1# ====================================================================== 2# 3# Copyright (C) 2000-2004 Paul Kulchenko (paulclinger@yahoo.com) 4# SOAP::Lite is free software; you can redistribute it 5# and/or modify it under the same terms as Perl itself. 6# 7# $Id: Serializer.pod 98 2007-10-09 09:41:55Z kutterma $ 8# 9# ====================================================================== 10 11=pod 12 13=head1 NAME 14 15SOAP::Serializer - the means by which the toolkit manages the expression of data as XML 16 17=head1 DESCRIPTION 18 19The SOAP::Serializer class is the means by which the toolkit manages the expression of data as XML. The object that a SOAP::Lite instance uses by default is generally enough for the task, with no need for the application to create its own. The main purpose of this class is to provide a place for applications to extend the serializer by defining additional methods for handling new datatypes. 20 21=head1 METHODS 22 23=over 24 25=item new(optional key/value pairs) 26 27 $serialize = SOAP::Serializer->new( ); 28 29This is the constructor method for the class. In addition to creating a basic object and initializing it with default values, the constructor can also take names and values for most of the accessor methods that the class supports. 30 31=item envelope(method, data arguments) 32 33 $serialize->envelope(fault => $fault_obj); 34 35Provides the core purpose for the SOAP::Serializer class. It creates the full SOAP envelope based on the input passed in to it. The data arguments passed in the list of parameters to the method are divided into two sublists: any parameters that are L<SOAP::Header> objects or derivatives of go into one list, while the remainder go into the other. The nonheader objects are used as the content for the message body, with the body itself being largely dependent on the value of the first argument in the list. This argument is expected to be a string and should be one of the following: 36 37=item context 38 39 $serialize->context->packager(); 40 41This provides access to the calling context of C<SOAP::Serializer>. In a client side context the often means a reference to an instance of SOAP::Lite. In a server side context this means a reference to a SOAP::Server instance. 42 43=over 44 45=item method 46 47The envelope is being created to encapsulate a RPC-style method call. 48 49=item response 50 51The message being created is that of a response stemming from a RPC-style method call. 52 53=item fault 54 55For this specifier, the envelope being created is to transmit a fault. 56 57=item freeform 58 59This identifier is used as a general-case encoding style for messages that don't fit into any of the previous cases. The arguments are encoded into the envelope's Body tag without any sort of context sensitivity. Any value other than these four results in an error. 60 61=back 62 63=item envprefix(optional value) 64 65 $serialize->envprefix('env'); 66 67Gets or sets the prefix that labels the SOAP envelope namespace. This defaults to SOAP-ENV. 68 69=item encprefix(optional value) 70 71 $serialize->envprefix('enc'); 72 73Gets or sets the prefix that labels the SOAP encoding namespace. Defaults to SOAP-ENC. 74 75=item soapversion(optional value) 76 77 $serial->soapversion('1.2'); 78 79If no parameter is given, returns the current version of SOAP that is being used as the basis for serializing messages. If a parameter is given, attempts to set that as the version of SOAP being used. The value should be either 1.1 or 1.2. When the SOAP version is being set, the package selects new URNs for envelope and encoding spaces and also calls the xmlschema method to set the appropriate schema definition. 80 81=item xmlschema(optional value) 82 83 $serial->xmlschema($xml_schema_1999); 84 85Gets or sets the URN for the schema being used to express the structure of the XML generated by the serializer. If setting the value, the input must be the full URN for the new schema and is checked against the list of known SOAP schemas. 86 87=item register_ns 88 89The register_ns subroutine allows users to register a global namespace 90with the SOAP Envelope. The first parameter is the namespace, the second 91parameter to this subroutine is an optional prefix. If a prefix is not 92provided, one will be generated automatically for you. All namespaces 93registered with the serializer get declared in the <soap:Envelope /> 94element. 