TECHNICAL FIELD 
       [0001]    The invention relates to methods for publishing public and private content. 
       BACKGROUND 
       [0002]    The last few years has seen tremendous growth in the use of Extensible Markup Language (XML) based feed formats to publish content. Well known XML based feed formats include the Really Simple Syndication (RSS) format and the Atom Syndication Format (Atom). Publishers use a feed format to create a “feed.” As used herein a “feed” encompasses any “data comprising content and meta-data (e.g., one or more tags) associated with the content.” Once a feed is created, the feed can be published. Publishing a feed may be accomplished by pushing the feed to subscribers and/or by associating the feed with a uniform resource locator (URL) and making the feed&#39;s URL available to subscribers so that the subscribers can use the feed&#39;s URL pull the feed from a server. 
         [0003]    A problem arises when a publisher desires to publish a logical set of content that includes both private content (e.g., content that the publisher desires to publish to only a limited set of entities, such as the publisher&#39;s friends and/or family) and public content (i.e., any non-private content). With current technology, the publisher would have to create and publish two feeds: (1) a public feed that contains only the public content and (2) a private feed that contains the private content (and, optionally, the public content). 
         [0004]    There is a need, therefore, to enable publishers to be able to publish in a simple and easy manner a set of content that includes both public content and private content. 
       SUMMARY 
       [0005]    Particular embodiments of the disclosed solution provide a method, apparatus and computer program product that enables a publisher to publish in a simple and easy manner a set of content that includes both public content and private content. In some embodiments, this advantageous solution is achieved by implementing a multi-step publishing process. In one step, the publisher publishes a feed that contains: (1) the public content and (2) information advertising the existence of the private content and the scope of the private content (e.g., information identifying the entities that have authorization from the publisher to access the private content). In another step, the publisher stores the private content on a server accessible to the authorized entities. In another step, an authorized entity that has received the feed may pull the private content from the server. Advantageously, in this manner, a publisher can publish a set of content that contains public and private content without having to create and publish more than one feed. 
         [0006]    Other advantages may also be achieved with various embodiments of the solution. For example, embodiments may provide fine grained policy control over feed content such that any uniquely identifiable piece of content of a feed can be policy controlled. Additionally, there need be no requirement as to how scopes are defined. That is, each publisher can define her own set of scopes, independent of other publishers&#39; scopes. Moreover, scopes may be dynamic (e.g., added as needed). Solutions described herein are also compatible with current feed standards. 
         [0007]    In one particular aspect, a method for publishing public content and private content associated with the public content is provided. In some embodiments, the method includes receiving content from a publisher, where the content includes public content and a piece of private content associated with the public content. The private content is then stored in a data store and creating a public feed is created. The public feed includes the public content and information indicating that the private content is available to be accessed by an authorized entity, but the public feed does not include the private content. Next, the public feed is published. Next, a request for the private content is received from a device operated by or on behalf of an entity. Next, in response to receiving the request, a determination is made as to whether the entity is authorized to access the requested private content. In response to determining that the entity is authorized to access the private content, the requested private may be transmitted to the device that requested the private content. 
         [0008]    In some embodiments, the method also includes creating a private feed prior to creating the public feed. In such embodiments, the private feed includes the public content and the private content, a first tag associated with the public content, and a second tag associated with the private content. The private content may be provided to a feed server that determines whether the feed contains private content. If the feed server determines that the feed contains private content, the feed server may (i) create the public feed, wherein the public feed includes the public content contained in the private feed and the first tag associated with the public content, but does not include the private content contained in the private feed and (ii) store the private content such that the private content is not publically accessible. 
         [0009]    The step of determining whether the private feed contains private content may include parsing the second tag to determine whether the second tag includes a predetermined attribute, and, if the second tag includes the predetermined attribute, then determining the value of the attribute. 
         [0010]    In some embodiments, the public feed comprises a tag associated with the private content that contains an attribute having a value that identifies the entities that have the authorization to access the private content. 
