Search Results

Search found 2138 results on 86 pages for 'daniel ball'.

Page 86/86 | < Previous Page | 82 83 84 85 86 

• Parse XML tree with no id using LINQ to XML

  - by Danny

  Requirement I want to read a XML tree, fill my objects with encountered attributes and after every run a method (insert it into my db). The amount of parents is not specified, also the order is not specified, it could be, address-death-death-address-address for example Input file Overview: <Root> <Element> <Element2> <Parent> <Child> <Grandchild> <Grandchild> </Child> </Parent> </Element2> </Element1> </Root> Full example: <?xml version="1.0" encoding="utf-8" ?> <Root> <Element1> <Element2> <Parent> <Child> <Grandchild> <number>01</number> <name>Person</name> <Rows> <Row> <number>0110</number> <name>ID</name> <value>123456789</value> </Row> </Rows> </Grandchild> <Grandchild> <number>08</number> <name>Address</name> <Rows> <Row> <number>1110</number> <name>street</name> <value>first aveneu</value> </Row> <Row> <number>1120</number> <name>streetnumber</name> <value>345</value> </Row> <Row> <number>1130</number> <name>zip</name> <value>2938PS</value> </Row> <Row> <number>1160</number> <name>country</name> <value>Germany</value> </Row> </Rows> </Grandchild> </Child> </Parent> <Parent> <Child> <Grandchild> <number>01</number> <name>Person</name> <Rows> <Row> <number>0110</number> <name>ID</name> <value>987654321</value> </Row> </Rows> </Grandchild> <Grandchild> <number>06</number> <name>Death</name> <Rows> <Row> <number>0810</number> <name>date</name> <value>2012-01-03</value> </Row> <Row> <number>0820</number> <name>placeOfDeath</name> <value>attic</value> </Row> <Row> <number>0830</number> <name>funeral</name> <value>burrial</value> </Row> </Rows> </Grandchild> </Child> </Parent> </Element2> </Element1> </Root> Desired result After encounter of parent determine type of grandchild (number 6 is death number 8 is address) Every parent has ALWAYS grandchild number 1 'Person', the second grandchild is either death or address. reading first parent Person person = new Person(); person.ID = value; <--- filled with 123456789 person.street = value; <--- filled with first aveneu person.streetnumber = value; <--- filled with 345 person.zip = value; <--- filled with 2938PS person.country = value; <--- filled with germany person.DoMethod(); // inserts the value in db Continue reading next parent. Person person = new Person(); person.ID = value; <--- filled with 987654321 person.date = value; <--- filled with 2012-01-03 person.placeOfDeath = value; <--- filled with attic person.funeral = value; <--- filled with burrial person.DoMethod(); // insert the values in db Continue reading till no parents found EDIT: how do I target the name element of the second grandchild for every child? Like address or death Code/Credit I got no further then this, with help of Daniel Hilgarth: Linq to XML (C#) parse XML tree with no attributes/id to object The XML tree has changed, and I am really stuck.. in the meantime I try to post new working code...

  Read the article

• Need Help Customizing a Grammar Checking Replace Rule in Java

  - by user567785

  Hello, I am currently adding the Khmer (Cambodian) language to LanguageTool, an opensource grammar checker for OpenOffice (http://www.languagetool.org). I don't know enough Java to customize one of the scripts and wanted to make a request here asking if anyone would be willing to customize it for me (I can put link to your website at http://www.sbbic.org/lang/en-us/volunteer/ if you help). Here is the script that needs customization KhmerWordCoherencyRule.java: /* LanguageTool, a natural language style checker * Copyright (C) 2005 Daniel Naber (http://www.danielnaber.de) * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 * USA */ package de.danielnaber.languagetool.rules.km; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Locale; import java.util.Map; import java.util.ResourceBundle; import de.danielnaber.languagetool.AnalyzedSentence; import de.danielnaber.languagetool.AnalyzedToken; import de.danielnaber.languagetool.AnalyzedTokenReadings; import de.danielnaber.languagetool.JLanguageTool; import de.danielnaber.languagetool.tools.StringTools; import de.danielnaber.languagetool.rules.Category; import de.danielnaber.languagetool.rules.RuleMatch; /** * A Khmer rule that matches words or phrases which should not be used and suggests * correct ones instead. Loads the relevant words from * <code>rules/km/coherency.txt</code>, where km is a code of the language. * * @author Andriy Rysin */ public abstract class KhmerWordCoherencyRule extends KhmerRule { private static final String FILE_ENCODING = "utf-8"; private Map<String, String> wrongWords; // e.g. "????? -> "?????" private static final String FILE_NAME = "/km/coherency.txt"; public abstract String getFileName(); public String getEncoding() { return FILE_ENCODING; } /** * Indicates if the rule is case-sensitive. Default value is <code>true</code>. * @return true if the rule is case-sensitive, false otherwise. */ //in Khmer there is no case public boolean isCaseSensitive() { return false; } /** * @return the locale used for case conversion when {@link #isCaseSensitive()} is set to <code>false</code>. */ public Locale getLocale() { return Locale.getDefault(); } public KhmerWordCoherencyRule(final ResourceBundle messages) throws IOException { if (messages != null) { super.setCategory(new Category(messages.getString("category_misc"))); } wrongWords = loadWords(JLanguageTool.getDataBroker().getFromRulesDirAsStream(getFileName())); } public String getId() { return "KM_WORD_COHERENCY"; } public String getDescription() { return "Checks for wrong words/phrases"; } public String getSuggestion() { return " does not match your previous spelling of the word, use "; } public String getShort() { return "Use a consistant spelling throughout"; } public final RuleMatch[] match(final AnalyzedSentence text) { final List<RuleMatch> ruleMatches = new ArrayList<RuleMatch>(); final AnalyzedTokenReadings[] tokens = text.getTokensWithoutWhitespace(); for (int i = 1; i < tokens.length; i++) { final String token = tokens[i].getToken(); final String origToken = token; final String replacement = isCaseSensitive()?wrongWords.get(token):wrongWords.get(token.toLowerCase(getLocale())); if (replacement != null) { final String msg = token + getSuggestion() + replacement; final int pos = tokens[i].getStartPos(); final RuleMatch potentialRuleMatch = new RuleMatch(this, pos, pos + origToken.length(), msg, getShort()); if (!isCaseSensitive() && StringTools.startsWithUppercase(token)) { potentialRuleMatch.setSuggestedReplacement(StringTools.uppercaseFirstChar(replacement)); } else { potentialRuleMatch.setSuggestedReplacement(replacement); } ruleMatches.add(potentialRuleMatch); } } return toRuleMatchArray(ruleMatches); } private Map<String, String> loadWords(final InputStream file) throws IOException { final Map<String, String> map = new HashMap<String, String>(); InputStreamReader isr = null; BufferedReader br = null; try { isr = new InputStreamReader(file, getEncoding()); br = new BufferedReader(isr); String line; while ((line = br.readLine()) != null) { line = line.trim(); if (line.length() < 1) { continue; } if (line.charAt(0) == '#') { // ignore comments continue; } final String[] parts = line.split(";"); if (parts.length != 2) { throw new IOException("Format error in file " + JLanguageTool.getDataBroker().getFromRulesDirAsUrl(getFileName()) + ", line: " + line); } map.put(parts[0], parts[1]); } } finally { if (br != null) { br.close(); } if (isr != null) { isr.close(); } } return map; } public void reset() { } } Here is what I need the SimpleReplaceRule.java to do: 1 - Be able to have more than two spelling variations in the coherency.txt file (right now it can only be Word1;Word2). 2 - Find the first use of ANY of the spelling variations in a document that are found in coherency.txt and then make sure only that spelling is used throughout the document (ex. in the coherency.txt I have Word1;Word2;Word3 then in my document on the first line I write Word2. then on next line I write Word1 and Word 3 - then the grammar checker will flag Word1 and Word3 saying that I should use the spelling "Word2" instead...etc.). If anyone can help I would be grateful! Thanks for your time, Nathan

  Read the article

• Ajax, Callback, postback and Sys.WebForms.PageRequestManager.getInstance().add_beginRequest

  - by user338262

  Hi, I have a user control which encapsulates a NumericUpDownExtender. This UserControl implements the interface ICallbackEventHandler, because I want that when a user changes the value of the textbox associated a custom event to be raised in the server. By the other hand each time an async postback is done I shoe a message of loading and disable the whole screen. This works perfect when something is changed in for example an UpdatePanel through this lines of code: Sys.WebForms.PageRequestManager.getInstance().add_beginRequest( function (sender, args) { var modalPopupBehavior = $find('programmaticSavingLoadingModalPopupBehavior'); modalPopupBehavior.show(); } ); The UserControl is placed inside a detailsview which is inside an UpdatePanel in an aspx. When the custom event is raised I want another textbox in the aspx to change its value. So far, When I click on the UpDownExtender, it goes correctly to the server and raises the custom event, and the new value of the textbox is assigned in the server. but it is not changed in the browser. I suspect that the problem is the callback, since I have the same architecture for a UserControl with an AutoCompleteExtender which implement IPostbackEventHandler and it works. Any clues how can I solve this here to make the UpDownNumericExtender user control to work like the AutComplete one? This is the code of the user control and the parent: using System; using System.Web.UI; using System.ComponentModel; using System.Text; namespace Corp.UserControls { [Themeable(true)] public partial class CustomNumericUpDown : CorpNumericUpDown, ICallbackEventHandler { protected void Page_PreRender(object sender, EventArgs e) { if (!Page.IsPostBack) { currentInstanceNumber = CorpAjaxControlToolkitUserControl.getNextInstanceNumber(); } registerControl(this.HFNumericUpDown.ClientID, currentInstanceNumber); string strCallServer = "NumericUpDownCallServer" + currentInstanceNumber.ToString(); // If this function is not written the callback to get the disponibilidadCliente doesn't work if (!Page.ClientScript.IsClientScriptBlockRegistered("ReceiveServerDataNumericUpDown")) { StringBuilder str = new StringBuilder(); str.Append("function ReceiveServerDataNumericUpDown(arg, context) {}").AppendLine(); Page.ClientScript.RegisterClientScriptBlock(typeof(CorpNumericUpDown), "ReceiveServerDataNumericUpDown", str.ToString(), true); } nudeNumericUpDownExtender.BehaviorID = "NumericUpDownEx" + currentInstanceNumber.ToString(); ClientScriptManager cm = Page.ClientScript; String cbReference = cm.GetCallbackEventReference(this, "arg", "ReceiveServerDataNumericUpDown", ""); String callbackScript = "function " + strCallServer + "(arg, context)" + Environment.NewLine + "{" + Environment.NewLine + cbReference + ";" + Environment.NewLine + "}" + Environment.NewLine; cm.RegisterClientScriptBlock(typeof(CustomNumericUpDown), strCallServer, callbackScript, true); base.Page_PreRender(sender,e); } [System.ComponentModel.Browsable(true)] [System.ComponentModel.Bindable(true)] public Int64 Value { get { return (string.IsNullOrEmpty(HFNumericUpDown.Value) ? Int64.Parse("1") : Int64.Parse(HFNumericUpDown.Value)); } set { HFNumericUpDown.Value = value.ToString(); //txtAutoCompleteCliente_AutoCompleteExtender.ContextKey = value.ToString(); // TODO: Change the text of the textbox } } [System.ComponentModel.Browsable(true)] [System.ComponentModel.Bindable(true)] [Description("The text of the numeric up down")] public string Text { get { return txtNumericUpDown.Text; } set { txtNumericUpDown.Text = value; } } public delegate void NumericUpDownChangedHandler(object sender, NumericUpDownChangedArgs e); public event NumericUpDownChangedHandler numericUpDownEvent; [System.ComponentModel.Browsable(true)] [System.ComponentModel.Bindable(true)] [System.ComponentModel.Description("Raised after the number has been increased or decreased")] protected virtual void OnNumericUpDownEvent(object sender, NumericUpDownChangedArgs e) { if (numericUpDownEvent != null) //check to see if anyone has attached to the event numericUpDownEvent(this, e); } #region ICallbackEventHandler Members public string GetCallbackResult() { return "";//throw new NotImplementedException(); } public void RaiseCallbackEvent(string eventArgument) { NumericUpDownChangedArgs nudca = new NumericUpDownChangedArgs(long.Parse(eventArgument)); OnNumericUpDownEvent(this, nudca); } #endregion } /// <summary> /// Class that adds the prestamoList to the event /// </summary> public class NumericUpDownChangedArgs : System.EventArgs { /// <summary> /// The current selected value. /// </summary> public long Value { get; private set; } public NumericUpDownChangedArgs(long value) { Value = value; } } } using System; using System.Collections.Generic; using System.Text; namespace Corp { /// <summary> /// Summary description for CorpAjaxControlToolkitUserControl /// </summary> public class CorpNumericUpDown : CorpAjaxControlToolkitUserControl { private Int16 _currentInstanceNumber; // This variable hold the instanceNumber assignated at first place. public short currentInstanceNumber { get { return _currentInstanceNumber; } set { _currentInstanceNumber = value; } } protected void Page_PreRender(object sender, EventArgs e) { const string strOnChange = "OnChange"; const string strCallServer = "NumericUpDownCallServer"; StringBuilder str = new StringBuilder(); foreach (KeyValuePair<String, Int16> control in controlsToRegister) { str.Append("function ").Append(strOnChange + control.Value).Append("(sender, eventArgs) ").AppendLine(); str.Append("{").AppendLine(); str.Append(" if (sender) {").AppendLine(); str.Append(" var hfield = document.getElementById('").Append(control.Key).Append("');").AppendLine(); str.Append(" if (hfield.value != eventArgs) {").AppendLine(); str.Append(" hfield.value = eventArgs;").AppendLine(); str.Append(" ").Append(strCallServer + control.Value).Append("(eventArgs, eventArgs);").AppendLine(); str.Append(" }").AppendLine(); str.Append(" }").AppendLine(); str.Append("}").AppendLine(); Page.ClientScript.RegisterClientScriptBlock(typeof(CorpNumericUpDown), Guid.NewGuid().ToString(), str.ToString(), true); } str = new StringBuilder(); foreach (KeyValuePair<String, Int16> control in controlsToRegister) { str.Append(" funcsPageLoad[funcsPageLoad.length] = function() { $find('NumericUpDownEx" + control.Value + "').add_currentChanged(").Append(strOnChange + control.Value).Append(");};").AppendLine(); str.Append(" funcsPageUnLoad[funcsPageUnLoad.length] = function() { $find('NumericUpDownEx" + control.Value + "').remove_currentChanged(").Append(strOnChange + control.Value).Append(");};").AppendLine(); } Page.ClientScript.RegisterClientScriptBlock(typeof(CorpNumericUpDown), Guid.NewGuid().ToString(), str.ToString(), true); } } } and to create the loading view I use this: //The beginRequest event is raised before the processing of an asynchronous postback starts and the postback is sent to the server. You can use this event to call custom script to set a request header or to start an animation that notifies the user that the postback is being processed. Sys.WebForms.PageRequestManager.getInstance().add_beginRequest( function (sender, args) { var modalPopupBehavior = $find('programmaticSavingLoadingModalPopupBehavior'); modalPopupBehavior.show(); } ); //The endRequest event is raised after an asynchronous postback is finished and control has been returned to the browser. You can use this event to provide a notification to users or to log errors. Sys.WebForms.PageRequestManager.getInstance().add_endRequest( function (sender, arg) { var modalPopupBehavior = $find('programmaticSavingLoadingModalPopupBehavior'); modalPopupBehavior.hide(); } ); Thanks in advance! Daniel.

