Using RSS as a means of notification in your Visual Objects applicatio= ns.
Imagine being a lead developer in the commuter train =
on your
way to a client in the City. You’ve delivered phase 1 of a project a=
few weeks
ago and are now going to discuss phase 2 design, life is good. You arrive =
at
the client’s office where a committee of users and their manager con=
front
you with a list of things that need fixing. Obviously they are not keen on
discussing any new development after having been through countless discuss=
ions
with the helpdesk and several developers from your company. If only you wo=
uld
have known what was going on, you would have prepared for this meeting very
differently.
Sure the helpdesk logs all calls in their system, but you can’t sift
through all helpdesk entries and filter out the ones concerning your clien=
t all
the time. The developers report to their manager and on their worksheets, =
but
you never see those. Nobody thought about keeping you in the loop though! =
This
situation can easily be prevented if their was a way to be notified of
everything that goes on with your project or your client. With RSS you can
implement that kind of an information stream, which in this example can be
dedicated to everything relevant to a particular client.
I’ve always been a big fan of making good use of existing functionality, especially when it comes for free or when you alre= ady have the bits on your PC. This is why I started to investigate the way Int= ernet Explorer and Outlook consume RSS feeds from that perspective. At one of the Launch events dedicated to Office 2007 and Windows Vista one of the speake= rs demonstrated how easy it is to look at the RSS-feeds a user has subscribed= to. He emphasized this was a Vista only feature but also showed he was using a COM-object, so I knew he must have been wrong. So this is not about Vista and Of= fice 2007 at all, it is actually about Internet Explorer 7 I found out after a = bit more digging around. So what I am saying is that all you have to do to make good use of the components I will discuss in this article is upgrade to Internet Explorer 7. Therefore this is available for all Windows XP PCR= 17;s as well as Vista and you do not need Office 2007 at all. That should be ea= sy enough to do for even the most in-experienced user as the IE 7 update can be downloaded and installed through the Windows Update services.
For those of you who know little or nothing about RSS; currently it is mainly used as a way to communicate updates to websites and bLogs and it allows end-users to quickly see what’s new and manage w= hat they want to see and check off when they have read it. This can be done fr= om within Internet Explorer (or Outlook 2007) but in this article I am going = to show you how to do this from a VO application. I am also going to discuss = how you would create and publish RSS-feeds that make sense in a business environment.
If you have no experience at all with RSS you should = start Internet Explorer, subscribe to a few feeds and have a look how RSS Feeds = are presented in Internet Explorer. Here’s the feed for the Article Archive in VoConversion. If you subscribe to this feed and run= the Demo VO application included for this article you will see the items appea= r in the Treeview.
Consuming Feeds
Let me sketch an example scenario where you might use existing RSS-feeds within you VO application before embarking on publishing your own feeds. An application might be about managing investment funds for clients, typically the users (or a specific subset of the users) will be interested in financial news that is freely available on various websites = or have subscriptions to specific sites feeding information they work with. Many of such sites provide RSS-fe= eds for their content, which is typical for news oriented sites as they exist toda= y. Instead of users having to go and use Internet Explorer, you could present information from those RSS feeds within your VO application. The good news= is that you do not have to take care of any administration or storage as this= is all done for you through Internet Explorer (although you might want to aut= omate some management as well).
As with all COM-components you first n=
eed to
generate the VO wrapper classes that access them, in the sample code for t=
his
article you will find the VOCRSSLibrary
that contains the wrapper classes I generated for the type library that co=
mes
in MSFeeds.dll which is responsible for all this nice free code we can use=
.
The first class that you will need is the FeedManager=
class,
this provides you with access to the feeds, folders and items in a structu=
red
way. A Folders can contain both Items and subfolders so you have to be car=
eful
to test what you are reading and take appropriate action.
Figure SEQ Figure \* ARABIC 2,
Accessing Folders and Feeds
The Loadbutton code in the VOCRssFeedConsumer demo application shows how to obtain a reference to the FeedManager object (the class generated by the wizard in Fig. 1) and recursively iterate the Feeds= the user has subscribed to. It fills a treeview showing the Folder structure t= he user has create, the feeds in each folder as well as the RSS-Items that are downloaded to the users’ PC at the moment.