         [0011]    In some embodiments, the step of publishing the public feed comprises pushing the public feed to one or more entities and/or storing the public feed such that an entity may download the public feed. 
         [0012]    In some embodiments, the method also includes: assigning a unique identifier to the private content; storing the unique identifier together with the private content; and including the unique identifier in the public feed as a value of an attribute of a tag included in the public feed that is associated with the private content. 
         [0013]    In some embodiments, the content received from the publisher further comprises a second piece of private content, and the method also includes the steps of: assigning a first identifier to the first piece of private content and the second piece of private content; storing the unique identifier together with the first and second pieces of private content; and including the unique identifier in the public feed as a value of an attribute of a tag included in the public feed that is associated with the first and second pieces of private content. The first piece of private content has a first scope and the second piece of private content may have a second scope that is different than the first scope. 
         [0014]    In another aspect, the solution provides a computer program product for publishing public content and private content associated with the public content. In some embodiments, the computer program product includes a computer readable medium storing computer readable program code. In some embodiments, the computer readable program code includes: (i) a set of instructions for receiving a private feed comprising a first tag containing public content and a second tag containing a piece of private content; (ii) a set of instructions for storing the private content in a data store; and (iii) a set of instructions for creating a public feed comprising (a) the public content and (b) information indicating that the private content is available to be accessed by an authorized entity, but not comprising the private content. The code may also include: (iv) a set of instructions for publishing the public feed; (v) a set of instructions for determining whether an entity is authorized to access the requested private content in response to receiving from a device a message sent by or on behalf of the entity; and (vi) a set of instructions for transmitting to the device the requested private content in response to determining that the entity is authorized to access the private content. 
         [0015]    In another aspect, there is provided a method for processing a public feed. The method may be performed by a feed reader. In some embodiments, the method includes: receiving a public feed and parsing the public feed to determine whether a server is storing private content associated with the public feed. In response to determining that the server stores the private content, the feed reader determines (a) the scope of the private content and (b) whether an entity falls within the scope of the private content, and transmits a request to the server in response to determining that the entity falls within the scope of the private content. After transmitting the request, the feed reader receives the private content from the server. 
         [0016]    In another aspect, there is provided a computer program product for processing a public feed, where the computer program product includes a computer readable medium storing computer readable program code. In some embodiments, the computer readable program code includes a set of instructions for receiving a public feed, a set of instructions for parsing the public feed to determine whether a server is storing private content associated with the public feed, a set of instructions for determining the scope of the private content, a set of instructions for determining whether an entity falls within the scope of the private content, a set of instructions for transmitting a request to the server in response to determining that the entity falls within the scope of the private content, and a set of instructions for receiving the private content after transmitting the request. 
         [0017]    The above and other aspects and embodiments are described below with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments of the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. In the drawings, like reference numbers indicate identical or functionally similar elements. 
           [0019]      FIG. 1  illustrates a particular embodiment of a publishing system. 
           [0020]      FIG. 2  is a functional diagram of a particular embodiment of a feed publishing apparatus and an example data flow diagram. 
           [0021]      FIG. 3  is a diagram of an example user interface for publishing content. 
           [0022]      FIG. 4  shows an example private feed. 
           [0023]      FIG. 5  shows example public feeds derived from the example private feed shown in  FIG. 4 . 
           [0024]      FIG. 6  is an example data flow diagram. 
           [0025]      FIG. 7  is a flow chart illustrating a process for publishing content. 
           [0026]      FIG. 8  is a flow chart illustrating a process for publishing content. 
           [0027]      FIG. 9  is a flow chart illustrating a process for processing a public feed. 
           [0028]      FIG. 10  is a block diagram of a feed publishing apparatus. 
           [0029]      FIG. 11  is a block diagram illustrating example software components of a feed publishing apparatus. 
           [0030]      FIG. 12  is a block diagram of a feed reader apparatus. 
           [0031]      FIG. 13 . is a block diagram illustrating example software components of a feed reader apparatus. 
           [0032]      FIG. 14  illustrates an example private feed and a corresponding example public feed. 
