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• RIF PRD: Presentation syntax issues

  - by Charles Young

  Over Christmas I got to play a bit with the W3C RIF PRD and came across a few issues which I thought I would record for posterity. Specifically, I was working on a grammar for the presentation syntax using a GLR grammar parser tool (I was using the current CTP of ‘M’ (MGrammer) and Intellipad – I do so hope the MS guys don’t kill off M and Intellipad now they have dropped the other parts of SQL Server Modelling). I realise that the presentation syntax is non-normative and that any issues with it do not therefore compromise the standard. However, presentation syntax is useful in its own right, and it would be great to iron out any issues in a future revision of the standard. The main issues are actually not to do with the grammar at all, but rather with the ‘running example’ in the RIF PRD recommendation. I started with the code provided in Example 9.1. There are several discrepancies when compared with the EBNF rules documented in the standard. Broadly the problems can be categorised as follows: ·      Parenthesis mismatch – the wrong number of parentheses are used in various places. For example, in GoldRule, the RHS of the rule (the ‘Then’) is nested in the LHS (‘the If’). In NewCustomerAndWidgetRule, the RHS is orphaned from the LHS. Together with additional incorrect parenthesis, this leads to orphanage of UnknownStatusRule from the entire Document. ·      Invalid use of parenthesis in ‘Forall’ constructs. Parenthesis should not be used to enclose formulae. Removal of the invalid parenthesis gave me a feeling of inconsistency when comparing formulae in Forall to formulae in If. The use of parenthesis is not actually inconsistent in these two context, but in an If construct it ‘feels’ as if you are enclosing formulae in parenthesis in a LISP-like fashion. In reality, the parenthesis is simply being used to group subordinate syntax elements. The fact that an If construct can contain only a single formula as an immediate child adds to this feeling of inconsistency. ·      Invalid representation of compact URIs (CURIEs) in the context of Frame productions. In several places the URIs are not qualified with a namespace prefix (‘ex1:’). This conflicts with the definition of CURIEs in the RIF Datatypes and Built-Ins 1.0 document. Here are the productions: CURIE          ::= PNAME_LN                  | PNAME_NS PNAME_LN       ::= PNAME_NS PN_LOCAL PNAME_NS       ::= PN_PREFIX? ':' PN_LOCAL       ::= ( PN_CHARS_U | [0-9] ) ((PN_CHARS|'.')* PN_CHARS)? PN_CHARS       ::= PN_CHARS_U                  | '-' | [0-9] | #x00B7                  | [#x0300-#x036F] | [#x203F-#x2040] PN_CHARS_U     ::= PN_CHARS_BASE                  | '_' PN_CHARS_BASE ::= [A-Z] | [a-z] | [#x00C0-#x00D6] | [#x00D8-#x00F6]                  | [#x00F8-#x02FF] | [#x0370-#x037D] | [#x037F-#x1FFF]                  | [#x200C-#x200D] | [#x2070-#x218F] | [#x2C00-#x2FEF]                  | [#x3001-#xD7FF] | [#xF900-#xFDCF] | [#xFDF0-#xFFFD]                  | [#x10000-#xEFFFF] PN_PREFIX      ::= PN_CHARS_BASE ((PN_CHARS|'.')* PN_CHARS)? The more I look at CURIEs, the more my head hurts! The RIF specification allows prefixes and colons without local names, which surprised me. However, the CURIE Syntax 1.0 working group note specifically states that this form is supported…and then promptly provides a syntactic definition that seems to preclude it! However, on (much) deeper inspection, it appears that ‘ex1:’ (for example) is allowed, but would really represent a ‘fragment’ of the ‘reference’, rather than a prefix! Ouch! This is so completely ambiguous that it surely calls into question the whole CURIE specification.   In any case, RIF does not allow local names without a prefix. ·      Missing ‘External’ specifiers for built-in functions and predicates.  The EBNF specification enforces this for terms within frames, but does not appear to enforce (what I believe is) the correct use of External on built-in predicates. In any case, the running example only specifies ‘External’ once on the predicate in UnknownStatusRule. External() is required in several other places. ·      The List used on the LHS of UnknownStatusRule is comma-delimited. This is not supported by the EBNF definition. Similarly, the argument list of pred:list-contains is illegally comma-delimited. ·      Unnecessary use of conjunction around a single formula in DiscountRule. This is strictly legal in the EBNF, but redundant.   All the above issues concern the presentation syntax used in the running example. There are a few minor issues with the grammar itself. Note that Michael Kiefer stated in his paper “Rule Interchange Format: The Framework” that: “The presentation syntax of RIF … is an abstract syntax and, as such, it omits certain details that might be important for unambiguous parsing.” ·      The grammar cannot differentiate unambiguously between strategies and priorities on groups. A processor is forced to resolve this by detecting the use of IRIs and integers. This could easily be fixed in the grammar.   ·      The grammar cannot unambiguously parse the ‘->’ operator in frames. Specifically, ‘-’ characters are allowed in PN_LOCAL names and hence a parser cannot determine if ‘status->’ is (‘status’ ‘->’) or (‘status-’ ‘>’).   One way to fix this is to amend the PN_LOCAL production as follows: PN_LOCAL ::= ( PN_CHARS_U | [0-9] ) ((PN_CHARS|'.')* ((PN_CHARS)-('-')))? However, unilaterally changing the definition of this production, which is defined in the SPARQL Query Language for RDF specification, makes me uncomfortable. ·      I assume that the presentation syntax is case-sensitive. I couldn’t find this stated anywhere in the documentation, but function/predicate names do appear to be documented as being case-sensitive. ·      The EBNF does not specify whitespace handling. A couple of productions (RULE and ACTION_BLOCK) are crafted to enforce the use of whitespace. This is not necessary. It seems inconsistent with the rest of the specification and can cause parsing issues. In addition, the Const production exhibits whitespaces issues. The intention may have been to disallow the use of whitespace around ‘^^’, but any direct implementation of the EBNF will probably allow whitespace between ‘^^’ and the SYMSPACE. Of course, I am being a little nit-picking about all this. On the whole, the EBNF translated very smoothly and directly to ‘M’ (MGrammar) and proved to be fairly complete. I have encountered far worse issues when translating other EBNF specifications into usable grammars.   I can’t imagine there would be any difficulty in implementing the same grammar in Antlr, COCO/R, gppg, XText, Bison, etc. A general observation, which repeats a point made above, is that the use of parenthesis in the presentation syntax can feel inconsistent and un-intuitive.   It isn’t actually inconsistent, but I think the presentation syntax could be improved by adopting braces, rather than parenthesis, to delimit subordinate syntax elements in a similar way to so many programming languages. The familiarity of braces would communicate the structure of the syntax more clearly to people like me.  If braces were adopted, parentheses could be retained around ‘var (frame | ‘new()’) constructs in action blocks. This use of parenthesis feels very LISP-like, and I think that this is my issue. It’s as if the presentation syntax represents the deformed love-child of LISP and C. In some places (specifically, action blocks), parenthesis is used in a LISP-like fashion. In other places it is used like braces in C. I find this quite confusing. Here is a corrected version of the running example (Example 9.1) in compliant presentation syntax: Document(    Prefix( ex1 <http://example.com/2009/prd2> )    (* ex1:CheckoutRuleset *)  Group rif:forwardChaining (     (* ex1:GoldRule *)    Group 10 (      Forall ?customer such that And(?customer # ex1:Customer                                     ?customer[ex1:status->"Silver"])        (Forall ?shoppingCart such that ?customer[ex1:shoppingCart->?shoppingCart]           (If Exists ?value (And(?shoppingCart[ex1:value->?value]                                  External(pred:numeric-greater-than-or-equal(?value 2000))))            Then Do(Modify(?customer[ex1:status->"Gold"])))))      (* ex1:DiscountRule *)    Group (      Forall ?customer such that ?customer # ex1:Customer        (If Or( ?customer[ex1:status->"Silver"]                ?customer[ex1:status->"Gold"])         Then Do ((?s ?customer[ex1:shoppingCart-> ?s])                  (?v ?s[ex1:value->?v])                  Modify(?s [ex1:value->External(func:numeric-multiply (?v 0.95))]))))      (* ex1:NewCustomerAndWidgetRule *)    Group (      Forall ?customer such that And(?customer # ex1:Customer                                     ?customer[ex1:status->"New"] )        (If Exists ?shoppingCart ?item                   (And(?customer[ex1:shoppingCart->?shoppingCart]                        ?shoppingCart[ex1:containsItem->?item]                        ?item # ex1:Widget ) )         Then Do( (?s ?customer[ex1:shoppingCart->?s])                  (?val ?s[ex1:value->?val])                  (?voucher ?customer[ex1:voucher->?voucher])                  Retract(?customer[ex1:voucher->?voucher])                  Retract(?voucher)                  Modify(?s[ex1:value->External(func:numeric-multiply(?val 0.90))]))))      (* ex1:UnknownStatusRule *)    Group (      Forall ?customer such that ?customer # ex1:Customer        (If Not(Exists ?status                       (And(?customer[ex1:status->?status]                            External(pred:list-contains(List("New" "Bronze" "Silver" "Gold") ?status)) )))         Then Do( Execute(act:print(External(func:concat("New customer: " ?customer))))                  Assert(?customer[ex1:status->"New"]))))  ) )   I hope that helps someone out there :-)