The demo application assumes that a user has already subscribed to some feeds and manages them in a folders structure. If there= are no folders present everything will be stored in the Rootfolder. You could = also setup a specific folder for your application and just look at the feeds st= ored in that specific folder, the code for this is displayed in Figure 3.
Figure 3, Inspecting a specific feed by name
In my Demo-app I actually store the references to the= actual FeedItems in the treeviewitem value property and access that to display the content (be it crudely) on the dialog when you click on one of the treeview items that represents a Feeditem.
Figure 4, Displaying Item information
That’s how simple it is to read the information=
stored
by Internet Explorer and Outlook 2007, I’ll leave the creation of an
appropriate User Interface to you as that will be an integral part of your=
own
application. In case you are now wondering, Internet Explorer has the UI f=
or
adding feeds, specifying how often they need to be queried for updating, h=
ow
long the items will be stored etc.
Figure 5, Managing RSS Feeds from Internet Explorer = 7
Using the FeedFolder class (CreateFeed method) you can actually programmatically add new feeds, and on the Feed class you can set= all the properties that determine their management behaviour. You can even mov= e and merge feeds and respond to specific events. This should give you enough information to get started consuming RSSFeeds in your applications. The documentation you will need for the COM-Classes can be found here on MSDN. There’s actually a very nice example of a screensaver application us= ing RSS which might give you some ideas about what to do with the RSS platform in = your applications.
Creating RSS Feeds
That concludes our discussion on consuming, now let&#=
8217;s
talk about creating and publishing feeds. Essentially all that is required=
is a
URL that returns a bunch of =
XML.
This can be a static file that you publish on a website, or something that=
gets
dynamically generated each time a consumer (like IE 7) navigates to the UR=
L. Here’s all the backgr=
ound you
need if you want get down to the nitty gritty details.
Internet Explorer on the client is responsible for vi= siting the feeds regularly (using the interval you specify when you subscribe). It reads the feed XML and decides which items are not yet cached on the clien= t and need to be downloaded. IE 7 and Outlook share the RSS-store and present th= eir information out that, and so does our VO Demo application. With the settin= gs on each feed the user can specify how long these items need to be saved, how = often the server needs to be queried and how the store is organised (in a folder structure).
Here’s a very rudimentary XML-file that will wo= rk as an RSSFeed:
There are alternatives to handcrafting a file, for ex= ample you might want to use a SQL Server statement that returns the XML-stream, = or you could use a server that already knows how to present its information a= s RSS Feeds such as a Microsoft SharePoint Server (v 3.), VoConversions.com.au h= as a few of those feeds. You can find those the URL’s to try out in the l= eft pane under URLs, if you click the links in IE you can see how those auto-generated feeds present their information. SharePoint allows you to s= pecify what List and what fields are actually exposed in the feed. When you look = at ours you can see we’ve include things like Category, abstract and pu= blish data so that as a consumer you can quickly see what’s going on and d= ecide if you need to zoom in on the details.
If you would like to know more about using SQL as a s= ource for feeds, here’s a link to an interesting article describing the process and here’s a complete solution you can= use.
As I am a great fan of SharePoint and most organisati= ons already have a 2003 server that they could use for running the free Windows SharePoint Services (WSS 3.0) server I will explain a bit more about that approach.
A scenario might be that your application produces re= ports that are exported and saved as PDF-files. You would like to publish an RSS= Feed to allow users to keep track of which reports are available for viewing an= d to be alerted to new Reports or updates. This is a very simple scenario to imple= ment in SharePoint, all you need to do is create a standard Document Library and store your files in that library. Any application can do that because WSS-Documented libraries can be accessed by using a UNC-path syntax. No sp= ecial coding is required to save files in SharePoint it is just like saving in a normal file share.
A Document Library in WSS 3.0 by default exposes an R= SS-feed and the SharePoint site where the Library is hosted has a UI to get to the= URL. As it happens this very article is stored in such a document library and t= he URL for the RSS Feed is: http://www.sof= twareobjectives.com.au/VoConversion/_layouts/listfeed.aspx?List=3D10630e5b= %2D7e03%2D4cf3%2Dadfb%2D4bcc5de13b08
Figure 6, RSS UI in SharePoint
As you ca=
n see in
Figure 6, SharePoint exposes a menu option to view and subscribe to the RSS
Feed and Inter Explorer also is aware of the existence of the RSS informat=
ion
on this Document Library. Figure 7 shows what the user see for the RSS
subscription in Internet Explorer.
