The obj.conf configuration file contains directives that instruct the Sun Java System Web Server how to handle HTTP and HTTPS requests from clients and service web server content such as native server plug-ins and CGI programs. You can modify and extend the request-handling process by adding or changing the instructions in obj.conf.
All obj.conf files are located in the instance_dir/config directory, where instance_dir is the path to the installation directory of the server instance. There is one obj.conf file for each virtual server class, unless several virtual server classes are configured to share an obj.conf file. Whenever this guide refers to "the obj.conf file," it refers to all obj.conf files or to the obj.conf file for the virtual server class being described.
By default, the obj.conf file for the initial virtual server class is named obj.conf, and the obj.conf files for the administrator-defined virtual server classes are named virtual_server_class_id.obj.conf. Editing one of these files directly or through the Administration interface changes the configuration of a virtual server class.
This chapter discusses server instructions in obj.conf, the use of OBJECT tags, the use of variables, the flow of control in obj.conf, the syntax rules for editing obj.conf, and a note about example directives.
For detailed information about the standard directives and predefined Server Application Functions (SAFs) that are used in the obj.conf file, see the Sun Java System Web Server 6.1 SP7 Administrator’s Configuration File Reference.
This chapter has the following sections:
Sun Java System Web Server is a web server that accepts and responds to Hypertext Transfer Protocol (HTTP) requests. Browsers such as Netscape™ Communicator communicate using several protocols including HTTP and FTP. The Sun Java System Web Server handles HTTP specifically.
For more information about the HTTP protocol, refer to Chapter 12, Hypertext Transfer Protocol specification.
As a quick summary, the HTTP/1.1 protocol works as follows:
The client (usually a browser) opens a connection to the server and sends a request.
The server processes the request, generates a response, and closes the connection if it finds a Connection: Close header.
The request consists of a line indicating a method such as GET or POST, a Uniform Resource Identifier (URI) indicating which resource is being requested, and an HTTP protocol version separated by spaces.
This is normally followed by a number of headers, a blank line indicating the end of the headers, and sometimes body data. Headers may provide various information about the request or the client body data. Headers are typically only sent for POST and PUT methods.
The example request shown below would be sent by a Netscape browser to request the server foo.com to send back the resource in /index.html. In this example, no body data is sent because the method is GET (the point of the request is to get some data, not to send it).
GET /index.html HTTP/1.0 User-agent: Mozilla Accept: text/html, text/plain, image/jpeg, image/gif, */* Host: foo.com
The server receives the request and processes it. It handles each request individually, although it may process many requests simultaneously. Each request is broken down into a series of steps that together make up the request-handling process.
The server generates a response that includes the HTTP protocol version, HTTP status code, and a reason phrase separated by spaces. This is normally followed by a number of headers. The end of the headers is indicated by a blank line. The body data of the response follows. A typical HTTP response might look like this:
HTTP/1.0 200 OK Server: Sun-Java System-Web-Server/6.1 content-type: text/html Content-length: 83 <HTML> <HEAD><TITLE>Hello World</Title></HEAD> <BODY>Hello World</BODY> </HTML> |
The status code and reason phrase tell the client how the server handled the request. Normally the status code 200 is returned, indicating that the request was handled successfully and the body data contains the requested item. Other result codes indicate redirection to another server or the browser’s cache, or various types of HTTP errors such as 404 Not Found.
In previous versions of the Web Server, the NSAPI API allowed multiple SAFs to interact in request processing. For example, one SAF could be used to authenticate the client after which a second SAF would generate the content.
In addition to the existing NSAPI interfaces, Sun Java System Web Server introduces NSAPI filters that enable a function to intercept (and potentially modify) the content presented to or generated by another function.
For more information on NSAPI filters in Sun Java System Web Server 6.1, see Chapter 4, Creating Custom Filters.
Two new NSAPI stages, Input and Output, can be used to insert filters in obj.conf. The Input and Output stages are described later in this chapter.
When the server first starts up it performs some initialization and then waits for an HTTP request from a client (such as a browser). When it receives a request, it first selects a virtual server. For details about how the virtual server is determined, see the Sun Java System Web Server 6.1 SP7 Administrator’s Configuration File Reference.
After the virtual server is selected, the obj.conf file for the virtual server class specifies how the request is handled in the following steps:
AuthTrans (authorization translation)
Verify any authorization information (such as name and password) sent in the request.
NameTrans (name translation)
Translate the logical URI into a local file system path.
PathCheck (path checking)
Check the local file system path for validity and check that the requestor has access privileges to the requested resource on the file system.