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• REST API Help in Rails

  - by dannymcc

  Hi Everyone, I am trying to get some information posted using our accountancy package (FreeAgentCentral) using their API via a GEM. http://github.com/aaronrussell/freeagent_api/ I have the following code to get it working (supposedly): Kase Controller def create @kase = Kase.new(params[:kase]) @company = Company.find(params[:kase][:company_id]) @kase = @company.kases.create!(params[:kase]) respond_to do |format| if @kase.save UserMailer.deliver_makeakase("[email protected]", "Highrise", @kase) @kase.create_freeagent_project(current_user) #flash[:notice] = 'Case was successfully created.' flash[:notice] = fading_flash_message("Case was successfully created & sent to Highrise.", 5) format.html { redirect_to(@kase) } format.xml { render :xml => @kase, :status => :created, :location => @kase } else format.html { render :action => "new" } format.xml { render :xml => @kase.errors, :status => :unprocessable_entity } end end end To save you looking through, the important part is: @kase.create_freeagent_project(current_user) Kase Model # FreeAgent API Project Create # Required attribues # :contact_id # :name # :payment_term_in_days # :billing_basis # must be 1, 7, 7.5, or 8 # :budget_units # must be Hours, Days, or Monetary # :status # must be Active or Completed def create_freeagent_project(current_user) p = Freeagent::Project.create( :contact_id => 0, :name => "#{jobno} - #{highrisesubject}", :payment_terms_in_days => 5, :billing_basis => 1, :budget_units => 'Hours', :status => 'Active' ) user = Freeagent::User.find_by_email(current_user.email) Freeagent::Timeslip.create( :project_id => p.id, :user_id => user.id, :hours => 1, :new_task => 'Setup', :dated_on => Time.now ) end lib/freeagent_api.rb require 'rubygems' gem 'activeresource', '< 3.0.0.beta1' require 'active_resource' module Freeagent class << self def authenticate(options) Base.authenticate(options) end end class Error < StandardError; end class Base < ActiveResource::Base def self.authenticate(options) self.site = "https://#{options[:domain]}" self.user = options[:username] self.password = options[:password] end end # Company class Company def self.invoice_timeline InvoiceTimeline.find :all, :from => '/company/invoice_timeline.xml' end def self.tax_timeline TaxTimeline.find :all, :from => '/company/tax_timeline.xml' end end class InvoiceTimeline < Base self.prefix = '/company/' end class TaxTimeline < Base self.prefix = '/company/' end # Contacts class Contact < Base end # Projects class Project < Base def invoices Invoice.find :all, :from => "/projects/#{id}/invoices.xml" end def timeslips Timeslip.find :all, :from => "/projects/#{id}/timeslips.xml" end end # Tasks - Complete class Task < Base self.prefix = '/projects/:project_id/' end # Invoices - Complete class Invoice < Base def mark_as_draft connection.put("/invoices/#{id}/mark_as_draft.xml", encode, self.class.headers).tap do |response| load_attributes_from_response(response) end end def mark_as_sent connection.put("/invoices/#{id}/mark_as_sent.xml", encode, self.class.headers).tap do |response| load_attributes_from_response(response) end end def mark_as_cancelled connection.put("/invoices/#{id}/mark_as_cancelled.xml", encode, self.class.headers).tap do |response| load_attributes_from_response(response) end end end # Invoice items - Complete class InvoiceItem < Base self.prefix = '/invoices/:invoice_id/' end # Timeslips class Timeslip < Base def self.find(*arguments) scope = arguments.slice!(0) options = arguments.slice!(0) || {} if options[:params] && options[:params][:from] && options[:params][:to] options[:params][:view] = options[:params][:from]+'_'+options[:params][:to] options[:params].delete(:from) options[:params].delete(:to) end case scope when :all then find_every(options) when :first then find_every(options).first when :last then find_every(options).last when :one then find_one(options) else find_single(scope, options) end end end # Users class User < Base self.prefix = '/company/' def self.find_by_email(email) users = User.find :all users.each do |u| u.email == email ? (return u) : next end raise Error, "No user matches that email!" end end end config/initializers/freeagent.rb Freeagent.authenticate({ :domain => 'XXXXX.freeagentcentral.com', :username => '[email protected]', :password => 'XXXXXX' }) The above render the following error when trying to create a new Case and send the details to FreeAgent: ActiveResource::ResourceNotFound in KasesController#create Failed with 404 Not Found and ActiveResource::ResourceNotFound (Failed with 404 Not Found): app/models/kase.rb:56:in `create_freeagent_project' app/controllers/kases_controller.rb:96:in `create' app/controllers/kases_controller.rb:93:in `create' Rendered rescues/_trace (176.5ms) Rendered rescues/_request_and_response (1.1ms) Rendering rescues/layout (internal_server_error) If anyone can shed any light on this problem it would be greatly appreciated! Thanks, Danny

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• Ext JS Tab Panel - Dynamic Tabs - Tab Exists Not Working

  - by Joey Ezekiel

  Hi Would appreciate if somebody could help me on this. I have a Tree Panel whose nodes when clicked load a tab into a tab panel. The tabs are loading alright, but my problem is duplication. I need to check if a tab exists before adding it to the tab panel. I cant seem to have this resolved and it is eating my brains. This is pretty simple and I have checked stackoverflow and the EXT JS Forums for solutions but they dont seem to work for me or I'm being blind. This is my code for the tree: var opstree = new Ext.tree.TreePanel({ renderTo: 'opstree', border:false, width: 250, height: 'auto', useArrows: false, animate: true, autoScroll: true, dataUrl: 'libs/tree-data.json', root: { nodeType: 'async', text: 'Tool Actions' }, listeners: { render: function() { this.getRootNode().expand(); } } }) opstree.on('click', function(n){ var sn = this.selModel.selNode || {}; // selNode is null on initial selection renderPage(n.id); }); function renderPage(tabId) { var TabPanel = Ext.getCmp('content-tab-panel'); var tab = TabPanel.getItem(tabId); //Ext.MessageBox.alert('TabGet',tab); if(tab){ TabPanel.setActiveTab(tabId); } else{ TabPanel.add({ title: tabId, html: 'Tab Body ' + (tabId) + '', closable:true }).show(); TabPanel.doLayout(); } } }); and this is the code for the Tab Panel new Ext.TabPanel({ id:'content-tab-panel', region: 'center', deferredRender: false, enableTabScroll:true, activeTab: 0, items: [{ contentEl: 'about', title: 'About the Billing Ops Application', closable: true, autoScroll: true, margins: '0 0 0 0' },{ contentEl: 'welcomescreen', title: 'PBRT Application Home', closable: false, autoScroll: true, margins: '0 0 0 0' }] }) Can somebody please help?

