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  • Altq limits not being applied to UDP transfers

    - by overkordbaever
    I have a OpenBSD server acting as a router/firewall with yhr packet filter ruleset shown below, a linux server, and a linux client. When transferring files (using netcat) by TCP, the limits are applied (for example the 100mbit limit in the example), though when transferring data by UDP, the limits aren't applied; the file always takes the same amount of time no matter the queue bandwidth limit I set (I can even turn off the queues completely, and will still get the same result). Why aren't the queuing rules applied to UDP packages? The rules used: #queue rules altq on { $int_if, $ext_if } cbq bandwidth 100Mb queue { def, low } queue def bandwidth 0Mb cbq(default) queue low bandwidth 100Mb cbq #Passrules test pass out quick from $int_if to $ext_if queue low pass in quick from $ext_if to $int_if queue low pass out quick from $ext_if to $int_if queue low pass in quick from $int_if to $ext_if queue low I suppose this may be related a question I've previously asked, though since it's more of a separate question, I suppose a separate question should be used for this

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  • Testing a Non-blocking Queue

    - by jsw
    I've ported the non-blocking queue psuedocode here to C#. The code below is meant as a near verbatim copy of the paper. What approach would you take to test the implementation? Note: I'm running in VS2010 so I don't have CHESS support yet. using System.Threading; #pragma warning disable 0420 namespace ConcurrentCollections { class QueueNodePointer<T> { internal QueueNode<T> ptr; internal QueueNodePointer() : this(null) { } internal QueueNodePointer(QueueNode<T> ptr) { this.ptr = ptr; } } class QueueNode<T> { internal T value; internal QueueNodePointer<T> next; internal QueueNode() : this(default(T)) { } internal QueueNode(T value) { this.value = value; this.next = new QueueNodePointer<T>(); } } public class ConcurrentQueue<T> { private volatile int count = 0; private QueueNodePointer<T> qhead = new QueueNodePointer<T>(); private QueueNodePointer<T> qtail = new QueueNodePointer<T>(); public ConcurrentQueue() { var node = new QueueNode<T>(); node.next.ptr = null; this.qhead.ptr = this.qtail.ptr = node; } public int Count { get { return this.count; } } public void Enqueue(T value) { var node = new QueueNode<T>(value); node.next.ptr = null; QueueNodePointer<T> tail; QueueNodePointer<T> next; while (true) { tail = this.qtail; next = tail.ptr.next; if (tail == this.qtail) { if (next.ptr == null) { var newtail = new QueueNodePointer<T>(node); if (Interlocked.CompareExchange(ref tail.ptr.next, newtail, next) == next) { Interlocked.Increment(ref this.count); break; } else { Interlocked.CompareExchange(ref this.qtail, new QueueNodePointer<T>(next.ptr), tail); } } } } Interlocked.CompareExchange(ref this.qtail, new QueueNodePointer<T>(node), tail); } public T Dequeue() { T value; while (true) { var head = this.qhead; var tail = this.qtail; var next = head.ptr.next; if (head == this.qhead) { if (head.ptr == tail.ptr) { if (next.ptr == null) { return default(T); } Interlocked.CompareExchange(ref this.qtail, new QueueNodePointer<T>(next.ptr), tail); } else { value = next.ptr.value; var newhead = new QueueNodePointer<T>(next.ptr); if (Interlocked.CompareExchange(ref this.qhead, newhead, head) == head) { Interlocked.Decrement(ref this.count); break; } } } } return value; } } } #pragma warning restore 0420

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  • Lockless queue implementation ends up having a loop under stress

    - by Fozi
    I have lockless queues written in C in form of a linked list that contains requests from several threads posted to and handled in a single thread. After a few hours of stress I end up having the last request's next pointer pointing to itself, which creates an endless loop and locks up the handling thread. The application runs (and fails) on both Linux and Windows. I'm debugging on Windows, where my COMPARE_EXCHANGE_PTR maps to InterlockedCompareExchangePointer. This is the code that pushes a request to the head of the list, and is called from several threads: void push_request(struct request * volatile * root, struct request * request) { assert(request); do { request->next = *root; } while(COMPARE_EXCHANGE_PTR(root, request, request->next) != request->next); } This is the code that gets a request from the end of the list, and is only called by a single thread that is handling them: struct request * pop_request(struct request * volatile * root) { struct request * volatile * p; struct request * request; do { p = root; while(*p && (*p)->next) p = &(*p)->next; // <- loops here request = *p; } while(COMPARE_EXCHANGE_PTR(p, NULL, request) != request); assert(request->next == NULL); return request; } Note that I'm not using a tail pointer because I wanted to avoid the complication of having to deal with the tail pointer in push_request. However I suspect that the problem might be in the way I find the end of the list. There are several places that push a request into the queue, but they all look generaly like this: // device->requests is defined as struct request * volatile requests; struct request * request = malloc(sizeof(struct request)); if(request) { // fill out request fields push_request(&device->requests, request); sem_post(device->request_sem); } The code that handles the request is doing more than that, but in essence does this in a loop: if(sem_wait_timeout(device->request_sem, timeout) == sem_success) { struct request * request = pop_request(&device->requests); // handle request free(request); } I also just added a function that is checking the list for duplicates before and after each operation, but I'm afraid that this check will change the timing so that I will never encounter the point where it fails. (I'm waiting for it to break as I'm writing this.) When I break the hanging program the handler thread loops in pop_request at the marked position. I have a valid list of one or more requests and the last one's next pointer points to itself. The request queues are usually short, I've never seen more then 10, and only 1 and 3 the two times I could take a look at this failure in the debugger. I thought this through as much as I could and I came to the conclusion that I should never be able to end up with a loop in my list unless I push the same request twice. I'm quite sure that this never happens. I'm also fairly sure (although not completely) that it's not the ABA problem. I know that I might pop more than one request at the same time, but I believe this is irrelevant here, and I've never seen it happening. (I'll fix this as well) I thought long and hard about how I can break my function, but I don't see a way to end up with a loop. So the question is: Can someone see a way how this can break? Can someone prove that this can not? Eventually I will solve this (maybe by using a tail pointer or some other solution - locking would be a problem because the threads that post should not be locked, I do have a RW lock at hand though) but I would like to make sure that changing the list actually solves my problem (as opposed to makes it just less likely because of different timing).