ObjectType (object typing)
Determine the MIME-type (Multi-purpose Internet Mail Encoding) of the requested resource (for example, text/html, image/gif, and so on).
Input (prepare to read input)
Select filters that will process incoming request data read by the Service step.
Output (prepare to send output)
Select filters that will process outgoing response data generated by the Service step.
Service (generate the response)
Generate and return the response to the client.
Add entries to log file(s).
This step is executed only if an error occurs in the previous steps. If an error occurs, the server logs an error message and aborts the process.
The file obj.conf contains a series of instructions, known as directives, that tell the Sun Java System Web Server what to do at each stage in the request-handling process. Each directive invokes a SAF with one or more arguments. Each directive applies to a specific stage in the request-handling process. The stages are AuthTrans, NameTrans, PathCheck, ObjectType, Input, Output, Service, and AddLog.
For example, the following directive applies during the NameTrans stage. It calls the document-root function with the root argument set to D://Sun/WebServer61/server1/docs. (The document-root function translates the http://server_name/ part of the URL to the document root, which in this example is D://Sun/WebServer61/server1/docs.)
NameTrans fn="document-root" root="D:/Sun/WebServer61/server1/docs"
The functions invoked by the directives in obj.conf are known as SAFs.
You do not need to restart the server for changes to certain configuration files to take effect (for example, obj.conf, mime.types, server.xml, and virtual server-specific ACL files). All you need to do is apply the changes by clicking the Apply link and then clicking the Load Configuration Files button on the Apply Changes screen. If there are errors in installing the new configuration, the previous configuration is restored.
When you edit obj.conf and apply the changes, a new configuration is loaded into memory that contains all of the information from the dynamically configurable files.
Every new connection references the newest configuration. Once the last session referencing a configuration ends, the now unused old configuration is deleted.
The obj.conf file contains directives that instruct the server how to handle requests received from clients such as browsers. These directives appear inside OBJECT tags.
Each directive calls a function, indicating when to call it and specifying arguments for it.
The syntax of each directive is:
Directive fn=func-name name1="value1"...nameN="valueN"
For example:
NameTrans fn="document-root" root="D:/Sun/WebServer61/server1/docs"
Directive indicates when this instruction is executed during the request-handling process. The value is one of AuthTrans, NameTrans, PathCheck, ObjectType, Service, AddLog, and Error.
The value of the fn argument is the name of the SAF to execute. All directives must supply a value for the fn parameter; if there’s no function, the instruction won’t do anything.
The remaining parameters are the arguments needed by the function, and they vary from function to function.
Sun Java System Web Server is shipped with a set of built-in SAFs that you can use to create and modify directives in obj.conf. For more information about these predefined SAFs, see the Sun Java System Web Server 6.1 SP7 Administrator’s Configuration File Reference. You can also define new SAFs, as discussed in Chapter 3, Creating Custom SAFs
The magnus.conf file contains Init directive SAFs that initialize the server. For more information, see Chapter 2, SAFs in the magnus.conf File
Following are the categories of server directives and a description of what each does. Each category corresponds to a stage in the request-handling process. The section Flow of Control in obj.conf explains exactly how the server decides which directive or directives to execute in each stage.
For detailed information about the standard directives and predefined SAFs that are used in the obj.conf file, see Sun Java System Web Server 6.1 SP7 Administrator’s Configuration File Reference.
Verifies any authorization information (normally sent in the Authorization header) provided in the HTTP request and translates it into a user and/or a group. Server access control occurs in two stages. AuthTrans verifies the authenticity of the user. Later, PathCheck tests the user’s access privileges for the requested resource.
AuthTrans fn=basic-auth userfn=ntauth auth-type=basic userdb=none
This example calls the basic-auth function, which calls a custom function (in this case ntauth, to verify authorization information sent by the client. The Authorization header is sent as part of the basic server authorization scheme.
Translates the URL specified in the request from a logical URL to a physical file system path for the requested resource. This may also result in redirection to another site. For example:
NameTrans fn="document-root" root="D:/Sun/WebServer61/server1/docs"
This example calls the document-root function with a root argument of D:/Sun/WebServer61/server1/docs. The function document-root function translates the http://server_name/ part of the requested URL to the document root, which in this case is D:/Sun/WebServer61/server1/docs. Thus a request for http://server-name/doc1.html is translated to D:/Sun/WebServer61/server1/docs/doc1.html.
Performs tests on the physical path determined by the NameTrans step. In general, these tests determine whether the path is valid and whether the client is allowed to access the requested resource. For example:
PathCheck fn="find-index" index-names="index.html,home.html"
This example calls the find-index function with an index-names argument of index.html,home.html. If the requested URL is a directory, this function instructs the server to look for a file called either index.html or home.html in the requested directory.