  Read the article

• SOA PARTNER COMMUNITY NEWSLETTER JULY 2012

  - by mseika

  SOA PARTNER COMMUNITY NEWSLETTER JULY 2012 Dear SOA partner community member To provide our community members the best of our knowledge, we want your feedback on our SOA Partner community. Thus we are organizing SOA Partner Community Survey 2012. We request you to participate in the survey and give your valuable feedback on various areas of marketing, sales and education. To continue our successful BPM Suite, Oracle is launching together with you Process Accelerators initiative. It’s your opportunity to co-develop and market predefined processes. Oracle Fusion Applications Design Patterns are a great tool to develop your SOA or BPM solution or process accelerators. To promote your SOA & BPM Specialization we continue to offer several benefits. This month we would like to highlight our Specialization Plaques - make sure you request one for your office! Our Fusion Middleware Summer Camps are booked out, if could not get a seat you can attend the SOA & BPM track @ Virtual Developer Day: Oracle Fusion Development Oracle demo systems offer´s two new demos: Business Driven Development based on BPM Suite & SOA Lifecycle Management. Jürgen KressOracle SOA & BPM Partner Adoption EMEA NEW CONTENT Community SurveyProcess Accelerators KitPlaques SOA & BPM SpecializedSOA & BPM at Virtual Developer Day News from our Partners & CommunityOverview of SOA Diagnostics in 11.1.1.6 Business driven development(BDD) demo now available! SOA Lifecycle Management Oracle Fusion applications design patterns Updated material by Oracle Connect and Network SOA Blogs SOA on Facebook SOA on LinkedIn SOA on Twitter Mix SOA Forum COMMUNITY SURVEY Like every year we would like to get your feedback in our SOA Partner Community Survey 2012. Make sure that You attend to further develop our community and support our planning! It is key for us to get your feedback to prepare for the next fiscal year. Back to top PROCESS ACCELERATORS KIT Oracle is very interested to co-develop and market with you, our partners, pre-defined processes for BPM Suite.I am very happy to announce a new program called “Oracle BPM Partner Solution Catalog”. This program will provide a one-stop shop for our customers looking for Oracle BPM partner solutions available in the market today.The Oracle BPM Solution Catalog will be hosted on our very popular Oracle Technology Network (OTN). To give you an idea of the scale of customer visibility, OTN today receives over 1Million hits per day from our business and developer community. We would like to invite you to list your Oracle BPM 11g solutions available today.In order to participate in this program, you need to do the following: Fill in the attached slide templates - #3 and #4 for each Oracle BPM 11g solution you would like to list on OTN.Please add links to whitepapers , videos, references to the specific solution in the template slide. We recommend that you create a landing page on your website for these linked artifacts and just point to the same from within the PowerPoint template. This will give you the flexibility to update the information as frequently as needed. If you have the particular solution in production or a reference available, please list them as well. Send the PowerPoint template slides (1 set of slides for each Oracle BPM solution) to [email protected]. In addition to having the opportunity to list your solutions on OTN for Oracle customers, you will have the chance to advertise your new wins/implementations/solutions in an Oracle Sponsored PM Webinar held every quarter. This program is targeted to go live by the end of summer 2012. At this point, we are targeting a soft launch in July end 2012 so send on your BPM solutions information as soon as possible. We would love to have your solution(s) listed in the “Oracle BPM Partner Solution Catalog” at the time of the launch. This will be a live repository so you can keep adding more solutions as they become available. If you have any questions, please feel free to contact us [email protected], Product Strategy Director, Oracle BPM , Phone +1 650.506.5486.Thank you and look forward to hearing from you. Oracle BPM team Process Accelerators Overview.pdf ProcessAcceleratorsDataSheet.pdf Demos draUPK.zip & trmUPK.zip BPM Solution repository slides.ppt Additional BPM material BPM Process Development Lifecycle Document that describes recommended approach to collaborative process modeling across business and IT tools ADF 11g PS5 Application with Customized BPM Worklist Task Flow (MDS Seeded Customization) by Andrejus Baranovskis BPMN process editor problems in 11.1.1.6 by Mark Nelson BPM – Disable DBMS job to refresh B2B Materialized View by Mark Nelson For the complete kit please visit the BPM folder at our SOA Community Workspace (SOA Community membership required). For the complete presentation please visit our SOA Community Workspace (SOA Community membership required). Information is Oracle and Partner confidential! Back to top PLAQUES SOA & BPM SPECIALIZED We continue to offer you a nice SOA & BPM Specialization plaque with your logo to proof your success. If you are a SOA or BPM Specialized partner and would like to request the plaque please send Brigitte an e-mail with the following information: Partner Name Partner logo (preferred eps file) Partner Status gold or platinum Your shipping address Your Specialization: SOA or BPM We recommend to mount the plaque at your office reception in addition you can use the SOA Specialization logos at your website download Logo: Gold & Platinum or the BPM logos Gold & Platinum Back to top SOA & BPM AT VIRTUAL DEVELOPER DAY Register now for this FREE hands-on online workshop Get up to date and learn everything you wanted to know about Oracle ADF & Fusion Development plus live Q&A chats with Oracle technical staffOracle Application Development Framework (ADF) is the standards based, strategic framework for Oracle Fusion Applications and Oracle Fusion Middleware. Oracle ADF’s integration with the Oracle SOA Suite, Oracle WebCenter and Oracle BI creates a complete productive development platform for your custom applications.Join us at this FREE virtual event and learn the latest in Fusion Development including: Is Oracle ADF development faster and simpler than Forms, Apex or .Net? Mobile Application Development with ADF Mobile Oracle ADF development with Eclipse Oracle WebCenter Portal and ADF Development Application Lifecycle Management with ADF Building Process Centric Applications with ADF and BPM Oracle Business Intelligence and ADF Integration Live Q&A chats with Oracle technical staff Developer lead, manager or architect - this event has something for everyone. Don’t miss this opportunity.Tuesday, July 10, 2012. 9:00 a.m. PT -1:00 p.m. PT 11:00 a.m. CT - 3:00 p.m. CT 12:00 p.m. ET - 4:00 p.m. ET 1:00 p.m. BRT - 5:00 p.m. BRT Register online now! for this FREE event. Agenda: 09:00 am Opening 09:30 am Keynote: Oracle Fusion Development Track1Introduction to Fusion Development Track2What's New in Fusion Development Track3Fusion Development in the Enterprise 10:00 am Is Oracle ADF Development Faster and Simpler than Oracle Forms, APEX or .Net? Mobile Application Development with ADF Mobile Oracle WebCenter Portal and ADF Development 11:00 am Rich Web UI made simple - an ADF Faces Overview Oracle Enterprise Pack for Eclipse - ADF Development Building Process Centric Applications with ADF and BPM 12:00 noon Next Generation Controller for JSF Application Lifecycle Management for ADF Oracle Business Intelligence and ADF Integration *Hands On Lab – WebCenter and ADF Lab w/ JDeveloper - Lab materials will be provided ahead of the event to give you ample time to work through the lab and increase the productivity of the live chat sessions the day of the event. Sessions abstractsRegister online now! for this FREE event Read more on Community Events and post your comment here. Back to top NEWS FROM OUR PARTNERS AND COMMUNITY Send your tweets @soacommunity #soacommunity and follow us at http://twitter.com/soacommunity JDeveloper & ADF?Troubleshooting BPMN process editor problems in 11.1.1.6http://dlvr.it/1p0FfS SOA Community?SOA & BPM @ Virtual Developer Day: Oracle Fusion Development - July 10th 2012https://soacommunity.wordpress.com/2012/07/02/soa-bpm-virtual-developer-day- oracle-fusion-developmentjuly-10th-2012/#soacommunity #soa #bom #education orclateamsoa ?A-Team Blog #ateam: BAM design pointers - In working recently with a large Oracle customer on SOA and BAM, I discove.http://ow.ly/1kYqES SOA CommunitySOA Community Newsletter June 2012http://wp.me/p10C8u-qw SOA CommunityBPMN process editor problems in 11.1.1.6 by Mark Nelsonhttp://redstack.wordpress.com/2012/06/27/ bpmn-process-editor-problems-in-11-1-1-6 #soacommunity #bpm OTNArchBeat ?SOA Learning Library: free short, topic-focused training on Oracle SOA & BPM products | @SOACommunity http://pub.vitrue.com/NE1G Andrejus Baranovskis ?ADF 11g PS5 Application with Customized BPM Worklist Task Flow (MDS Seeded Customization)http://fb.me/1coX4r1X1 SOA CommunitySOA Learning Library provides a comprehensive curriculum for the SOA and BPM product suites https://soacommunity.wordpress.com/2012/06/27/soa-learning-library #soacommunity #soa #bpm OTNArchBeat ?A Universal JMX Client for Weblogic - Part 1: Monitoring BPEL Thread Pools in SOA 11g | Stefan Koserhttp://pub.vitrue.com/mQVZ OTNArchBeat ?BPM - Disable DBMS job to refresh B2B Materialized View | Mark Nelson http://pub.vitrue.com/3PR0Oracle SOA ?Learn how Choice Hotels Implements Innovative Google Maps Solution with #OracleSOA http://bit.ly/MTwIJ3 SOA Communitytop Tweets SOA Partner Community - June 2012 Send your tweets @soacommunity #soacommunity https://soacommunity.wordpress.com/2012/06/25/top-tweets-soa-partner-community-june-2012 Torsten Winterberg#OPITZ is pushing Oracle commitment to the next level: New Specializations done: ADF, BPM, WLS, Exadatahttp://bit.ly/KX1WVS ServiceTechSymposium ?Only 8 more days left until Super Early Bird Registration Discount expires! http://www.servicetechsymposium.com OracleBlogsSOA Management in 3 minutes - Video explainerhttp://ow.ly/1kN5pn SOA Community ?SOA, Cloud & Service Technology Symposium 2012 London - Enter Promo Code: Djmxz370https://soacommunity.wordpress.com/2012/06/22/soa-cloud-service-technology-symposium-2012-london #soasymposium #soacommunity #soa Heidi BuelowGreat course! w David Read RT @soacommunity: product management ADF for BPM training 5 seats left https://soacommunity.wordpress.com/2012/06/12/fusion-middleware-summer-campsadvanced-partner-trainings/ #bpm #soacommunity SOA Community ?product management ADF for BPM training 5 seats lefthttps://soacommunity.wordpress.com/2012/06/12/fusion-middleware-summer-campsadvanced-partner-trainings/ #bpm #soacommunity OTNArchBeat ?Oacle Fusion Applications Design Patterns Now Available For Developers | Ultan O'Broinhttp://pub.vitrue.com/UEiF OTNArchBeat ?SOA, Cloud & Service Technology Symposium 2012London - Special Oracle Discounthttp://pub.vitrue.com/8E0J SOA CommunityBecome a facebook fan of soacommunity http://www.facebook.com/soacommunity #soacommunity SOA Community ?SOA Suite HealthCare Integration Architecture https://blogs.oracle.com/SOAForHealthcare/entry/soa_suite_healthcare_integration_architecture #soacommunity #soa Andrejus Baranovskis ?Running Pre-built Virtual Machine for SOA Suite and BPM Suite 11g PS5 on Mac OS X Snow Leopard (10.6http://fb.me/vB8nO0Vg OracleBlogsPrinciples of Service-Oriented Architecture by Douwe P. van den Bos http://ow.ly/1kIcOP OTNArchBeatOracle Public Cloud Architecture | @TylerJewell http://ow.ly/bHAcL The SOA Network ?Business Process Management, Service-Oriented Architecture, and Web 2.0: Business Transformation or.http://bit.ly/LBgREL #ITNews #SOA OracleBlogs ?Oracle SOA Foundation Practitioner Certificationhttp://ow.ly/1kGYYg Frank Nimphius ?Learn Advanced ADF. ORACLE Fusion Middleware Summer Camps in Lisbon - July 9th - 13thhttp://bit.ly/KGCl3i SOA CommunityTransform Your Application Integration with Best Practices from Oracle Customershttps://blogs.oracle.com/SOA/entry/transform_your_application_integration_with #soacommunity #soa #bpm Simone GeibWhat you always wanted to know about #oraclesoa diagnostics: Shawn Bailey, Overview of SOA Diagnostics in 11.1.1.6,http://ow.ly/bxK0M Oracle SOA ?Save the date: Jun 21 10AM, SOA & BPM Customer Insight Series. Hear how Choice Hotels went from legacy to #oraclesoa http://bit.ly/LsNDGl OTNArchBeat ?New VirtualBox images for Oracle SOA Suite & Oracle BPM Suite 11.1.1.6.0http://ow.ly/bwDAl OracleBlogs ?Process development lifecycle in Oracle BPM 11g http://ow.ly/1ktesY Daniel AmadeiNew post: Oracle BPEL 11g Message Delivery & Recovery.http://amadei.com.br/blog/index.php /oracle-bpel-11g-message-delivery SOA Community ?Sending out the June edition of the #soacommunity newsletter - read it or become a member http://www.oracle.com/goto/emea/soa!#soa #bpm Arun Pareek ?For the past six months Ahmed Aboulnaga and me have been working on Oracle SOA Suite 11g Administrator's Handbook.http://lnkd.in/CAvpUQ SOA CommunitySun shine all day no clouds - solar eclipse is over... #sunshine #cloud http://www.infoq.com/presentations/Swarm-Computing Michel SchildmeijerWatch my blog Oracle Service Bus 11g: listing projects and services with WLST - part 1 http://lnkd.in/B7f3GQ @TITAN_GS @wlscommunity OTNArchBeatBook Review: Oracle Application Integration Architecture (AIA) Foundation Pack 11gR1: Essentials | Rajesh Rahejahttp://ow.ly/bn2cc OTNArchBeat ?Driving from Business Architecture to Business Process Services | @vghariharan http://ow.ly/bn5UB OTNArchBeat ?SOA Analysis within the Department of Defense Architecture Framework (DoDAF) 2.0 - Part II | Dawit Lessanu http://ow.ly/bn6sX Simone Geib ?Contact me directly for ideas how to improvehttp://bit.ly/advancedsoasuite and additional posts, presentations, white papers, ... #soasuite Simone Geib ?