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  • Cash Application Work Queue in Oracle Receivables Release 12.1.1

    - by Robert Story
    Upcoming WebcastTitle: Cash Application Work Queue in Oracle Receivables Release 12.1.1Date: March 24, 2010Time: 10:00 am EDT, 7:00 am PDT, 14:00 GMT Product Family: E-Business Suite Receivables 12.1.1 Receipts Summary Understand the setups and processes for the Cash Application Work Queue in Release 12.1.1 and learn how to diagnose basic functional issues. This one-hour session is recommended for technical and functional users. We will be covering topics related to processing receipts efficiently, managing the work load of cash application owners and diagnosing issues. Topics will include: Description of Cash Application Work Queue Setup and Work Queue Process Dependencies and Interactions Basic Troubleshooting Steps A short, live demonstration (only if applicable) and question and answer period will be included. Click here to register for this session....... ....... ....... ....... ....... ....... .......The above webcast is a service of the E-Business Suite Communities in My Oracle Support.For more information on other webcasts, please reference the Oracle Advisor Webcast Schedule.Click here to visit the E-Business Communities in My Oracle Support Note that all links require access to My Oracle Support.

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  • how to make a queue in php with mysql

    - by robert
    hy, in my script i run a exec() function to make a movie file with ffmpeg. the problem is ffmpeg can run only 1 time on the server, if 2 people are online on server and first one already run ffmpeg i want the second to wait until the first end the process how to code this? thank you

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  • Any other kinds of "Task Queue" APIs ?

    - by sork
    I'm curious if it's common practice outside of the GAE platform to be able to defer tasks to background workers via webhooks. I find it particularly useful to speed up the front-end of webapps, by delegating any long process to background tasks. I'd like to hear about open source software allowing to implement a TaskQueue-like API, with webhooks preferably, if anyone has some experience in this area. Thanks!

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  • Which persistent & lightweight queue messaging for cross domain (> 2) data exchange with rails integ

    - by Erwan
    Hi all, I'm looking for the right messaging system for my needs. Can you help me ? For now, there won't be a huge amount of data to process, but I don't want to be limited later ... The machines are not just web servers, so the messaging tool should be lightweight, even if processing is not very speed. When some data change on a server, all servers should have the information and process it locally. (should I create one channel per server on each of them ?) The frontend is written on Rails, so it is important, in order to simplify the development, that there is a gem / plugin to manage communications and data sent. At this time : RabbitMQ + workling seems to fit my needs. Could this be a right choice ? ActiveMQ make me afraid, because of Java (I really don't know very well Java, but it seems to me to be big CPU consumer) Others don't seem to be as mature as them. There might be lot of development using this kind of technology, so I can't go to the wrong way ! Thank you for help.

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  • Processing a database queue across multiple threads - design advice

    - by rwmnau
    I have a SQL Server table full of orders that my program needs to "follow up" on (call a webservice to see if something has been done with them). My application is multi-threaded, and could have instances running on multiple servers. Currently, every so often (on a Threading timer), the process selects 100 rows, at random (ORDER BY NEWID()), from the list of "unconfirmed" orders and checks them, marking off any that come back successfully. The problem is that there's a lot of overlap between the threads, and between the different processes, and their's no guarantee that a new order will get checked any time soon. Also, some orders will never be "confirmed" and are dead, which means that they get in the way of orders that need to be confirmed, slowing the process down if I keep selecting them over and over. What I'd prefer is that all outstanding orders get checked, systematically. I can think of two easy ways do this: The application fetches one order to check at a time, passing in the last order it checked as a parameter, and SQL Server hands back the next order that's unconfirmed. More database calls, but this ensures that every order is checked in a reasonable timeframe. However, different servers may re-check the same order in succession, needlessly. The SQL Server keeps track of the last order it asked a process to check up on, maybe in a table, and gives a unique order to every request, incrementing its counter. This involves storing the last order somewhere in SQL, which I wanted to avoid, but it also ensures that threads won't needlessly check the same orders at the same time Are there any other ideas I'm missing? Does this even make sense? Let me know if I need some clarification.