Determines the MIME (Multi-purpose Internet Mail Encoding) type of the requested resource. The MIME type has attributes type (which indicates content type), encoding, and language. The MIME type is sent in the headers of the response to the client. The MIME type also helps determine which Service directive the server should execute.
The resulting type may be:
A common document type such as text/html or image/gif (for example, the file name extension .gif translates to the MIME type image/gif).
An internal server type. Internal types always begin with magnus-internal.
For example:
ObjectType fn="type-by-extension"
This example calls the type-by-extension function, which causes the server to determine the MIME type according to the requested resource’s file extension.
Selects filters that will process incoming request data read by the Service step. The Input directive allows you to invoke the insert-filter SAF in order to install filters that process incoming data. All Input directives are executed when the server or a plug-in first attempts to read entity body data from the client. The Input directives are executed at most once per request. For example:
Input fn="insert-filter" filter="http-decompression"
This directive instructs the insert-filter function to add a filter named http-decompression to the filter stack, which would decompress incoming HTTP request data before passing it to the Service step.
Selects filters that will process outgoing response data generated by the Service step. The Output directive allows you to invoke the insert-filter SAF to install filters that process outgoing data. All Output directives are executed when the server or a plug-in first attempts to write entity body data from the client. The Output directives are executed at most once per request. For example:
Output fn="insert-filter" filter="http-compression"
This directive instructs the insert-filter function to add a filter named http-compression to the filter stack, which would compress outgoing HTTP response data generated by the Service step.
Generates and sends the response to the client. This involves setting the HTTP result status, setting up response headers (such as content-type and Content-Length), and generating and sending the response data. The default response is to invoke the send-file function to send the contents of the requested file along with the appropriate header files to the client.
The default Service directive is:
Service method="(GET|HEAD|POST)" type="*~magnus-internal/*" fn="send-file"
This directive instructs the server to call the send-file function in response to any request whose method is GET, HEAD, or POST, and whose type does not begin with magnus-internal/. (Note the use of the special characters *~ to mean “does not match.”)
Another example is:
Service method="(GET|HEAD)" type="magnus-internal/imagemap" fn="imagemap"
In this case, if the method of the request is either GET or HEAD, and the type of the requested resource is "magnus-internal/imagemap," the function imagemap is called.
Adds an entry to a log file to record information about the transaction. For example:
AddLog fn="flex-log" name="access"
This example calls the flex-log function to log information about the current request in the log file named access.
Handles an HTTP error. This directive is invoked if a previous directive results in an error. Typically the server handles an error by sending a custom HTML document to the user describing the problem and possible solutions.
For example:
Error fn="send-error" reason="Unauthorized" path="D:/Sun/WebServer61/server1/errors/unauthorized.html"
In this example, the server sends the file in D:/Sun/WebServer61/server1/errors/unauthorized.html whenever a client requests a resource that it is not authorized to access.
When compression is enabled in the server, an entry gets added to the obj.conf file. A sample entry is shown below:
Output fn="insert-filter" filter="http-compression" type="text/*"
Depending on the options specified, this line might also contain these options:
vary="on" compression-level="9"
To restrict compression to documents of only a particular type, or to exclude browsers that don’t work well with compressed content, you would need to edit the obj.conf file, as discussed below.
The option that appears as:
type="text/*"
restricts compression to documents that have a MIME type of text/* (for example, text/ascii, text/css, text/html, and so on). This can be modified to compress only certain types of documents. If you want to compress only HTML documents, for example, you would change the option to:
type="text/html"
Alternatively, you can specifically exclude browsers that are known to misbehave when they receive compressed content (but still request it anyway) by using the <Client> tag as follows:
<Client match="none"\ browser="*MSIE [1-3]*"\ browser="*MSIE [1-5]*Mac*"\ browser="Mozilla/[1-4]*Nav*"> Output fn="insert-filter" filter="http-compression" type="text/*" </Client> |
This restricts compression to browsers that are not any of the following:
Internet Explorer for Windows earlier than version 4
Internet Explorer for Macintosh earlier than version 6
Netscape Navigator/Communicator earlier than version 6
Internet Explorer on Windows earlier than version 4 may request compressed data at times, but does not correctly support it. Internet Explorer on Macintosh earlier than version 6 does the same. Netscape Communicator version 4.x requests compression, but only correctly handles compressed HTML. It will not correctly handle linked CSS or JavaScript from the compressed HTML, so administrators often simply prevent their servers from sending any compressed content to that browser (or earlier).