#soasuite advanced OTN page has become too cluttered. Broke it into separate pages to start with. http://bit.ly/advancedsoasuite OracleBlogs ?June Webcast: SOA Gateway Implementation and Troubleshooting (2 sessions) http://ow.ly/1kbRFA ServiceTechSymposium ?New session just posted to calendar: "NoSQL for Data Services, Data Virtualization & Big Data" by Guido Schmutz, Trivadis AG ://ow.ly/bjjOeDebra Lilley ?looks good - real proof people are using the apps ! RT @fteter: Very cool Fusion Applications Help site: http://bit.ly/L3nvOR #FusionApps demed ?rapid proliferation of cloud computing will drive convergence of SOA and cloud paradigms" http://ovum.com/2012/05/18/soa-paves-the-way-for-cloud/ SOA CommunityMiddleware Oracle Excellence Awards 2012-HAPPY NEW YEAR! https://soacommunity.wordpress.com/2012/05/31/middleware-oracle-excellence-awards-2012happy-new-year/ #soacommunity #opn #opnaward #specialization #oracle SOA CommunityHappy New Year #soacommunity thanks for the business! Time for a drink http://pic.twitter.com/zkK08KWB OTNArchBeat ?Who should ‘own’ the Enterprise Architecture? | Michael Glas http://bit.ly/K0ge0Q SOA Communitytop Tweets SOA Partner Community &ndash; May 2012 http://wp.me/p10C8u-pP ServiceTechSymposiumNew session just posted to Symposium calendar: "Elastic SOA in the Cloud" by Steve Millidge, C2B2 Consulting http://www.servicetechsymposium.com/agenda2012.php #elastic_soa_in_the_cloud orclateamsoa ?A-Team Blog #ateam: How to Set JVM Parameters in Oracle SOA 11Ghttp://ow.ly/1k2cnl ServiceTechSymposium ?New session just posted to Symposium calendar: "SOA Governance at EDP: A Global Energy Company" by Manuel Rosa, Linkhttp://www.servicetechsymposium.com/agenda2012.php#soa_governance_at_edp SOA Community ?VirtualBox image SOA Suite & BPM Suite 11.1.1.6.0&ndash;Your feedback?http://wp.me/p10C8u-qh Oracle MiddlewareSave the date: Jun 21 10AM, SOA & BPM Customer Insight Series. Hear how Choice Hotels went from legacy to#oraclesoa http://bit.ly/LU1y5N OTNArchBeat ?Goodbye, Silos. Hello SOA. | @stephanieoverbyhttp://pub.vitrue.com/NJJO SOA CommunityBPM Standard Edition - to start your BPM project http://wp.me/p10C8u-qj Please feel free to send us your news! And add your blog to our SOA blog wiki. Back to top OVERVIEW OF SOA DIAGNOSTICS IN 11.1.1.6 What tools are available for diagnosing SOA Suite issues? There are a variety of tools available to help you and Support diagnose SOA Suite issues in 11g but it can be confusing as to which tool is appropriate for a particular situation and what their relationships are. This blog post will introduce the various tools and attempt to clarify what each is for and how they are related. Let's first list the tools we'll be addressing: RDA: Remote Diagnostic Agent DFW: Diagnostic Framework Selective Tracing DMS: Dynamic Monitoring Service ODL: Oracle Diagnostic Logging ADR: Automatic Diagnostics Repository ADRCI: Automatic Diagnostics Repository Command Interpreter WLDF: WebLogic Diagnostic Framework This overview is not mean to be a comprehensive guide on using all of these tools, however, extensive reference materials are included that will provide many more details on their execution. Another point to note is that all of these tools are applicable for Fusion Middleware as a whole but specific products may or may not have implemented features to leverage them. A couple of the tools have a WebLogic Scripting Tool or 'WLST' interface. WLST is a command interface for executing pre-built functions and custom scripts against a domain. A detailed WLST tutorial is beyond the scope of this post but you can find general information here. There are more specific resources in the below sections.In this post when we refer to 'Enterprise Manager' or 'EM' we are referring to Enterprise Manager Fusion Middleware Control. read the full blog post here. Read more on Oracle and post your comment here. Back to top BUSINESS DRIVEN DEVELOPMENT (BDD) DEMO NOW AVAILABLE! For access to the Oracle demo systems please visit OPN and talk to your Partner Expert DSS is pleased to announce the availability of the demo “Business Driven Development“. This innovative demonstration uses a case-study approach to show business users how they can easily streamline their Business Processes - delivering greater efficiency, agility, visibility and collaboration with Oracle BPM and WebCenter. The BDD demonstration uses a case study-based approach to highlight a business problem at a fictional company, Avitek Corporation, and uses Oracle BPM and Oracle WebCenter to solve the business problem. This holistic approach has specifically been used to appeal to a non-technical business analyst user. This demo is NOT focused on product features, but aims to guide users through a complete BPM lifecycle. The scenario is based on improving a simple order process (scenario details are in the demo script). Avitek Corporation is sufferinng from a manual email-driven ordering process. Sales reps don’t know where the customer orders are stuck (no visibility) and finance users are unable to manually approve every order (no automation). There are several areas where this process can be improved with Business Process Management technology. This demo shows how improving following areas will ignificantly help resolve the business problems Avitek Corporation is facing. Areas for improvement include: Utilizing BPM for process management, rather than an unregulated, email-based process. Utilizing automated services, rather than requiring a human to key into a system. For example, Finance checking the customer’s credit rating is something that could be automated. Centralizing business rules that can be integrated into a business process, rather than requiring a human to process them. For example, Finance must determine when orders can be automatically approved. Provide insight and visibility into the process. For example, Sales Rep needs to know the status of their customer’s orders. The BDD Demo uses the following products. Oracle BPM Suite 11g PS4FP Oracle WebCenter 11g PS4FP (for Process Spaces) Oracle Business Activity Monitoring 11g Oracle Database 11g Back to top SOA LIFECYCLE MANAGEMENT For access to the Oracle demo systems please visit OPN and talk to your Partner Expert We are pleased to announce the availability of the SOA Management demo that showcases some of the key provisioning and lifecycle management capabilities of SOA Management Pack Enterprise Edition (EE). This demo specifically focuses on some of the lifecycle management solutions for Oracle SOA Suite and Oracle Service Bus (OSB). Demo Highlights The demo showcases the following capabilities. Provisioning of SOA Composites Provisioning of OSB Projects Provision SOA and OSB artifacts in a future maintenance window Back to top ORACLE FUSION APPLICATIONS DESIGN PATTERNS The Oracle Fusion Applications user experience design patterns are published! These new, reusable usability solutions and best-practices, which will join the Oracle dashboard patterns and guidelines that are already available online, are used by Oracle to artfully bring to life a new standard in the user experience, or UX, of enterprise applications. Now, the Oracle applications development community can benefit from the science behind the Oracle Fusion Applications user experience, too. These Oracle Fusion Applications UX Design Patterns, or blueprints, enable Oracle applications developers and system implementers everywhere to leverage professional usability insight when: tailoring an Oracle Fusion application, creating coexistence solutions that existing users will be delighted with, thus enabling graceful user transitions to Oracle Fusion Applications down the road, or designing exciting, new, highly usable applications in the cloud or on-premise. Based on the Oracle Application Development Framework (ADF) components, the Oracle Fusion Applications patterns and guidelines are proven with real users and in the Applications UX usability labs, so you can get right to work coding productivity-enhancing designs that provide an advantage for your entire business. What’s the best way to get started? We’ve made that easy, too. The Design Filter Tool (DeFT) selects the best pattern for your user type and task. Simply adapt your selection for your own task flow and content, and you’re on your way to a really great applications user experience. More Oracle applications design patterns and training are coming your way in the future. To provide feedback on the sets that are currently available, let me know in the comments! Read more on Fusionapps and post your comment here. Back to top UPDATED ORACLE MATERIAL Integrated SOA Gateway Documentation - Implementation Guide | Developer’s Guide Webcast Series: Oracle’s SOA and Oracle Business Process Management Solutions (Choice Hotels, Eaton, Farmers Insurance) BAM design pointers By Kavitha Srinivasan Seeking Oracle Fusion Middleware Go Live StoriesOracle Fusion Middleware product management is looking for recent go live stories to share with the Oracle sales team, sales consulting, product management and other internal groups. Customer contact details may remain anonymous. Your successful implementation will be featured in a quarterly report. The chance to present on an internal webcast is also available. Contact Maria Forney ([email protected]) if you have a noteworthy implementation success story. This is a good opportunity for partners interested in showcasing Oracle Fusion Middleware implementations, and gaining more exposure within Oracle. Performance tuning resources. All in one: docs, blogs, WPs, ppts: http://bit.ly/soa_resources Back to top HAVE YOU MISSED OUR LAST SOA PARTNER COMMUNITY WEBCASTS? UPK Webcast Business Driven Application Management & BPM11g & Application Grid & GoldenGate & Fusion Middleware Pricing & OC4J to WebLogic & Next Generation SOA & Fusion Middleware in Utility & Fusion Middleware in Communications & Fusion Middleware in Public Services & Fusion Middleware in Financial Services Please check your local OPN trainings calendar for additional training dates and locations. Back to top SOA PARTNER COMMUNITY CALENDAR On-Demand Trainings Event Name Language Type SOA Virtual Developers Day English Tech In-Class Trainings Date Event name Location / Country Contact person Type 09-13.07.2012 BPM Suite 11g advanced training by David Read Lisbon, Portugal Jürgen Kress Tech 09-13.07.2012 ADF 11g advanced training by Grant Ronald and Frank Nimphius Lisbon, Portugal Jürgen Kress Tech 09-13.07.2012 WebCenter Portal advanced training by Stefan Krantz and Angelo Santagata Lisbon, Portugal Jürgen Kress Tech 10.07.2012 Fusion Middleware Virtual Developer Day Online OTN Tech 10- 12.07.2012 WebLogic 12c training by Cosmin Tudor Lisbon, Portugal Jürgen Kress Tech 16-18.07.2012 SOA Suite 11g advanced training by Niall Commiskey Munich, Germany Jürgen Kress Tech 16-18.07.2012 ADF for BPM Suite 11g advanced training by David Read Munich, Germany Jürgen Kress Tech 16-18.07.2012 WebCenter Sites 11g advanced training by Product Management Munich, Germany Jürgen Kress Tech 17-20.07.2012 Oracle BPM 11g Implementation Bootcamp Live Virtual Class Oracle University Tech 23-26.07.2012 Oracle BPM 11g Implementation Bootcamp Utrecht, Netherlands Oracle University Tech 29-31.08.2012 Oracle BPM 11g Implementation Bootcamp Live Virtual Class Oracle University Tech 02-05.10.2012 Oracle BPM 11g Implementation Bootcamp Utrecht, Netherlands Oracle University Tech 15-18.10.2012 Oracle BPM 11g Implementation Bootcamp Utrecht, Netherlands Oracle University Tech 28-30.11.2012 Oracle AIA 11g Implementation Bootcamp Live Virtual Class Oracle University Tech 11-14.12.2012 Oracle BPM 11g Implementation Bootcamp Live Virtual Class Oracle University Tech 20-22.2.2013 Oracle AIA 11g Implementation Bootcamp Utrecht, Netherlands Oracle University Tech 14-17.1.2013 Oracle BPM 11g Implementation Bootcamp Utrecht, Netherlands Oracle University Tech 15-18.3.2013 Oracle BPM 11g Implementation Bootcamp Utrecht, Netherlands Oracle University Tech Please check your local OPN Training Calendar for additional training and locations here. Back to top SOASCHOOL.COM - SOA CERTIFIED PROFESSIONAL(SOACP) PROGRAM The SOASchool.com - SOA Certified Professional (SOACP) program is dedicated to excellence in the field of SOA and service-oriented computing. Through a series of seasoned course modules and exams, IT professionals have the opportunity to obtain a number of different certifications to recognize their accomplishment of gaining "project ready" SOA proficiency. This comprehensive and strictly vendor-neutral program was developed in cooperation with best-selling SOA author Thomas Erl and several major SOA organizations and academic institutions. Through the involvement of the SOA Education Committee, course contents and certification requirements are constantly reviewed and revised to stay current with developments in the service-oriented computing industry. The program is currently comprised of 12 course modules and 5 certifications and is expanding to 18 course modules and 8 certifications throughout 2009. For more information, visit www.soaschool.com and www.soacp.com. Blog Twitter LinkedIn Mix Forum Wiki Back to top YOUR CONTENT ON THE NEWSLETTER AND ON THE SOA COMMUNITY PORTAL Publishing Your StoriesWe would like to invite our partners to publish information in the newsletter or on our SOA Community portal. Especially we are looking for your real life experience with our SOA technology. Please send your documents to Jürgen Kress. We look forward to getting your suggestions! Back to top SOA DISCUSSION FORUM BECOMES INTERACTIVE AT THE SOA COMMUNITY! Do you want to chat to experts, including partners and Oracle SOA Product Development? Do you want to get the latest information about our SOA solutions and events?Attend our private online SOA Discussion Forum at OTN. Please send your OTN forums user name to Brigitte Felisaz. You must be a registered user to access the SOA Discussion Forum. Back to top INVITE YOUR COLLEAGUES TO JOIN THE SOA COMMUNITY Please feel free to invite your colleagues to join the SOA Community and to participate in the SOA Assessment tests. For registration please login the Oracle PartnerNetwork and go to: www.oracle.com/goto/emea/soa For any questions on the above or concerning SOA and Oracle in general please contact the Oracle EMEA Alliances & Channels SOA Team. Best regardsOracle EMEA SOA TeamJürgen Kress Jürgen KressSOA Partner Adoption EMEATel. +49 89 1430 1479E-Mail: [email protected]