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  • PHP Priority Queue Implementation

    - by Zahymaka
    I just finished coding a complex job assignment application where a lot of the work was done using priority queues. When I deployed, however, I discovered the web server ran PHP 5.2. Has there been an implementation for PHP<5.3 that can server as a drop-in replacement for SPLPriorityQueue?

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  • DB optimization to use it as a queue

    - by anony
    We have a table called worktable which has some columns(key(primary key), ptime, aname, status, content) we have something called producer which puts in rows in this table and we have consumer which does an order-by on the key column and fetches the first row which has status as 'pending'. The consumer does some processing on this row: 1. updates status to "processing" 2. does some processing using content 3. deletes the row we are facing contention issues when we try to run multiple consumers(probably due to the order-by which does a full table scan)... using Advanced queues would be our next step but before we go there we want to check what is the max throughput we can achieve with multiple consumers and producer on the table. What are the optimizations we can do to get the best numbers possible? Can we do an in-memory processing where a consumer fetches 1000 rows at a time processes and deletes? will that improve? What are other possibilities? partitioning of table? parallelization? Index organized tables?...

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  • Java Sorting "queue" list based on DateTime and Z Position (part of school project)

    - by Kuchinawa
    For a school project i have a list of 50k containers that arrive on a boat. These containers need to be sorted in a list in such a way that the earliest departure DateTimes are at the top and the containers above those above them. This list then gets used for a crane that picks them up in order. I started out with 2 Collection.sort() methods: 1st one to get them in the right XYZ order Collections.sort(containers, new Comparator<ContainerData>() { @Override public int compare(ContainerData contData1, ContainerData contData2) { return positionSort(contData1.getLocation(),contData2.getLocation()); } }); Then another one to reorder the dates while keeping the position in mind: Collections.sort(containers, new Comparator<ContainerData>() { @Override public int compare(ContainerData contData1, ContainerData contData2) { int c = contData1.getLeaveDateTimeFrom().compareTo(contData2.getLeaveDateTimeFrom()); int p = positionSort2(contData1.getLocation(), contData2.getLocation()); if(p != 0) c = p; return c; } }); But i never got this method to work.. What i got working now is rather quick and dirty and takes a long time to process (50seconds for all 50k): First a sort on DateTime: Collections.sort(containers, new Comparator<ContainerData>() { @Override public int compare(ContainerData contData1, ContainerData contData2) { return contData1.getLeaveDateTimeFrom().compareTo(contData2.getLeaveDateTimeFrom()); } }); Then a correction function that bumps top containers up: containers = stackCorrection(containers); private static List<ContainerData> stackCorrection(List<ContainerData> sortedContainerList) { for(int i = 0; i < sortedContainerList.size(); i++) { ContainerData current = sortedContainerList.get(i); // 5 = Max Stack (0 index) if(current.getLocation().getZ() < 5) { //Loop through possible containers above current for(int j = 5; j > current.getLocation().getZ(); --j) { //Search for container above for(int k = i + 1; k < sortedContainerList.size(); ++k) if(sortedContainerList.get(k).getLocation().getX() == current.getLocation().getX()) { if(sortedContainerList.get(k).getLocation().getY() == current.getLocation().getY()) { if(sortedContainerList.get(k).getLocation().getZ() == j) { //Found -> move container above current sortedContainerList.add(i, sortedContainerList.remove(k)); k = sortedContainerList.size(); i++; } } } } } } return sortedContainerList; } I would like to implement this in a better/faster way. So any hints are appreciated. :)

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  • A queue in C using structs and dynamic memory allocation (linked list)

    - by Martin Pugh
    I am tasked with making a queue data structure in C, as a linked list. Our lecturer gave us a large amount of code to implement a stack, but we have to adapt it to create a queue. The code our lecturer gave us ends up not compiling and segfaulting at the exact same point as the code I wrote for the queue. I'm very new to structs, malloc and C in general, so there could be something painfully obvious I've overlooked. Here is the code I am using: #include <stdio.h> #include <stdlib.h> struct node{ int data; //contains the actual data struct node *prev; //pointer to previous node (Closer to front) struct node *next; //pointer to next node (Closer to back) }; typedef struct node *Nodepointer; struct queue{ Nodepointer front; Nodepointer back; }; typedef struct queue *Queuepointer; main(){ Queuepointer myqueue; //create a queue called myqueue init(myqueue); //initialise the queue Nodepointer new = (Nodepointer)malloc(sizeof(struct node)); myqueue->front = new; } int init(Queuepointer q){ q = (Queuepointer)malloc(sizeof(struct queue)); q->front = NULL; q->back = NULL; } The idea is that the queue struct 'contains' the first and last nodes in a queue, and when a node is created, myqueue is updated. However, I cannot even get to that part (pop and push are written but omitted for brevity). The code is segfaulting at the line myqueue->front = new; with the following gdb output: Program received signal SIGSEGV, Segmentation fault. 0x08048401 in main () at queue.c:27 27 myqueue->front = new; Any idea what I'm doing wrong?