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• boost.serialization and lazy initialization

  - by niXman

  i need to serialize directory tree. i have no trouble with this type: std::map< std::string, // string(path name) std::vector<std::string> // string array(file names in the path) > tree; but for the serialization the directory tree with the content i need other type: std::map< std::string, // string(path name) std::vector< // files array std::pair< std::string, // file name std::vector< // array of file pieces std::pair< // <<<<<<<<<<<<<<<<<<<<<< for this i need lazy initialization std::string, // piece buf boost::uint32_t // crc32 summ on piece > > > > > tree; how can i serialize the object of type "std::pair" in the moment of its serialization?

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• Hibernate SetParameter driving me nuts.

  - by cbmeeks

  This works hql = "from State where StateCode like 'T%'"; Query query = session.createQuery(hql); This does not hql = "from State where StateCode like :StateCode"; Query query = session.createQuery(hql); query.setParameter("StateCode", "T%"); I get this 1568 [main] DEBUG org.hibernate.hql.ast.ErrorCounter - throwQueryException() : no errors 1596 [main] DEBUG org.hibernate.hql.antlr.HqlSqlBaseWalker - select << begin [level=1, statement=select] 1608 [main] DEBUG org.hibernate.hql.ast.tree.FromElement - FromClause{level=1} : com.kencogroup.kkms.models.State (no alias) -> state0_ 1610 [main] DEBUG org.hibernate.hql.ast.tree.FromReferenceNode - Resolved : {synthetic-alias} -> {synthetic-alias} 1611 [main] DEBUG org.hibernate.hql.ast.tree.DotNode - getDataType() : StateCode -> org.hibernate.type.StringType@a39137 1611 [main] DEBUG org.hibernate.hql.ast.tree.FromReferenceNode - Resolved : {synthetic-alias}.StateCode -> state0_.StateCode SELECT Exception: java.lang.reflect.UndeclaredThrowableException Notice the UndeclaredThrowableException exception. What am I doing wrong? The database is SQL Server 2008 if that helps. But like I said, other queries work just fine. Thanks

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• How to avoid an HttpException due to timeout

  - by Dan

  I'm working on a website powered by .NET asp/C# code. The clients require that sessions have a 25 minute timeout. However, sometimes the site is used, and a user stays connected for long periods of time (longer than 25 mins). Session_End is triggered: protected void Session_End(Object sender, EventArgs e) { Hashtable trackingInformaiton = (Hashtable)Application["trackingInformation"]; trackingInformaiton.Remove(Session["trackingID"]); } The user returns some time later, but when they interact with the website, they get an error, and we get this email notification: User: Unauthenticated User Error: System.Web.HttpException Description: Failed to load viewstate. The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request... The telling part of the stack trace is System.Web.UI.Control.AddedControl. Apparently, the server has thrown away the session data, and is sending new data, but the client is trying to deal with old data. Hence the error that "the control tree into which viewstate is being loaded [doesn't] match the control tree that was used to save the viewstate during the prevoius request." So here's the question. How can I force instruct the user's browser to redirect to a "you're logged out" screen when the connection times out? (Is it something I should add to the Session_End method?)

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• viewstack causing error 1065 variable not defined issue?

  - by jason

  I've got an flex application where I have a left side TREE control and a viewstack on the right and when someone selects the tree it loads the named viewstack based on the hidden node value of the XML of the tree. But it's throwing a error 1065 variable not defined on a viewstack which worked on the last browser refresh/reload. It's not related to a particular viewstack from what I can tell it just seems to throw the error on certain render events. I've tried to use creationpolicy="all" on the viewstack but it seems to not be of any help. public function treeChanged(event:Event):void { selectedNode=Tree(event.target).selectedItem as XML; //trace(selectedNode.@hidden); //Alert.show([email protected]() + " *"); if([email protected]() == '' || [email protected]() == null){ //Alert.show("NULL !"); return; } mainviewstack.selectedChild = Container(mainviewstack.getChildByName([email protected]())); //Container(mainviewstack.getChildByName(selectedNode.@hidden)); If I add in an alert box before the getchildbyname option the viewstack has time to render and everything works fine, so it leads me to believe the app is not giving it enough time to load the viewstack?

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• How do I send an XML document to an ASP.NET MVC page for manipuation

  - by Decker

  I have some hierarchical data stored as an multiple XML files on the server according to a vendor's schema. In my ASP.NET MVC (2!) application, I'd like the user to choose one of these hierarchies (i.e. file -- I provide a list in my controller's Index action). When the user selects one to "edit" my edit action should return a page that presents the XML hierarchy (it's a representation of a folder tree). So my thoughts are that the view would return HTML that contained a JQuery on load ajax call back to the server for the XML data -- at which point I would present the tree using one of the many JQuery tree controls. On the client side I'd like the user to manipulate the tree and when done, I'd like to post back the new hierarchy where I would replace the original XML file that represents that hierarchy. So my questions are: What form should I use to send the data down? XML or JSON?. If I send down XML then I would have to not only read the XML -- which JQuery can do -- but I would also have to be able to modify that XML and then send it back. Can I use JQuery to modify this XML DOM? And will all the namespace declarations be preserved? What form should I send the data back? If I originally sent the client the hierarchy as JSON (using JsonResult), then presumably I would have a hierarchy of javascript objects. What options would I have to post that back? Would I have to recreate the XML reprentation on the client and post that back? Or should I serialize back to JSON, post that to the server, and then have the server do the work of recreating the XML according to the schema. Thanks for any advice.

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• JQuery printfunction: no content, no view

  - by Joris

  I got a JQuery printfunction: function doPrintPage() { myWindow = window.open('', '', 'titlebar=yes,menubar=yes,status=yes,scrollbars=yes,width=800,height=600'); myWindow.document.open(); myWindow.document.write(document.getElementById("studentnummer").value); myWindow.document.write(document.getElementById("Voornaam").value + " " + document.getElementById("Tussenvoegsel").value + " " + document.getElementById("Achternaam").value); myWindow.document.write("</br>"); myWindow.document.write("Result"); myWindow.document.write(document.getElementById('tab1').innerHTML); myWindow.document.write("</br>"); myWindow.document.write("Tree"); myWindow.document.write(document.getElementById('tab2').innerHTML); myWindow.document.write("</br>"); myWindow.document.write("Open"); myWindow.document.write(document.getElementById('tab3').innerHTML); myWindow.document.write("</br>"); myWindow.document.write("Free"); myWindow.document.write(document.getElementById('tab4').innerHTML); myWindow.document.close(); myWindow.focus(); } There are 3 gridviews (elements in "tab#"), and on the page that is generated by this script, eacht gridview gets a header (Results, Tree, Open, Free). It is possible that there is no gridview for "Tree". It would be nice if the "tree" header wouldn't be shown either. EDIT: I tried this: if ($('tab4')[0]) {myWindow.document.write("Free"); myWindow.document.write(document.getElementById('tab4').innerHTML); but it seems not to work either... Anyone knows the solution?

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• jsTree: How to create a new ID for the new added node?

  - by marknt15

  Hi, I can normally get the ID of the default tree nodes but my problem is onCreate then jsTree will add a new node but it doesn't have an ID. My question is how can I add an ID to the newly created tree node? What I'm thinking to do is adding the ID HTML attribute to the newly created tree node but how? I need to get the ID of all of the nodes because it will serve as a reference for the node's respective div storage. HTML code: <div class="demo" id="demo_1"> <ul> <li id="phtml_1" class="file"><a href="#"><ins>&nbsp;</ins>Root node 1</a></li> <li id="phtml_2" class="file"><a href="#"><ins>&nbsp;</ins>Root node 2</a></li> </ul> </div> JS code: $("#demo_1").tree({ ui : { theme_name : "apple" }, callback : { onrename : function (NODE, TREE_OBJ) { alert(TREE_OBJ.get_text(NODE)); alert($(NODE).attr('id')); } } }); Cheers, Mark

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• Find three numbers appeared only once

  - by shilk

  In a sequence of length n, where n=2k+3, that is there are k unique numbers appeared twice and three numbers appeared only once. The question is: how to find the three unique numbers that appeared only once? for example, in sequence 1 1 2 6 3 6 5 7 7 the three unique numbers are 2 3 5. Note: 3<=n<1e6 and the number will range from 1 to 2e9 Memory limits: 1000KB , this implies that we can't store the whole sequence. Method I have tried(Memory limit exceed): I initialize a tree, and when read in one number I try to remove it from the tree, if the remove returns false(not found), I add it to the tree. Finally, the tree has the three numbers. It works, but is Memory limit exceed. I know how to find one or two such number(s) using bit manipulation. So I wonder if we can find three using the same method(or some method similar)? Method to find one/two number(s) appeared only once: If there is one number appeared only once, we can apply XOR to the sequence to find it. If there are two, we can first apply XOR to the sequence, then separate the sequence into 2 parts by one bit of the result that is 1, and again apply XOR to the 2 parts, and we will find the answer.

