NAME¶
make_method - Turn Perl code into an XML description for RPC::XML::Server
SYNOPSIS¶
make_method --name=system.identification --helptext='System ID string'
--signature=string --code=ident.pl --output=ident.xpl
make_method --base=methods/identification
DESCRIPTION¶
This is a simple tool to create the XML descriptive files for specifying methods
to be published by an
RPC::XML::Server-based server.
If a server is written such that the methods it exports (or
publishes)
are a part of the running code, then there is no need for this tool. However,
in cases where the server may be separate and distinct from the code (such as
an Apache-based RPC server), specifying the routines and filling in the
supporting information can be cumbersome.
One solution that the
RPC::XML::Server package offers is the means to
load publishable code from an external file. The file is in a simple XML
dialect that clearly delinates the externally-visible name, the method
signatures, the help text and the code itself. These files may be created
manually, or this tool may be used as an aide.
REQUIRED ARGUMENTS¶
There are no required arguments, but if there are not sufficient options passed
you will be told by an error message.
OPTIONS¶
The tool recognizes the following options:
- --help
- Prints a short summary of the options.
- --name=STRING
- Specifies the published name of the method being encoded. This is the name
by which it will be visible to clients of the server.
- --namespace=STRING
- Specifies a namespace that the code of the method will be evaluated in,
when the XPL file is loaded by a server instance.
- --type=STRING
- Specify the type for the resulting file. "Type" here refers to
whether the container tag used in the resulting XML will specify a
procedure or a method. The default is method. The
string is treated case-independant, and only the first character
("m" or "p") is actually regarded.
- --version=STRING
- Specify a version stamp for the code routine.
- --hidden
- If this is passe, the resulting file will include a tag that tells the
server daemon to not make the routine visible through any introspection
interfaces.
- --signature=STRING [ --signature=STRING ... ]
- Specify one or more signatures for the method. Signatures should be the
type names as laid out in the documentation in RPC::XML, with the elements
separated by a colon. You may also separate them with spaces, if you quote
the argument. This option may be specified more than once, as some methods
may have several signatures.
- --helptext=STRING
- Specify the help text for the method as a simple string on the command
line. Not suited for terribly long help strings.
- --helpfile=FILE
- Read the help text for the method from the file specified.
- --code=FILE
- Read the actual code for the routine from the file specified. If this
option is not given, the code is read from the standard input file
descriptor.
- --output=FILE
- Write the resulting XML representation to the specified file. If this
option is not given, then the output goes to the standard output file
descriptor.
- --base=NAME
- This is a special, "all-in-one" option. If passed, all other
options are ignored.
The value is used as the base element for reading information from a file
named BASE.base. This file will contain specification of the name,
version, hidden status, signatures and other method information. Each line
of the file should look like one of the following:
- Name: STRING
- Specify the name of the routine being published. If this line does not
appear, then the value of the --base argument with all directory
elements removed will be used.
- Version: STRING
- Provide a version stamp for the function. If no line matching this pattern
is present, no version tag will be written.
- Hidden: STRING
- If present, STRING should be either "yes" or
"no" (case not important). If it is "yes", then the
method is marked to be hidden from any introspection API.
- Signature: STRING
- This line may appear more than once, and is treated cumulatively. Other
options override previous values if they appear more than once. The
portion following the "Signature:" part is taken to be a
published signature for the method, with elements separated by whitespace.
Each method must have at least one signature, so a lack of any will cause
an error.
- Helpfile: STRING
- Specifies the file from which to read the help text. It is not an error if
no help text is specified.
- Codefile: STRING
- Specifies the file from which to read the code. Code is assumed to be
Perl, and will be tagged as such in the resulting file.
- Codefile[lang]: string
- Specifies the file from which to read code, while also identifying the
language that the code is in. This allows for the creation of a XPL
file that includes multiple language implementations of the given method
or procedure.
Any other lines than the above patterns are ignored.
If no code has been read, then the tool will exit with an error message.
The output is written to
BASE.xpl, preserving the path information so
that the resulting file is right alongside the source files. This allows
constructs such as:
make_method --base=methods/introspection
The file format for these published routines is a very simple XML dialect. This
is less due to XML being an ideal format than it is the availability of the
parser, given that the
RPC::XML::Server class will already have the
parser code in core. Writing a completely new format would not have gained
anything.