           [0033]      FIG. 15  illustrates an example private feed. 
           [0034]      FIG. 16  illustrates example public feeds corresponding to the private feed shown in  FIG. 15 . 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    Referring now to  FIG. 1 ,  FIG. 1  illustrates an improved publishing system  100 . Publishing system  100  includes a feed publishing apparatus (FPA)  102 , a plurality of feed readers (FRs)  104 , and a network  110  connecting FRs  104  with FPA  102 . In the example, only two FRs (FR  104   a  and FR  104   b ) are shown, but system  100  may include any number of FRs. FPA  102  is configured to be used by a publisher (e.g., publisher  101 ) to publish content to, for example, subscribers (e.g. user  1  and user  2 ). 
         [0036]    Referring now to  FIG. 2 ,  FIG. 2  illustrates an example embodiment of FPA  102 . As shown in  FIG. 2 , FPA  102  may include a content management system (CMS)  202 , a feed server  204 , and a data store  206  for storing feeds and private content. While CMS  202 , feed server  204  and data store  206  are shown as separate devices, which may or may not be co-located, they may also be implemented in a single device. Additionally, data store  206  may comprise a number of data storage devices, which may or may not be co-located.  FIG. 2  also illustrates some of the steps that may be involved in the process of publishing content in some embodiments. 
         [0037]    As shown in  FIG. 2 , publisher  101  provides content  291  to CMS  202 . For the sake of illustration, we will assume that content  291  includes public and private content. Referring now to  FIG. 3 ,  FIG. 3  is an illustration of an example user interface  300  that may be provided by CMS  202  to facilitate publisher  101  in providing public and private content  291  to CMS  202 . In the example shown, interface  300  enables publisher  101  to publish a set of photographs and a summary of the photographs and to indicate the scope of each photograph. 
         [0038]    In the illustrated example, publisher  101  desires to publish some photographs from a recent travel adventure. More specifically, in the example shown, publisher  101  has some photographs that anyone should be able to view (e.g., “Photo  1 ”), some photographs that only friends and/or family should be able to view (e.g., “Photo  2 ”), and some photographs that only friends should be able to view (e.g., “Photo  3 ”). Additionally, the photograph summary information should be published to everyone. 
         [0039]    In some embodiments, interface  300  may be implemented as a web page. After inputting information into interface  300 , publisher  101  may click on the “publish” button  301 , which, in the case were interface  300  is a web page, cause the publisher&#39;s web page browser to transmit to CMS  202  the inputted content  291  as well as the inputted scope information  290  for each piece of private content (e.g., information identifying the entities that have authorization from the publisher to access the private content). 
         [0040]    Upon receiving content  291  and the scope information  290 , CMS  202  uses the content  291  and scope information  290  to create a feed  292  that contains some or all of the content. In this example, we shall assume that feed  292  contains all of the content  291 . Since feed  292  contains not only the public content, but also the private content, feed  292  is considered a “private feed.” The private feed  292  may be provided to feed server  204 . 
         [0041]    Referring now to  FIG. 4 ,  FIG. 4  illustrates an example private feed  292  that CMS  202  may create in response to receiving from publisher  101  content  291  and scope information  290 . As shown in  FIG. 4 , feed  292  comprises tagged content. More specifically, in the example shown, feed  292  is an Atom like XML based feed that includes public content (e.g., “Enjoy these photos from my recent trip to Albania”), one or more tags associated with this public content (e.g., the “&lt;summary&gt;” tag  401 ), private content (e.g., “mysite.com/Albania/p3.jpg”), and one or more tags associated with this private content (e.g. the “&lt;content&gt;” tag  410  and the “&lt;img&gt;” tag  406 ). As illustrated in  FIG. 4 , in some embodiments, each piece of private content is associated with at least one tag (e.g., a piece of private content may be delimited by at least one tag such that the private content is the value of a tag&#39;s attribute or the private content is positioned between a begin tag marker and an end tag marker for the tag). As further shown, this tag with which the private content is associated has an attribute named “scope,” the value of which defines the scope of the private content. That is, the scope attribute defines the entities that have authorization from the publisher to access the private content. Thus, the value of a scope attribute is akin to an access control list. 