  Read the article

• Syncing Data with a Server using Silverlight and HTTP Polling Duplex

  - by dwahlin

  Many applications have the need to stay in-sync with data provided by a service. Although web applications typically rely on standard polling techniques to check if data has changed, Silverlight provides several interesting options for keeping an application in-sync that rely on server “push” technologies. A few years back I wrote several blog posts covering different “push” technologies available in Silverlight that rely on sockets or HTTP Polling Duplex. We recently had a project that looked like it could benefit from pushing data from a server to one or more clients so I thought I’d revisit the subject and provide some updates to the original code posted. If you’ve worked with AJAX before in Web applications then you know that until browsers fully support web sockets or other duplex (bi-directional communication) technologies that it’s difficult to keep applications in-sync with a server without relying on polling. The problem with polling is that you have to check for changes on the server on a timed-basis which can often be wasteful and take up unnecessary resources. With server “push” technologies, data can be pushed from the server to the client as it changes. Once the data is received, the client can update the user interface as appropriate. Using “push” technologies allows the client to listen for changes from the data but stay 100% focused on client activities as opposed to worrying about polling and asking the server if anything has changed. Silverlight provides several options for pushing data from a server to a client including sockets, TCP bindings and HTTP Polling Duplex.  Each has its own strengths and weaknesses as far as performance and setup work with HTTP Polling Duplex arguably being the easiest to setup and get going.  In this article I’ll demonstrate how HTTP Polling Duplex can be used in Silverlight 4 applications to push data and show how you can create a WCF server that provides an HTTP Polling Duplex binding that a Silverlight client can consume.   What is HTTP Polling Duplex? Technologies that allow data to be pushed from a server to a client rely on duplex functionality. Duplex (or bi-directional) communication allows data to be passed in both directions.  A client can call a service and the server can call the client. HTTP Polling Duplex (as its name implies) allows a server to communicate with a client without forcing the client to constantly poll the server. It has the benefit of being able to run on port 80 making setup a breeze compared to the other options which require specific ports to be used and cross-domain policy files to be exposed on port 943 (as with sockets and TCP bindings). Having said that, if you’re looking for the best speed possible then sockets and TCP bindings are the way to go. But, they’re not the only game in town when it comes to duplex communication. The first time I heard about HTTP Polling Duplex (initially available in Silverlight 2) I wasn’t exactly sure how it was any better than standard polling used in AJAX applications. I read the Silverlight SDK, looked at various resources and generally found the following definition unhelpful as far as understanding the actual benefits that HTTP Polling Duplex provided: "The Silverlight client periodically polls the service on the network layer, and checks for any new messages that the service wants to send on the callback channel. The service queues all messages sent on the client callback channel and delivers them to the client when the client polls the service." Although the previous definition explained the overall process, it sounded as if standard polling was used. Fortunately, Microsoft’s Scott Guthrie provided me with a more clear definition several years back that explains the benefits provided by HTTP Polling Duplex quite well (used with his permission): "The [HTTP Polling Duplex] duplex support does use polling in the background to implement notifications – although the way it does it is different than manual polling. It initiates a network request, and then the request is effectively “put to sleep” waiting for the server to respond (it doesn’t come back immediately). The server then keeps the connection open but not active until it has something to send back (or the connection times out after 90 seconds – at which point the duplex client will connect again and wait). This way you are avoiding hitting the server repeatedly – but still get an immediate response when there is data to send." After hearing Scott’s definition the light bulb went on and it all made sense. A client makes a request to a server to check for changes, but instead of the request returning immediately, it parks itself on the server and waits for data. It’s kind of like waiting to pick up a pizza at the store. Instead of calling the store over and over to check the status, you sit in the store and wait until the pizza (the request data) is ready. Once it’s ready you take it back home (to the client). This technique provides a lot of efficiency gains over standard polling techniques even though it does use some polling of its own as a request is initially made from a client to a server. So how do you implement HTTP Polling Duplex in your Silverlight applications? Let’s take a look at the process by starting with the server. Creating an HTTP Polling Duplex WCF Service Creating a WCF service that exposes an HTTP Polling Duplex binding is straightforward as far as coding goes. Add some one way operations into an interface, create a client callback interface and you’re ready to go. The most challenging part comes into play when configuring the service to properly support the necessary binding and that’s more of a cut and paste operation once you know the configuration code to use. To create an HTTP Polling Duplex service you’ll need to expose server-side and client-side interfaces and reference the System.ServiceModel.PollingDuplex assembly (located at C:\Program Files (x86)\Microsoft SDKs\Silverlight\v4.0\Libraries\Server on my machine) in the server project. For the demo application I upgraded a basketball simulation service to support the latest polling duplex assemblies. The service simulates a simple basketball game using a Game class and pushes information about the game such as score, fouls, shots and more to the client as the game changes over time. Before jumping too far into the game push service, it’s important to discuss two interfaces used by the service to communicate in a bi-directional manner. The first is called IGameStreamService and defines the methods/operations that the client can call on the server (see Listing 1). The second is IGameStreamClient which defines the callback methods that a server can use to communicate with a client (see Listing 2).   [ServiceContract(Namespace = "Silverlight", CallbackContract = typeof(IGameStreamClient))] public interface IGameStreamService { [OperationContract(IsOneWay = true)] void GetTeamData(); } Listing 1. The IGameStreamService interface defines server operations that can be called on the server.   [ServiceContract] public interface IGameStreamClient { [OperationContract(IsOneWay = true)] void ReceiveTeamData(List<Team> teamData); [OperationContract(IsOneWay = true, AsyncPattern=true)] IAsyncResult BeginReceiveGameData(GameData gameData, AsyncCallback callback, object state); void EndReceiveGameData(IAsyncResult result); } Listing 2. The IGameStreamClient interfaces defines client operations that a server can call.   The IGameStreamService interface is decorated with the standard ServiceContract attribute but also contains a value for the CallbackContract property.  This property is used to define the interface that the client will expose (IGameStreamClient in this example) and use to receive data pushed from the service. Notice that each OperationContract attribute in both interfaces sets the IsOneWay property to true. This means that the operation can be called and passed data as appropriate, however, no data will be passed back. Instead, data will be pushed back to the client as it’s available.  Looking through the IGameStreamService interface you can see that the client can request team data whereas the IGameStreamClient interface allows team and game data to be received by the client. One interesting point about the IGameStreamClient interface is the inclusion of the AsyncPattern property on the BeginReceiveGameData operation. I initially created this operation as a standard one way operation and it worked most of the time. However, as I disconnected clients and reconnected new ones game data wasn’t being passed properly. After researching the problem more I realized that because the service could take up to 7 seconds to return game data, things were getting hung up. By setting the AsyncPattern property to true on the BeginReceivedGameData operation and providing a corresponding EndReceiveGameData operation I was able to get around this problem and get everything running properly. I’ll provide more details on the implementation of these two methods later in this post. Once the interfaces were created I moved on to the game service class. The first order of business was to create a class that implemented the IGameStreamService interface. Since the service can be used by multiple clients wanting game data I added the ServiceBehavior attribute to the class definition so that I could set its InstanceContextMode to InstanceContextMode.Single (in effect creating a Singleton service object). Listing 3 shows the game service class as well as its fields and constructor.   [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.Single)] public class GameStreamService : IGameStreamService { object _Key = new object(); Game _Game = null; Timer _Timer = null; Random _Random = null; Dictionary<string, IGameStreamClient> _ClientCallbacks = new Dictionary<string, IGameStreamClient>(); static AsyncCallback _ReceiveGameDataCompleted = new AsyncCallback(ReceiveGameDataCompleted); public GameStreamService() { _Game = new Game(); _Timer = new Timer { Enabled = false, Interval = 2000, AutoReset = true }; _Timer.Elapsed += new ElapsedEventHandler(_Timer_Elapsed); _Timer.Start(); _Random = new Random(); }} Listing 3. The GameStreamService implements the IGameStreamService interface which defines a callback contract that allows the service class to push data back to the client. By implementing the IGameStreamService interface, GameStreamService must supply a GetTeamData() method which is responsible for supplying information about the teams that are playing as well as individual players.  GetTeamData() also acts as a client subscription method that tracks clients wanting to receive game data.  Listing 4 shows the GetTeamData() method. public void GetTeamData() { //Get client callback channel var context = OperationContext.Current; var sessionID = context.SessionId; var currClient = context.GetCallbackChannel<IGameStreamClient>(); context.Channel.Faulted += Disconnect; context.Channel.Closed += Disconnect; IGameStreamClient client; if (!_ClientCallbacks.TryGetValue(sessionID, out client)) { lock (_Key) { _ClientCallbacks[sessionID] = currClient; } } currClient.ReceiveTeamData(_Game.GetTeamData()); //Start timer which when fired sends updated score information to client if (!_Timer.Enabled) { _Timer.Enabled = true; } } Listing 4. The GetTeamData() method subscribes a given client to the game service and returns. The key the line of code in the GetTeamData() method is the call to GetCallbackChannel<IGameStreamClient>().  This method is responsible for accessing the calling client’s callback channel. The callback channel is defined by the IGameStreamClient interface shown earlier in Listing 2 and used by the server to communicate with the client. Before passing team data back to the client, GetTeamData() grabs the client’s session ID and checks if it already exists in the _ClientCallbacks dictionary object used to track clients wanting callbacks from the server. If the client doesn’t exist it adds it into the collection. It then pushes team data from the Game class back to the client by calling ReceiveTeamData().  Since the service simulates a basketball game, a timer is then started if it’s not already enabled which is then used to randomly send data to the client. When the timer fires, game data is pushed down to the client. Listing 5 shows the _Timer_Elapsed() method that is called when the timer fires as well as the SendGameData() method used to send data to the client. void _Timer_Elapsed(object sender, ElapsedEventArgs e) { int interval = _Random.Next(3000, 7000); lock (_Key) { _Timer.Interval = interval; _Timer.Enabled = false; } SendGameData(_Game.GetGameData()); } private void SendGameData(GameData gameData) { var cbs = _ClientCallbacks.Where(cb => ((IContextChannel)cb.Value).State == CommunicationState.Opened); for (int i = 0; i < cbs.Count(); i++) { var cb = cbs.ElementAt(i).Value; try { cb.BeginReceiveGameData(gameData, _ReceiveGameDataCompleted, cb); } catch (TimeoutException texp) { //Log timeout error } catch (CommunicationException cexp) { //Log communication error } } lock (_Key) _Timer.Enabled = true; } private static void ReceiveGameDataCompleted(IAsyncResult result) { try { ((IGameStreamClient)(result.AsyncState)).EndReceiveGameData(result); } catch (CommunicationException) { // empty } catch (TimeoutException) { // empty } } LIsting 5. _Timer_Elapsed is used to simulate time in a basketball game. When _Timer_Elapsed() fires the SendGameData() method is called which iterates through the clients wanting to be notified of changes. As each client is identified, their respective BeginReceiveGameData() method is called which ultimately pushes game data down to the client. Recall that this method was defined in the client callback interface named IGameStreamClient shown earlier in Listing 2. Notice that BeginReceiveGameData() accepts _ReceiveGameDataCompleted as its second parameter (an AsyncCallback delegate defined in the service class) and passes the client callback as the third parameter. The initial version of the sample application had a standard ReceiveGameData() method in the client callback interface. However, sometimes the client callbacks would work properly and sometimes they wouldn’t which was a little baffling at first glance. After some investigation I realized that I needed to implement an asynchronous pattern for client callbacks to work properly since 3 – 7 second delays are occurring as a result of the timer. Once I added the BeginReceiveGameData() and ReceiveGameDataCompleted() methods everything worked properly since each call was handled in an asynchronous manner. The final task that had to be completed to get the server working properly with HTTP Polling Duplex was adding configuration code into web.config. In the interest of brevity I won’t post all of the code here since the sample application includes everything you need. However, Listing 6 shows the key configuration code to handle creating a custom binding named pollingDuplexBinding and associate it with the service’s endpoint.   <bindings> <customBinding> <binding name="pollingDuplexBinding"> <binaryMessageEncoding /> <pollingDuplex maxPendingSessions="2147483647" maxPendingMessagesPerSession="2147483647" inactivityTimeout="02:00:00" serverPollTimeout="00:05:00"/> <httpTransport /> </binding> </customBinding> </bindings> <services> <service name="GameService.GameStreamService" behaviorConfiguration="GameStreamServiceBehavior"> <endpoint address="" binding="customBinding" bindingConfiguration="pollingDuplexBinding" contract="GameService.IGameStreamService"/> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services>   Listing 6. Configuring an HTTP Polling Duplex binding in web.config and associating an endpoint with it. Calling the Service and Receiving “Pushed” Data Calling the service and handling data that is pushed from the server is a simple and straightforward process in Silverlight. Since the service is configured with a MEX endpoint and exposes a WSDL file, you can right-click on the Silverlight project and select the standard Add Service Reference item. After the web service proxy is created you may notice that the ServiceReferences.ClientConfig file only contains an empty configuration element instead of the normal configuration elements created when creating a standard WCF proxy. You can certainly update the file if you want to read from it at runtime but for the sample application I fed the service URI directly to the service proxy as shown next: var address = new EndpointAddress("http://localhost.:5661/GameStreamService.svc"); var binding = new PollingDuplexHttpBinding(); _Proxy = new GameStreamServiceClient(binding, address); _Proxy.ReceiveTeamDataReceived += _Proxy_ReceiveTeamDataReceived; _Proxy.ReceiveGameDataReceived += _Proxy_ReceiveGameDataReceived; _Proxy.GetTeamDataAsync(); This code creates the proxy and passes the endpoint address and binding to use to its constructor. It then wires the different receive events to callback methods and calls GetTeamDataAsync().  Calling GetTeamDataAsync() causes the server to store the client in the server-side dictionary collection mentioned earlier so that it can receive data that is pushed.  As the server-side timer fires and game data is pushed to the client, the user interface is updated as shown in Listing 7. Listing 8 shows the _Proxy_ReceiveGameDataReceived() method responsible for handling the data and calling UpdateGameData() to process it.   Listing 7. The Silverlight interface. Game data is pushed from the server to the client using HTTP Polling Duplex. void _Proxy_ReceiveGameDataReceived(object sender, ReceiveGameDataReceivedEventArgs e) { UpdateGameData(e.gameData); } private void UpdateGameData(GameData gameData) { //Update Score this.tbTeam1Score.Text = gameData.Team1Score.ToString(); this.tbTeam2Score.Text = gameData.Team2Score.ToString(); //Update ball visibility if (gameData.Action != ActionsEnum.Foul) { if (tbTeam1.Text == gameData.TeamOnOffense) { AnimateBall(this.BB1, this.BB2); } else //Team 2 { AnimateBall(this.BB2, this.BB1); } } if (this.lbActions.Items.Count > 9) this.lbActions.Items.Clear(); this.lbActions.Items.Add(gameData.LastAction); if (this.lbActions.Visibility == Visibility.Collapsed) this.lbActions.Visibility = Visibility.Visible; } private void AnimateBall(Image onBall, Image offBall) { this.FadeIn.Stop(); Storyboard.SetTarget(this.FadeInAnimation, onBall); Storyboard.SetTarget(this.FadeOutAnimation, offBall); this.FadeIn.Begin(); } Listing 8. As the server pushes game data, the client’s _Proxy_ReceiveGameDataReceived() method is called to process the data. In a real-life application I’d go with a ViewModel class to handle retrieving team data, setup data bindings and handle data that is pushed from the server. However, for the sample application I wanted to focus on HTTP Polling Duplex and keep things as simple as possible.   Summary Silverlight supports three options when duplex communication is required in an application including TCP bindins, sockets and HTTP Polling Duplex. In this post you’ve seen how HTTP Polling Duplex interfaces can be created and implemented on the server as well as how they can be consumed by a Silverlight client. HTTP Polling Duplex provides a nice way to “push” data from a server while still allowing the data to flow over port 80 or another port of your choice.   Sample Application Download

