Search Results

Search found 8367 results on 335 pages for 'temporal difference'.

Page 81/335 | < Previous Page | 77 78 79 80 81 82 83 84 85 86 87 88  | Next Page >

• Android Calendar API vs Calendar Provider API

  - by John Roberts

  I'm a little bit confused about the difference between the two. An example of the Calendar API is supposedly located here: http://samples.google-api-java-client.googlecode.com/hg/calendar-android-sample/instructions.html, but the author himself suggests using the Calendar Provider API, details about which are here: http://developer.android.com/guide/topics/providers/calendar-provider.html. Can someone explain to me the difference between the two, and which would be better for me to use for a simple calendar app?

  Read the article

• Char and Chr in Delphi

  - by JamesB

  The difference between Chr and Char when used in converting types is that one is a function and the other is cast So: Char(66) = Chr(66) I don't think there is any performance difference (at least I've never noticed any, one probably calls the other).... I'm fairly sure someone will correct me on this! Which do you use in your code and why?

  Read the article

• Types questions in ANSI C

  - by shaharg

  Hi, I having few questions about typed in ANSI C: 1. what's the difference between "\x" in the beginning of a char to 0x in the beginning of char (or in any other case for this matter). AFAIK, they both means that this is hexadecimal.. so what's the difference. when casting char to (unsigned), not (unsigned char) - what does it mean? why (unsigned)'\xFF' != 0xFF? Thanks!

  Read the article

• Android WebView and default browser with different UserAgent

  - by Udi I

  From some reason on several android devices, I'm getting different User Agent from the browser and from my application's WebView. I have used this line of code to get the UA in the app: new WebView(this).getSettings().getUserAgentString(); This is the part with the difference The application retruns: HTC One X Build While the browser returns: HTC_One_X Build Notice the underscores in the browser's version. Any ideas what causes the difference? Tx!

  Read the article

• OpenGL - GL_FRONT versus GL_FRONT_AND_BACK

  - by Drew Noakes

  I'm tinkering with an open source project that uses OpenGL for rendering in 3D. In the construction of the materials I see code like this: // set ambient material reflectance glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, mAmbient); In other examples, this is used: glMaterialfv(GL_FRONT, GL_AMBIENT, mAmbient); So my question is, what is the difference here? Under what circumstances would it look different and, if my volume is enclosed with all normals pointing outwards, is there any performance difference?

  Read the article

• Why does my simple hello world console app use so much memory?

  - by CodingThunder

  Looking in Process Explorer it uses; Virtual Size: 550,000k , Working Set: 28000k Why does my simple hello world console app use so much memory? I take it the difference between the Working Set and Virtual Size means that difference will be paged to disk? /I am running 64 bit XP. Thanks class Program { static void Main(string[] args) { Console.WriteLine("Hello world"); Console.ReadLine(); } }

  Read the article

• is it possible to continue a file upload after a browser has been quit?

  - by sprugman

  If a user starts uploading a file (in a web app), and they close their browser before the upload completes, what happens? My guess would be that the upload gets abandoned, and the server has some garbage cleaning mechanism that kicks in eventually, but I'm not sure. Any difference between servers or server languages? Any difference between quitting the browser and just closing a window?

  Read the article

• Raising events vs direct method calls differences

  - by dotnetdev

  Hi Raising an event, will call its event handler. eg http://msdn.microsoft.com/en-us/library/aa645739%28VS.71%29.aspx What is the difference between using the events mechanism and direct calls to other methods (eg if a condition is met in method A(), call B() )? And what is the difference between consuming and raising events? Thanks

  Read the article

• WCF : Diffrence between NetTCP and NetPeerTCP ?

  - by nettguy

  What is the difference between netTCP and netPeerTCP bindings.I know netTCP uses TCP as transport and netPeerTCP uses P2P as transport.Apart from this is there any main difference between these two?

  Read the article

• Java - String Pool

  - by Gogi

  What is meant by String Pool ? What is difference between the following declarations : String s="hello"; String s=new String("hello"); Is there any difference between the Storing of this two strings by JVM ?