         [0042]    In some embodiments, tags that delimit only public content (e.g., &lt;img&gt; tag  402 ) may also have a scope attribute with the value set to, for example, “public.” If a tag does not contain a scope attribute-value pair, then it may inherent its parent&#39;s scope. For example, in the private feed  292  shown in  FIG. 4 , the &lt;summary&gt; tag  401 , which delimits the content “Enjoy these photos from my recent trip to Albania,” does not have a scope attribute so it may inherit it&#39;s parent&#39;s (or grand-parent&#39;s, etc.) scope. Specifically, in the example shown, the &lt;summary&gt; tag  401  inherits the scope of the &lt;entry&gt; tag  420 , which is the parent tag of &lt;summary&gt; tag  401 . 
         [0043]    In some embodiments, feed server  204 , in direct response to obtaining feed  292  from CMS  202 , processes feed  292  to, among other things, remove private content  293  from the private feed  292 , thereby forming a public feed version  294  of the private feed. The removed private content  293  is then stored in the data store  206 . The public feed  294  may also be stored in data store  206  and/or pushed to one or more subscribers of the feed. 
         [0044]    Referring now to  FIG. 5 ,  FIG. 5  illustrates a first example public feed  294   a  and a second example public feed  294   b  that feed server  204  may create in response to receiving from CMS  202  the private feed  292 . As shown in  FIG. 5 , public feeds  294   a  and  294   b  each comprises tagged content. A difference between public feeds  294  and private feed  292  is that public feeds  294  do not contain any private content. That is, feed server  204  has removed the private content from private feed  292  to create the public feeds  294 . As the example public feed  294   a  shows, not only has the private content been removed from private feed  292 , but also all of the leaf tags (i.e., tags  404  and  406 ) that contain the private content. In contrast, public feed  294   b  includes the leaf tags  404  and  406 , but has removed from the private content from the leaf tags  404  and  406 . 
         [0045]    As also shown in the example public feeds  294 , feed server  204  may modify one or more of the tags contained in private feed  292 . Referring to example public feed  294   a , it can be seen that feed server  202  has added a scope attribute-value pair to &lt;content&gt; tag  410 . The value that is assigned to the scope attribute that has been added to the &lt;content&gt; tag  410  is a sting that identifies the entities that are authorized to access at least some of the private content contained within the &lt;content&gt; tag  410 . Additionally, as shown in example  294   a  and  294 , feed server  204  may assign an identifier (“id”) to each piece of private content and include an “id” attribute-value pair in the tags present in the public feed that contain private content. As example public feed  294   a  illustrates, feed server  204  has (i) assigned the value of “111” to the private content that was contained within the &lt;content&gt; tag  410 , (ii) added an “id” attribute to tag  410 , and (iii) set the value of the “id” attribute to the assigned value (i.e., “111”). Likewise As example public feed  294   b  illustrates, feed server  204  has (i) assigned the value of “112” to the private content that was contained within the &lt;img&gt; tag  404  and assigned the value of “113” to the private content that was contained within the &lt;img&gt; tag  406 , (ii) added an “id” attribute to tags  404  and  406 , and (iii) set the value of the “id” attributes to the assigned values (i.e., “112” and “113,” respectively). 
         [0046]    As discussed above, feed server  204  stores in data store  206  the private content removed from private feed  292 . Additionally, in embodiments where feed server  204  assigns an id value to the private content, feed server  204  may also store with the private content the assigned id value, which may be used as an index to retrieve the private content from data store  206 . Using public feed  294   b  as an example, feed server  204 , for each of &lt;img&gt; tags  404  and  406 , may store in data store  206  a record having at least two fields: a first field for storing the id value assigned to the private content contained in the tag and a second field for storing the private content itself. 