  Read the article

• Implementing an async "read all currently available data from stream" operation

  - by Jon

  I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a console's standard output Stream. Console output streams are of type FileStream; the implementation can cast to that, if needed. There is also an associated StreamReader already present to leverage. There is only one thing I need to implement in this class to achieve my desired functionality: an async "read all the data available this moment" operation. Reading to the end of the stream is not viable because the stream will not end unless the process closes the console output handle, and it will not do that because it is interactive and expecting input before continuing. I will be using that hypothetical async operation to implement event-based notification, which will be more convenient for my callers. The public interface of the class is this: public class ConsoleAutomator { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Remember that the goal here is to read all of the chunk and call event subscribers exactly once for each chunk. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream. private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer (in which case we know that there was no more data to be read during the last read operation), all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Never more than one event for each time data is available to be read Is almost agnostic to the buffer size The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this. Update: I definitely did not communicate the scenario well in my initial writeup. I have since revised the writeup quite a bit, but to be extra sure: The question is about how to implement an async "read all the data available this moment" operation. My apologies to the people who took the time to read and answer without me making my intent clear enough.

  Read the article

• Array help Index out of range exeption was unhandled

  - by Michael Quiles

  I am trying to populate combo boxes from a text file using comma as a delimiter everything was working fine, but now when I debug I get the "Index out of range exeption was unhandled" warning. I guess I need a fresh pair of eyes to see where I went wrong, I commented on the line that gets the error //Fname = fields[1]; using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Drawing.Printing; using System.Linq; using System.Text; using System.Windows.Forms; using System.IO; namespace Sullivan_Payroll { public partial class xEmpForm : Form { bool complete = false; public xEmpForm() { InitializeComponent(); } private void xEmpForm_Resize(object sender, EventArgs e) { this.xCenterPanel.Left = Convert.ToInt16((this.Width - this.xCenterPanel.Width) / 2); this.xCenterPanel.Top = Convert.ToInt16((this.Height - this.xCenterPanel.Height) / 2); Refresh(); } private void exitToolStripMenuItem_Click(object sender, EventArgs e) { //Exits the application this.Close(); } private void xEmpForm_FormClosing(object sender, FormClosingEventArgs e) //use this on xtrip calculator { DialogResult Response; if (complete == true) { Application.Exit(); } else { Response = MessageBox.Show("Are you sure you want to Exit?", "Exit", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2); if (Response == DialogResult.No) { complete = false; e.Cancel = true; } else { complete = true; Application.Exit(); } } } private void xEmpForm_Load(object sender, EventArgs e) { //file sources string fileDept = "source\\Department.txt"; string fileSex = "source\\Sex.txt"; string fileStatus = "source\\Status.txt"; if (File.Exists(fileDept)) { using (System.IO.StreamReader sr = System.IO.File.OpenText(fileDept)) { string dept = ""; while ((dept = sr.ReadLine()) != null) { this.xDeptComboBox.Items.Add(dept); } } } else { MessageBox.Show("The Department file can not be found.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); } if (File.Exists(fileSex)) { using (System.IO.StreamReader sr = System.IO.File.OpenText(fileSex)) { string sex = ""; while ((sex = sr.ReadLine()) != null) { this.xSexComboBox.Items.Add(sex); } } } else { MessageBox.Show("The Sex file can not be found.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); } if (File.Exists(fileStatus)) { using (System.IO.StreamReader sr = System.IO.File.OpenText(fileStatus)) { string status = ""; while ((status = sr.ReadLine()) != null) { this.xStatusComboBox.Items.Add(status); } } } else { MessageBox.Show("The Status file can not be found.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); } } private void xFileSaveMenuItem_Click(object sender, EventArgs e) { { const string fileNew = "source\\New Staff.txt"; string recordIn; FileStream outFile = new FileStream(fileNew, FileMode.Create, FileAccess.Write); StreamWriter writer = new StreamWriter(outFile); for (int count = 0; count <= this.xEmployeeListBox.Items.Count - 1; count++) { this.xEmployeeListBox.SelectedIndex = count; recordIn = this.xEmployeeListBox.SelectedItem.ToString(); writer.WriteLine(recordIn); } writer.Close(); outFile.Close(); this.xDeptComboBox.SelectedIndex = -1; this.xStatusComboBox.SelectedIndex = -1; this.xSexComboBox.SelectedIndex = -1; MessageBox.Show("your file is saved"); } } private void xViewFacultyMenuItem_Click(object sender, EventArgs e) { const string fileStaff = "source\\Staff.txt"; const char DELIM = ','; string Lname, Fname, Depart, Stat, Sex, Salary, cDept, cStat, cSex; double Gtotal; string recordIn; string[] fields; cDept = this.xDeptComboBox.SelectedItem.ToString(); cStat = this.xStatusComboBox.SelectedItem.ToString(); cSex = this.xSexComboBox.SelectedItem.ToString(); FileStream inFile = new FileStream(fileStaff, FileMode.Open, FileAccess.Read); StreamReader reader = new StreamReader(inFile); recordIn = reader.ReadLine(); while (recordIn != null) { fields = recordIn.Split(DELIM); Lname = fields[0]; Fname = fields[1]; // this is where the error appears Depart = fields[2]; Stat = fields[3]; Sex = fields[4]; Salary = fields[5]; Fname = fields[1].TrimStart(null); Depart = fields[2].TrimStart(null); Stat = fields[3].TrimStart(null); Sex = fields[4].TrimStart(null); Salary = fields[5].TrimStart(null); Gtotal = double.Parse(Salary); if (Depart == cDept && cStat == Stat && cSex == Sex) { this.xEmployeeListBox.Items.Add(recordIn); } recordIn = reader.ReadLine(); } reader.Close(); inFile.Close(); if (this.xEmployeeListBox.Items.Count >= 1) { this.xFileSaveMenuItem.Enabled = true; this.xFilePrintMenuItem.Enabled = true; this.xEditClearMenuItem.Enabled = true; } else { this.xFileSaveMenuItem.Enabled = false; this.xFilePrintMenuItem.Enabled = false; this.xEditClearMenuItem.Enabled = false; MessageBox.Show("Records not found"); } } private void xEditClearMenuItem_Click(object sender, EventArgs e) { this.xEmployeeListBox.Items.Clear(); this.xDeptComboBox.SelectedIndex = -1; this.xStatusComboBox.SelectedIndex = -1; this.xSexComboBox.SelectedIndex = -1; this.xFileSaveMenuItem.Enabled = false; this.xFilePrintMenuItem.Enabled = false; this.xEditClearMenuItem.Enabled = false; } } } Source file -- Anderson, Kristen, Accounting, Assistant, Female, 43155 Ball, Robin, Accounting, Instructor, Female, 42723 Chin, Roger, Accounting, Full, Male,59281 Coats, William, Accounting, Assistant, Male, 45371 Doepke, Cheryl, Accounting, Full, Female, 52105 Downs, Clifton, Accounting, Associate, Male, 46887 Garafano, Karen, Finance, Associate, Female, 49000 Hill, Trevor, Management, Instructor, Male, 38590 Jackson, Carole, Accounting, Instructor, Female, 38781 Jacobson, Andrew, Management, Full, Male, 56281 Lewis, Karl, Management, Associate, Male, 48387 Mack, Kevin, Management, Assistant, Male, 45000 McKaye, Susan, Management, Instructor, Female, 43979 Nelsen, Beth, Finance, Full, Female, 52339 Nelson, Dale, Accounting, Full, Male, 54578 Palermo, Sheryl, Accounting, Associate, Female, 45617 Rais, Mary, Finance, Instructor, Female, 27000 Scheib, Earl, Management, Instructor, Male, 37389 Smith, Tom, Finance, Full, Male, 57167 Smythe, Janice, Management, Associate, Female, 46887 True, David, Accounting, Full, Male, 53181 Young, Jeff, Management, Assistant, Male, 43513

  Read the article

• Implementing a robust async stream reader

  - by Jon

  I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output, but that is a detail and does not play an important role. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