  Read the article

• C# loop - break vs. continue

  - by Terrapin

  In a C# (feel free to answer for other languages) loop, what's the difference between break and continue as a means to leave the structure of the loop, and go to the next iteration? Example: foreach (DataRow row in myTable.Rows){ if (someConditionEvalsToTrue) { break; //what's the difference between this and continue ? //continue; }}

  Read the article

• Static method,new thread performance question

  - by ylazez

  Hey guys i just have two questions about two methods used in many controllers/servlets in my app: 1-what is the difference between calling a static method in a util class or a non static method (like methods dealing with dates i.e getting current time,converting between timezones), which is better ? 2-what is the difference between calling a method(contain too many logic like sending emails) in the controller directly or running this method in a different thread ?

  Read the article

• visually show diff output in a java program

  - by Muhammad Asaduzzaman

  I am currently developing a java program where I need to show the difference between two text. Is there any library available for visually show the difference, that is the diff output in my java program or how can I do so. Any suggestion will be very helpful for me.

  Read the article

• One question with array declaration in C++

  - by skydoor

  Hi What's the difference between the two code below. int a[] = {0,0}; int a[2] = {0,0}; It seems I can assign value to a[3] in both cases. I can access a[3] in any case. So what's the difference?

  Read the article

• Why is the application not starting from top...

  - by user536213

  i have created iphone game.When i pause the game using pause button i quit cliking quit button... Now when i start the game again ..the previous counter i created using this code... [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateTimerFunc) userInfo:nil repeats:YES]; the timer is 100 sec and moves to zero...now it start giving the difference of twwo ,,98,96,94 if i quit the game again ans start this time the difference will become of 4 96,92 ...its keep on increasing ....what is this issue? kindly help

  Read the article

• function overloading and overriding in php

  - by Phoenix

  In php what do you mean by function overloading and function overriding. and what is the difference between both of them? couldn't figure out what is the difference between them. Thanks in advance for any help

  Read the article

• storage classes

  - by ramyabanu

  what is the difference between a variable declared as an auto and static? what is the difference in allocation of memory in auto and static variable? why do we use static with array of pointers and what is its significance?

  Read the article

• ruby looping question

  - by jonepatr

  Hello! I want to make a loop on a variable that can be altered inside of the loop. first_var.sort.each do |first_id, first_value| second_var.sort.each do |second_id, second_value_value| difference = first_value - second_value if difference >= 0 second_var.delete(second_id) else second_var[second_id] += first_value if second_var[second_id] == 0 second_var.delete(second_id) end first_var.delete(first_id) end end end How do I do this, because this doesn't work?

  Read the article

• Return 0 when a value of a cell is negative

  - by Robert

  I have a google spreadsheet that uses this function: =SUM(E:E) - SUM(C:C) It adds up all the values of column E and column C and them subtracts the difference. I would like to be able to return a 0 if the difference is negative.

  Read the article

• mysql_real_escape more than once

  - by Aran

  I was just wondering whether it makes a difference if I mysql_real_escape data more than once? So if I escaped data in one part of my website, and then again in another part of code. Would this be a problem? Or make a difference?