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  • JMS Step 4 - How to Create an 11g BPEL Process Which Writes a Message Based on an XML Schema to a JMS Queue

    - by John-Brown.Evans
    JMS Step 4 - How to Create an 11g BPEL Process Which Writes a Message Based on an XML Schema to a JMS Queue ol{margin:0;padding:0} .c11_4{vertical-align:top;width:129.8pt;border-style:solid;background-color:#f3f3f3;border-color:#000000;border-width:1pt;padding:5pt 5pt 5pt 5pt} .c9_4{vertical-align:top;width:207pt;border-style:solid;background-color:#f3f3f3;border-color:#000000;border-width:1pt;padding:5pt 5pt 5pt 5pt}.c14{vertical-align:top;width:207pt;border-style:solid;border-color:#000000;border-width:1pt;padding:5pt 5pt 5pt 5pt} .c17_4{vertical-align:top;width:129.8pt;border-style:solid;border-color:#000000;border-width:1pt;padding:5pt 5pt 5pt 5pt} .c7_4{vertical-align:top;width:130pt;border-style:solid;border-color:#000000;border-width:1pt;padding:0pt 5pt 0pt 5pt} .c19_4{vertical-align:top;width:468pt;border-style:solid;border-color:#000000;border-width:1pt;padding:5pt 5pt 5pt 5pt} .c22_4{background-color:#ffffff} .c20_4{list-style-type:disc;margin:0;padding:0} .c6_4{font-size:8pt;font-family:"Courier New"} .c24_4{color:inherit;text-decoration:inherit} .c23_4{color:#1155cc;text-decoration:underline} .c0_4{height:11pt;direction:ltr} .c10_4{font-size:10pt;font-family:"Courier New"} .c3_4{padding-left:0pt;margin-left:36pt} .c18_4{font-size:8pt} .c8_4{text-align:center} .c12_4{background-color:#ffff00} .c2_4{font-weight:bold} .c21_4{background-color:#00ff00} .c4_4{line-height:1.0} .c1_4{direction:ltr} .c15_4{background-color:#f3f3f3} .c13_4{font-family:"Courier New"} .c5_4{font-style:italic} .c16_4{border-collapse:collapse} .title{padding-top:24pt;line-height:1.15;text-align:left;color:#000000;font-size:36pt;font-family:"Arial";font-weight:bold;padding-bottom:6pt} .subtitle{padding-top:18pt;line-height:1.15;text-align:left;color:#666666;font-style:italic;font-size:24pt;font-family:"Georgia";padding-bottom:4pt} li{color:#000000;font-size:10pt;font-family:"Arial"} p{color:#000000;font-size:10pt;margin:0;font-family:"Arial"} h1{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:18pt;font-family:"Arial";font-weight:normal;padding-bottom:0pt} h2{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:18pt;font-family:"Arial";font-weight:bold;padding-bottom:0pt} h3{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:14pt;font-family:"Arial";font-weight:normal;padding-bottom:0pt} h4{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-style:italic;font-size:11pt;font-family:"Arial";padding-bottom:0pt} h5{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:10pt;font-family:"Arial";font-weight:normal;padding-bottom:0pt} h6{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-style:italic;font-size:10pt;font-family:"Arial";padding-bottom:0pt} This post continues the series of JMS articles which demonstrate how to use JMS queues in a SOA context. The previous posts were: JMS Step 1 - How to Create a Simple JMS Queue in Weblogic Server 11g JMS Step 2 - Using the QueueSend.java Sample Program to Send a Message to a JMS Queue JMS Step 3 - Using the QueueReceive.java Sample Program to Read a Message from a JMS Queue In this example we will create a BPEL process which will write (enqueue) a message to a JMS queue using a JMS adapter. The JMS adapter will enqueue the full XML payload to the queue. This sample will use the following WebLogic Server objects. The first two, the Connection Factory and JMS Queue, were created as part of the first blog post in this series, JMS Step 1 - How to Create a Simple JMS Queue in Weblogic Server 11g. If you haven't created those objects yet, please see that post for details on how to do so. The Connection Pool will be created as part of this example. Object Name Type JNDI Name TestConnectionFactory Connection Factory jms/TestConnectionFactory TestJMSQueue JMS Queue jms/TestJMSQueue eis/wls/TestQueue Connection Pool eis/wls/TestQueue 1. Verify Connection Factory and JMS Queue As mentioned above, this example uses a WLS Connection Factory called TestConnectionFactory and a JMS queue TestJMSQueue. As these are prerequisites for this example, let us verify they exist. Log in to the WebLogic Server Administration Console. Select Services > JMS Modules > TestJMSModule You should see the following objects: If not, or if the TestJMSModule is missing, please see the abovementioned article and create these objects before continuing. 2. Create a JMS Adapter Connection Pool in WebLogic Server The BPEL process we are about to create uses a JMS adapter to write to the JMS queue. The JMS adapter is deployed to the WebLogic server and needs to be configured to include a connection pool which references the connection factory associated with the JMS queue. In the WebLogic Server Console Go to Deployments > Next and select (click on) the JmsAdapter Select Configuration > Outbound Connection Pools and expand oracle.tip.adapter.jms.IJmsConnectionFactory. This will display the list of connections configured for this adapter. For example, eis/aqjms/Queue, eis/aqjms/Topic etc. These JNDI names are actually quite confusing. We are expecting to configure a connection pool here, but the names refer to queues and topics. One would expect these to be called *ConnectionPool or *_CF or similar, but to conform to this nomenclature, we will call our entry eis/wls/TestQueue . This JNDI name is also the name we will use later, when creating a BPEL process to access this JMS queue! Select New, check the oracle.tip.adapter.jms.IJmsConnectionFactory check box and Next. Enter JNDI Name: eis/wls/TestQueue for the connection instance, then press Finish. Expand oracle.tip.adapter.jms.IJmsConnectionFactory again and select (click on) eis/wls/TestQueue The ConnectionFactoryLocation must point to the JNDI name of the connection factory associated with the JMS queue you will be writing to. In our example, this is the connection factory called TestConnectionFactory, with the JNDI name jms/TestConnectionFactory.