For more information about the <Client> tag, see the The Client Tag.
This section discusses the use of <Object> and <Client> tags in the file obj.conf.
<Object> tags group directives that apply to requests for particular resources, while <Client> tags group directives that apply to requests received from specific clients.
These tags are described in the following topics:
Directives in the obj.conf file are grouped into objects that begin with an <Object> tag and end with an </Object> tag. The default object provides instructions to the server about how to process requests by default. Each new object modifies the default object’s behavior.
An Object tag may have a name attribute or a ppath attribute. Either parameter may be a wildcard pattern. For example:
<Object name="cgi">
- or -
<Object ppath="/usr/sun/webserver61/server1/docs/private/*">
The server always starts handling a request by processing the directives in the default object. However, the server switches to processing directives in another object after the NameTrans stage of the default object if either of the following conditions is true:
The successful NameTrans directive specifies a name argument.
The physical path name that results from the NameTrans stage matches the ppath attribute of another object.
When the server has been alerted to use an object other than the default object, it processes the directives in the other object before processing the directives in the default object. For some steps in the process, the server stops processing directives in that particular stage (such as the Service stage) as soon as one is successfully executed, whereas for other stages the server processes all directives in that stage, including the ones in the default object as well as those in the additional object. For more details, see Flow of Control in obj.conf.
If a NameTrans directive in the default object specifies a name argument, the server switches to processing the directives in the object of that name before processing the remaining directives in the default object.
For example, the following NameTrans directive in the default object assigns the name cgi to any request whose URL starts with http://server_name/cgi/:
<Object name="default"> NameTrans fn="pfx2dir" from="/cgi" dir="D:/sun/webserver61/server1/docs/mycgi" name="cgi"... </Object>
When that NameTrans directive is executed, the server starts processing directives in the object named cgi:
<Object name="cgi"> more directives... </Object> |
When the server finishes processing the NameTrans directives in the default object, the logical URL of the request will have been converted to a physical path name. If this physical path name matches the ppath attribute of another object in obj.conf, the server switches to processing the directives in that object before processing the remaining ones in the default object.
For example, the following NameTrans directive translates the http://server_name/ part of the requested URL to D:/Sun/WebServer61/server1/docs/ (which is the document root directory):
<Object name="default"> NameTrans fn="document-root" root="D:/Sun/WebServer61/server1/docs" ... </Object> |
The URL http://server_name/internalplan1.html would be translated to D:/Sun/WebServer61/server1/docs/internalplan1.html. However, suppose that obj.conf contains the following additional object:
<Object ppath="*internal*"> more directives... </Object>
In this case, the partial path *internal* matches the path D:/Sun/WebServer61/server1/docs/internalplan1.html. So now the server starts processing the directives in this object before processing the remaining directives in the default object.
The <Client> tag is used to limit execution of a set of directives to requests received from specific clients. Directives listed between the <Client> and </Client> tags are executed only when information in the client request matches the parameter values specified.
The following table lists the <Client> tag parameters.
Table 1–1 Client Tag Parameters
Parameter |
Description |
---|---|
browser |
User-agent string sent by a browser to the Web Server |
chunked |
Boolean value set by a client requesting chunked encoding |
code |
HTTP response code |
dns |
DNS name of the client |
internal |
Boolean value indicating internally generated request |
ip |
IP address of the client |
keep-alive |
Boolean value indicating the client has requested a keep-alive connection |
keysize |
Key size used in an SSL transaction |
match |
Match mode for the <Client> tag; valid values are all, any, and none |
method |
HTTP method used by the browser |
name |
Name of an object as specified in a previous NameTrans statement |
odds |
Sets a random value for evaluating the enclosed directive; specified as either a percentage or a ratio (for example, 20% or 1/5) |
path |
Physical path to the requested resource |
ppath |
Physical path of the requested resource |
query |
Query string sent in the request |
reason |
Text version of the HTTP response code |
restarted |
Boolean value indicating a request has been restarted |
secret-keysize |
Secret key size used in an SSL transaction |
security |
Indicates an encrypted request |
type |
Type of document requested (such as text/html or image/gif) |
uri |
URI section of the request from the browser |
urlhost |
DNS name of the virtual server requested by the client (the value is provided in the Host header of the client request) |
The <Client> tag parameters provide greater control over when and if directives are executed. In the following example, use of the odds parameter gives a request a 25% chance of being redirected:
<Client odds="25%"> NameTrans fn="redirect" from="/Pogues" url-prefix="http://pogues.example.com" </Client>
One or more wildcard patterns can be used to specify Client tag parameter values.