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• SWT Drag and Drop support for Text widget

  - by bryantsai

  I've written an application recently using SWT. In one of its dialog box, I have a few widgets, one of which is Text, which is designed to support DND with other widgets. I've first added DND support for the 2 Tree widgets on the same dialog box (both drag source and drop target). Before I added DND support for that Text widget, I noticed that on Linux platform (gtk), SWT Text widget automatically get drag and drop support. That is, I can already drag from the other Tree widgets and drop on this Text (at any position to inserted there), as well as selecting and dragging any text from this Text to other Tree or Text widget. However, this is only working on Linux platform but not on Windows. The same program, if running on Windows, will not have any DND support for that Text widget (Tree widgets of course have DND support since I specifically write for them). So here's what I want to achieve on Windows as well: drop text at any position in Text widget. before dropping and while hovering, able to see the caret position clearly where the intended position to drop. caret position should move along with the mouse cursor. support multi-line in Text widget SOLUTION: DropTarget target = new DropTarget(sytledText, DND.DROP_MOVE | DND.DROP_COPY); target.setTransfer(new Transfer[] { TextTransfer.getInstance() }); target.addDropListener(new StyleTextDropTargetEffect(sytledText)); Use StyledText instead of Text widget Use StyledTextDropTargetEffect (or extend it) and add it as dr op listener

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• Query notation for the sitecore 'source' field in template builder

  - by M.R.

  I am trying to set the the source field of a template using the query notation (or xpath - whichever works), but none of them seems to be working. My content tree is a multisite content tree: France --Page 1 ----Page1A -------Page1AA --Page 2 --Page 3 --METADATA ----Regions US --Page 1 ----Page1A -------Page1AA --Page 2 --Page 3 --METADATA ----Regions Each site has its own METADATA folder, and I want it so that when adding a page inside each of the main country nodes, I want the values to reflect whatever is in the METADATA of that site. I have two different fields for now - a droplink and a treelistex field. So I thought I can just get the parent item that is a country site, and get the metadata folder for that. When I put the following query in both the fields, I get different results: query:./ancestor::*[@@templatename='CountryHome']/METADATA/Regions/* For the droplink field, I get only the first Region (one item) For the treelistex field, I get the entire content tree I then tried to modify the query a little bit and took the 'query' notation out ./ancestor::*[@@templatename='CountryHome']/METADATA/Regions/* If I go to the developer center/xpath builder, and set the context node to any item underneath the main country site, it returns me exactly what I need, but when I put this in the source, I get the entire content tree in both the cases. Help!

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• How do I get Google Chrome's root bookmarks folder?

  - by Wayne

  Hi, I'm trying to write a better bookmark manager in chrome extensions. The problem is there are no simple examples (that I can find) about how to actually use the bookmarks api (available here: http://code.google.com/chrome/extensions/bookmarks.html ) I've looked at the example source (when I d/led and installed it on my computer it didn't do anything except provide a search box. Typing/typing and pressing return failed to do anything) and can't find anything useful. My ultimate goal is to make an extension that allows me to save pages to come and read later without having to go sign up for an account on some service somewhere. So I plan to create either one or two bookmark folders in the root folder/other bookmarks - at minimum an "unread pages" folder. In that folder I'll create the unread bookmarks. When the user marks the item as read, it will be removed from that folder. So that's what I'm trying to do... any help will be greatly appreciated, even if it's just pointing me to some good examples. UPDATE: ...<script> function display(tree){ document.getElementById("Output").innerHTML = tree; } function start(){ chrome.bookmarks.getTree(display); } </script> </head> <body> <h4 id="Output"></h4> <script> start(); </script> ... That displays [object Object], that suggests (at least to me with a limited JavaScript experience) that an object exists. But how to access the members of that object? changing tree to tree.id or any other of what look to be parameters displays "undefined".

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• I need to speed up a function. Should I use cython, ctypes, or something else?

  - by Peter Stewart

  I'm having a lot of fun learning Python by writing a genetic programming type of application. I've had some great advice from Torsten Marek, Paul Hankin and Alex Martelli on this site. The program has 4 main functions: generate (randomly) an expression tree. evaluate the fitness of the tree crossbreed mutate As all of generate, crossbreed and mutate call 'evaluate the fitness'. it is the busiest function and is the primary bottleneck speedwise. As is the nature of genetic algorithms, it has to search an immense solution space so the faster the better. I want to speed up each of these functions. I'll start with the fitness evaluator. My question is what is the best way to do this. I've been looking into cython, ctypes and 'linking and embedding'. They are all new to me and quite beyond me at the moment but I look forward to learning one and eventually all of them. The 'fitness function' needs to compare the value of the expression tree to the value of the target expression. So it will consist of a postfix evaluator which will read the tree in a postfix order. I have all the code in python. I need advice on which I should learn and use now: cython, ctypes or linking and embedding. Thank you.

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• How to create a new ID for the new added node?

  - by marknt15

  Hi, I can normally get the ID of the default tree nodes but my problem is onCreate then jsTree will add a new node but it doesn't have an ID. My question is how can I add an ID to the newly created tree node? What I'm thinking to do is adding the ID HTML attribute to the newly created tree node but how? I need to get the ID of all of the nodes because it will serve as a reference for the node's respective div storage. HTML code: <div class="demo" id="demo_1"> <ul> <li id="phtml_1" class="file"><a href="#"><ins>&nbsp;</ins>Root node 1</a></li> <li id="phtml_2" class="file"><a href="#"><ins>&nbsp;</ins>Root node 2</a></li> </ul> </div> JS code: $("#demo_1").tree({ ui : { theme_name : "apple" }, callback : { onrename : function (NODE, TREE_OBJ) { alert(TREE_OBJ.get_text(NODE)); alert($(NODE).attr('id')); } } }); Cheers, Mark

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• best practices question: How to save a collection of images and a java object in a single file? File

  - by Richard

  Hi all, I am making a java program that has a collection of flash-card like objects. I store the objects in a jtree composed of defaultmutabletreenodes. Each node has a user object attached to it with has a few string/native data type parameters. However, i also want each of these objects to have an image (typical formats, jpg, png etc). I would like to be able to store all of this information, including the images and the tree data to the disk in a single file so the file can be transferred between users and the entire tree, including the images and parameters for each object, can be reconstructed. I had not approached a problem like this before so I was not sure what the best practices were. I found XLMEncoder (http://java.sun.com/j2se/1.4.2/docs/api/java/beans/XMLEncoder.html) to be a very effective way of storing my tree and the native data type information. However I couldn't figure out how to save the image data itself inside of the XML file, and I'm not sure it is possible since the data is binary (so restricted characters would be invalid). My next thought was to associate a hash string instead of an image within each user object, and then gzip together all of the images, with the hash strings as the names and the XMLencoded tree in the same compmressed file. That seemed really contrived though. Does anyone know a good approach for this type of issue? THanks! Thanks!