( As a reminder, this connection factory is contained in the JMS Module called TestJMSModule, under Services > Messaging > JMS Modules > TestJMSModule which we verified at the beginning of this document. )Enter jms/TestConnectionFactory  into the Property Value field for Connection Factory Location. After entering it, you must press Return/Enter then Save for the value to be accepted. If your WebLogic server is running in Development mode, you should see the message that the changes have been activated and the deployment plan successfully updated. If not, then you will manually need to activate the changes in the WebLogic server console. Although the changes have been activated, the JmsAdapter needs to be redeployed in order for the changes to become effective. This should be confirmed by the message Remember to update your deployment to reflect the new plan when you are finished with your changes as can be seen in the following screen shot: The next step is to redeploy the JmsAdapter.Navigate back to the Deployments screen, either by selecting it in the left-hand navigation tree or by selecting the “Summary of Deployments” link in the breadcrumbs list at the top of the screen. Then select the checkbox next to JmsAdapter and press the Update button On the Update Application Assistant page, select “Redeploy this application using the following deployment files” and press Finish. After a few seconds you should get the message that the selected deployments were updated. The JMS adapter configuration is complete and it can now be used to access the JMS queue. To summarize: we have created a JMS adapter connection pool connector with the JNDI name jms/TestConnectionFactory. This is the JNDI name to be accessed by a process such as a BPEL process, when using the JMS adapter to access the previously created JMS queue with the JNDI name jms/TestJMSQueue. In the following step, we will set up a BPEL process to use this JMS adapter to write to the JMS queue. 3. Create a BPEL Composite with a JMS Adapter Partner Link This step requires that you have a valid Application Server Connection defined in JDeveloper, pointing to the application server on which you created the JMS Queue and Connection Factory. You can create this connection in JDeveloper under the Application Server Navigator. Give it any name and be sure to test the connection before completing it. This sample will use the connection name jbevans-lx-PS5, as that is the name of the connection pointing to my SOA PS5 installation. When using a JMS adapter from within a BPEL process, there are various configuration options, such as the operation type (consume message, produce message etc.), delivery mode and message type. One of these options is the choice of the format of the JMS message payload. This can be structured around an existing XSD, in which case the full XML element and tags are passed, or it can be opaque, meaning that the payload is sent as-is to the JMS adapter. In the case of an XSD-based message, the payload can simply be copied to the input variable of the JMS adapter. In the case of an opaque message, the JMS adapter’s input variable is of type base64binary. So the payload needs to be converted to base64 binary first. I will go into this in more detail in a later blog entry. This sample will pass a simple message to the adapter, based on the following simple XSD file, which consists of a single string element: stringPayload.xsd <?xml version="1.0" encoding="windows-1252" ?> <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.example.org" targetNamespace="http://www.example.org" elementFormDefault="qualified" <xsd:element name="exampleElement" type="xsd:string"> </xsd:element> </xsd:schema> The following steps are all executed in JDeveloper. The SOA project will be created inside a JDeveloper Application. If you do not already have an application to contain the project, you can create a new one via File > New > General > Generic Application. Give the application any name, for example JMSTests and, when prompted for a project name and type, call the project JmsAdapterWriteWithXsd and select SOA as the project technology type. If you already have an application, continue below. Create a SOA Project Create a new project and choose SOA Tier > SOA Project as its type. Name it JmsAdapterWriteSchema. When prompted for the composite type, choose Composite With BPEL Process. When prompted for the BPEL Process, name it JmsAdapterWriteSchema too and choose Synchronous BPEL Process as the template. This will create a composite with a BPEL process and an exposed SOAP service. Double-click the BPEL process to open and begin editing it. You should see a simple BPEL process with a Receive and Reply activity. As we created a default process without an XML schema, the input and output variables are simple strings. Create an XSD File An XSD file is required later to define the message format to be passed to the JMS adapter. In this step, we create a simple XSD file, containing a string variable and add it to the project. First select the xsd item in the left-hand navigation tree to ensure that the XSD file is created under that item. Select File > New > General > XML and choose XML Schema. Call it stringPayload.xsd and when the editor opens, select the Source view. then replace the contents with the contents of the stringPayload.xsd example above and save the file. You should see it under the xsd item in the navigation tree. Create a JMS Adapter Partner Link We will create the JMS adapter as a service at the composite level. If it is not already open, double-click the composite.xml file in the navigator to open it. From the Component Palette, drag a JMS adapter over onto the right-hand swim lane, under External References. This will start the JMS Adapter Configuration Wizard. Use the following entries: Service Name: JmsAdapterWrite Oracle Enterprise Messaging Service (OEMS): Oracle Weblogic JMS AppServer Connection: Use an existing application server connection pointing to the WebLogic server on which the above JMS queue and connection factory were created. You can use the “+” button to create a connection directly from the wizard, if you do not already have one. This example uses a connection called jbevans-lx-PS5. Adapter Interface > Interface: Define from operation and schema (specified later) Operation Type: Produce Message Operation Name: Produce_message Destination Name: Press the Browse button, select Destination Type: Queues, then press Search. Wait for the list to populate, then select the entry for TestJMSQueue , which is the queue created earlier. JNDI Name: The JNDI name to use for the JMS connection. This is probably the most important step in this exercise and the most common source of error. This is the JNDI name of the JMS adapter’s connection pool created in the WebLogic Server and which points to the connection factory. JDeveloper does not verify the value entered here. If you enter a wrong value, the JMS adapter won’t find the queue and you will get an error message at runtime, which is very difficult to trace. In our example, this is the value eis/wls/TestQueue . (See the earlier step on how to create a JMS Adapter Connection Pool in WebLogic Server for details.) MessagesURL: We will use the XSD file we created earlier, stringPayload.xsd to define the message format for the JMS adapter. Press the magnifying glass icon to search for schema files. Expand Project Schema Files > stringPayload.xsd and select exampleElement: string. Press Next and Finish, which will complete the JMS Adapter configuration. Wire the BPEL Component to the JMS Adapter In this step, we link the BPEL process/component to the JMS adapter. From the composite.xml editor, drag the right-arrow icon from the BPEL process to the JMS adapter’s in-arrow. This completes the steps at the composite level. 