Wildcards can also be used to exclude clients that match the parameter value specified in the <Client tag>. In the following example, the <Client> tag and the AddLog directive are combined to direct the Web Server to log access requests from all clients except those from the specified subnet:
<Client ip="~192.85.250.*">AddLog fn="flex-log" name="access"</Client>
Using the ~ wildcard negates the expression, so the Web Server excludes clients from the specified subnet.
You can also create a negative match by setting the match parameter of the Client tag to none. In the following example, access requests from the specified subnet are excluded, as are all requests to the virtual server www.sunone.com:
<Client match="none" ip="192.85.250.*" urlhost="www.sunone.com">AddLog fn="flex-log" name="access"</Client>
For more information about wildcard patterns, see Chapter 9, Using Wildcard Patterns.
You can define variables in the server.xml file and reference them in an obj.conf file. For example, the following server.xml code defines and uses a variable called docroot:
<!DOCTYPE SERVER SYSTEM "server.dtd" [ <!ATTLIST VARS docroot CDATA #IMPLIED > ]> ... <VS id="a.com" connections="ls1" urlhosts="a.com" mime="mime1" aclids="std"> <property name=”docroot” value=”/opt/SUNWwbsvr/docs”/> </VS> ...
You can reference the variable in obj.conf as follows:
NameTrans fn=document-root root="$docroot"
Using this docroot variable saves you from having to define document roots for virtual server classes in the obj.conf files. It also allows you to define different document roots for different virtual servers within the same virtual server class.
Variable substitution is allowed only in an obj.conf file. It is not allowed in any other Sun Java System Web Server configuration files. Any variable referenced in an obj.conf file must be defined in the server.xml file.
For more information about defining variables, see the Sun Java System Web Server 6.1 SP7 Administrator’s Configuration File Reference.
Before the server can process a request, it must direct the request to the correct virtual server. For details about how the virtual server is determined, see the Sun Java System Web Server 6.1 SP7 Administrator’s Configuration File Reference.
After the virtual server is determined, the server executes the obj.conf file for the virtual server class to which the virtual server belongs. This section discusses how the server decides which directives to execute in obj.conf.
When the server receives a request, it executes the AuthTrans directives in the default object to check that the client is authorized to access the server.
If there is more than one AuthTrans directive, the server executes them all (unless one of them results in an error). If an error occurs, the server skips all other directives except for Error directives.
Next, the server executes a NameTrans directive in the default object to map the logical URL of the requested resource to a physical path name on the server’s file system. The server looks at each NameTrans directive in the default object in turn, until it finds one that can be applied.
If there is more than one NameTrans directive in the default object, the server considers each directive until one succeeds.
The NameTrans section in the default object must contain exactly one directive that invokes the document-root function. This function translates the http://server_name/part of the requested URL to a physical directory that has been designated as the server’s document root. For example:
NameTrans fn="document-root" root="D:/Sun/WebServer61/server1/docs"
The directive that invokes document-root must be the last directive in the NameTrans section so that it is executed if no other NameTrans directive is applicable.
The pfx2dir (prefix to directory) function is used to set up additional mappings between URLs and directories. For example, the following directive translates the URL http://server_name/cgi/ into the directory path name D:/Sun/WebServer61/server1/docs/mycgi/:
NameTrans fn="pfx2dir" from="/cgi" dir="D:/Sun/WebServer61/server1/docs/mycgi"
Notice that if this directive appeared after the one that calls document-root, it would never be executed, with the result that the resultant directory path name would be D:/Sun/WebServer61/server1/docs/cgi/ (not mycgi). This illustrates why the directive that invokes document-root must be the last one in the NameTrans section.
As a result of executing a NameTrans directive, the server might start processing directives in another object. This happens if the NameTrans directive that was successfully executed specifies a name or generates a partial path that matches the name or ppath attribute of another object.
If the successful NameTrans directive assigns a name by specifying a name argument, the server starts processing directives in the named object (defined with the OBJECT tag) before processing directives in the default object for the rest of the request-handling process.
For example, the following NameTrans directive in the default object assigns the name cgi to any request whose URL starts with http://server_name/cgi/.
<Object name="default"> ... NameTrans fn="pfx2dir" from="/cgi" dir="D:/Sun/WebServer61/server1/docs/mycgi" name="cgi" ... </Object>
When that NameTrans directive is executed, the server starts processing directives in the object named cgi:
<Object name="cgi"> more directives... </Object>
When a NameTrans directive has been successfully executed, there will be a physical path name associated with the requested resource. If the resultant path name matches the ppath (partial path) attribute of another object, the server starts processing directives in the other object before processing directives in the default object for the rest of the request-handling process.