  Read the article

• How to retrive message list from p2p

  - by cre-johnny07

  Hello friends I have a messaging system that uses p2p. Each peer has a incoming message list and a outgoing message list. What I need to do is whenever a new peer will join the mesh he will get the all the incoming messages from other peers and add those into it's own incoming message list. Now I know when I get the other peer info from I can ask them to give their own list to me. But I'm not finding the way how..? Any suggestion on this or help would be highly appreciated. I'm giving my code below. Thanking in Advance Johnny #region Instance Fields private string strOrigin = ""; //the chat member name private string m_Member; //the channel instance where we execute our service methods against private IServerChannel m_participant; //the instance context which in this case is our window since it is the service host private InstanceContext m_site; //our binding transport for the p2p mesh private NetPeerTcpBinding m_binding; //the factory to create our chat channel private ChannelFactory<IServerChannel> m_channelFactory; //an interface provided by the channel exposing events to indicate //when we have connected or disconnected from the mesh private IOnlineStatus o_statusHandler; //a generic delegate to execute a thread against that accepts no args private delegate void NoArgDelegate(); //an object to hold user details private IUserService userService; //an Observable Collection of object to get all the Application Instance Details in databas ObservableCollection<AppLoginInstance> appLoginInstances; // an Observable Collection of object to get all Incoming Messages types ObservableCollection<MessageType> inComingMessageTypes; // an Observable Collection of object to get all Outgoing Messages ObservableCollection<PDCL.ERP.DataModels.Message> outGoingMessages; // an Observable Collection of object to get all Incoming Messages ObservableCollection<PDCL.ERP.DataModels.Message> inComingMessages; //an Event Aggregator to publish event for other modules to subscribe private readonly IEventAggregator eventAggregator; /// <summary> /// an IUnityCOntainer to get the container /// </summary> private IUnityContainer container; private RefreshConnectionStatus refreshConnectionStatus; private RefreshConnectionStatusEventArgs args; private ReplyRequestMessage replyMessageRequest; private ReplyRequestMessageEventArgs eventsArgs; #endregion public P2pMessageService(IUserService UserService, IEventAggregator EventAggregator, IUnityContainer container) { userService = UserService; this.container = container; appLoginInstances = new ObservableCollection<AppLoginInstance>(); inComingMessageTypes = new ObservableCollection<MessageType>(); inComingMessages = new ObservableCollection<PDCL.ERP.DataModels.Message>(); outGoingMessages = new ObservableCollection<PDCL.ERP.DataModels.Message>(); this.args = new RefreshConnectionStatusEventArgs(); this.eventsArgs = new ReplyRequestMessageEventArgs(); this.eventAggregator = EventAggregator; this.refreshConnectionStatus = this.eventAggregator.GetEvent<RefreshConnectionStatus>(); this.replyMessageRequest = this.eventAggregator.GetEvent<ReplyRequestMessage>(); } #region IOnlineStatus Event Handlers void ostat_Offline(object sender, EventArgs e) { // we could update a status bar or animate an icon to //indicate to the user they have disconnected from the mesh //currently i don't have a "disconnect" button but adding it //should be trivial if you understand the rest of this code } void ostat_Online(object sender, EventArgs e) { try { m_participant.Join(userService.AppInstance); } catch (Exception Ex) { Logger.Exception(Ex, Ex.TargetSite.Name + ": " + Ex.TargetSite + ": " + Ex.Message); } } #endregion #region IServer Members //this method gets called from a background thread to //connect the service client to the p2p mesh specified //by the binding info in the app.config public void ConnectToMesh() { try { m_site = new InstanceContext(this); //use the binding from the app.config with default settings m_binding = new NetPeerTcpBinding("P2PMessageBinding"); m_channelFactory = new DuplexChannelFactory<IServerChannel>(m_site, "P2PMessageEndPoint"); m_participant = m_channelFactory.CreateChannel(); o_statusHandler = m_participant.GetProperty<IOnlineStatus>(); o_statusHandler.Online += new EventHandler(ostat_Online); o_statusHandler.Offline += new EventHandler(ostat_Offline); //m_participant.InitializeMesh(); //this.appLoginInstances.Add(this.userService.AppInstance); BackgroundWorkerHelper.DoWork<object>(() => { //this is an empty unhandled method on the service interface. //why? because for some reason p2p clients don't try to connect to the mesh //until the first service method call. so to facilitate connecting i call this method //to get the ball rolling. m_participant.InitializeMesh(); //SynchronizeMessage(this.inComingMessages); return new object(); }, arg => { }); this.appLoginInstances.Add(this.userService.AppInstance); } catch (Exception Ex) { Logger.Exception(Ex, Ex.TargetSite.Name + ": " + Ex.TargetSite + ": " + Ex.Message); } } public void Join(AppLoginInstance obj) { try { // Adding Instance to the PeerList if (appLoginInstances.SingleOrDefault(a => a.InstanceId == obj.InstanceId)==null) { appLoginInstances.Add(obj); this.refreshConnectionStatus.Publish(new RefreshConnectionStatusEventArgs() { Status = m_channelFactory.State }); } //this will retrieve any new members that have joined before the current user m_participant.SynchronizeMemberList(userService.AppInstance); } catch(Exception Ex) { Logger.Exception(Ex,Ex.TargetSite.Name + ": " + Ex.TargetSite + ": " + Ex.Message); } } /// <summary> /// Synchronizes member list /// </summary> /// <param name="obj">The AppLoginInstance Param</param> public void SynchronizeMemberList(AppLoginInstance obj) { //as member names come in we simply disregard duplicates and //add them to the member list, this way we can retrieve a list //of members already in the chatroom when we enter at any time. //again, since this is just an example this is the simplified //way to do things. the correct way would be to retrieve a list //of peernames and retrieve the metadata from each one which would //tell us what the member name is and add it. we would want to check //this list when we join the mesh to make sure our member name doesn't //conflict with someone else try { if (appLoginInstances.SingleOrDefault(a => a.InstanceId == obj.InstanceId) == null) { appLoginInstances.Add(obj); } } catch (Exception Ex) { Logger.Exception(Ex, Ex.TargetSite.Name + ": " + Ex.TargetSite + ": " + Ex.Message); } } /// <summary> /// This methos broadcasts the mesasge to all peers. /// </summary> /// <param name="msg">The whole message which is to be broadcasted</param> /// <param name="securityLevels"> Level of security</param> public void BroadCastMsg(PDCL.ERP.DataModels.Message msg, List<string> securityLevels) { try { foreach (string s in securityLevels) { if (this.userService.IsInRole(s)) { if (this.inComingMessages.Count == 0 && msg.CreatedByApp != this.userService.AppInstanceId) { this.inComingMessages.Add(msg); } else if (this.inComingMessages.SingleOrDefault(a => a.MessageId == msg.MessageId) == null && msg.CreatedByApp != this.userService.AppInstanceId) { this.inComingMessages.Add(msg); } } } } catch (Exception Ex) { Logger.Exception(Ex, Ex.TargetSite.Name + ": " + Ex.TargetSite + ": " + Ex.Message); } } /// <summary> /// /// </summary> /// <param name="msg">The Message to denyed</param> public void BroadCastReplyMsg(PDCL.ERP.DataModels.Message msg) { try { //if (this.inComingMessages.SingleOrDefault(a => a.MessageId == msg.MessageId) != null) //{ this.replyMessageRequest.Publish(new ReplyRequestMessageEventArgs() { Message = msg }); this.inComingMessages.Remove(this.inComingMessages.SingleOrDefault(o => o.MessageId == msg.MessageId)); //} } catch (Exception ex) { Logger.Exception(ex, ex.TargetSite.Name + ": " + ex.TargetSite + ": " + ex.Message); } } //again we need to sync the worker thread with the UI thread via Dispatcher public void Whisper(string Member, string MemberTo, string Message) { } public void InitializeMesh() { //do nothing } public void Leave(AppLoginInstance obj) { if (this.appLoginInstances.SingleOrDefault(a => a.InstanceId == obj.InstanceId) != null) { this.appLoginInstances.Remove(this.appLoginInstances.Single(a => a.InstanceId == obj.InstanceId)); } } //public void SynchronizeRemoveMemberList(AppLoginInstance obj) //{ // if (appLoginInstances.SingleOrDefault(a => a.InstanceId == obj.InstanceId) != null) // { // appLoginInstances.Remove(obj); // } //} #endregion

  Read the article

• Floats will not align, stay staggered, can't find a solution?

  - by Sarah Proper

  What I am trying to do is build a multi column layout. The main two sections are divided 2/3 to 1/3 and inside the 2/3 column is divided 2/3 1/3 as well. My problem is that my floats will not align nicely with each other, choosing instead to stagger like stairs. I have tried declaring the widths smaller, floating them individually, including in the float sections display:block,inline, or inline-block and nothing seems to be working. I am getting really frustrated and would appreciate any help! Thanks! <div class="wrapper"> <div class="width50" style="float:left;"> <h1>Our Mission:</h1> <p> Bacon ipsum dolor sit amet swine spare ribs pork meatloaf pancetta filet mignon. Rump frankfurter pork belly prosciutto beef boudin andouille pig pork chop meatball ham drumstick filet mignon. Strip steak flank shank pig, tongue tri-tip jowl leberkas sirloin brisket t-bone. Ground round spare ribs salami capicola filet mignon. Capicola turkey t-bone corned beef sausage ham hock. Corned beef capicola leberkas pork chop, swine pastrami drumstick. Frankfurter fatback bacon jowl short loin, jerky pancetta bresaola corned beef shoulder drumstick ball tip tri-tip.</p> <div class="width50 float-left"> <img src="@Url.StaticContent(Links.Content.images.map_homepage_png)" alt="Map" /> </div> <div class="width33 float-right"> <img src="@Url.StaticContent(Links.Content.images.address_line_text_png)" alt="addressline" /> <br /> <h3>address</h3> <b>405 Empire Boulevard<br /> Rochester, NY 14609 </b> </div> </div> <div class="width33" style="float:right;"> <h1>Events</h1> <ul class="events"> <li> <h2>Fall Volunteer Festival</h2> <p> <b>october 6<br /> 10 am to 3pm </b> </p> <p> come to our town location for some fun activities for family and friends! </p> </li> <li> <h2>Fall Volunteer Festival</h2> <p> <b>october 6<br /> 10 am to 3pm </b> </p> <p> come to our town location for some fun activities for family and friends! </p> </li> <li> <h2>Fall Volunteer Festival</h2> <p> <b>october 6<br /> 10 am to 3pm </b> </p> <p> come to our town location for some fun activities for family and friends! </p> </li> </ul> </div> </div> </div> and the css: .clearfix:before, .clearfix:after, .grid-block:before, .grid-block:after, .deepest:before, .deepest:after { content: ""; display: table; } .clearfix:after, .grid-block:after, .deepest:after { clear: both; } .grid-box { float: left; } /* Grid Units */ .width16 { width: 16.666%; } .width20 { width: 20%; } .width25 { width: 25%; } .width33 { width: 39.333%; } .width40 { width: 40%; } .width50 { width: 50%; } .width60 { width: 60%; } .width66 { width: 66.666%; } .width75 { width: 75%; } .width80 { width: 80%; } .width100 { width: 100%; } .width16, .width20, .width25, .width33, .width40, .width50, .width60, .width66, .width75, .width80, .width100 { -moz-box-sizing: border-box; -webkit-box-sizing: border-box; box-sizing: border-box; padding: 5px 10px 5px 10px; } /* Create new Block Formatting Contexts */ .bfc-o { overflow: hidden; } .bfc-f { -moz-box-sizing: border-box; -webkit-box-sizing: border-box; box-sizing: border-box; width: 100%; float: left; } /* Align Boxes */ .float-left { float: left; } .float-right { float: right; } /* Grid Gutter */ .grid-gutter.grid-block { margin: 0 -15px; } .grid-gutter > .grid-box > * { margin: 0 15px; } .grid-gutter > .grid-box > * > :first-child { margin-top: 0; } .grid-gutter > .grid-box > * > :last-child { margin-bottom: 0; } /* Layout Defaults --------------------------------------------------------------------------------------- -------------*/ /* Center Page */ .wrapper { -moz-box-sizing: border-box; -webkit-box-sizing: border-box; box-sizing: border-box; margin: auto; } /* Header */ #header { position: relative; padding-top: 10px; } #toolbar .float-left .module, #toolbar .float-left > time { margin: 0 15px 0 0; float: left; } #toolbar .float-right .module { margin: 0 0 0 15px; float: right; } #headerbar .module { max-width: 300px; margin-right: 0; float: right; } #logo, #logo > img, #menu { float: left; } #search { float: right; } #banner { position: absolute; top: 0; right: -200px; } /* Footer */ #footer { position: relative; text-align: center; } /* Absolute */ #absolute { position: absolute; z-index: 15; width: 100%; }

  Read the article

• Implementing a robust async stream reader for a console

  - by Jon

  I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. Edit: There are comments below correctly stating that since the data is coming from a stream, there is absolutely nothing that the receiver can infer about the structure of the data unless it is fully prepared to parse it. What I am trying to do here is leverage the "flush the output" "structure" that the owner of the console imparts while writing on it. I am prepared to assume (better: allow my caller to have the option to assume) that the OS will pass me the data written between two flushes of the stream in exactly one piece. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

  Read the article

• ubuntu: sem_timedwait not waking (C)