         [0047]    Referring now to  FIG. 6 ,  FIG. 6  shows public feed  294  being received by a feed reader (FR)  104 . Feed reader  104  may have pulled public feed  294  from FPA  102  or FPA  102  may have pushed public feed  294  to feed reader  104 . In any event, feed reader  104  may, in direct response to receiving public feed  294 , parse public feed  294  to extract the public content contained therein and to present the extracted public content to a user upon request. Because public feed  294  does not contain any of the private content, feed reader  104  must request the private content from FPA  102  before feed reader  104  can present this information to a user. In some embodiments, feed reader  104  will request private content associated with public feed  294  if and only if a user of feed reader  104  is authorized to access the private content. If a user of feed reader  104  is authorized to access the private content, then feed reader  104  may transmit to FPA  102  a request  602  for private content. The request  602  may contain the id value assigned to the private content, which id value is contained in the public feed  294  as a value assigned to an “id” attribute of a tag associated with private content, as discussed above. After receiving the request (and assuming the user is indeed authorized to access the private content  293 ), FPA  102  will transmit to feed reader  104  the requested private content. 
         [0048]    Referring now to  FIG. 7 ,  FIG. 7  is a flow chart illustrating a process  700  that may be performed by FPA  102  in some embodiments. Process  700  may begin in step  702 , where FPA  102  receives content from a publisher. In step  704 , FPA  102  determines whether the received content includes private content. If it does not, process  700  may proceed to step  720 , where FPA creates a public feed containing content received in step  702 . Otherwise process  700  may proceed to steps  706 - 718 . In step  706 , FPA  102  stores the private content (e.g., FPA  102  may store the private content in data store  206 ). In step  708 , FPA  102  creates a public feed containing the public content received in step  702 , but not containing any of the private content. In step  710 , FPA  102  publishes the public feed (e.g., FPA  102  may store the public feed in a particular location from which any member of the public can download the public feed and/or FPA may push the public feed to one or more subscribers). After the public feed is published (i.e., after step  710 ), FPA  102  may receive from a feed reader operating on behalf of an entity a request for private content associated with the published public content (step  712 ). In step  714 , FPA  102  determines whether the entity is authorized to access the private content. If not, then FPA  102  may transmit to the feed reader a request denied message (step  716 ), otherwise FPA  102  may transmit to the feed reader the requested private content (step  718 ). 
         [0049]    Referring now to  FIG. 8 ,  FIG. 8  is a flow chart illustrating a process  800  that may be performed by FPA  102  in some other embodiments. Process  800  may begin in step  802 , where CMS  202  receives content from a publisher. In step  804 , CMS  202  creates a feed containing the received content. In step  806 , CMS  202  provides the feed to feed server  204 , which receives the feed. In step  808 , feed server  204  determines whether the received feed includes private content. If the feed does not include private content, then process  800  may proceed to step  830 , where feed server  204  publishes the received feed. If the feed includes private content, then process  800  may proceed to steps  810 - 828 . 
         [0050]    In step  810 , feed server  204 , for each tag included in the received feed, parses the tag to determines the value assigned to the tag&#39;s scope attribute. If a tag does not have an explicitly defined scope attribute, then feed server  204  will assume that the tag inherits its scope attribute from its parent. In step  812 , feed server  204  propagates scopes upwards from child tags to parent tags if the child tag has a scope not specified in the parent tag. This is illustrated in  FIG. 5 , which shows the scope of &lt;img&gt; tag  404  (i.e., “friends, family”) has been propagated upward to the &lt;content&gt; tag  410 . In step  814 , each piece of private content included in the received feed is assigned an identifier. In some embodiments, each piece of private content included in the received feed is assigned a unique identifier, whereas in other embodiments, a single identifier may be assigned to multiple pieces of private content. In step  816 , the each piece of private content included in the received feed is stored together the assigned identifiers such that an identifier assigned to a piece of private content can be used to locate and retrieve the piece of private content. 