For example, suppose obj.conf contains an object as follows:
<Object ppath="*internal*"> more directives... </Object> |
Now suppose the successful NameTrans directive translates the requested URL to the path name D:/Sun/WebServer61/server1/docs/internalplan1.html. In this case, the partial path *internal* matches the path D:/Sun/WebServer61/server1/docs/internalplan1.html. So now the server would start processing the directives in this object before processing the remaining directives in the default object.
After converting the logical URL of the requested resource to a physical path name in the NameTrans step, the server executes PathCheck directives to verify that the client is allowed to access the requested resource.
If there is more than one PathCheck directive, the server executes all of the directives in the order in which they appear, unless one of the directives denies access. If access is denied, the server switches to executing directives in the Error section.
If the NameTrans directive assigned a name or generated a physical path name that matches the name or ppath attribute of another object, the server first applies the PathCheck directives in the matching object before applying the directives in the default object.
Assuming that the PathCheck directives all approve access, the server next executes the ObjectType directives to determine the MIME type of the request. The MIME type has three attributes: type, encoding, and language. When the server sends the response to the client, the type, language, and encoding values are transmitted in the headers of the response. The type also frequently helps the server to determine which Service directive to execute to generate the response to the client.
If there is more than one ObjectType directive, the server applies all of the directives in the order in which they appear. However, once a directive sets an attribute of the MIME type, further attempts to set the same attribute are ignored. The reason that all ObjectType directives are applied is that one directive may set one attribute, for example type, while another directive sets a different attribute, such as language.
As with the PathCheck directives, if another object has been matched to the request as a result of the NameTrans step, the server executes the ObjectType directives in the matching object before executing the ObjectType directives in the default object.
Usually the default way the server figures out the MIME type is by calling the type-by-extension function. This function instructs the server to look up the MIME type according to the requested resource’s file extension in the MIME types table. This table was created during virtual server initialization by the MIME types file (which is usually called mime.types).
For example, the entry in the MIME types table for the extensions .html and.htm is usually:
type=text/html exts=htm,html
which says that all files with the extension .htm or .html are text files formatted as HTML, and the type is text/html.
Note that if you make changes to the MIME types file, you must reconfigure the server before those changes can take effect.
For more information about MIME types, see Sun Java System Web Server 6.1 SP7 Administrator’s Configuration File Reference.
If no previous ObjectType directive has set the type, and the server does not find a matching file extension in the MIME types table, the type still has no value even after type-by-expression has been executed. Usually if the server does not recognize the file extension, it is a good idea to force the type to be text/plain, so that the content of the resource is treated as plain text. There are also other situations where you might want to set the type regardless of the file extension, such as forcing all resources in the designated CGI directory to have the MIME type magnus-internal/cgi.
The function that forces the type is force-type.
For example, the following directives first instruct the server to look in the MIME types table for the MIME type, then if the type attribute has not been set (that is, the file extension was not found in the MIME types table), set the type attribute to text/plain.
ObjectType fn="type-by-extension" ObjectType fn="force-type" type="text/plain"
If the server receives a request for a file abc.dogs, it looks in the MIME types table, does not find a mapping for the extension .dogs, and consequently does not set the type attribute. Since the type attribute has not already been set, the second directive is successful, forcing the type attribute to text/plain.
The following example illustrates another use of force-type. In this example, the type is forced to magnus-internal/cgi before the server gets a chance to look in the MIME types table. In this case, all requests for resources in http://server_name/cgi/ are translated into requests for resources in the directory D:/Sun/WebServer61/server1/docs/mycgi/. Since a name is assigned to the request, the server processes ObjectType directives in the object named cgi before processing the ones in the default object. This object has one ObjectType directive, which forces the type to be magnus-internal/cgi.
NameTrans fn="pfx2dir" from="/cgi" dir="D:/Sun/WebServer61/server1/docs/mycgi" name="cgi" <Object name="cgi"> ObjectType fn="force-type" type="magnus-internal/cgi" Service fn="send-cgi" </Object>
The server continues processing all ObjectType directives including those in the default object, but since the type attribute has already been set, no other directive can set it to another value.
The Input directive selects filters that will process incoming request data read by the Service step. It allows you to invoke the insert-filter SAF in order to install filters that process incoming data.
The Input directives are executed at most once per request.
You can define the appropriate position of a specific filter within the filter stack. For example, filters that translate content from XML to HTML are placed higher in the filter stack than filters that compress data for transmission. You can use the filter_create function to define the filter's position in the filter stack, and init-filter-order to override the defined position.