  Read the article

• Troubleshooting latency spikes on ESXi NFS datastores

  - by exo_cw

  I'm experiencing fsync latencies of around five seconds on NFS datastores in ESXi, triggered by certain VMs. I suspect this might be caused by VMs using NCQ/TCQ, as this does not happen with virtual IDE drives. This can be reproduced using fsync-tester (by Ted Ts'o) and ioping. For example using a Grml live system with a 8GB disk: Linux 2.6.33-grml64: root@dynip211 /mnt/sda # ./fsync-tester fsync time: 5.0391 fsync time: 5.0438 fsync time: 5.0300 fsync time: 0.0231 fsync time: 0.0243 fsync time: 5.0382 fsync time: 5.0400 [... goes on like this ...] That is 5 seconds, not milliseconds. This is even creating IO-latencies on a different VM running on the same host and datastore: root@grml /mnt/sda/ioping-0.5 # ./ioping -i 0.3 -p 20 . 4096 bytes from . (reiserfs /dev/sda): request=1 time=7.2 ms 4096 bytes from . (reiserfs /dev/sda): request=2 time=0.9 ms 4096 bytes from . (reiserfs /dev/sda): request=3 time=0.9 ms 4096 bytes from . (reiserfs /dev/sda): request=4 time=0.9 ms 4096 bytes from . (reiserfs /dev/sda): request=5 time=4809.0 ms 4096 bytes from . (reiserfs /dev/sda): request=6 time=1.0 ms 4096 bytes from . (reiserfs /dev/sda): request=7 time=1.2 ms 4096 bytes from . (reiserfs /dev/sda): request=8 time=1.1 ms 4096 bytes from . (reiserfs /dev/sda): request=9 time=1.3 ms 4096 bytes from . (reiserfs /dev/sda): request=10 time=1.2 ms 4096 bytes from . (reiserfs /dev/sda): request=11 time=1.0 ms 4096 bytes from . (reiserfs /dev/sda): request=12 time=4950.0 ms When I move the first VM to local storage it looks perfectly normal: root@dynip211 /mnt/sda # ./fsync-tester fsync time: 0.0191 fsync time: 0.0201 fsync time: 0.0203 fsync time: 0.0206 fsync time: 0.0192 fsync time: 0.0231 fsync time: 0.0201 [... tried that for one hour: no spike ...] Things I've tried that made no difference: Tested several ESXi Builds: 381591, 348481, 260247 Tested on different hardware, different Intel and AMD boxes Tested with different NFS servers, all show the same behavior: OpenIndiana b147 (ZFS sync always or disabled: no difference) OpenIndiana b148 (ZFS sync always or disabled: no difference) Linux 2.6.32 (sync or async: no difference) It makes no difference if the NFS server is on the same machine (as a virtual storage appliance) or on a different host Guest OS tested, showing problems: Windows 7 64 Bit (using CrystalDiskMark, latency spikes happen mostly during preparing phase) Linux 2.6.32 (fsync-tester + ioping) Linux 2.6.38 (fsync-tester + ioping) I could not reproduce this problem on Linux 2.6.18 VMs. Another workaround is to use virtual IDE disks (vs SCSI/SAS), but that is limiting performance and the number of drives per VM. Update 2011-06-30: The latency spikes seem to happen more often if the application writes in multiple small blocks before fsync. For example fsync-tester does this (strace output): pwrite(3, "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"..., 1048576, 0) = 1048576 fsync(3) = 0 ioping does this while preparing the file: [lots of pwrites] pwrite(3, "********************************"..., 4096, 1036288) = 4096 pwrite(3, "********************************"..., 4096, 1040384) = 4096 pwrite(3, "********************************"..., 4096, 1044480) = 4096 fsync(3) = 0 The setup phase of ioping almost always hangs, while fsync-tester sometimes works fine. Is someone capable of updating fsync-tester to write multiple small blocks? My C skills suck ;) Update 2011-07-02: This problem does not occur with iSCSI. I tried this with the OpenIndiana COMSTAR iSCSI server. But iSCSI