Figure 7, Contents of a SharePoint =
RSS Feed
in Internet Explorer
That’s how easy it is to create an RSS feed in SharePoint. Its not always appropriate to use Documents, you might have a = need to publish information in a more structured way. SharePoint also has a qui= ck solution for that. You can create a custom list with any fields you like in WSS, in a similar way you would create a table in a database. Such lists a= lso have the RSS-feed capabilities just demonstrated for Document Libraries or= you could start by using on of the standard list templates such as announcemen= ts and add a few fields of your own. The list settings also allow you to spec= ify which fields are included in the actual RSS Items (Figure 8).
Figure 8, RSS Settings on Lists in
SharePoint
=
Actually, a
Document Library is a special kind of list so you have the same flexibilit=
y of
adding fields to a Document Library and configuring the RSS-settings.
=
The final
piece of the puzzle we need to solve when using WSS-lists is how to add it=
ems
to a SharePoint list from our VO application. This is where Web Services c=
ome
into play, SharePoint servers expose default Web Services that can be used=
to
add list items (amongst heaps of other functionality). The code would be
different for you when it comes to the name of the list to use, the server=
url
and probably the fields that are being submitted in the XML for the batch.=
More
information on how to use the SharePoint Web Services can be found on m=
sdn.
=
I actually
had a bit of trouble directly using the WSS 3.0 Web Service from inside a =
VO
application, normally it is not a problem but in this case the method we n=
eed
(UpdateListItems) actually expects an Xmlnode I wasn’t quickly able =
to
pass in as a parameter using the SOAP Oleobject you would normally use for
accessing a Web Service. After wasting an hour or so on this (you can stil=
l see
my attempts in the demo aef, look in the Ok button code) I decided to do i=
t the
way I usually do these things. Write a .net class library that does the wo=
rk
(in C#), wrap that using an automation wrapper also written in .net and si=
mply
call that from my VO application. It might sound and look complex but it
actually is just a few simple layers of code stacked on top of each other =
which
allow for re-use from various scenarios.&=
nbsp;
I did it in C#, but by the time you read this you might be able to =
do
the same thing in Vulcan .net which would make it even simpler for VO
developers.
=
So I start
out with a Visual Studio solution (included in the downloadable sample cod=
e)
and create a class that does the real work, here’s the C# code that =
calls
the SharePoint Web Service to add a new item to the announcements list:
using=
Sys=
tem;
using=
System.Collections.Generic;
using=
System.Text;
namespace
VOCCreateAnnouncement
{
public
class VOCCrea=
teAnnouncement
{
public void
CreateAnnouncement(string sList, string sTitle,
string<=
/span>
sBody)
{
// Grab a referenc=
e to
the Web service
// added using Add=
web
reference to
//
http://<server>/_vti_bin/Lists.asxm
=
;
spLists.Lists oService =3D new spLists.Lists();
oService.Credentials =3D
System.Net.CredentialCache.DefaultCredentials;
// Use currently l=
ogged
on user
=
;
// Or create a login:
=
;
// NetworkCredential credential =3D
// new NetworkCredential("Username"=
;,
"Pwd", "DOMAIN");
// Now call the Update method, paasing in the XML
instructions
=
//
more info in the WSS SDK on MSDN
=
;
string sBatch =3D "<Method
ID=3D\"1\" Cmd=3D\"New\">";
=
;
sBatch +=3D "<Field
Name=3D\"ID\">New</Field>";
=
;
sBatch +=3D "<Field Name=3D\&q=
uot;Title\">"
+ sTitle + "</Field>";=
=
;
sBatch +=3D "<Field
Name=3D\"Body\">" + sBody + "</Field>";
=
;
sBatch +=3D "</Method>"=
;;
=
;
System.Xml.XmlDocument xDoc =3D <=
span
style=3D'color:blue'>new System.Xml.XmlD=
ocument();
=