When two or more filters are defined to occupy the same position in the filter stack, filters that were inserted later will appear higher than filters that were inserted earlier. That is, the order of Input fn="insert-filter" and Output fn="insert-filter" directives in obj.conf becomes important.
For more information, see Chapter 4, Creating Custom Filters.
The Output directive selects filters that will process outgoing response data generated by the Service step. The Output directive allows you to invoke the insert-filter SAF to install filters that process outgoing data. All Output directives are executed when the server or a plug-in first attempts to write entity body data from the client.
The Output directives are executed at most once per request.
You can define the appropriate position of a specific filter within the filter stack. For example, filters that translate content from XML to HTML are placed higher in the filter stack than filters that compress data for transmission. You can use the filter_create function to define the filter's position in the filter stack, init-filter-order to override the defined position.
When two or more filters are defined to occupy the same position in the filter stack, filters that were inserted later will appear higher than filters that were inserted earlier. That is, the order of Input fn="insert-filter" and Output fn="insert-filter" directives in obj.conf becomes important.
For more information, see Chapter 4, Creating Custom Filters.
Next, the server needs to execute a Service directive to generate the response to send to the client. The server looks at each Service directive in turn, to find the first one that matches the type, method and query string. If a Service directive does not specify type, method, or query string, then the unspecified attribute matches anything.
If there is more than one Service directive, the server applies the first one that matches the conditions of the request, and ignores all remaining Service directives.
As with the PathCheck and ObjectType directives, if another object has been matched to the request as a result of the NameTrans step, the server considers the Service directives in the matching object before considering the ones in the default object. If the server successfully executes a Service directive in the matching object, it will not get around to executing the Service directives in the default object, since it only executes one Service directive.
For an example of how Service directives work, consider what happens when the server receives a request for the URL D:/server_name/jos.html. In this case, all directives executed by the server are in the default object.
The following NameTrans directive translates the requested URL to D:/Sun/WebServer61/server1/docs/jos.html:
NameTrans fn="document-root" root="D:/Sun/WebServer61/server1/docs"
Assume that the PathCheck directives all succeed.
The following ObjectType directive tells the server to look up the resource’s MIME type in the MIME types table:
ObjectType fn="type-by-extension"
The server finds the following entry in the MIME types table, which sets the type attribute to text/html:
type=text/html exts=htm,html
The server invokes the following Service directive. The value of the type parameter matches anything that does not begin with magnus-internal/. (For a list of all wildcard patterns, see Chapter 9, Using Wildcard Patterns client.)
Service method="(GET|HEAD|POST)" type="*~magnus-internal/*" fn="send-file"" |
Here is an example that involves using another object:
The following NameTrans directive assigns the name personnel to the request.
NameTrans fn=assign-name name=personnel from=/personnel |
As a result of the name assignment, the server switches to processing the directives in the object named personnel. This object is defined as:
<Object name="personnel"> Service fn="index-simple" </Object> |
The personnel object has no PathCheck or ObjectType directives, so the server processes the PathCheck and ObjectType directives in the default object. Let's assume that all PathCheck and ObjectType directives succeed.
When processing Service directives, the server starts by considering the Service directive in the personnel object, which is:
Service fn="index-simple"
The server executes this Service directive, which calls the index-simple function.
Since a Service directive has now been executed, the server does not process any other Service directives. (However, if the matching object had not had a Service directive that was executed, the server would continue looking at Service directives in the default object.)
There is usually a Service directive that does the default task (sends a file) if no other Service directive matches a request sent by a browser. This default directive should come last in the list of Service directives in the default object, to ensure it only gets called if no other Service directives have succeeded. The default Service directive is usually:
Service method="(GET|HEAD|POST)" type="*~magnus-internal/*" fn="send-file" |
This directive matches requests whose method is GET, HEAD, or POST, which covers nearly virtually all requests sent by browsers. The value of the type argument uses special pattern-matching characters. For complete information about the special pattern-matching characters, seeChapter 9, Using Wildcard Patterns
The characters “*~” mean “anything that doesn’t match the following characters,” so the expression *~magnus-internal/ means “anything that doesn’t match magnus-internal/.” An asterisk by itself matches anything, so the whole expression *~magnus-internal/* matches anything that does not begin with magnus-internal/.
So if the server has not already executed a Service directive when it reaches this directive, it executes the directive so long as the request method is GET, HEAD or POST, and the value of the type attribute does not begin with magnus-internal/. The invoked function is send-file, which simply sends the contents of the requested file to the client.