does not give you easy access to the VMDK files so you can move them between hosts with snapshots and rsync. Update 2011-07-06: This is part of a wireshark capture, captured by a third VM on the same vSwitch. This all happens on the same host, no physical network involved. I've started ioping around time 20. There were no packets sent until the five second delay was over: No. Time Source Destination Protocol Info 1082 16.164096 192.168.250.10 192.168.250.20 NFS V3 WRITE Call (Reply In 1085), FH:0x3eb56466 Offset:0 Len:84 FILE_SYNC 1083 16.164112 192.168.250.10 192.168.250.20 NFS V3 WRITE Call (Reply In 1086), FH:0x3eb56f66 Offset:0 Len:84 FILE_SYNC 1084 16.166060 192.168.250.20 192.168.250.10 TCP nfs > iclcnet-locate [ACK] Seq=445 Ack=1057 Win=32806 Len=0 TSV=432016 TSER=769110 1085 16.167678 192.168.250.20 192.168.250.10 NFS V3 WRITE Reply (Call In 1082) Len:84 FILE_SYNC 1086 16.168280 192.168.250.20 192.168.250.10 NFS V3 WRITE Reply (Call In 1083) Len:84 FILE_SYNC 1087 16.168417 192.168.250.10 192.168.250.20 TCP iclcnet-locate > nfs [ACK] Seq=1057 Ack=773 Win=4163 Len=0 TSV=769110 TSER=432016 1088 23.163028 192.168.250.10 192.168.250.20 NFS V3 GETATTR Call (Reply In 1089), FH:0x0bb04963 1089 23.164541 192.168.250.20 192.168.250.10 NFS V3 GETATTR Reply (Call In 1088) Directory mode:0777 uid:0 gid:0 1090 23.274252 192.168.250.10 192.168.250.20 TCP iclcnet-locate > nfs [ACK] Seq=1185 Ack=889 Win=4163 Len=0 TSV=769821 TSER=432716 1091 24.924188 192.168.250.10 192.168.250.20 RPC Continuation 1092 24.924210 192.168.250.10 192.168.250.20 RPC Continuation 1093 24.924216 192.168.250.10 192.168.250.20 RPC Continuation 1094 24.924225 192.168.250.10 192.168.250.20 RPC Continuation 1095 24.924555 192.168.250.20 192.168.250.10 TCP nfs > iclcnet_svinfo [ACK] Seq=6893 Ack=1118613 Win=32625 Len=0 TSV=432892 TSER=769986 1096 24.924626 192.168.250.10 192.168.250.20 RPC Continuation 1097 24.924635 192.168.250.10 192.168.250.20 RPC Continuation 1098 24.924643 192.168.250.10 192.168.250.20 RPC Continuation 1099 24.924649 192.168.250.10 192.168.250.20 RPC Continuation 1100 24.924653 192.168.250.10 192.168.250.20 RPC Continuation 2nd Update 2011-07-06: There seems to be some influence from TCP window sizes. I was not able to reproduce this problem using FreeNAS (based on FreeBSD) as a NFS server. The wireshark captures showed TCP window updates to 29127 bytes in regular intervals. I did not see them with OpenIndiana, which uses larger window sizes by default. I can no longer reproduce this problem if I set the following options in OpenIndiana and restart the NFS server: ndd -set /dev/tcp tcp_recv_hiwat 8192 # default is 128000 ndd -set /dev/tcp tcp_max_buf 1048575 # default is 1048576 But this kills performance: Writing from /dev/zero to a file with dd_rescue goes from 170MB/s to 80MB/s. Update 2011-07-07: I've uploaded this tcpdump capture (can be analyzed with wireshark). In this case 192.168.250.2 is the NFS server (OpenIndiana b148) and 192.168.250.10 is the ESXi host. Things I've tested during this capture: Started "ioping -w 5 -i 0.2 ." at time 30, 5 second hang in setup, completed at time 40. Started "ioping -w 5 -i 0.2 ." at time 60, 5 second hang in setup, completed at time 70. Started "fsync-tester" at time 90, with the following output, stopped at time 120: fsync time: 0.0248 fsync time: 5.0197 fsync time: 5.0287 fsync time: 5.0242 fsync time: 5.0225 fsync time: 0.0209 2nd Update 2011-07-07: Tested another NFS server VM, this time NexentaStor 3.0.5 community edition: Shows the same problems. Update 2011-07-31: I can also reproduce this problem on the new ESXi build 4.1.0.433742.