         [0051]    In step  818 , feed server  204  creates a public feed based on the received feed. For example, in step  818 , feed server  204  may create a copy of the received feed and then remove from the copy all of the private content, thereby creating the public feed. In addition, feed server  204 , as discussed above, may add to the public feed the identifiers assigned to the private content as well as scope information for the private content. 
         [0052]    After the public feed is published, feed server  204  may receive from a feed reader operating on behalf of an entity a request for private content associated with the published public feed (step  822 ). In step  824 , feed server  204  determines whether the entity is authorized to access the private content. If not, then feed server  204  may transmit to the feed reader a request denied message (step  826 ), otherwise feed server  204  may transmit to the feed reader the requested private content. (step  828 ) 
         [0053]    Referring now to  FIG. 9 ,  FIG. 9  is a flow chart illustrating a process  900  that may be performed by a feed reader  104  according to some embodiments. In the embodiment shown, process  900  may being in step  902 , where feed reader  104  receives public feed  294 . In step  904 , feed reader  104  parses the public feed. In step  906 , feed reader  104  determines whether there is any private content associate with the public feed  294 . In some embodiments, feed reader  104  makes this determination by examining a tag included in the public feed to determine whether the tag includes a particular attribute (e.g., the scope attribute). In some embodiments, if the tag includes the particular attribute, then feed reader  104  may then determine the value assigned to the attribute in order to determine whether there exists any private content that is associated with the public feed. For example, in step  906 , if we assume feed reader  104  received public feed  294   a  (see  FIG. 5 ), feed reader  104  will determine that private content is associated with this public feed because the &lt;content&gt; tag  410  includes a “scope” attribute whose value set to something other than merely “public.” If there exists private content that is associated with the public feed, then process  900  may proceed to step  908 . 
         [0054]    In step  908 , feed reader  104  determines the scope of the private content (e.g., feed reader  104  determines the entities that have authorization to access the private content). In some embodiments, where there are several pieces of private content associated with the public feed, feed reader determines the scope of each piece of private content. In some embodiments, the scope of a piece of private content is determined by parsing a tag that contains the piece of private content to extract the value assigned to a particular attribute of the tag (e.g. the “scope” attribute). In some embodiments, the value of this particular attributes defines the scope of the particular piece private content. For example, if we assume feed reader  104  received public feed  294   b  (see  FIG. 5 ), feed reader  104  will determine that the scope of the private content contained in &lt;img&gt; tag  406  consists of the “friends” of the publisher of public feed  294   b.    
         [0055]    In step  910 , feed reader determines whether the entity on whose behalf feed reader  104  is operating matches the scope of any of the pieces of private content. For example, in some embodiments, feed reader  104  may have access (direct or indirect) to the list of entities that are on the publisher&#39;s “friends” list. Thus, for example, if the entity on whose behalf feed reader  104  is operating is identified on the friends list, then, feed reader  104  will determine that the entity is authorized to access those pieces of private content whose scope includes “friends.” If feed reader  104  determines that the entity on whose behalf feed reader  104  is operating matches the scope of any of the pieces of private content, then process  900  may proceed to step  912 . 
         [0056]    In step  912 , feed reader  104  creates a request message requesting the private content that the entity has authorization to access and transmits to FPA  102  the request message. The request message may contain a string identifying the private content. This string may include an identifier associated with received public feed  294  (e.g., some or all of the content contained in &lt;id&gt; tag  491 ) and/or an id value assigned to the private content (e.g. the value of the “id” attribute of the tag associated with the private content). Using public feed  294   b  as an example, if feed reader  104  may request the private content associated with &lt;img&gt; tag  406  by creating and transmitting a request message that contains the following identifier string, which may uniquely identify the private content associated with &lt;img&gt; tag  406 : “mysite.com/travelphotos:113.” 