After the server generates the response and sends it to the client, it executes AddLog directives to add entries to the log files.
All AddLog directives are executed. The server can add entries to multiple log files.
Depending on which log files are used and which format they use, the Init section in magnus.conf may need to have directives that initialize the logs. For example, if one of the AddLog directives calls flex-log, which uses the extended log format, the Init section must contain a directive that invokes flex-init to initialize the flexible logging system.
For more information about initializing logs, see the discussion of the functions flex-init and init-clf in Chapter 2, SAFs in the magnus.conf File
For more information about flex-log, see information about predefined SAFs in the obj.conf file in the Sun Java System Web Server 6.1 SP7 Administrator’s Configuration File Reference.
If an error occurs during the request-handling process, such as if a PathCheck or AuthTrans directive denies access to the requested resource, or the requested resource does not exist, the server immediately stops executing all other directives and immediately starts executing the Error directives.
There are times when the function flow changes from the normal request-handling process. This happens during internal redirects, restarts, and URI translation functions.
An example of an internal redirect is a servlet include or forward. In this case, because there is no exposed NSAPI function to handle an internal redirect, when an internal redirect occurs, the request structure is copied into rq->orig_rq. For more information on the request data structure, seeRequest
A restart occurs when a REQ_RESTART is returned from a PathCheck or Service function. For example, when a CGI is redirected using a relative path.
On a restart, much of the request is cleared. Some elements of the HTTP request (rq->reqpb), the server’s “working” variables (rq->vars), and response headers (rq->srvhdrs) are cleared. The method, protocol, and clf-request variables from rq->reqpb are saved. The saved variables are put back into the data structure. The new URI is inserted (and if there is a query string in the new URI, that too is inserted) into rq->reqpb. The parameter rq->rq_attr.req_restarted is set to 1. For more information on the request data structure, seeRequest.
At times it is necessary to find the physical path for a URI without actually running a request. The function request_translate_uri does this. A new request structure is created and run through the AuthTrans and NameTrans stages to get the physical path. Thereafter, the new request is freed.
Several rules are important in the obj.conf file. Be very careful when editing this file. Simple mistakes can make the server fail to start or operate correctly.
Do not remove any directives from any obj.conf file that are present in the obj.conf file that exists when you first install Sun Java System Web Server. The server may not function properly.
The order of directives is important, since the server executes them in the order they appear in obj.conf. The outcome of some directives affect the execution of other directives.
For PathCheck directives, the order within the PathCheck section is not so important, since the server executes all PathCheck directives. However, the order within the ObjectType section is very important, because if an ObjectType directive sets an attribute value, no other ObjectType directive can change that value. For example, if the default ObjectType directives were listed in the following order (which is the wrong way around), every request would have its type value set to text/plain, and the server would never have a chance to set the type according to the extension of the requested resource.
ObjectType fn="force-type" type="text/plain" ObjectType fn="type-by-extension" |
Similarly, the order of directives in the Service section is very important. The server executes the first Service directive that matches the current request and does not execute any others.
The number and names of parameters depends on the function. The order of parameters on the line is not important.
Items in the obj.conf file are case-sensitive including function names, parameter names, many parameter values, and path names.
The C language allows function names to be composed only of letters, digits, and underscores. You may use the hyphen (-) character in the configuration file in place of underscore (_) for your C code function names. This is only true for function names.
Quotes (") are only required around value strings when there is a space in the string. Otherwise they are optional. Each open-quote must be matched by a close-quote.
Spaces are not allowed at the beginning of a line except when continuing the previous line.
Spaces are not allowed before or after the equal (=) sign that separates the name and value.
Spaces are not allowed at the end of a line or on a blank line.
A long line may be continued on the next line by beginning the next line with a space or tab.
Always use forward slashes (/) rather than backslashes (\) in path names under Windows. Backslash escapes the next character.
Comments begin with a pound (#) sign. If you manually add comments to obj.conf, then use the Server Manager interface to make changes to your server, the Server Manager will wipe out your comments when it updates obj.conf.
Every line in the obj.conf file begins with one of the following keywords:
AuthTrans NameTrans PathCheck ObjectType Input Output Service AddLog Error <Object </Object>
If any line of any example begins with a different word in the manual, the line is wrapping in a way that it does not in the actual file. In some cases this is due to line length limitations imposed by the PDF and HTML formats of the manuals.
For example, the following directive is all on one line in the actual obj.conf file:
NameTrans fn="pfx2dir" from="/cgi" dir="D:/Sun/WebServer61/server1/docs/mycgi" name="cgi"