  Read the article

• Intermittent HTTP 401 errors

  - by forthrin

  I am using an Intranet solution which requires basic HTTP login. However, there is an intermittent error which requires me to log in again, and then the server says "Forbidden" whether I give the correct login information or not. To add insult to injury, Safari (and Chrome) seems to show the login dialog for every included resource in the HTML, and it's impossible to cancel this modal dialog sequence, so the whole browser is blocked until I've pressed Esc some 30 odd times. After an hour, I may gain access again, without having really done anything. My questions: What could cause temporal 401 errors? Why do the browsers show the login dialog 30 times per page load (assumedly for every included resource in the HTML from the same domain)?

  Read the article

• What kind of time lapse image stitching software is out there?

  - by AaronLS

  I took a bunch of digital images(jpg format) of a sunrise that I want to make into a time lapse movie. The only recommendation I've seen was some iStopMotion for Mac, but I am running Windows. I would prefer the software to take into account the metadata in the image that indicates what time the image was taken when determining how long to display each frame, as they won't be accurately consistent in their temporal spacing. Onion skinning would be a cool feature to. Please, one software suggestion per answer to allow the voting system to do it's job. Thanks in advance.

  Read the article

• Java JPA Hibernate Spring @EntityListeners throws org.springframework.dao.DataIntegrityViolationException

  - by user

  I am using Spring 3 with Hibernate 3. I would like to update the last modification date automatically when an entity is updated. Below is the sample code: HibernateConfig: @Configuration public class HibernateConfig { @Bean public DataSource dataSource() throws Exception { DriverManagerDataSource dataSource = new DriverManagerDataSource(); Properties properties = new Properties(); properties.load(ClassLoader.getSystemResourceAsStream(new String("hibernate.properties"))); dataSource.setUrl(properties.getProperty(new String("jdbc.url"))); dataSource.setUsername(properties.getProperty(new String("jdbc.username"))); dataSource.setPassword(properties.getProperty(new String("jdbc.password"))); dataSource.setDriverClassName(properties.getProperty(new String("jdbc.driverClassName"))); return dataSource; } @Bean public AnnotationSessionFactoryBean sessionFactory() throws Exception { AnnotationSessionFactoryBean sessionFactory = new AnnotationSessionFactoryBean(); Properties hibernateProperties = new Properties(); Properties properties = new Properties(); properties.load(ClassLoader.getSystemResourceAsStream(new String("hibernate.properties"))); // set the Hibernate Properties hibernateProperties.setProperty(new String("hibernate.dialect"), properties.getProperty(new String("hibernate.dialect"))); hibernateProperties.setProperty(new String("hibernate.show_sql"), properties.getProperty(new String("hibernate.show_sql"))); hibernateProperties.setProperty(new String("hibernate.hbm2ddl.auto"), properties.getProperty(new String("hibernate.hbm2ddl.auto"))); sessionFactory.setDataSource(dataSource()); sessionFactory.setHibernateProperties(hibernateProperties); sessionFactory.setAnnotatedClasses(new Class[]{Message.class}) return sessionFactory; } @Bean public HibernateTemplate hibernateTemplate() throws Exception { HibernateTemplate hibernateTemplate = new HibernateTemplate(); hibernateTemplate.setSessionFactory(sessionFactory().getObject()); return hibernateTemplate; } } DAOConfig: @Configuration public class DAOConfig { @Autowired private HibernateConfig hibernateConfig; @Bean public MessageDAO messageDAO() throws Exception { MessageDAO messageDAO = new MessageHibernateDAO(hibernateConfig.hibernateTemplate()); return messageDAO; } } Message: import java.util.Date; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.EntityListeners; import javax.persistence.Table; import javax.persistence.Temporal; import javax.persistence.TemporalType; import java.io.Serializable; import javax.persistence.Column; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; @Entity @Table @EntityListeners(value = MessageListener.class) public class Message implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column private int id; @Column(nullable = false) @Temporal(TemporalType.TIMESTAMP) private Date lastMod; public Message() { } public int getId() { return id; } public void setId(int id) { this.id = id; } public Date getLastMod() { return lastMod; } public void setLastMod(Date lastMod) { this.lastMod = lastMod; } } MessageListener: import java.util.Date; import javax.persistence.PrePersist; import javax.persistence.PreUpdate; import org.springframework.stereotype.Component; @Component public class MessageListener { @PrePersist @PreUpdate public void setLastMod(Message message) { message.setLastMod(new Date()); } } When running this the MessageListener is not being invoked. I use a DAO design pattern and when calling dao.update(Message) it throws the following Exception: org.springframework.dao.DataIntegrityViolationException: not-null property references a null or transient value: com.persistence.entities.MessageStatus.lastMod; nested exception is org.hibernate.PropertyValueException: not-null property references a null or transient value: com.persistence.entities.Message.lastMod at org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:665) at org.springframework.orm.hibernate3.HibernateAccessor.convertHibernateAccessException(HibernateAccessor.java:412) at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:411) at org.springframework.orm.hibernate3.HibernateTemplate.executeWithNativeSession(HibernateTemplate.java:374) at org.springframework.orm.hibernate3.HibernateTemplate.save(HibernateTemplate.java:683) at com.persistence.dao.hibernate.GenericHibernateDAO.save(GenericHibernateDAO.java:38) Having looked at a number of websites there seems not to be a solution.