The Document Type Declaration for the format can be summarized by:
<!ELEMENT proceduredef (name, namespace?, version?, hidden?,
signature+, help?, code)>
<!ELEMENT methoddef (name, namespace?, version?, hidden?,
signature+, help?, code)>
<!ELEMENT functiondef (name, namespace?, version?, hidden?,
signature+, help?, code)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT namespace (#PCDATA)>
<!ELEMENT version (#PCDATA)>
<!ELEMENT hidden EMPTY>
<!ELEMENT signature (#PCDATA)>
<!ELEMENT help (#PCDATA)>
<!ELEMENT code (#PCDATA)>
<!ATTLIST code language (#PCDATA)>
The file "rpc-method.dtd" that comes with the distribution has some
commentary in addition to the actual specification.
A file is (for now) limited to one definition. This is started by the one of the
opening tags "<methoddef>", "<functiondef>" or
"<proceduredef>". This is followed by exactly one
"<name>" container specifying the method name, an optional
version stamp, an optional hide-from-introspection flag, one or more
"<signature>" containers specifying signatures, an optional
"<help>" container with the help text, then the
"<code>" container with the actual program code. All text
should use entity encoding for the symbols:
& C<&> (ampersand)
E<lt> C<<> (less-than)
E<gt> C<>> (greater-than)
The parsing process within the server class will decode the entities. To make
things easier, the tool scans all text elements and encodes the above entities
before writing the file.
The Specification of Code¶
This is not
"Programming 101", nor is it
"Perl for the
Somewhat Dim". The code that is passed in via one of the
"*.xpl" files gets passed to "eval" with next to no
modification (see below). Thus, badly-written or malicious code can very well
wreak havoc on your server. This is not the fault of the server code. The
price of the flexibility this system offers is the responsibility on the part
of the developer to ensure that the code is tested and safe.
Code itself is treated as verbatim as possible. Some edits may occur on the
server-side, as it make the code suitable for creating an anonymous subroutine
from. The
make_method tool will attempt to use a "CDATA"
section to embed the code within the XML document, so that there is no need to
encode entities or such. This allows for the resulting
*.xpl files to
be syntax-testable with "perl -cx". You can aid this by ensuring
that the code does not contain either of the two following character
sequences:
]]>
__DATA__
The first is the "CDATA" terminator. If it occurs naturally in the
code, it would trigger the end-of-section in the parser. The second is the
familiar Perl token, which is inserted so that the remainder of the XML
document does not clutter up the Perl parser.
EXAMPLES¶
The
RPC::XML distribution comes with a number of default methods in a
subdirectory called (cryptically enough) "methods". Each of these is
expressed as a set of ("*.base", "*.code",
"*.help") files. The Makefile.PL file configures the resulting
Makefile such that these are used to create "*.xpl" files using this
tool, and then install them.
DIAGNOSTICS¶
Most problems come out in the form of error messages followed by an abrupt exit.
EXIT STATUS¶
The tool exits with a status of 0 upon success, and 255 otherwise.
CAVEATS¶
I don't much like this approach to specifying the methods, but I liked my other
ideas even less.
BUGS¶
Please report any bugs or feature requests to "bug-rpc-xml at
rt.cpan.org", or through the web interface at
<
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=RPC-XML>. I will be
notified, and then you'll automatically be notified of progress on your bug as
I make changes.
SUPPORT¶
- •
- RT: CPAN's request tracker
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=RPC-XML>
- •
- AnnoCPAN: Annotated CPAN documentation
<http://annocpan.org/dist/RPC-XML>
- •
- CPAN Ratings
<http://cpanratings.perl.org/d/RPC-XML>
- •
- Search CPAN
<http://search.cpan.org/dist/RPC-XML>
- •
- Source code on GitHub
<http://github.com/rjray/rpc-xml>
LICENSE AND COPYRIGHT¶
This module and the code within are released under the terms of the Artistic
License 2.0 (
http://www.opensource.org/licenses/artistic-license-2.0.php).
This code may be redistributed under either the Artistic License or the GNU
Lesser General Public License (LGPL) version 2.1
(
http://www.opensource.org/licenses/lgpl-2.1.php).
SEE ALSO¶
RPC::XML, RPC::XML::Server
CREDITS¶
The
XML-RPC standard is Copyright (c) 1998-2001, UserLand Software, Inc.
See <
http://www.xmlrpc.com> for more information about the
XML-RPC specification.
AUTHOR¶
Randy J. Ray <rjray@blackperl.com>