A Response object represents an HTTP response that an application returns to a Web server to complete a cycle of the request-response loop. The composition of a response occurs during the third and final phase of this loop, a phase marked by the propagation of the appendToResponse message through the objects of the application. The Application object first sends this message, passing in a newly-created Response object as an argument. Element objects, which represent the dynamic and static HTML elements on a page, respond to the message by appending their HTML representation to the content of the Response object. Application, Session, and Component objects can also respond to the message by adding information to the Response object.
A Response has two major parts: HTML content and HTTP information. The content is what is displayed in a Web browser; it can include escaped HTML, which is HTML code shown "as is," uninterpreted. The other information encapsulated by a Response object is in the handling the response. This HTTP data includes headers, status codes, and version string. See the HTTP specification or HTTP documentation for descriptions of these items.
As you might expect, the methods of the Response class can be divided into two groups, those that add to a response's HTML content and those that read and set HTTP information. The former group consists of methods that escape HTML (appendContentHTMLAttributeValue and appendContentHTMLString) and those that don't. For images and other binary data, you can use the appendContentData. You can obtain and set the entire content of the response with content and setContent. The following example shows a sequence of "appendContent" messages that compose an HTTP "POST" message:
aResponse.appendContentString("<form method=\"POST\" action=\""); aResponse.appendContentHTMLAttributeValue(aContext.url()); aResponse.appendContentCharacter('"'); aResponse.appendContentString(">");
Most of the remaining Response methods set and read the response's HTTP headers, the HTTP status code, and the HTTP version.
Content Encodings
You can set the string encoding used for the response content with setContentEncoding and you find out what the current encoding is with contentEncoding. An integer represents the type of encoding. The following table lists these integer values along with their OPENSTEP string-constant names.
int Value | OPENSTEP Name | Notes |
---|---|---|
1 | NSASCIIStringEncoding | 0 through 127 |
2 | NSNEXTSTEPStringEncoding | |
3 | NSJapaneseEUCStringEncoding | |
4 | NSUTF8StringEncoding | |
5 | NSISOLatin1StringEncoding | default |
6 | NSSymbolStringEncoding | |
7 | NSNonLossyASCIIStringEncoding | 7-bit verbose ASCII to represent all unichars |
8 | NSShiftJISStringEncoding | |
9 | NSISOLatin2StringEncoding | |
10 | NSUnicodeStringEncoding | |
11 | NSWindowsCP1251StringEncoding | Cyrillic; same as AdobeStandardCyrillic |
12 | NSWindowsCP1252StringEncoding | Windows Latin1 |
13 | NSWindowsCP1253StringEncoding | Windows Greek |
14 | NSWindowsCP1254StringEncoding | Windows Turkish |
15 | NSWindowsCP1250StringEncoding | Windows Latin2 |
21 | NSISO2022JPStringEncoding | ISO 2022 Japanese encoding for electronic mail |
Returns an initialized Response instance. HTTP status is set to 200 (OK), client caching is enabled, and the default string encoding is made ISO Latin 1.
Appends a single ASCII character (aChar) to the HTTP response.
Example:
// ... if (aFlag) aResponse.appendContentCharacter('Y'); else aResponse.appendContentCharacter('N');
Appends a data-encapsulating object (dataObject) to the HTTP response.
Appends an HTML attribute value to the HTTP content after transforming the string aValue into an ImmutableBytes object using the receiver's content encoding. Special HTML characters ("<", ">", "&", and double quote) are escaped so that the browser does not interpret them. In other words, the message
aResponse.appendContentHTMLAttributeValue("<B>");
would transform the argument to "&lt;B&gt;".
See Also: setContentEncoding
Appends an HTML string to the HTTP response after transforming the string aString into an ImmutableBytes object using the receiver's content encoding. Special HTML characters ("<", ">", "&", and double quote) are escaped so that the browser does not interpret them. For example, "<P>" becomes "&ltP&gt".
See Also: setContentEncoding
Appends a string to the content of the HTTP response. The string is transformed into an ImmutableBytes object using the receiver's content encoding. The special HTML characters "<", ">", "&", and double-quote are not escaped so the browser can interpret them as HTML.
Returns the HTML content of the receiver as an ImmutableBytes data object. An exception is raised if you attempt to get the content when all elements of the page have not had their chance to append HTML to the response. Thus you should invoke this method only in the application object's appendToResponse method, and then only after super's appendToResponse has been invoked. (For scripted applications, the appendToResponse is implemented in Application.wos).
See Also: setContent, setContentEncoding
Returns an integer representing the encoding used for the response content. See Content Encodings in the class description for a mapped list of supported encodings and their Objective-C names. Usually, you will want the response encoding to be the same as that used by the submitting form on the client browser. In this case it is preferable to use Request's formValueEncoding:
int theEncoding = aContext.request().formValueEncoding();
The default string encoding is ISO Latin1.
See Also: setContent, setContentEncoding
Returns the HTTP header information identified by aKey. If there are multiple headers associated with the one key, only the first one is returned. Returns null if there are no headers for the key.
See Also: setHeader
Returns an array of string keys associated with the receiver's HTTP headers. Returns null if there are no headers. You could easily test to see if a header is included by doing something similar to this:
ImmutableVector hKeys = aResponse.headerKeys(); if (hKeys.contains("expires")) { // do something }
See Also: setHeaders
Returns all HTTP headers identified by aKey.
See Also: setHeaders
Returns the version of HTTP used for the response (for example, "HTTP/1.0").
See Also: setHTTPVersion
Sets the HTML content of the HTTP response to someData.
See Also: content
Sets the encoding used for the content of the HTTP response. See Content Encodings in the class description for a mapped list of supported encodings and their Objective-C names. The default string encoding is ISO Latin1.
See Also: contentEncoding
Sets the version of HTTP used for the response (for example, "HTTP/1.0").
See Also: httpVersion
Sets the HTTP header aHeader in the receiver and associates, for retrieval, the HTTP key aKey with the header. This method is commonly used to set the type of content in a response, for example:
aResponse.setHeader("text/html", "content-type");
See Also: headerForKey
Sets the list of HTTP headers headerList in the receiver and associates, for retrieval, the HTTP key aKey with the list of header elements.
See Also: headerKeys, headersForKey
Sets the HTTP status to anInt. Consult the HTTP specification or HTTP documentation for the significance of status integers.
See Also: status
Sets a dictionary (of type ImmutableHashtable) in the Response object that, as a convenience, can contain any kind of information related to the current response. Objects further down the appendToResponse message "chain" can retrieve this information using userInfo.
Returns an integer code representing the HTTP status. Consult the HTTP specification or HTTP documentation for the significance of these status codes. By default, the status is 200 ("OK" status).
See Also: setStatus
Returns a dictionary (of type ImmutableHashtable) that, as a convenience, can contain any kind of information related to the current response. An object further "upstream" in the appendToResponse message "chain" can set this dictionary in the Response object as a way to pass information to other objects.
See Also: setUserInfo