95 96=item find_prefix 97 98The find_prefix subroutine takes a namespace as a parameter and returns 99the assigned prefix to that namespace. This eliminates the need to declare 100and redeclare namespaces within an envelope. This subroutine is especially 101helpful in determining the proper prefix when assigning a type to a 102SOAP::Data element. A good example of how this might be used is as follows: 103 104 SOAP::Data->name("foo" => $inputParams{'foo'}) 105 ->type($client->serializer->find_prefix('urn:Foo').':Foo'); 106 107=back 108 109=head1 CUSTOM DATA TYPES 110 111When serializing an object, or blessed hash reference, into XML, C<SOAP::Serializer> first checks to see if a subroutine has been defined for the corresponding class name. For example, in the code below, C<SOAP::Serializer> will check to see if a subroutine called C<as_MyModule__MyPackage> has been defined. If so, then it will pass C<$foo> to that subroutine along with other data known about the C<SOAP::Data> element being encoded. 112 113 $foo = MyModule::MyPackage->new; 114 my $client = SOAP::Lite 115 ->uri($NS) 116 ->proxy($HOST); 117 $som = $client->someMethod(SOAP::Data->name("foo" => $foo)); 118 119=head1 as_TypeName SUBROUTINE REQUIREMENTS 120 121=over 122 123=item Naming Convention 124 125The subroutine should always be prepended with C<as_> followed by the type's name. The type's name must have all colons (':') substituded with an underscore ('_'). 126 127=item Input 128 129The input to C<as_TypeName> will have at least one parameter, and at most four parameters. The first parameter will always be the value or the object to be encoded. The following three parameters depend upon the context of the value/object being encoded. 130 131If the value/object being encoded was part of a C<SOAP::Data> object (as in the above example), then the second, third and fourth parameter will be the C<SOAP::Data> element's name, type, and attribute set respectively. If on the other hand, the value/object being encoded is I<not> part of a C<SOAP::Data> object, as in the code below: 132 133 $foo = MyModule::MyPackage->new; 134 my $client = SOAP::Lite 135 ->uri($NS) 136 ->proxy($HOST); 137 $som = $client->someMethod($foo); 138 139Then the second and third parameters will be the class name of the value/object being encoded (e.g. "MyModule::MyPackage" in the example above), and the fourth parameter will be an empty hash. 140 141=item Output 142 143The encoding subroutine must return an array containing three elements: 1) the name of the XML element, 2) a hash containing the attributes to be placed into the element, and 3) the value of the element. 144 145=back 146 147=head1 AUTOTYPING 148 149When the type of an element has not been declared explicitly, SOAP::Lite must "guess" at the object's type. That is due to the fact that the only form of introspection that Perl provides (through the use of the C<ref> subroutine) does not provide enough information to C<SOAP::Serializer> to allow SOAP::Lite to determine the exact type of an element being serialized. 150 151To work around this limitation, the C<SOAP::Serializer::typelookup> hash was created. This hash is populated with all the data types that the current C<SOAP::Serializer> can auto detect. Users and developers are free to modify the contents of this hash allowing them to register new data types with the system. 152 153When C<SOAP::Serializer> is asked to encode an object into XML, it goes through the following steps. First, C<SOAP::Serializer> checks to see if a type has been explicitly stated for the current object. If a type has been provided C<SOAP::Serializer> checks to see if an C<as_TypeName> subroutine as been defined for that type. If such a subroutine exists, then C<SOAP::Serializer> passes the object to it to be encoded. If the subroutine does not exist, or the type has not been provided, then C<SOAP::Serializer> must attempt to "guess" the type of the object being serialized. 154 155To do so, C<SOAP::Serializer> runs in sequence a set of tests stored in the C<SOAP::Serializer::typelookup> hash. C<SOAP::Serializer> continues to run each test until one of the tests returns true, indicating that the type of the object has been detected. When the type of the object has been detected, then C<SOAP::Serializer> passes the object to the encoding subroutine that corresponds with the test that was passed. If all the tests fail, and the type was not determined, then C<SOAP::Serializer> will as a last resort encode the object based on one of the four basic data types known to Perl: REF, SCALAR, ARRAY and HASH. 156 157The following table contains the set of data types detectable by C<SOAP::Lite> by default and the order in which their corresponding test subroutine will be run, according to their precedence value. 