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• Global name not defined error in Django/Python trying to set foreignkey

  - by Mark

  Summary: I define a method createPage within a file called PageTree.py that takes a Source model object and a string. The method tries to generate a Page model object. It tries to set the Page model object's foreignkey to refer to the Source model object which was passed in. This throws a NameError exception! I'm trying to represent a website which is structured like a tree. I define the Django models Page and Source, Page representing a node on the tree and Source representing the contents of the page. (You can probably skip over these, this is a basic tree implementation using doubly linked nodes). class Page(models.Model): name = models.CharField(max_length=50) parent = models.ForeignKey("self", related_name="children", null=True); firstChild = models.ForeignKey("self", related_name="origin", null=True); nextSibling = models.ForeignKey("self", related_name="prevSibling", null=True); previousSibling = models.ForeignKey("self", related_name="nxtSibling", null=True); source = models.ForeignKey("Source"); class Source(models.Model): #A source that is non dynamic will be refered to as a static source #Dynamic sources contain locations that are names of functions #Static sources contain locations that are places on disk name = models.CharField(primary_key=True, max_length=50) isDynamic = models.BooleanField() location = models.CharField(max_length=100); I've coded a python program called PageTree.py which allows me to request nodes from the database and manipulate the structure of the tree. Here is the trouble making method: def createPage(pageSource, pageName): page = Page() page.source = pageSource page.name = pageName page.save() return page I'm running this program in a shell through manage.py in Windows 7 manage.py shell from mysite.PageManager.models import Page, Source from mysite.PageManager.PageTree import * ... create someSource = Source(), populate the fields, and save it ... createPage(someSource, "test") ... NameError: global name 'source' is not defined When I type in the function definition for createPage into the shell by hand, the call works without error. This is driving me bonkers and help is appreciated.

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• Is there an algorithm for finding an item that matches certain properties, like a 20 questions game?

  - by lala

  A question about 20 questions games was asked here: However, if I'm understanding it correctly, the answers seem to assume that each question will go down a hierarchal branching tree. A binary tree should work if the game went like this: Is it an animal? Yes. Is it a mammal? Yes. Is it a feline? Yes. Because feline is an example of a mammal and mammal is an example of an animal. But what if the questions go like this? Is it a mammal? Yes. Is it a predator? Yes. Does it have a long nose? No. You can't branch down a tree with those kinds of questions, because there are plenty of predators that aren't mammals. So you can't have your program just narrow it down to mammal and have predators be a subset of mammals. So is there a way to use a binary search tree that I'm not understanding or is there a different algorithm for this problem?

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• finding long repeated substrings in a massive string

  - by Will

  I naively imagined that I could build a suffix trie where I keep a visit-count for each node, and then the deepest nodes with counts greater than one are the result set I'm looking for. I have a really really long string (hundreds of megabytes). I have about 1 GB of RAM. This is why building a suffix trie with counting data is too inefficient space-wise to work for me. To quote Wikipedia's Suffix tree: storing a string's suffix tree typically requires significantly more space than storing the string itself. The large amount of information in each edge and node makes the suffix tree very expensive, consuming about ten to twenty times the memory size of the source text in good implementations. The suffix array reduces this requirement to a factor of four, and researchers have continued to find smaller indexing structures. And that was wikipedia's comments on the tree, not trie. How can I find long repeated sequences in such a large amount of data, and in a reasonable amount of time (e.g. less than an hour on a modern desktop machine)? (Some wikipedia links to avoid people posting them as the 'answer': Algorithms on strings and especially Longest repeated substring problem ;-) )

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• A specific data structure

  - by user550413

  Well, this question is a bit specific but I think there is some general idea in it that I can't get it. Lets say I got K servers (which is a constant that I know its size). I have a program that get requests and every request has an id and server id that will handle it. I have n requests - unknown size and can be any number. I need a data structure to support the next operations within the given complexity: GetServer - the function gets the request ID and returns the server id that is supposed to handle this request at the current situation and not necessarily the original server (see below). Complexity: O(log K) at average. KillServer - the function gets as input a server id that should be removed and another server id that all the requests of the removed server should be passed to. Complexity: O(1) at the worst case. -- Place complexity for all the structure is O(K+n) -- The KillServer function made me think using a Union-Find as I can do the union in O(1) as requested but my problem is the first operation. Why it's LogK? Actually, no matter how I "save" the requests if I want to access to any request (lets say it's an AVL tree) so the complexity will be O(log n) at the worst case and said that I can't assume Kn (and probably K Tried thinking about it a couple of hours but I can't find any solution. Known structures that can be used are: B+ tree, AVL tree, skip list, hash table, Union-Find, rank tree and of course all the basics like arrays and such.

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• Which DVCS would work best on Windows for my scenario?

  - by PoorLuzer

  At work I use ClearCase and SourceSafe, but have found some time to do some time to code for myself enroute thanks to a disposable laptop. However, I wish I had a lightweight VCS on my system using which I would be able to make changes to my code during the commute and then push/grab them from my Linux systems. I use git on my home system, but I can't really get it working on Windows. I don't want all that cygwin hack. If it does not run natively on Windows, it just won't do. What have you guys tried on your Windows system? Something that YOU use. The big player at the moment seems to be Mercurial? What would be best for a one (or maybe two) man team? I just need to maintain : Versioned copies of source code. Checking in and out should be as less obtrusive as possible. I am looking forward to a multiple Undo kind of feature (like that in an EMacs buffer) but persistent. I really like the way git keeps track of lines moving between files in a source code set I should be able to move part(s)/sub tree(s) of the source tree (each sub tree implies a module/plugin to my the main software I am building) to an archival system either completly or partially and restore them back from the archive as and when required and the system should track any changes to this tree as well. I actually want to experiment with my code as much as possible without me manually keeping track of what I modified and what I need to undo once I try out some idea, so that I am back to where I want to continue from. Notes : A similar topic came up a year ago : http://stackoverflow.com/questions/4670/dvcs-choices-whats-good-for-windows I hope things have changed, and I really want people to share their own, real life experiences. Not something they recommend without using it or they think will work.

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• Tip/Trick: Fix Common SEO Problems Using the URL Rewrite Extension