  Read the article

• Issuing Current Time Increments in StreamInsight (A Practical Example)

  The issuing of a Current Time Increment, Cti, in StreamInsight is very definitely one of the most important concepts to learn if you want your Streams to be responsive. A full discussion of how to issue Ctis is beyond the scope of this article but a very good explanation in addition to Books Online can be found in these three articles by a member of the StreamInsight team at Microsoft, Ciprian Gerea. Time in StreamInsight Series http://blogs.msdn.com/b/streaminsight/archive/2010/07/23/time-in-streaminsight-i.aspx http://blogs.msdn.com/b/streaminsight/archive/2010/07/30/time-in-streaminsight-ii.aspx http://blogs.msdn.com/b/streaminsight/archive/2010/08/03/time-in-streaminsight-iii.aspx A lot of the problems I see with unresponsive or stuck streams on the MSDN Forums are to do with how Ctis are enqueued or in a lot of cases not enqueued. If you enqueue events and never enqueue a Cti then StreamInsight will be perfectly happy. You, on the other hand, will never see data on the output as you have not told StreamInsight to flush the stream. This article deals with a specific implementation problem I had recently whilst working on a StreamInsight project. I look at some possible options and discuss why they would not work before showing the way I solved the problem. The stream of data I was dealing with on this project was very bursty that is to say when events were flowing they came through very quickly and in large numbers (1000 events/sec), but when the stream calmed down it could be a few seconds between each event. When enqueuing events into the StreamInsight engne it is best practice to do so with a StartTime that is given to you by the system producing the event . StreamInsight processes events and it doesn't matter whether those events are being pushed into the engine by a source system or the events are being read from something like a flat file in a directory somewhere. You can apply the same logic and temporal algebra to both situations. Reading from a file is an excellent example of where the time of the event on the source itself is very important. We could be reading that file a long time after it was written. Being able to read the StartTime from the events allows us to define windows that will hold the correct sets of events. I was able to do this with my stream but this is where my problems started. Below is a very simple script to create a SQL Server table and populate it with sample data that will show exactly the problem I had. CREATE TABLE [dbo].[t] ( [c1] [int] PRIMARY KEY, [c2] [datetime] NULL ) INSERT t VALUES (1,'20100810'),(2,'20100810'),(3,'20100810') Column c2 defines the StartTime of the event on the source and as you can see the values in all 3 rows of data is the same. If we read Ciprian’s articles we know that we can define how Ctis get injected into the stream in 3 different places The Stream Definition The Input Factory The Input Adapter I personally have always been a fan of enqueing Ctis through the factory. Below is code typical of what I would use to do this On the class itself I do some inheriting public class SimpleInputFactory : ITypedInputAdapterFactory<SimpleInputConfig>, ITypedDeclareAdvanceTimeProperties<SimpleInputConfig> And then I implement the following function public AdapterAdvanceTimeSettings DeclareAdvanceTimeProperties<TPayload>(SimpleInputConfig configInfo, EventShape eventShape) { return new AdapterAdvanceTimeSettings( new AdvanceTimeGenerationSettings(configInfo.CtiFrequency, TimeSpan.FromTicks(-1)), AdvanceTimePolicy.Adjust); } The configInfo .CtiFrequency property is a value I pass through to define after how many events I want a Cti to be injected and this in turn will flush through the stream of data. I usually pass a value of 1 for this setting. The second parameter determines the CTI timestamp in terms of a delay relative to the events. -1 ticks in the past results in 1 tick in the future, i.e., ahead of the event. The problem with this method though is that if consecutive events have the same StartTime then only one of those events will be enqueued. In this example I use the following to define how I assign the StartTime of my events currEvent.StartTime = (DateTimeOffset)dt.c2; If I go ahead and run my StreamInsight process with this configuration i can see on the output adapter that two events have been removed To see this in a little more depth I can use the StreamInsight Debugger and see what happens internally. What is happening here is that the first event arrives and a Cti is injected with a time of 1 tick after the StartTime of that event (Also the EndTime of the event). The second event arrives and it has a StartTime of before the Cti and even though we specified AdvanceTimePolicy.Adjust on the factory we know that a point event can never be adjusted like this and the event is dropped. The same happens for the third event as well (The second and third events get trumped by the Cti). For a more detailed discussion of why this happens look