         [0057]    In response to receiving the request, FPA  102  may issues an authentication challenge to feed reader  104 . In step  914 , feed reader  104  receives the challenge and, in step  91 , replies to the challenge by transmitting to FPA  102  a reply message. For example, in some embodiments, in response to receiving the challenge, feed reader  104  may a create a digital signature of a message using a private key belonging to the entity and include this digital signature in the reply message transmitted to FPA  102  in response to the challenge. Assuming, the entity is authenticated, FPA  102  may use the private content identifier string(s) included in the request message to retrieve the requested private content and transmit the requested private content to feed reader  104 , which, in step  918 , receives the requested private content. 
         [0058]    Referring now to  FIG. 10 ,  FIG. 10  illustrates a block diagram of FPA  102  according to some embodiments of the invention. As shown in  FIG. 10 , FPA  102  may include: a data processing system  1002 , which may include one or more microprocessors and/or one or more circuits, such as an application specific integrated circuit (ASIC), Field-programmable gate arrays (FPGAs), etc; a network interface  1004 ; data store  206 , which may include one or more non-volatile storage devices and/or one or more volatile storage devices (e.g., random access memory (RAM)). As shown, data store  206  may be used to store a database  1066  of public feeds and a database  1067  of private content. In embodiments where data processing system  1002  includes a microprocessor, computer readable program code  1043  may be stored in a computer readable medium  1042 , such as, but not limited, to magnetic media (e.g., a hard disk), optical media (e.g., a DVD), memory devices (e.g., random access memory), etc. In some embodiments, computer readable program code  1043  is configured such that when executed, code  1043  causes FPA  102  to perform steps described above (e.g., steps describe above with reference to the flow charts shown in  FIGS. 7 and 8 ). In other embodiments, FPA  102  is configured to perform steps described above without the need for code  1043 . That is, for example, data processing system  1002  may consist merely of one or more ASICs. Hence, the features of the present invention described above may be implemented in hardware and/or software. For example, in particular embodiments, the functional components of apparatus  102  described above may be implemented by data processing system processor  1002  executing computer instructions  1043 , by processor  1002  operating independent of any computer instructions  1043 , or by any suitable combination of hardware and/or software. 
         [0059]    Referring now to  FIG. 11 ,  FIG. 11  illustrates an embodiment of computer readable program code (CRPC)  1043 . In the embodiment shown, CRPC  1043  includes: (1) a set of instructions  1102  for receiving a private feed comprising a first tag containing public content and a second tag containing a piece of private content, (2) a set of instructions  1104  for storing the private content in a data store, (3) a set of instructions  1106  for creating a public feed comprising (a) the public content and (b) information indicating that the private content is available to be accessed by an authorized entity, but not comprising the private content, (4) a set of instructions  1108  for publishing the public feed, (5) a set of instructions  1110  for determining whether a subscriber is authorized to access the requested private content in response to receiving from a device a message sent by or on behalf of the subscriber, and (6) a set of instructions for transmitting to the device the requested private content in response to determining that the subscriber is authorized to access the private content. 
         [0060]    Referring now to  FIG. 12 ,  FIG. 12  illustrates a block diagram of feed reader  104  according to some embodiments of the invention. As shown in  FIG. 12 , feed reader  104  may include: a data processing system  1202 , which may include one or more microprocessors and/or one or more circuits, such as an application specific integrated circuit (ASIC), Field-programmable gate arrays (FPGAs), etc; a network interface  1204 ; data store  206 , which may include one or more non-volatile storage devices and/or one or more volatile storage devices (e.g., random access memory (RAM)). In embodiments where data processing system  1202  includes a microprocessor, computer readable program code  1243  may be stored in a computer readable medium  1242 , such as, but not limited, to magnetic media (e.g., a hard disk), optical media (e.g., a DVD), memory devices (e.g., random access memory), etc. In some embodiments, computer readable program code  1243  is configured such that when executed, code  1243  causes feed reader  104  to perform steps described above (e.g., steps describe above with reference to the flow chart shown in  FIG. 9 ). In other embodiments, feed reader  104  is configured to perform steps described above without the need for code  1243 . That is, for example, data processing system  1202  may consist merely of one or more ASICs. Hence, the features of the present invention described above may be implemented in hardware and/or software. For example, in particular embodiments, the functional components of apparatus  104  described above may be implemented by data processing system processor  1202  executing computer instructions  1243 , by processor  1202  operating independent of any computer instructions  1243 , or by any suitable combination of hardware and/or software. 
