revoked. They do not list certificates that are still valid.

Fields

Constructors

>

constructor Create();

Creates an empty CRL object.

ExternalCrypto Type

Specifies the parameters of external cryptographic calls.

Remarks

External cryptocalls are used in a Distributed Cryptography (DC) subsystem, which allows the delegation of security operations to the remote agent. For instance, it can be used to compute the signature value on the server, while retaining the client's private key locally.

Fields

Constructors

>

constructor Create();

Creates a new ExternalCrypto object with default field values.

HTTPRequestParameters Type

Represents the headers of the HTTP request to make.

Remarks

If a header is not assigned but required for a successful request (such as Connection or Host), it will be generated automatically by the component.

Fields

Constructors

>

constructor Create();

Creates a new HTTPRequestParameters object.

HTTPResponseParameters Type

This object is a container for HTTP server response details.

Remarks

An HTTP response is sent by the server when it has processed the client's request. The response consists of the status code (perhaps, the most annoying and widely known one is 404), the reason phrase, the response headers, and the body (the actual data) of the response.

Fields

Constructors

>

constructor Create();

Creates a new HTTPResponseParameters object.

OCSPResponse Type

Represents a single OCSP response originating from an OCSP responder.

Remarks

OCSP is a protocol that allows verification of certificate status in real-time, and is an alternative to Certificate Revocation Lists (CRLs).

An OCSP response is a snapshot of the certificate status at a given time.

Fields

Constructors

>

constructor Create();

Creates an empty OCSP response object.

ProxySettings Type

A container for proxy server settings.

Remarks

This type exposes a collection of properties for tuning up the proxy server configuration.

Fields

Constructors

>

constructor Create();

Creates a new ProxySettings object.

SocketSettings Type

A container for the socket settings.

Remarks

This type is a container for socket-layer parameters.

Fields

Constructors

>

constructor Create();

Creates a new SocketSettings object.

StringNameValuePair Type

A simple name-value pair object.

Remarks

The component represents a name-value string pair used in a variety of network components.

Fields

Constructors

>

constructor Create(valName: String; valValue: String);

Creates a name-value pair from a name and a value.

>

constructor Create();

Creates an empty name-value object.

TLSSettings Type

A container for TLS connection settings.

Remarks

The TLS (Transport Layer Security) protocol provides security for information exchanged over insecure connections such as TCP/IP.

Fields

Constructors

>

constructor Create();

Creates a new TLSSettings object.

Config Settings (HTTPClient Component)

The component accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

HTTPClient Config Settings

Base Config Settings

Trappable Errors (HTTPClient Component)

HTTPClient Errors

	1048577   Invalid parameter value (SB_ERROR_INVALID_PARAMETER)
	1048578   Component is configured incorrectly (SB_ERROR_INVALID_SETUP)
	1048579   Operation cannot be executed in the current state (SB_ERROR_INVALID_STATE)
	1048580   Attempt to set an invalid value to a property (SB_ERROR_INVALID_VALUE)
	1048581   Certificate does not have its private key loaded (SB_ERROR_NO_PRIVATE_KEY)
	1048581   Cancelled by the user (SB_ERROR_CANCELLED_BY_USER) 
	19922945   Unsupported keep-alive policy (SB_ERROR_HTTP_UNSUPPORTED_KEEPALIVEPOLICY)