  - by ScottGu

  Search engine optimization (SEO) is important for any publically facing web-site.  A large % of traffic to sites now comes directly from search engines, and improving your site’s search relevancy will lead to more users visiting your site from search engine queries.  This can directly or indirectly increase the money you make through your site. This blog post covers how you can use the free Microsoft URL Rewrite Extension to fix a bunch of common SEO problems that your site might have.  It takes less than 15 minutes (and no code changes) to apply 4 simple URL Rewrite rules to your site, and in doing so cause search engines to drive more visitors and traffic to your site.  The techniques below work equally well with both ASP.NET Web Forms and ASP.NET MVC based sites.  They also works with all versions of ASP.NET (and even work with non-ASP.NET content). [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] Measuring the SEO of your website with the Microsoft SEO Toolkit A few months ago I blogged about the free SEO Toolkit that we’ve shipped.  This useful tool enables you to automatically crawl/scan your site for SEO correctness, and it then flags any SEO issues it finds.  I highly recommend downloading and using the tool against any public site you work on.  It makes it easy to spot SEO issues you might have in your site, and pinpoint ways to optimize it further. Below is a simple example of a report I ran against one of my sites (www.scottgu.com) prior to applying the URL Rewrite rules I’ll cover later in this blog post:   Search Relevancy and URL Splitting Two of the important things that search engines evaluate when assessing your site’s “search relevancy” are: How many other sites link to your content.  Search engines assume that if a lot of people around the web are linking to your content, then it is likely useful and so weight it higher in relevancy. The uniqueness of the content it finds on your site.  If search engines find that the content is duplicated in multiple places around the Internet (or on multiple URLs on your site) then it is likely to drop the relevancy of the content. One of the things you want to be very careful to avoid when building public facing sites is to not allow different URLs to retrieve the same content within your site.  Doing so will hurt with both of the situations above.  In particular, allowing external sites to link to the same content with multiple URLs will cause your link-count and page-ranking to be split up across those different URLs (and so give you a smaller page rank than what it would otherwise be if it was just one URL).  Not allowing external sites to link to you in different ways sounds easy in theory – but you might wonder what exactly this means in practice and how you avoid it. 4 Really Common SEO Problems Your Sites Might Have Below are 4 really common scenarios that can cause your site to inadvertently expose multiple URLs for the same content.  When this happens external sites linking to yours will end up splitting their page links across multiple URLs - and as a result cause you to have a lower page ranking with search engines than you deserve. SEO Problem #1: Default Document IIS (and other web servers) supports the concept of a “default document”.  This allows you to avoid having to explicitly specify the page you want to serve at either the root of the web-site/application, or within a sub-directory.  This is convenient – but means that by default this content is available via two different publically exposed URLs (which is bad).  For example: http://scottgu.com/ http://scottgu.com/default.aspx SEO Problem #2: Different URL Casings Web developers often don’t realize URLs are case sensitive to search engines on the web.  This means that search engines will treat the following links as two completely different URLs: http://scottgu.com/Albums.aspx http://scottgu.com/albums.aspx SEO Problem #3: Trailing Slashes Consider the below two URLs – they might look the same at first, but they are subtly different. The trailing slash creates yet another situation that causes search engines to treat the URLs as different and so split search rankings: http://scottgu.com http://scottgu.com/ SEO Problem #4: Canonical Host Names Sometimes sites support scenarios where they support a web-site with both a leading “www” hostname prefix as well as just the hostname itself.  This causes search engines to treat the URLs as different and split search rankling: http://scottgu.com/albums.aspx/ http://www.scottgu.com/albums.aspx/ How to Easily Fix these SEO Problems in 10 minutes (or less) using IIS Rewrite If you haven’t been careful when coding your sites, chances are you are suffering from one (or more) of the above SEO problems.  Addressing these issues will improve your search engine relevancy ranking and drive more traffic to your site. The “good news” is that fixing the above 4 issues is really easy using the URL Rewrite Extension.  This is a completely free Microsoft extension available for IIS 7.x (on Windows Server 2008, Windows Server 2008 R2, Windows 7 and Windows Vista).  The great thing about using the IIS Rewrite extension is that it allows you to fix the above problems *without* having to change any code within your applications.  You can easily install the URL Rewrite Extension in under 3 minutes using the Microsoft Web Platform Installer (a free tool we ship that automates setting up web servers and development machines).  Just click the green “Install Now” button on the URL Rewrite Spotlight page to install it on your Windows Server 2008, Windows 7 or Windows Vista machine: Once installed you’ll find that a new “URL Rewrite” icon is available within the IIS 7 Admin Tool: Double-clicking the icon will open up the URL Rewrite admin panel – which will display the list of URL Rewrite rules configured for a particular application or site: Notice that our rewrite rule list above is currently empty (which is the default when you first install the extension).  We can click the “Add Rule…” link button in the top-right of the panel to add and enable new URL Rewriting logic for our site.  Scenario 1: Handling Default Document Scenarios One of the SEO problems I discussed earlier in this post was the scenario where the “default document” feature of IIS causes you to inadvertently expose two URLs for the same content on your site.  For example: http://scottgu.com/ http://scottgu.com/default.aspx We can fix this by adding a new IIS Rewrite rule that automatically redirects anyone who navigates to the second URL to instead go to the first one.  We will setup the HTTP redirect to be a “permanent redirect” – which will indicate to search engines that they should follow the redirect and use the new URL they are redirected to as the identifier of the content they retrieve.  Let’s look at how we can create such a rule.  We’ll begin by clicking the “Add Rule” link in the screenshot above.  This will cause the below dialog to display: We’ll select the “Blank Rule” template within the “Inbound rules” section to create a new custom URL Rewriting rule.  This will display an empty pane like below: Don’t worry – setting up the above rule is easy.  The following 4 steps explain how to do so: Step 1: Name the Rule Our first step will be to name the rule we are creating.  Naming it with a descriptive name will make it easier to find and understand later.  Let’s name this rule our “Default Document URL Rewrite” rule: Step 2: Setup the Regular Expression that Matches this Rule Our second step will be to specify a regular expression filter that will cause this rule to execute when an incoming URL matches the regex pattern.   Don’t worry if you aren’t good with regular expressions - I suck at them too. The trick is to know someone who is good at them or copy/paste them from a web-site.  Below we are going to specify the following regular expression as our pattern rule: (.*?)/?Default\.aspx$ This pattern will match any URL string that ends with Default.aspx. The "(.*?)" matches any preceding character zero or more times. The "/?" part says to match the slash symbol zero or one times. The "$" symbol at the end will ensure that the pattern will only match strings that end with Default.aspx.  Combining all these regex elements allows this rule to work not only for the root of your web site (e.g. http://scottgu.com/default.aspx) but also for any application or subdirectory within the site (e.g. http://scottgu.com/photos/default.aspx.  Because the “ignore case” checkbox is selected it will match both “Default.aspx” as well as “default.aspx” within the URL.   One nice feature built-into the rule editor is a “Test pattern” button that you can click to bring up a dialog that allows you to test out a few URLs with the rule you are configuring: Above I've added a “products/default.aspx” URL and clicked the “Test” button.  This will give me immediate feedback on whether the rule will execute for it.  Step 3: Setup a Permanent Redirect Action We’ll then setup an action to occur when our regular expression pattern matches the incoming URL: In the dialog above I’ve changed the “Action Type” drop down to be a “Redirect” action.  The “Redirect Type” will be a HTTP 301 Permanent redirect – which means search engines will follow it. I’ve also set the “Redirect URL” property to be: {R:1}/ This indicates that we want to redirect the web client requesting the original URL to a new URL that has the originally requested URL path - minus the "Default.aspx" in it.  For example, requests for http://scottgu.com/default.aspx will be redirected to http://scottgu.com/, and requests for http://scottgu.com/photos/default.aspx will be redirected to http://scottgu.com/photos/ The "{R:N}" regex construct, where N >= 0, is called a back-reference and N is the back-reference index. In the case of our pattern "(.*?)/?Default\.aspx$", if the input URL is "products/Default.aspx" then {R:0} will contain "products/Default.aspx" and {R:1} will contain "products".  We are going to use this {R:1}/ value to be the URL we redirect users to.  Step 4: Apply and Save the Rule Our final step is to click the “Apply” button in the top right hand of the IIS admin tool – which will cause the tool to persist the URL Rewrite rule into our application’s root web.config file (under a <system.webServer/rewrite> configuration section): <configuration>     <system.webServer>         <rewrite>             <rules>                 <rule name="Default Document" stopProcessing="true">                     <match url="(.*?)/?Default\.aspx$" />                     <action type="Redirect" url="{R:1}/" />                 </rule>             </rules>         </rewrite>     </system.webServer> </configuration> Because IIS 7.x and ASP.NET share the same web.config files, you can actually just copy/paste the above code into your web.config files using Visual Studio and skip the need to run the admin tool entirely.  This also makes adding/deploying URL Rewrite rules with your ASP.NET applications really easy. Step 5: Try the Rule Out Now that we’ve saved the rule, let’s try it out on our site.  Try the following two URLs on my site: http://scottgu.com/ http://scottgu.com/default.aspx Notice that the second URL automatically redirects to the first one.  Because it is a permanent redirect, search engines will follow the URL and should update the page ranking of http://scottgu.com to include links to http://scottgu.com/default.aspx as well. Scenario 2: Different URL Casing Another common SEO problem I discussed earlier in this post is that URLs are case sensitive to search engines on the web.  This means that search engines will treat the following links as two completely different URLs: http://scottgu.com/Albums.aspx http://scottgu.com/albums.aspx We can fix this by adding a new IIS Rewrite rule that automatically redirects anyone who navigates to the first URL to instead go to the second (all lower-case) one.  Like before, we will setup the HTTP redirect to be a “permanent redirect” – which will indicate to search engines that they should follow the redirect and use the new URL they are redirected to as the identifier of the content they retrieve. To create such a rule we’ll click the “Add Rule” link in the URL Rewrite admin tool again.  