4. Complete the BPEL Process Design Invoke the JMS Adapter Open the BPEL component by double-clicking it in the design view of the composite.xml, or open it from the project navigator by selecting the JmsAdapterWriteSchema.bpel file. This will display the BPEL process in the design view. You should see the JmsAdapterWrite partner link under one of the two swim lanes. We want it in the right-hand swim lane. If JDeveloper displays it in the left-hand lane, right-click it and choose Display > Move To Opposite Swim Lane. An Invoke activity is required in order to invoke the JMS adapter. Drag an Invoke activity between the Receive and Reply activities. Drag the right-hand arrow from the Invoke activity to the JMS adapter partner link. This will open the Invoke editor. The correct default values are entered automatically and are fine for our purposes. We only need to define the input variable to use for the JMS adapter. By pressing the green “+” symbol, a variable of the correct type can be auto-generated, for example with the name Invoke1_Produce_Message_InputVariable. Press OK after creating the variable. ( For some reason, while I was testing this, the JMS Adapter moved back to the left-hand swim lane again after this step. There is no harm in leaving it there, but I find it easier to follow if it is in the right-hand lane, because I kind-of think of the message coming in on the left and being routed through the right. But you can follow your personal preference here.) Assign Variables Drag an Assign activity between the Receive and Invoke activities. We will simply copy the input variable to the JMS adapter and, for completion, so the process has an output to print, again to the process’s output variable. Double-click the Assign activity and create two Copy rules: for the first, drag Variables > inputVariable > payload > client:process > client:input_string to Invoke1_Produce_Message_InputVariable > body > ns2:exampleElement for the second, drag the same input variable to outputVariable > payload > client:processResponse > client:result This will create two copy rules, similar to the following: Press OK. This completes the BPEL and Composite design. 5. Compile and Deploy the Composite We won’t go into too much detail on how to compile and deploy. In JDeveloper, compile the process by pressing the Make or Rebuild icons or by right-clicking the project name in the navigator and selecting Make... or Rebuild... If the compilation is successful, deploy it to the SOA server connection defined earlier. (Right-click the project name in the navigator, select Deploy to Application Server, choose the application server connection, choose the partition on the server (usually default) and press Finish. You should see the message ---- Deployment finished. ---- in the Deployment frame, if the deployment was successful. 6. Test the Composite This is the exciting part. Open two tabs in your browser and log in to the WebLogic Administration Console in one tab and the Enterprise Manager 11g Fusion Middleware Control (EM) for your SOA installation in the other. We will use the Console to monitor the messages being written to the queue and the EM to execute the composite. In the Console, go to Services > Messaging > JMS Modules > TestJMSModule > TestJMSQueue > Monitoring. Note the number of messages under Messages Current. In the EM, go to SOA > soa-infra (soa_server1) > default (or wherever you deployed your composite to) and click on JmsAdapterWriteSchema [1.0], then press the Test button. Under Input Arguments, enter any string into the text input field for the payload, for example Test Message then press Test Web Service. If the instance is successful you should see the same text in the Response message, “Test Message”. In the Console, refresh the Monitoring screen to confirm a new message has been written to the queue. Check the checkbox and press Show Messages. Click on the newest message and view its contents. They should include the full XML of the entered payload. 7. Troubleshooting If you get an exception similar to the following at runtime ... BINDING.JCA-12510 JCA Resource Adapter location error. Unable to locate the JCA Resource Adapter via .jca binding file element The JCA Binding Component is unable to startup the Resource Adapter specified in the element: location='eis/wls/QueueTest'. The reason for this is most likely that either 1) the Resource Adapters RAR file has not been deployed successfully to the WebLogic Application server or 2) the '' element in weblogic-ra.xml has not been set to eis/wls/QueueTest. In the last case you will have to add a new WebLogic JCA connection factory (deploy a RAR). Please correct this and then restart the Application Server at oracle.integration.platform.blocks.adapter.fw.AdapterBindingException. createJndiLookupException(AdapterBindingException.java:130) at oracle.integration.platform.blocks.adapter.fw.jca.cci. JCAConnectionManager$JCAConnectionPool.createJCAConnectionFactory (JCAConnectionManager.java:1387) at oracle.integration.platform.blocks.adapter.fw.jca.cci. JCAConnectionManager$JCAConnectionPool.newPoolObject (JCAConnectionManager.java:1285) ... then this is very likely due to an incorrect JNDI name entered for the JMS Connection in the JMS Adapter Wizard. Recheck those steps. The error message prints the name of the JNDI name used. In this example, it was incorrectly entered as eis/wls/QueueTest instead of eis/wls/TestQueue. This concludes this example. Best regards John-Brown Evans Oracle Technology Proactive Support Delivery