158 159 Table 1 - Autotyping Precedence 160 161 TYPENAME PRECEDENCE VALUE 162 ---------------------------- 163 base64 10 164 int 20 165 long 25 166 float 30 167 gMonth 35 168 gDay 40 169 gYear 45 170 gMonthDay 50 171 gYearMonth 55 172 date 60 173 time 70 174 dateTime 75 175 duration 80 176 boolean 90 177 anyURI 95 178 string 100 179 180 181=head2 REGISTERING A NEW DATA TYPE 182 183To register a new data type that can be automatically detected by C<SOAP::Lite> and then serialized into XML, the developer must provide the following four things: 184 185=over 186 187=item * 188 189The name of the new data type. 190 191=item * 192 193A subroutine that is capable of detecting whether a value passed to it is of the corresponding data type. 194 195=item * 196 197A number representing the test subroutine's precedence relative to all the other types' test subroutinestypes. See I<Table 1 - Autotyping Precedence>. 198 199=item * 200 201A subroutine that is capable of providing C<SOAP::Serializer> with the information necessary to serialize an object of the corresponding data type into XML. 202 203=back 204 205=head3 EXAMPLE 1 206 207If, for example, you wish to create a new datatype called C<uriReference> for which you would like Perl values to be automatically detected and serialized into, then you follow these steps. 208 209B<Step 1: Write a Test Subroutine> 210 211The test subroutine will have passed to it by C<SOAP::Serializer> a value to be tested. The test subroutine must return 1 if the value passed to it is of the corresponding type, or else it must return 0. 212 213 sub SOAP::Serializer::uriReferenceTest { 214 my ($value) = @_; 215 return 1 if ($value =~ m!^http://!); 216 return 0; 217 } 218 219B<Step 2: Write an Encoding Subroutine> 220 221The encoding subroutine provides C<SOAP::Serializer> with the data necessary to encode the value passed to it into XML. The encoding subroutine name's should be of the following format: C<as_><Type Name>. 222 223The encoding subroutine will have passed to it by C<SOAP::Serializer> four parameters: the value to be encoded, the name of the element being encoded, the assumed type of the element being encoded, and a reference to a hash containing the attributes of the element being encoded. The encoding subroutine must return an array representing the encoded datatype. C<SOAP::Serializer> will use the contents of this array to generate the corresponding XML of the value being encoded, or serialized. This array contains the following 3 elements: the name of the XML element, a hash containing the attributes to be placed into the element, and the value of the element. 224 225 sub SOAP::Serializer::as_uriReference { 226 my $self = shift; 227 my($value, $name, $type, $attr) = @_; 228 return [$name, {'xsi:type' => 'xsd:uriReference', %$attr}, $value]; 229 } 230 231B<Step 3: Register the New Data Type> 232 233To register the new data type, simply add the type to the C<SOAP::Serializer::typelookup> hash using the type name as the key, and an array containing the precedence value, the test subroutine, and the encoding subroutine. 234 235 $s->typelookup->{uriReference} 236 = [11, \&uriReferenceTest, 'as_uriReference']; 237 238I<Tip: As a short hand, you could just as easily use an anonymous test subroutine when registering the new datatype in place of the C<urlReferenceTest> subroutine above. For example:> 239 240 $s->typelookup->{uriReference} 241 = [11, sub { $_[0] =~ m!^http://! }, 'as_uriReference']; 242 243Once complete, C<SOAP::Serializer> will be able to serialize the following C<SOAP::Data> object into XML: 244 245 $elem = SOAP::Data->name("someUri" => 'http://yahoo.com')->type('uriReference'); 246 247C<SOAP::Serializer> will also be able to automatically determine and serialize the following untyped C<SOAP::Data> object into XML: 248 249 $elem = SOAP::Data->name("someUri" => 'http://yahoo.com'); 250 251=head1 ACKNOWLEDGEMENTS 252 253Special thanks to O'Reilly publishing which has graciously allowed SOAP::Lite to republish and redistribute large excerpts from I<Programming Web Services with Perl>, mainly the SOAP::Lite reference found in Appendix B. 254 255=head1 COPYRIGHT 256 257Copyright (C) 2000-2004 Paul Kulchenko. All rights reserved. 258 259This library is free software; you can redistribute it and/or modify 260it under the same terms as Perl itself. 261 262=head1 AUTHORS 263 264Paul Kulchenko (paulclinger@yahoo.com) 265 266Randy J. Ray (rjray@blackperl.com) 267 268Byrne Reese (byrne@majordojo.com) 269 270=cut 271