This will cause the “Add Rule” dialog to appear again: Unlike the previous scenario (where we created a “Blank Rule”), with this scenario we can take advantage of a built-in “Enforce lowercase URLs” rule template.  When we click the “ok” button we’ll see the following dialog which asks us if we want to create a rule that enforces the use of lowercase letters in URLs: When we click the “Yes” button we’ll get a pre-written rule that automatically performs a permanent redirect if an incoming URL has upper-case characters in it – and automatically send users to a lower-case version of the URL: We can click the “Apply” button to use this rule “as-is” and have it apply to all incoming URLs to our site.  Because my www.scottgu.com site uses ASP.NET Web Forms, I’m going to make one small change to the rule we generated above – which is to add a condition that will ensure that URLs to ASP.NET’s built-in “WebResource.axd” handler are excluded from our case-sensitivity URL Rewrite logic.  URLs to the WebResource.axd handler will only come from server-controls emitted from my pages – and will never be linked to from external sites.  While my site will continue to function fine if we redirect these URLs to automatically be lower-case – doing so isn’t necessary and will add an extra HTTP redirect to many of my pages.  The good news is that adding a condition that prevents my URL Rewriting rule from happening with certain URLs is easy.  We simply need to expand the “Conditions” section of the form above We can then click the “Add” button to add a condition clause.  This will bring up the “Add Condition” dialog: Above I’ve entered {URL} as the Condition input – and said that this rule should only execute if the URL does not match a regex pattern which contains the string “WebResource.axd”.  This will ensure that WebResource.axd URLs to my site will be allowed to execute just fine without having the URL be re-written to be all lower-case. Note: If you have static resources (like references to .jpg, .css, and .js files) within your site that currently use upper-case characters you’ll probably want to add additional condition filter clauses so that URLs to them also don’t get redirected to be lower-case (just add rules for patterns like .jpg, .gif, .js, etc).  Your site will continue to work fine if these URLs get redirected to be lower case (meaning the site won’t break) – but it will cause an extra HTTP redirect to happen on your site for URLs that don’t need to be redirected for SEO reasons.  So setting up a condition clause makes sense to add. When I click the “ok” button above and apply our lower-case rewriting rule the admin tool will save the following additional rule to our web.config file: <configuration>     <system.webServer>         <rewrite>             <rules>                 <rule name="Default Document" stopProcessing="true">                     <match url="(.*?)/?Default\.aspx$" />                     <action type="Redirect" url="{R:1}/" />                 </rule>                 <rule name="Lower Case URLs" stopProcessing="true">                     <match url="[A-Z]" ignoreCase="false" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{URL}" pattern="WebResource.axd" negate="true" />                     </conditions>                     <action type="Redirect" url="{ToLower:{URL}}" />                 </rule>             </rules>         </rewrite>     </system.webServer> </configuration> Try the Rule Out Now that we’ve saved the rule, let’s try it out on our site.  Try the following two URLs on my site: http://scottgu.com/Albums.aspx http://scottgu.com/albums.aspx Notice that the first URL (which has a capital “A”) automatically does a redirect to a lower-case version of the URL.  Scenario 3: Trailing Slashes Another common SEO problem I discussed earlier in this post is the scenario of trailing slashes within URLs.  The trailing slash creates yet another situation that causes search engines to treat the URLs as different and so split search rankings: http://scottgu.com http://scottgu.com/ We can fix this by adding a new IIS Rewrite rule that automatically redirects anyone who navigates to the first URL (that does not have a trailing slash) to instead go to the second one that does.  Like before, we will setup the HTTP redirect to be a “permanent redirect” – which will indicate to search engines that they should follow the redirect and use the new URL they are redirected to as the identifier of the content they retrieve.  To create such a rule we’ll click the “Add Rule” link in the URL Rewrite admin tool again.  This will cause the “Add Rule” dialog to appear again: The URL Rewrite admin tool has a built-in “Append or remove the trailing slash symbol” rule template.  When we select it and click the “ok” button we’ll see the following dialog which asks us if we want to create a rule that automatically redirects users to a URL with a trailing slash if one isn’t present: Like within our previous lower-casing rewrite rule we’ll add one additional condition clause that will exclude WebResource.axd URLs from being processed by this rule.  This will avoid an unnecessary redirect for happening for those URLs. When we click the “OK” button we’ll get a pre-written rule that automatically performs a permanent redirect if the URL doesn’t have a trailing slash – and if the URL is not processed by either a directory or a file.  This will save the following additional rule to our web.config file: <configuration>     <system.webServer>         <rewrite>             <rules>                 <rule name="Default Document" stopProcessing="true">                     <match url="(.*?)/?Default\.aspx$" />                     <action type="Redirect" url="{R:1}/" />                 </rule>                 <rule name="Lower Case URLs" stopProcessing="true">                     <match url="[A-Z]" ignoreCase="false" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{URL}" pattern="WebResource.axd" negate="true" />                     </conditions>                     <action type="Redirect" url="{ToLower:{URL}}" />                 </rule>                 <rule name="Trailing Slash" stopProcessing="true">                     <match url="(.*[^/])$" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />                         <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />                         <add input="{URL}" pattern="WebResource.axd" negate="true" />                     </conditions>                     <action type="Redirect" url="{R:1}/" />                 </rule>             </rules>         </rewrite>     </system.webServer> </configuration> Try the Rule Out Now that we’ve saved the rule, let’s try it out on our site.  Try the following two URLs on my site: http://scottgu.com http://scottgu.com/ Notice that the first URL (which has no trailing slash) automatically does a redirect to a URL with the trailing slash.  Because it is a permanent redirect, search engines will follow the URL and update the page ranking. Scenario 4: Canonical Host Names The final SEO problem I discussed earlier are scenarios where a site works with both a leading “www” hostname prefix as well as just the hostname itself.  This causes search engines to treat the URLs as different and split search rankling: http://www.scottgu.com/albums.aspx http://scottgu.com/albums.aspx We can fix this by adding a new IIS Rewrite rule that automatically redirects anyone who navigates to the first URL (that has a www prefix) to instead go to the second URL.  Like before, we will setup the HTTP redirect to be a “permanent redirect” – which will indicate to search engines that they should follow the redirect and use the new URL they are redirected to as the identifier of the content they retrieve.  To create such a rule we’ll click the “Add Rule” link in the URL Rewrite admin tool again.  This will cause the “Add Rule” dialog to appear again: The URL Rewrite admin tool has a built-in “Canonical domain name” rule template.  When we select it and click the “ok” button we’ll see the following dialog which asks us if we want to create a redirect rule that automatically redirects users to a primary host name URL: Above I’m entering the primary URL address I want to expose to the web: scottgu.com.  When we click the “OK” button we’ll get a pre-written rule that automatically performs a permanent redirect if the URL has another leading domain name prefix.  This will save the following additional rule to our web.config file: <configuration>     <system.webServer>         <rewrite>             <rules>                 <rule name="Cannonical Hostname">                     <match url="(.*)" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{HTTP_HOST}" pattern="^scottgu\.com$" negate="true" />                     </conditions>                     <action type="Redirect" url="http://scottgu.com/{R:1}" />                 </rule>                 <rule name="Default Document" stopProcessing="true">                     <match url="(.*?)/?Default\.aspx$" />                     <action type="Redirect" url="{R:1}/" />                 </rule>                 <rule name="Lower Case URLs" stopProcessing="true">                     <match url="[A-Z]" ignoreCase="false" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{URL}" pattern="WebResource.axd" negate="true" />                     </conditions>                     <action type="Redirect" url="{ToLower:{URL}}" />                 </rule>                 <rule name="Trailing Slash" stopProcessing="true">                     <match url="(.*[^/])$" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />                         <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />                         <add input="{URL}" pattern="WebResource.axd" negate="true" />                     </conditions>                     <action type="Redirect" url="{R:1}/" />                 </rule>             </rules>         </rewrite>     </system.webServer> </configuration> Try the Rule Out Now that we’ve saved the rule, let’s try it out on our site.  Try the following two URLs on my site: http://www.scottgu.com/albums.aspx http://scottgu.com/albums.aspx Notice that the first URL (which has the “www” prefix) now automatically does a redirect to the second URL which does not have the www prefix.  Because it is a permanent redirect, search engines will follow the URL and update the page ranking. 4 Simple Rules for Improved SEO The above 4 rules are pretty easy to setup and should take less than 15 minutes to configure on existing sites you already have.  The beauty of using a solution like the URL Rewrite Extension is that you can take advantage of it without having to change code within your web-site – and without having to break any existing links already pointing at your site.  Users who follow existing links will be automatically redirected to the new URLs you wish to publish.  And search engines will start to give your site a higher search relevancy ranking – which will list your site higher in search results and drive more traffic to it. Customizing your URL Rewriting rules further is easy to-do either by editing the web.config file directly, or alternatively, just double click the URL Rewrite icon within the IIS 7.x admin tool and it will list all the active rules for your web-site or application: Clicking any of the rules above will open the rules editor back up and allow you to tweak/customize/save them further. Summary Measuring and improving SEO is something every developer building a public-facing web-site needs to think about and focus on.  If you haven’t already, download and use the SEO Toolkit to analyze the SEO of your sites today. New URL Routing features in ASP.NET MVC and ASP.NET Web Forms 4 make it much easier to build applications that have more control over the URLs that are published.  Tools like the URL Rewrite Extension that I’ve talked about in this blog post make it much easier to improve the URLs that are published from sites you already have built today – without requiring you to change a lot of code. The URL Rewrite Extension provides a bunch of additional great capabilities – far beyond just SEO - as well.  I’ll be covering these additional capabilities more in future blog posts. Hope this helps, Scott