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  • Architecting Python application consisting of many small scripts

    - by Duke Dougal
    I am building an application which, at the moment, consists of many small Python scripts. Each Python script processes items from one Amazon SQS queue. Emails come into an initial queue and are processed by a script and typically the script will do a small unit of processing (for example, parse email and store some database fields), then an item will be placed on the next queue for further processing, until eventually the email has finished going through the various scripts and queues. What I like about this approach is that it is very loosely coupled. However, I'm not sure how I should implement live. Should I make each script a daemon which is constantly polling it's inbound queue for things to do? Or should there be some overarching orchestration program or process? Or maybe I should not have lots of small Python scripts but one large application? Specific questions: How should I run each of these scripts - as a daemon with some sort or restart monitor to restart them in case they stop for any reason? If yes, should I have some program which orchestrates this? Or is the idea of many small script not a good one, would it make more sense to have a larger python program which contains all the functionality and does all the queue polling and execution of functionality for each queue? What is the current preferred approach to daemonising Python scripts? Broadly I would welcome any comments or opinions on any aspect of this. thanks

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  • Queuing using table or MSMQ?

    - by Lieven Cardoen
    A part of the application I'm working on is an swf that shows a test with some 80 questions. Each question is saved to a sql server through WebORB and asp.net. If a candidate finisheds the test, the session needs to be validated. Problem now is that sometimes 350 candidates finish their test at the same moment, and cpu on webserver and sql server explodes (350 validations concurrently). Now, how would I implement queuing here? In the database, there's a table that has a record for each session. One column holds the status. 1 is finished, 2 is validated. I could implement queuing in two ways (as I see it, maybe you have other propositions): A process that checks the table for records with status 1. If it finds one, it validates the session. So, sessions are validated one after one. If a candidate finishes its session, a message is sent to a MSMQ queue. Another process listens to the queue and validates sessions one after one. Now, What would be the best approach? Where do you start the process that will validate sessions? In your global.asax (application_start)? As a windows service? As an exe on the root of the website that is started in application_start? To me, using the table and looking for records with status 1 seems the easiest way.

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  • [Java]Queue in while loop, cannot modify the value?

    - by javaLearner.java
    This is my code: Iterator it = queue.iterator(); while(it.hasNext()){ random = randNumber(1,2); if(random == 1){ queue.poll(); } else { queue.add("new"); queue.poll(); } } It gives me: Exception in thread "test" java.util.ConcurrentModificationException at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:761) at java.util.LinkedList$ListItr.next(LinkedList.java:696) Edit @Jon Skeet: What I want to do is: I have a queue list in, let say the size is 10, lets say: a,b,c,d ... j Generate a number between 1 and 2. if 1, pull (remove the top element) else if 2 add new element I will stop the loop until I added 3 new elements

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  • Which Message Queue should I choose (must run on Linux)

    - by MHS
    There are many open source Message queues for Linux, and I need some help deciding what I should go for. My problem is simple - I get sent a list of files that needs to be processed. Each job can't be split up, but they are self contained and can be spread to multiple computers. I'm thinking of solving this using a message queue. Multiple clients send a message to a central queue. Each queue has a number of subscribers that will take jobs from that queue when they have finished processing the current job. Ideally it should have the following qualities Message queue must be able to store unprocessed messages in case of a shutdown/reboot A job can only be processed by a single subscriber (don't want duplicate jobs) The subscribers should be able to send jobs of their own, that will be processed by a different set of subscribers. Can anyone suggest a simple to use message queue?