         [0061]    Referring now to  FIG. 13 ,  FIG. 13  illustrates an embodiment of computer readable program code (CRPC)  1243 . In the embodiment shown, CRPC  1243  includes: (1) a set of instructions  1302  for receiving a public feed, (2) a set of instructions  1304  for parsing the public feed to determine whether a server is storing private content associated with the public feed, (3) a set of instructions  1306  for determining the scope of the private content, (4) a set of instructions  1308  for determining whether an entity falls within the scope of the private content, (5) a set of instructions  1310  for transmitting a request to the server in response to determining that the entity falls within the scope of the private content, and (6) a set of instructions  1312  for receiving the private content after transmitting the request. 
         [0062]    Referring now to  FIG. 14 ,  FIG. 14  illustrates an example private feed  1402 . Feed  1402  may be created manually by a publisher or automatically by a content management system. As illustrated, feed  1402  includes various pieces of content some of which is private and some of which is public. Specifically, feed  1402  includes the following pieces of content: (1) a summary, (2) the name of a city, and (3) the name of a street. The summary is public content but the location information (city and street names are private). The city information is contained in the &lt;city&gt; tag and, since this tag does not have a scope attribute defined, the tag inherits its parent&#39;s scope (i.e., it inherits the scope of the &lt;location&gt; tag). Thus, the city information may be accessed by the publisher&#39;s friends or family. The street information, on the other hand, may be accessed only by the entities included in the publisher&#39;s family list. 
         [0063]      FIG. 14  also shows a public feed  1404  that corresponds to private feed  1402 . Public feed  1404  may be automatically created by a feed server (e.g. feed server  204 ) as described herein. As shown in  FIG. 14 , the public feed  1404  does not contain any of the private information from feed  1402 , but feed  1404  provides information indicating that private content associated with public feed  1404  is available for access by an authorized entity. Specifically, the &lt;location&gt; tag included in feed  1404  contains a “scope” attribute having a value set to “friends, family,” which signals to any feed reader that private location information is associated with feed  1404  and at least some of this private content my be accessed by an any entity that is a friend or family member of the publisher. 
         [0064]    The above describes systems and methods can be applied to any feed type information. For example, a feed using the ATOM Syndication format with the Activity Streams and GeoRSS extensions can be used.  FIG. 15  shows a typical ATOM Entry private feed  1502 . 
         [0065]    The ATOM entry  1502  shown in  FIG. 15  is a typical Activity Streams entry. It describes a picture taken and provides very detailed information about that picture: a link to the picture itself, its thumbnail, exactly where it was taken, how the surroundings was (noise level). It is apparent that the entry contains information that are not at the same “level”, giving away an exact geo position is something different from naming the city. Similarly, a thumbnail is different from the full resolution picture and so on. Still, it might be useful to publically announce this picture, with some control. In this example we want to protect it using three levels: public (the default), semi-protected (address information and actual picture), and very-protected (sensor information—e.g., gps and noise). A public feed  1602  (see  FIG. 16 ) corresponds to private feed  1502 . 
         [0066]    If we on the other hand would have used the following schema for protection: public (the default), semi-protected (the activity-object), and very-protected (sensor information—e.g., gps and noise), then the public feed created from feed  1502  may resemble public feed  1604  (see  FIG. 16 ). 
         [0067]    While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. 
         [0068]    Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel.
A publishing method is disclosed, which process enables a publisher to publish in a simple and easy manner a set of content that includes both public content and private content. In some embodiments, this advantageous solution is achieved by implementing a multi-step publishing process. In one step, the publisher publishes a feed that contains: ( 1) the public content and ( 2) information advertising the existence of the private content and the scope of the private content. In another step, the publisher stores the private content on a server accessible to the authorized entities.