here http://www.sqlis.com/sqlis/post/AdvanceTimePolicy-and-Point-Event-Streams-In-StreamInsight.aspx We end up with a single event being pushed into the output adapter and our result now makes sense. The next way I tried to solve this problem by changing the value of the second parameter to TimeSpan.Zero Here is how my factory code now looks public AdapterAdvanceTimeSettings DeclareAdvanceTimeProperties<TPayload>(SimpleInputConfig configInfo, EventShape eventShape) { return new AdapterAdvanceTimeSettings( new AdvanceTimeGenerationSettings(configInfo.CtiFrequency, TimeSpan.Zero), AdvanceTimePolicy.Adjust); } What I am doing here is declaring a policy that says inject a Cti together with every event and stamp it with a StartTime that is equal to the start time of the event itself (TimeSpan.Zero). This method has plus points as well as a downside. The upside is that no events will be lost by having the same StartTime as previous events. The Downside is that because the Cti is declared with the StartTime of the event itself then it does not actually flush that particular event because in the StreamInsight algebra, a Cti commits only those events that occurred strictly before them. To flush the events we need a Cti to be enqueued with a greater StartTime than the events themselves. Here is what happened when I ran this configuration As you can see all we got through was the Cti and none of the events. The debugger output shows the stamps on the Cti and the events themselves. Because the Cti issued has the same timestamp (StartTime) as the events then none of the events get flushed. I was nearly there but not quite. Because my stream was bursty it was possible that the next event would not come along for a few seconds and this was far too long for an event to be enqueued and not be flushed to the output adapter. I needed another solution. Two possible solutions crossed my mind although only one of them made sense when I explored it some more. Where multiple events have the same StartTime I could add 1 tick to the first event, two to the second, three to third etc thereby giving them unique StartTime values. Add a timer to manually inject Ctis The problem with the first implementation is that I would be giving the events a new StartTime. This would cause me the following problems If I want to define windows over the stream then some events may not be captured in the right windows and therefore any calculations on those windows I did would be wrong What would happen if we had 10,000 events with the same StartTime? I would enqueue them with StartTime + n ticks. Along comes a genuine event with a StartTime of the very first event + 1 tick. It is now too far in the past as far as my stream is concerned and it would be dropped. Not what I would want to do at all. I decided then to look at the Timer based solution I created a timer on my input adapter that elapsed every 200ms. private Timer tmr; public SimpleInputAdapter(SimpleInputConfig configInfo) { ctx = new SimpleTimeExtractDataContext(configInfo.ConnectionString); this.configInfo = configInfo; tmr = new Timer(200); tmr.Elapsed += new ElapsedEventHandler(t_Elapsed); tmr.Enabled = true; } void t_Elapsed(object sender, ElapsedEventArgs e) { ts = DateTime.Now - dtCtiIssued; if (ts.TotalMilliseconds >= 200 && TimerIssuedCti == false) { EnqueueCtiEvent(System.DateTime.Now.AddTicks(-100)); TimerIssuedCti = true; } }   In the t_Elapsed event handler I find out the difference in time between now and when the last event was processed (dtCtiIssued). I then check to see if that is greater than or equal to 200ms and if the last issuing of a Cti was done by the timer or by a genuine event (TimerIssuedCti). If I didn’t do this check then I would enqueue a Cti every time the timer elapsed which is not something I wanted. If the difference between the two times is greater than or equal to 500ms and the last event enqueued was by a real event then I issue a Cti through the timer to flush the event Queue, otherwise I do nothing. When I enqueue the Ctis into my stream in my ProduceEvents method I also set the values of dtCtiIssued and TimerIssuedCti   currEvent = CreateInsertEvent(); currEvent.StartTime = (DateTimeOffset)dt.c2; TimerIssuedCti = false; dtCtiIssued = currEvent.StartTime; If I go ahead and run this configuration I see the following in my output. As we can see the first Cti gets enqueued as before but then another is enqueued by the timer and because this has a later timestamp it flushes the enqueued events through the engine. Conclusion Hopefully this has shown how the enqueuing of Ctis can have a dramatic effect on the responsiveness of your output in StreamInsight. Understanding the temporal nature of the product is for me one of the most important things you can learn. I have attached my solution for the demos. It is all in one project and testing each variation is a simple matter of commenting and un-commenting the parts in the code we have been dealing with here.

  Read the article

< Previous Page | 77 78 79 80 81 82 83 84 85 86 87 88  | Next Page >