  - by gillez

  I have 3 processes which need to be synchronized. Process one does something then wakes process two and sleeps, which does something then wakes process three and sleeps, which does something and wakes process one and sleeps. The whole loop is timed to run around 25hz (caused by an external sync into process one before it triggers process two in my "real" application). I use sem_post to trigger (wake) each process, and sem_timedwait() to wait for the trigger. This all works successfully for several hours. However at some random time (usually after somewhere between two and four hours), one of the processes starts timing out in sem_timedwait(), even though I am sure the semaphore is being triggered with sem_post(). To prove this I even use sem_getvalue() immediately after the timeout, and the value is 1, so the timedwait should have been triggered. Please see following code: #include <stdio.h> #include <time.h> #include <string.h> #include <errno.h> #include <semaphore.h> sem_t trigger_sem1, trigger_sem2, trigger_sem3; // The main thread process. Called three times with a different num arg - 1, 2 or 3. void *thread(void *arg) { int num = (int) arg; sem_t *wait, *trigger; int val, retval; struct timespec ts; struct timeval tv; switch (num) { case 1: wait = &trigger_sem1; trigger = &trigger_sem2; break; case 2: wait = &trigger_sem2; trigger = &trigger_sem3; break; case 3: wait = &trigger_sem3; trigger = &trigger_sem1; break; } while (1) { // The first thread delays by 40ms to time the whole loop. // This is an external sync in the real app. if (num == 1) usleep(40000); // print sem value before we wait. If this is 1, sem_timedwait() will // return immediately, otherwise it will block until sem_post() is called on this sem. sem_getvalue(wait, &val); printf("sem%d wait sync sem%d. val before %d\n", num, num, val); // get current time and add half a second for timeout. gettimeofday(&tv, NULL); ts.tv_sec = tv.tv_sec; ts.tv_nsec = (tv.tv_usec + 500000); // add half a second if (ts.tv_nsec > 1000000) { ts.tv_sec++; ts.tv_nsec -= 1000000; } ts.tv_nsec *= 1000; /* convert to nanosecs */ retval = sem_timedwait(wait, &ts); if (retval == -1) { // timed out. Print value of sem now. This should be 0, otherwise sem_timedwait // would have woken before timeout (unless the sem_post happened between the // timeout and this call to sem_getvalue). sem_getvalue(wait, &val); printf("!!!!!! sem%d sem_timedwait failed: %s, val now %d\n", num, strerror(errno), val); } else printf("sem%d wakeup.\n", num); // get value of semaphore to trigger. If it's 1, don't post as it has already been // triggered and sem_timedwait on this sem *should* not block. sem_getvalue(trigger, &val); if (val <= 0) { printf("sem%d send sync sem%d. val before %d\n", num, (num == 3 ? 1 : num+1), val); sem_post(trigger); } else printf("!! sem%d not sending sync, val %d\n", num, val); } } int main(int argc, char *argv[]) { pthread_t t1, t2, t3; // create semaphores. val of sem1 is 1 to trigger straight away and start the whole ball rolling. if (sem_init(&trigger_sem1, 0, 1) == -1) perror("Error creating trigger_listman semaphore"); if (sem_init(&trigger_sem2, 0, 0) == -1) perror("Error creating trigger_comms semaphore"); if (sem_init(&trigger_sem3, 0, 0) == -1) perror("Error creating trigger_vws semaphore"); pthread_create(&t1, NULL, thread, (void *) 1); pthread_create(&t2, NULL, thread, (void *) 2); pthread_create(&t3, NULL, thread, (void *) 3); pthread_join(t1, NULL); pthread_join(t2, NULL); pthread_join(t3, NULL); } The following output is printed when the program is running correctly (at the start and for a random but long time after). The value of sem1 is always 1 before thread1 waits as it sleeps for 40ms, by which time sem3 has triggered it, so it wakes straight away. The other two threads wait until the semaphore is received from the previous thread. [...] sem1 wait sync sem1. val before 1 sem1 wakeup. sem1 send sync sem2. val before 0 sem2 wakeup. sem2 send sync sem3. val before 0 sem2 wait sync sem2. val before 0 sem3 wakeup. sem3 send sync sem1. val before 0 sem3 wait sync sem3. val before 0 sem1 wait sync sem1. val before 1 sem1 wakeup. sem1 send sync sem2. val before 0 [...] However, after a few hours, one of the threads begins to timeout. I can see from the output that the semaphore is being triggered, and when I print the value after the timeout is is 1. So sem_timedwait should have woken up well before the timeout. I would never expect the value of the semaphore to be 1 after the timeout, save for the very rare occasion (almost certainly never but it's possible) when the trigger happens after the timeout but before I call sem_getvalue. Also, once it begins to fail, every sem_timedwait() on that semaphore also fails in the same way. See the following output, which I've line-numbered: 01 sem3 wait sync sem3. val before 0 02 sem1 wakeup. 03 sem1 send sync sem2. val before 0 04 sem2 wakeup. 05 sem2 send sync sem3. val before 0 06 sem2 wait sync sem2. val before 0 07 sem1 wait sync sem1. val before 0 08 !!!!!! sem3 sem_timedwait failed: Connection timed out, val now 1 09 sem3 send sync sem1. val before 0 10 sem3 wait sync sem3. val before 1 11 sem3 wakeup. 12 !! sem3 not sending sync, val 1 13 sem3 wait sync sem3. val before 0 14 sem1 wakeup. [...] On line 1, thread 3 (which I have confusingly called sem1 in the printf) waits for sem3 to be triggered. On line 5, sem2 calls sem_post for sem3. However, line 8 shows sem3 timing out, but the value of the semaphore is 1. thread3 then triggers sem1 and waits again (10). However, because the value is already 1, it wakes straight away. It doesn't send sem1 again as this has all happened before control is given to thread1, however it then waits again (val is now 0) and sem1 wakes up. This now repeats for ever, sem3 always timing out and showing that the value is 1. So, my question is why does sem3 timeout, even though the semaphore has been triggered and the value is clearly 1? I would never expect to see line 08 in the output. If it times out (because, say thread 2 has crashed or is taking too long), the value should be 0. And why does it work fine for 3 or 4 hours first before getting into this state? This is using Ubuntu 9.4 with kernel 2.6.28. The same procedure has been working properly on Redhat and Fedora. But I'm now trying to port to ubuntu! Thanks for any advice, Giles

  Read the article

• The Incremental Architect&rsquo;s Napkin - #5 - Design functions for extensibility and readability