;
System.Xml.XmlElement xBatch =3D =
xDoc.CreateElement("Batch");
=
;
xBatch.SetAttribute("OnError"=
;,
"Return");
=
;
xBatch.InnerXml =3D sBatch;
=
;
oService.UpdateListItems(sList, xBatch);
}
}
}
=
Your list
might have different fieldnames but that should be easy to change. In the =
VS
2005 Solution you will also find a Windows form project that uses this cla=
ss to
test if it works from VS. The third project in the solution is a class lib=
rary
that I have exposed as a com-object (I could have directly exposed the fir=
st
one but I like things separate). Again a little bit of code:
using=
Sys=
tem;
using=
System.Collections.Generic;
using=
System.Text;
using=
System.Runtime.InteropServices;
namespace
iVOCCreateAnnouncement
{
[ClassInterface(ClassInterfaceType.AutoDual)]
p=
ublic
class iVOCCre=
ateAnnouncement
{
public string Test()
{
=
;
return "iVOCCreateAnnouncement
V 1.0";
}
public void
CreateAnnouncement(string sList,
string sTi=
tle, string sBody)
{
=
;
VOCCreateAnnouncement.VOCCreateAnnouncem=
ent
o =3D
new
VOCCreateAnnouncement.VOCCreateAnnouncement();
=
;
o.CreateAnnouncement(sList, sTitle, sBody);
}
}
}
=
=
This just
calls my VOCCreateAnnouncement class, exposing itself as a com-object and =
registering
the class for automation is done using the project-property dialog, more i=
nfo
about this her=
e on
msdn. This way you can h=
ave a
thin com-layer with just the methods you would like to expose and maybe do=
some
processing with data types, parameters, defaults etc.
=
Once these
projects have been build and tested from Visual Studio you can go into VO =
and
generate the automation server class for iVOCCreateAnnouncement. I have al=
ready
done that in the Demo aef, the following code uses the wrapper class in VO:
METHOD CreateButton( ) =
CLASS
MainDialog
LOCAL oWrapper AS _iVOCCreateAnnouncement
oWrapper :=3D _iVOCCreateAnnouncement{}
oWrapper:CreateAnnouncement("{6B5FD9D7-2CC3-4CF9-99C7-E7D8BA0FED99}&q=
uot;,;
"My Title",SELF:oDCBody:TextValue)
RETURN SELF
=
The
internal name of your SharePoint announcement list will be different but o=
ther
than that you should quickly be up and running. You can use the same Web s=
ervice
to find out the names for the lists by executing the GetListCollection met=
hod.
I’ve include a crude call to that method in the VOCreateAnnouncement=
UI
form that display the return XML, that should be enough to look it up.
=
So now you
know how to consume RSS Feeds from a VO application (or Outlook and Intern=
et
Explorer for that matter) and have some options for publishing your own fe=
eds.
I hope this article gave you the inspiration and motivation to have a think
about using RSS in your Line Of Business Applications. I’d be interested to hear f=
rom you
on the topic.
=
The file VOCR=
ss.zip,
that is located in the downloads of softwareojectives.com.au (link below) =
contains
all the sample code you need. Any questions that you might have will be
answered in the forum on the same website or by email.
=
Ed Richard
(Ed@SoftwareObjectives.com.au)
=
Software
Objectives, Melbourne, Jan. =
2007 –
updated Feb 2008 – download link sourcecode
=
List of
Human readable hyperlinks in this document in case you are using a printed
version:
Link to VoConversion Article RSS Feed:
RSS Feed API on MSDN: http://msdn.microsoft.com/library/en-us/FeedsAPI/rss/overvie= ws/msfeeds_ovw.asp
Generic RSS Info: http://w= ww.rss-specifications.com/creating-rss-feeds.htm
How to create RSS XML from SQL : http://www.informit.com/guides/content.asp?g=3Dsqlserve= r&seqNum=3D98&rl=3D1
SharePoint Web Services docs on MSDN: http://msd= n2.microsoft.com/en-us/library/ms441339.aspx
Register a .net class as com-object info on MSDN: htt= p://msdn2.microsoft.com/en-us/library/kew41ycz(VS.80).aspx
Source code for this Article: http= ://www.softwareobjectives.com.au/Downloads/VO/VOCRss.zip
=
=
=
=