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• MvcExtensions - PerRequestTask

  - by kazimanzurrashid

  In the previous post, we have seen the BootstrapperTask which executes when the application starts and ends, similarly there are times when we need to execute some custom logic when a request starts and ends. Usually, for this kind of scenario we create HttpModule and hook the begin and end request events. There is nothing wrong with this approach, except HttpModules are not at all IoC containers friendly, also defining the HttpModule execution order is bit cumbersome, you either have to modify the machine.config or clear the HttpModules and add it again in web.config. Instead, you can use the PerRequestTask which is very much container friendly as well as supports execution orders. Lets few examples where it can be used. Remove www Subdomain Lets say we want to remove the www subdomain, so that if anybody types http://www.mydomain.com it will automatically redirects to http://mydomain.com. public class RemoveWwwSubdomain : PerRequestTask { public RemoveWww() { Order = DefaultOrder - 1; } protected override TaskContinuation ExecuteCore(PerRequestExecutionContext executionContext) { const string Prefix = "http://www."; Check.Argument.IsNotNull(executionContext, "executionContext"); HttpContextBase httpContext = executionContext.HttpContext; string url = httpContext.Request.Url.ToString(); bool startsWith3W = url.StartsWith(Prefix, StringComparison.OrdinalIgnoreCase); bool shouldContinue = true; if (startsWith3W) { string newUrl = "http://" + url.Substring(Prefix.Length); HttpResponseBase response = httpContext.Response; response.StatusCode = (int)HttpStatusCode.MovedPermanently; response.Status = "301 Moved Permanently"; response.RedirectLocation = newUrl; response.SuppressContent = true; shouldContinue = false; } return shouldContinue ? TaskContinuation.Continue : TaskContinuation.Break; } } As you can see, first, we are setting the order so that we do not have to execute the remaining tasks of the chain when we are redirecting, next in the ExecuteCore, we checking the whether www is present, if present we are sending a permanently moved http status code and breaking the task execution chain otherwise we are continuing with the chain. Blocking IP Address Lets take another scenario, your application is hosted in a shared hosting environment where you do not have the permission to change the IIS setting and you want to block certain IP addresses from visiting your application. Lets say, you maintain a list of IP address in database/xml files which you want to block, you have a IBannedIPAddressRepository service which is used to match banned IP Address. public class BlockRestrictedIPAddress : PerRequestTask { protected override TaskContinuation ExecuteCore(PerRequestExecutionContext executionContext) { bool shouldContinue = true; HttpContextBase httpContext = executionContext.HttpContext; if (!httpContext.Request.IsLocal) { string ipAddress = httpContext.Request.UserHostAddress; HttpResponseBase httpResponse = httpContext.Response; if (executionContext.ServiceLocator.GetInstance<IBannedIPAddressRepository>().IsMatching(ipAddress)) { httpResponse.StatusCode = (int)HttpStatusCode.Forbidden; httpResponse.StatusDescription = "IPAddress blocked."; shouldContinue = false; } } return shouldContinue ? TaskContinuation.Continue : TaskContinuation.Break; } } Managing Database Session Now, let see how it can be used to manage NHibernate session, assuming that ISessionFactory of NHibernate is already registered in our container. public class ManageNHibernateSession : PerRequestTask { private ISession session; protected override TaskContinuation ExecuteCore(PerRequestExecutionContext executionContext) { ISessionFactory factory = executionContext.ServiceLocator.GetInstance<ISessionFactory>(); session = factory.OpenSession(); return TaskContinuation.Continue; } protected override void DisposeCore() { session.Close(); session.Dispose(); } } As you can see PerRequestTask can be used to execute small and precise tasks in the begin/end request, certainly if you want to execute other than begin/end request there is no other alternate of HttpModule. That’s it for today, in the next post, we will discuss about the Action Filters, so stay tuned.

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• Rules and advice for logging?

  - by Nick Rosencrantz

  In my organization we've put together some rules / guildelines about logging that I would like to know if you can add to or comment. We use Java but you may comment in general about loggin - rules and advice Use the correct logging level ERROR: Something has gone very wrong and need fixing immediately WARNING: The process can continue without fixing. The application should tolerate this level but the warning should always get investigated. INFO: Information that an important process is finished DEBUG. Is only used during development Make sure that you know what you're logging. Avoid that the logging influences the behavior of the application The function of the logging should be to write messages in the log. Log messages should be descriptive, clear, short and concise. There is not much use of a nonsense message when troubleshooting. Put the right properties in log4j Put in that the right method and class is written automatically. Example: Datedfile -web log4j.rootLogger=ERROR, DATEDFILE log4j.logger.org.springframework=INFO log4j.logger.waffle=ERROR log4j.logger.se.prv=INFO log4j.logger.se.prv.common.mvc=INFO log4j.logger.se.prv.omklassning=DEBUG log4j.appender.DATEDFILE=biz.minaret.log4j.DatedFileAppender log4j.appender.DATEDFILE.layout=org.apache.log4j.PatternLayout log4j.appender.DATEDFILE.layout.ConversionPattern=%d{HH:mm:ss,SSS} %-5p [%C{1}.%M] - %m%n log4j.appender.DATEDFILE.Prefix=omklassning. log4j.appender.DATEDFILE.Suffix=.log log4j.appender.DATEDFILE.Directory=//localhost/WebSphereLog/omklassning/ Log value. Please log values from the application. Log prefix. State which part of the application it is that the logging is written from, preferably with something for the project agreed prefix e.g. PANDORA_DB The amount of text. Be careful so that there is not too much logging text. It can influence the performance of the app. Loggning format: -There are several variants and methods to use with log4j but we would like a uniform use of the following format, when we log at exceptions: logger.error("PANDORA_DB2: Fel vid hämtning av frist i TP210_RAPPORTFRIST", e); In the example above it is assumed that we have set log4j properties so that it automatically write the class and the method. Always use logger and not the following: System.out.println(), System.err.println(), e.printStackTrace() If the web app uses our framework you can get very detailed error information from EJB, if using try-catch in the handler and logging according to the model above: In our project we use this conversion pattern with which method and class names are written out automatically . Here we use two different pattents for console and for datedfileappender: log4j.appender.CONSOLE.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n log4j.appender.DATEDFILE.layout.ConversionPattern=%d [%t] %-5p %c - %m%n In both the examples above method and class wioll be written out. In the console row number will also be written our. toString() Please have a toString() for every object. EX: @Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append(" DwfInformation [ "); sb.append("cc: ").append(cc); sb.append("pn: ").append(pn); sb.append("kc: ").append(kc); sb.append("numberOfPages: ").append(numberOfPages); sb.append("publicationDate: ").append(publicationDate); sb.append("version: ").append(version); sb.append(" ]"); return sb.toString(); } instead of special method which make these outputs public void printAll() { logger.info("inbet: " + getInbetInput()); logger.info("betdat: " + betdat); logger.info("betid: " + betid); logger.info("send: " + send); logger.info("appr: " + appr); logger.info("rereg: " + rereg); logger.info("NY: " + ny); logger.info("CNT: " + cnt); } So is there anything you can add, comment or find questionable with these ways of using the logging? Feel free to answer or comment even if it is not related to Java, Java and log4j is just an implementation of how this is reasoned.

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