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  • Stats/Monitor/Inspector for beanstalkd

    - by Tim Lytle
    Does anyone know of an app that can monitor a beanstalkd queue? I'm looking for something that shows stats on tubes and jobs, and allows you to inspect the details. I'm not really picky about language/platform, just want to know if there's something out there before I write my own.

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  • How to make a queue switches from FIFO mode to priority mode?

    - by enzom83
    I would like to implement a queue capable of operating both in the FIFO mode and in the priority mode. This is a message queue, and the priority is first of all based on the message type: for example, if the messages of A type have higher priority than the messages of the B type, as a consequence all messages of A type are dequeued first, and finally the messages of B type are dequeued. Priority mode: my idea consists of using multiple queues, one for each type of message; in this way, I can manage a priority based on the message type: just take first the messages from the queue at a higher priority and progressively from lower priority queues. FIFO mode: how to handle FIFO mode using multiple queues? In other words, the user does not see multiple queues, but it uses the queue as if it were a single queue, so that the messages leave the queue in the order they arrive when the priority mode is disabled. In order to achieve this second goal I have thought to use a further queue to manage the order of arrival of the types of messages: let me explain better with the following code snippet. int NUMBER_OF_MESSAGE_TYPES = 4; int CAPACITY = 50; Queue[] internalQueues = new Queue[NUMBER_OF_MESSAGE_TYPES]; Queue<int> queueIndexes = new Queue<int>(CAPACITY); void Enqueue(object message) { int index = ... // the destination queue (ie its index) is chosen according to the type of message. internalQueues[index].Enqueue(message); queueIndexes.Enqueue(index); } object Dequeue() { if (fifo_mode_enabled) { // What is the next type that has been enqueued? int index = queueIndexes.Dequeue(); return internalQueues[index].Dequeue(); } if (priority_mode_enabled) { for(int i=0; i < NUMBER_OF_MESSAGE_TYPES; i++) { int currentQueueIndex = i; if (!internalQueues[currentQueueIndex].IsEmpty()) { object result = internalQueues[currentQueueIndex].Dequeue(); // The following statement is fundamental to a subsequent switching // from priority mode to FIFO mode: the messages that have not been // dequeued (since they had lower priority) remain in the order in // which they were queued. queueIndexes.RemoveFirstOccurrence(currentQueueIndex); return result; } } } } What do you think about this idea? Are there better or more simple implementations?

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  • Iptables QUEUE Target and Snort

    - by bradlis7
    I'm trying to set up a firewall with support for snort, and it is dropping all of my packets when I add the QUEUE target. I've made it like this, but the QUEUE target is not allowing the packets to be processed any further: -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT -A INPUT -j QUEUE -A INPUT -j ACCEPT # It's not allowing anything past QUEUE, as you can see below in the count. > iptables -I INPUT -nv pkts bytes target prot opt in out source destination 6707 395K ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 933 138K QUEUE all -- * * 0.0.0.0/0 0.0.0.0/0 0 0 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 I'm eventually going to change it to forward, but I'm just trying to get it working for now. I start snort like so: snort -Q -D -c /etc/snort/snort.conf EDIT: More Information When I run it, it still sees the packets without having an iptables QUEUE target rule, but when I add a QUEUE target, it starts losing all of my packets. # snort -Qc /etc/snort/snort.conf -N -A console Enabling inline operation Running in IDS mode --== Initializing Snort ==-- Initializing Output Plugins! Initializing Preprocessors! Initializing Plug-ins! Parsing Rules file "/etc/snort/snort.conf" ## === CUT === *** *** interface device lookup found: bond0 *** Initializing Network Interface bond0 Decoding Ethernet on interface bond0 ## === CUT === Not Using PCAP_FRAMES So, it says inline, but the it says it's using bond0. Inline should not require an interface, right?

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  • how to check if something is in the queue of torque?

    - by kloop
    I want to re-run some jobs that completed prematurely under torque. These jobs are run through .job scripts (using qsub). However, I don't want to re-run a job which is already in the queue. Given a script filename, how can I know whether it is already in torque's queue (using qstat?) or not? I prefer to do it programmatically, of course, so any oneliner that searches for a given script name would be great. I will note that I can grep submit_args in qstat -f, but I can't get it to display the whole script name when it is too long. This is crucial. EDIT: I managed to solve it using the following command: qstat -x | perl -pi -e 's/\<\//\n/g' | grep job$ | grep -v submit_args | perl -pi -e 's/Job_Id\>\<Job_Name\>//' works because all my scripts end in the string "job".

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