  - by Ralf Westphal

  Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/08/24/the-incremental-architectrsquos-napkin---5---design-functions-for.aspx The functionality of programs is entered via Entry Points. So what we´re talking about when designing software is a bunch of functions handling the requests represented by and flowing in through those Entry Points. Designing software thus consists of at least three phases: Analyzing the requirements to find the Entry Points and their signatures Designing the functionality to be executed when those Entry Points get triggered Implementing the functionality according to the design aka coding I presume, you´re familiar with phase 1 in some way. And I guess you´re proficient in implementing functionality in some programming language. But in my experience developers in general are not experienced in going through an explicit phase 2. “Designing functionality? What´s that supposed to mean?” you might already have thought. Here´s my definition: To design functionality (or functional design for short) means thinking about… well, functions. You find a solution for what´s supposed to happen when an Entry Point gets triggered in terms of functions. A conceptual solution that is, because those functions only exist in your head (or on paper) during this phase. But you may have guess that, because it´s “design” not “coding”. And here is, what functional design is not: It´s not about logic. Logic is expressions (e.g. +, -, && etc.) and control statements (e.g. if, switch, for, while etc.). Also I consider calling external APIs as logic. It´s equally basic. It´s what code needs to do in order to deliver some functionality or quality. Logic is what´s doing that needs to be done by software. Transformations are either done through expressions or API-calls. And then there is alternative control flow depending on the result of some expression. Basically it´s just jumps in Assembler, sometimes to go forward (if, switch), sometimes to go backward (for, while, do). But calling your own function is not logic. It´s not necessary to produce any outcome. Functionality is not enhanced by adding functions (subroutine calls) to your code. Nor is quality increased by adding functions. No performance gain, no higher scalability etc. through functions. Functions are not relevant to functionality. Strange, isn´t it. What they are important for is security of investment. By introducing functions into our code we can become more productive (re-use) and can increase evolvability (higher unterstandability, easier to keep code consistent). That´s no small feat, however. Evolvable code can hardly be overestimated. That´s why to me functional design is so important. It´s at the core of software development. To sum this up: Functional design is on a level of abstraction above (!) logical design or algorithmic design. Functional design is only done until you get to a point where each function is so simple you are very confident you can easily code it. Functional design an logical design (which mostly is coding, but can also be done using pseudo code or flow charts) are complementary. Software needs both. If you start coding right away you end up in a tangled mess very quickly. Then you need back out through refactoring. Functional design on the other hand is bloodless without actual code. It´s just a theory with no experiments to prove it. But how to do functional design? An example of functional design Let´s assume a program to de-duplicate strings. The user enters a number of strings separated by commas, e.g. a, b, a, c, d, b, e, c, a. And the program is supposed to clear this list of all doubles, e.g. a, b, c, d, e. There is only one Entry Point to this program: the user triggers the de-duplication by starting the program with the string list on the command line C:\>deduplicate "a, b, a, c, d, b, e, c, a" a, b, c, d, e …or by clicking on a GUI button. This leads to the Entry Point function to get called. It´s the program´s main function in case of the batch version or a button click event handler in the GUI version. That´s the physical Entry Point so to speak. It´s inevitable. What then happens is a three step process: Transform the input data from the user into a request. Call the request handler. Transform the output of the request handler into a tangible result for the user. Or to phrase it a bit more generally: Accept input. Transform input into output. Present output. This does not mean any of these steps requires a lot of effort. Maybe it´s just one line of code to accomplish it. Nevertheless it´s a distinct step in doing the processing behind an Entry Point. Call it an aspect or a responsibility - and you will realize it most likely deserves a function of its own to satisfy the Single Responsibility Principle (SRP). Interestingly the above list of steps is already functional design. There is no logic, but nevertheless the solution is described - albeit on a higher level of abstraction than you might have done yourself. But it´s still on a meta-level. The application to the domain at hand is easy, though: Accept string list from command line De-duplicate Present de-duplicated strings on standard output And this concrete list of processing steps can easily be transformed into code:static void Main(string[] args) { var input = Accept_string_list(args); var output = Deduplicate(input); Present_deduplicated_string_list(output); } Instead of a big problem there are three much smaller problems now. If you think each of those is trivial to implement, then go for it. You can stop the functional design at this point. But maybe, just maybe, you´re not so sure how to go about with the de-duplication for example. Then just implement what´s easy right now, e.g.private static string Accept_string_list(string[] args) { return args[0]; } private static void Present_deduplicated_string_list( string[] output) { var line = string.Join(", ", output); Console.WriteLine(line); } Accept_string_list() contains logic in the form of an API-call. Present_deduplicated_string_list() contains logic in the form of an expression and an API-call. And then repeat the functional design for the remaining processing step. What´s left is the domain logic: de-duplicating a list of strings. How should that be done? Without any logic at our disposal during functional design you´re left with just functions. So which functions could make up the de-duplication? Here´s a suggestion: De-duplicate Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Processing step 2 obviously was the core of the solution. That´s where real creativity was needed. That´s the core of the domain. But now after this refinement the implementation of each step is easy again:private static string[] Parse_string_list(string input) { return input.Split(',') .Select(s => s.Trim()) .ToArray(); } private static Dictionary<string,object> Compile_unique_strings(string[] strings) { return strings.Aggregate( new Dictionary<string, object>(), (agg, s) => { agg[s] = null; return agg; }); } private static string[] Serialize_unique_strings( Dictionary<string,object> dict) { return dict.Keys.ToArray(); } With these three additional functions Main() now looks like this:static void Main(string[] args) { var input = Accept_string_list(args); var strings = Parse_string_list(input); var dict = Compile_unique_strings(strings); var output = Serialize_unique_strings(dict); Present_deduplicated_string_list(output); } I think that´s very understandable code: just read it from top to bottom and you know how the solution to the problem works. It´s a mirror image of the initial design: Accept string list from command line Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Present de-duplicated strings on standard output You can even re-generate the design by just looking at the code. Code and functional design thus are always in sync - if you follow some simple rules. But about that later. And as a bonus: all the functions making up the process are small - which means easy to understand, too. So much for an initial concrete example. Now it´s time for some theory. Because there is method to this madness ;-) The above has only scratched the surface. Introducing Flow Design Functional design starts with a given function, the Entry Point. Its goal is to describe the behavior of the program when the Entry Point is triggered using a process, not an algorithm. An algorithm consists of logic, a process on the other hand consists just of steps or stages. Each processing step transforms input into output or a side effect. Also it might access resources, e.g. a printer, a database, or just memory. Processing steps thus can rely on state of some sort. This is different from Functional Programming, where functions are supposed to not be stateful and not cause side effects.[1] In its simplest form a process can be written as a bullet point list of steps, e.g. Get data from user Output result to user Transform data Parse data Map result for output Such a compilation of steps - possibly on different levels of abstraction - often is the first artifact of functional design. It can be generated by a team in an initial design brainstorming. Next comes ordering the steps. What should happen first, what next etc.? Get data from user Parse data Transform data Map result for output Output result to user That´s great for a start into functional design. It´s better than starting to code right away on a given function using TDD. Please get me right: TDD is a valuable practice. But it can be unnecessarily hard if the scope of a functionn is too large. But how do you know beforehand without investing some thinking? And how to do this thinking in a systematic fashion? My recommendation: For any given function you´re supposed to implement first do a functional design. Then, once you´re confident you know the processing steps - which are pretty small - refine and code them using TDD. You´ll see that´s much, much easier - and leads to cleaner code right away. For more information on this approach I call “Informed TDD” read my book of the same title. Thinking before coding is smart. And writing down the solution as a bunch of functions possibly is the simplest thing you can do, I´d say. It´s more according to the KISS (Keep It Simple, Stupid) principle than returning constants or other trivial stuff TDD development often is started with. So far so good. A simple ordered list of processing steps will do to start with functional design. As shown in the above example such steps can easily be translated into functions. Moving from design to coding thus is simple. However, such a list does not scale. Processing is not always that simple to be captured in a list. And then the list is just text. Again. Like code. That means the design is lacking visuality. Textual representations need more parsing by your brain than visual representations. Plus they are limited in their “dimensionality”: text just has one dimension, it´s sequential. Alternatives and parallelism are hard to encode in text. In addition the functional design using numbered lists lacks data. It´s not visible what´s the input, output, and state of the processing steps. That´s why functional design should be done using a lightweight visual notation. No tool is necessary to draw such designs. Use pen and paper; a flipchart, a whiteboard, or even a napkin is sufficient. Visualizing processes The building block of the functional design notation is a functional unit. I mostly draw it like this: Something is done, it´s clear what goes in, it´s clear what comes out, and it´s clear what the processing step requires in terms of state or hardware. Whenever input flows into a functional unit it gets processed and output is produced and/or a side effect occurs. Flowing data is the driver of something happening. That´s why I call this approach to functional design Flow Design. It´s about data flow instead of control flow. Control flow like in algorithms is of no concern to functional design. Thinking about control flow simply is too low level. Once you start with control flow you easily get bogged down by tons of details. That´s what you want to avoid during design. Design is supposed to be quick, broad brush, abstract. It should give overview. But what about all the details? As Robert C. Martin rightly said: “Programming is abot detail”. Detail is a matter of code. Once you start coding the processing steps you designed you can worry about all the detail you want. Functional design does not eliminate all the nitty gritty. It just postpones tackling them. To me that´s also an example of the SRP. Function design has the responsibility to come up with a solution to a problem posed by a single function (Entry Point). And later coding has the responsibility to implement the solution down to the last detail (i.e. statement, API-call). TDD unfortunately mixes both responsibilities. It´s just coding - and thereby trying to find detailed implementations (green phase) plus getting the design right (refactoring). To me that´s one reason why TDD has failed to deliver on its promise for many developers. Using functional units as building blocks of functional design processes can be depicted very easily. Here´s the initial process for the example problem: For each processing step draw a functional unit and label it. Choose a verb or an “action phrase” as a label, not a noun. Functional design is about activities, not state or structure. Then make the output of an upstream step the input of a downstream step. Finally think about the data that should flow between the functional units. Write the data above the arrows connecting the functional units in the direction of the data flow. Enclose the data description in brackets. That way you can clearly see if all flows have already been specified. Empty brackets mean “no data is flowing”, but nevertheless a signal is sent. A name like “list” or “strings” in brackets describes the data content. Use lower case labels for that purpose. A name starting with an upper case letter like “String” or “Customer” on the other hand signifies a data type. If you like, you also can combine descriptions with data types by separating them with a colon, e.g. (list:string) or (strings:string[]). But these are just suggestions from my practice with Flow Design. You can do it differently, if you like. Just be sure to be consistent. Flows wired-up in this manner I call one-dimensional (1D). Each functional unit just has one input and/or one output. A functional unit without an output is possible. It´s like a black hole sucking up input without producing any output. Instead it produces side effects. A functional unit without an input, though, does make much sense. When should it start to work? What´s the trigger? That´s why in the above process even the first processing step has an input. If you like, view such 1D-flows as pipelines. Data is flowing through them from left to right. But as you can see, it´s not always the same data. It get´s transformed along its passage: (args) becomes a (list) which is turned into (strings). The Principle of Mutual Oblivion A very characteristic trait of flows put together from function units is: no functional units knows another one. They are all completely independent of each other. Functional units don´t know where their input is coming from (or even when it´s gonna arrive). They just specify a range of values they can process. And they promise a certain behavior upon input arriving. Also they don´t know where their output is going. They just produce it in their own time independent of other functional units. That means at least conceptually all functional units work in parallel. Functional units don´t know their “deployment context”. They now nothing about the overall flow they are place in. They are just consuming input from some upstream, and producing output for some downstream. That makes functional units very easy to test. At least as long as they don´t depend on state or resources. I call this the Principle of Mutual Oblivion (PoMO). Functional units are oblivious of others as well as an overall context/purpose. They are just parts of a whole focused on a single responsibility. How the whole is built, how a larger goal is achieved, is of no concern to the single functional units. By building software in such a manner, functional design interestingly follows nature. Nature´s building blocks for organisms also follow the PoMO. The cells forming your body do not know each other. Take a nerve cell “controlling” a muscle cell for example:[2] The nerve cell does not know anything about muscle cells, let alone the specific muscel cell it is “attached to”. Likewise the muscle cell does not know anything about nerve cells, let a lone a specific nerve cell “attached to” it. Saying “the nerve cell is controlling the muscle cell” thus only makes sense when viewing both from the outside. “Control” is a concept of the whole, not of its parts. Control is created by wiring-up parts in a certain way. Both cells are mutually oblivious. Both just follow a contract. One produces Acetylcholine (ACh) as output, the other consumes ACh as input. Where the ACh is going, where it´s coming from neither cell cares about. Million years of evolution have led to this kind of division of labor. And million years of evolution have produced organism designs (DNA) which lead to the production of these different cell types (and many others) and also to their co-location. The result: the overall behavior of an organism. How and why this happened in nature is a mystery. For our software, though, it´s clear: functional and quality requirements needs to be fulfilled. So we as developers have to become “intelligent designers” of “software cells” which we put together to form a “software organism” which responds in satisfying ways to triggers from it´s environment. My bet is: If nature gets complex organisms working by following the PoMO, who are we to not apply this recipe for success to our much simpler “machines”? So my rule is: Wherever there is functionality to be delivered, because there is a clear Entry Point into software, design the functionality like nature would do it. Build it from mutually oblivious functional units. That´s what Flow Design is about. In that way it´s even universal, I´d say. Its notation can also be applied to biology: Never mind labeling the functional units with nouns. That´s ok in Flow Design. You´ll do that occassionally for functional units on a higher level of abstraction or when their purpose is close to hardware. Getting a cockroach to roam your bedroom takes 1,000,000 nerve cells (neurons). Getting the de-duplication program to do its job just takes 5 “software cells” (functional units). Both, though, follow the same basic principle. Translating functional units into code Moving from functional design to code is no rocket science. In fact it´s straightforward. There are two simple rules: Translate an input port to a function. Translate an output port either to a return statement in that function or to a function pointer visible to that function. The simplest translation of a functional unit is a function. That´s what you saw in the above example. Functions are mutually oblivious. That why Functional Programming likes them so much. It makes them composable. Which is the reason, nature works according to the PoMO. Let´s be clear about one thing: There is no dependency injection in nature. For all of an organism´s complexity no DI container is used. Behavior is the result of smooth cooperation between mutually oblivious building blocks. Functions will often be the adequate translation for the functional units in your designs. But not always. Take for example the case, where a processing step should not always produce an output. Maybe the purpose is to filter input. Here the functional unit consumes words and produces words. But it does not pass along every word flowing in. Some words are swallowed. Think of a spell checker. It probably should not check acronyms for correctness. There are too many of them. Or words with no more than two letters. Such words are called “stop words”. In the above picture the optionality of the output is signified by the astrisk outside the brackets. It means: Any number of (word) data items can flow from the functional unit for each input data item. It might be none or one or even more. This I call a stream of data. Such behavior cannot be translated into a function where output is generated with return. Because a function always needs to return a value. So the output port is translated into a function pointer or continuation which gets passed to the subroutine when called:[3]void filter_stop_words( string word, Action<string> onNoStopWord) { if (...check if not a stop word...) onNoStopWord(word); } If you want to be nitpicky you might call such a function pointer parameter an injection. And technically you´re right. Conceptually, though, it´s not an injection. Because the subroutine is not functionally dependent on the continuation. Firstly continuations are procedures, i.e. subroutines without a return type. Remember: Flow Design is about unidirectional data flow. Secondly the name of the formal parameter is chosen in a way as to not assume anything about downstream processing steps. onNoStopWord describes a situation (or event) within the functional unit only. Translating output ports into function pointers helps keeping functional units mutually oblivious in cases where output is optional or produced asynchronically. Either pass the function pointer to the function upon call. Or make it global by putting it on the encompassing class. Then it´s called an event. In C# that´s even an explicit feature.class Filter { public void filter_stop_words( string word) { if (...check if not a stop word...) onNoStopWord(word); } public event Action<string> onNoStopWord; } When to use a continuation and when to use an event dependens on how a functional unit is used in flows and how it´s packed together with others into classes. You´ll see examples further down the Flow Design road. Another example of 1D functional design Let´s see Flow Design once more in action using the visual notation. How about the famous word wrap kata? Robert C. Martin has posted a much cited solution including an extensive reasoning behind his TDD approach. So maybe you want to compare it to Flow Design. The function signature given is:string WordWrap(string text, int maxLineLength) {...} That´s not an Entry Point since we don´t see an application with an environment and users. Nevertheless it´s a function which is supposed to provide a certain functionality. The text passed in has to be reformatted. The input is a single line of arbitrary length consisting of words separated by spaces. The output should consist of one or more lines of a maximum length specified. If a word is longer than a the maximum line length it can be split in multiple parts each fitting in a line. Flow Design Let´s start by brainstorming the process to accomplish the feat of reformatting the text. What´s needed? Words need to be assembled into lines Words need to be extracted from the input text The resulting lines need to be assembled into the output text Words too long to fit in a line need to be split Does sound about right? I guess so. And it shows a kind of priority. Long words are a special case. So maybe there is a hint for an incremental design here. First let´s tackle “average words” (words not longer than a line). Here´s the Flow Design for this increment: The the first three bullet points turned into functional units with explicit data added. As the signature requires a text is transformed into another text. See the input of the first functional unit and the output of the last functional unit. In between no text flows, but words and lines. That´s good to see because thereby the domain is clearly represented in the design. The requirements are talking about words and lines and here they are. But note the asterisk! It´s not outside the brackets but inside. That means it´s not a stream of words or lines, but lists or sequences. For each text a sequence of words is output. For each sequence of words a sequence of lines is produced. The asterisk is used to abstract from the concrete implementation. Like with streams. Whether the list of words gets implemented as an array or an IEnumerable is not important during design. It´s an implementation detail. Does any processing step require further refinement? I don´t think so. They all look pretty “atomic” to me. And if not… I can always backtrack and refine a process step using functional design later once I´ve gained more insight into a sub-problem. Implementation The implementation is straightforward as you can imagine. The processing steps can all be translated into functions. Each can be tested easily and separately. Each has a focused responsibility. And the process flow becomes just a sequence of function calls: Easy to understand. It clearly states how word wrapping works - on a high level of abstraction. And it´s easy to evolve as you´ll see. Flow Design - Increment 2 So far only texts consisting of “average words” are wrapped correctly. Words not fitting in a line will result in lines too long. Wrapping long words is a feature of the requested functionality. Whether it´s there or not makes a difference to the user. To quickly get feedback I decided to first implement a solution without this feature. But now it´s time to add it to deliver the full scope. Fortunately Flow Design automatically leads to code following the Open Closed Principle (OCP). It´s easy to extend it - instead of changing well tested code. How´s that possible? Flow Design allows for extension of functionality by inserting functional units into the flow. That way existing functional units need not be changed. The data flow arrow between functional units is a natural extension point. No need to resort to the Strategy Pattern. No need to think ahead where extions might need to be made in the future. I just “phase in” the remaining processing step: Since neither Extract words nor Reformat know of their environment neither needs to be touched due to the “detour”. The new processing step accepts the output of the existing upstream step and produces data compatible with the existing downstream step. Implementation - Increment 2 A trivial implementation checking the assumption if this works does not do anything to split long words. The input is just passed on: Note how clean WordWrap() stays. The solution is easy to understand. A developer looking at this code sometime in the future, when a new feature needs to be build in, quickly sees how long words are dealt with. Compare this to Robert C. Martin´s solution:[4] How does this solution handle long words? Long words are not even part of the domain language present in the code. At least I need considerable time to understand the approach. Admittedly the Flow Design solution with the full implementation of long word splitting is longer than Robert C. Martin´s. At least it seems. Because his solution does not cover all the “word wrap situations” the Flow Design solution handles. Some lines would need to be added to be on par, I guess. But even then… Is a difference in LOC that important as long as it´s in the same ball park? I value understandability and openness for extension higher than saving on the last line of code. Simplicity is not just less code, it´s also clarity in design. But don´t take my word for it. Try Flow Design on larger problems and compare for yourself. What´s the easier, more straightforward way to clean code? And keep in mind: You ain´t seen all yet ;-) There´s more to Flow Design than described in this chapter. In closing I hope I was able to give you a impression of functional design that makes you hungry for more. To me it´s an inevitable step in software development. Jumping from requirements to code does not scale. And it leads to dirty code all to quickly. Some thought should be invested first. Where there is a clear Entry Point visible, it´s functionality should be designed using data flows. Because with data flows abstraction is possible. For more background on why that´s necessary read my blog article here. For now let me point out to you - if you haven´t already noticed - that Flow Design is a general purpose declarative language. It´s “programming by intention” (Shalloway et al.). Just write down how you think the solution should work on a high level of abstraction. This breaks down a large problem in smaller problems. And by following the PoMO the solutions to those smaller problems are independent of each other. So they are easy to test. Or you could even think about getting them implemented in parallel by different team members. Flow Design not only increases evolvability, but also helps becoming more productive. All team members can participate in functional design. This goes beyon collective code ownership. We´re talking collective design/architecture ownership. Because with Flow Design there is a common visual language to talk about functional design - which is the foundation for all other design activities.   PS: If you like what you read, consider getting my ebook “The Incremental Architekt´s Napkin”. It´s where I compile all the articles in this series for easier reading. I like the strictness of Function Programming - but I also find it quite hard to live by. And it certainly is not what millions of programmers are used to. Also to me it seems, the real world is full of state and side effects. So why give them such a bad image? That´s why functional design takes a more pragmatic approach. State and side effects are ok for processing steps - but be sure to follow the SRP. Don´t put too much of it into a single processing step. ? Image taken from www.physioweb.org ? My code samples are written in C#. C# sports typed function pointers called delegates. Action is such a function pointer type matching functions with signature void someName(T t). Other languages provide similar ways to work with functions as first class citizens - even Java now in version 8. I trust you find a way to map this detail of my translation to your favorite programming language. I know it works for Java, C++, Ruby, JavaScript, Python, Go. And if you´re using a Functional Programming language it´s of course a no brainer. ? Taken from his blog post “The Craftsman 62, The Dark Path”. ?

  Read the article

< Previous Page | 82 83 84 85 86