I've an idea and I don't know if it is doable in Cobol or not, I want to use Online VSAM file in online program, so my online VSAM file has multiple of records and i want if there is new record added to the file my online program detect that and do some of process, is it doable and please give me some of hint
What your describing is basically a trigger based on an event. You described COBOL as the language but in order to achieve what you want you also need to choose a runtime environment. Something like CICS, IMS Db2, WebSphere (Java), MQ, etc.
VSAM itself does not provide a triggering mechanism. An approach that would start to achieve what you want would be to create an MQ queue that processes the records to be written and they could write the record and take additional action. MQ cuts across all the runtimes listed above and is probably the most reliable.
Another option is to look at using Db2 where you could create a Triggers or user defined function that might achieve what your looking for. Here is a reference article that describes many methods.
Here is a list of some of the articles in the link mentioned above:
Utilizing Triggers within DB2 by Aleksey Shevchenko
Using Stored Procedures as Communication Mechanism to a Mainframe by
Robert Catterall
Workload Manager Implementation and Exploitation
Stored Procedures, UDFs and Triggers-Common Logic or Common Problem?
If you are looking to process records simply written from any source to VSAM there are really no inherent capabilities to achieve that in the Access Method Services where VSAM datasets are defined.
You need to consider your runtime environment, capabilities and goals as you continue your design.
If this is a high volume application you could consider IBM's "Change Data Capture" product. On every update to a chosen VSAM file it will dump a before and after image of the record into a message queue. Which can then be processed by the language and platform of your choice.
Also worth considering is if by "online" you mean a CICS application, then, the VSAM file will be exclusively owned by a single CICS region, and all updates will be processed by programs running in this region. You may be able to tweak the application to kick off some post processing (As simple as adding "EXEC CICS START yourtransacion ..." to the existing program(s).
Check out CICS Events. You can set an event for when the VSAM file is written to and action it with a COBOL program. There are several event adapters, you will probably be interested in the one that writes to a TS queue.
Related
You know, when an application opens a file and write to it, the system chooses in which cluster will be stored. I want to choose myself ! Let me tell you what I really want to do... In fact, I don't necessarily want to write anything. I have a HDD with a BAD range of clusters in the middle and I want to mark that space as it is occupied by a file, and eventually set it as a hidden-unmoveable-system one (like page file in windows) so that it won't be accessed anymore. Any ideas on how to do that ?
Later Edit:
I think THIS is my last hope. I just found it, but I need to investigate... Maybe a file could be created anywhere and then relocated to the desired cluster. But that requires writing, and the function may fail if that cluster is bad.
I believe the answer to your specific question: "Can I write a file to a specific cluster location" is, in general, "No".
The reason for that is that the architecture of modern operating systems is layered so that the underlying disk store is accessed at a lower level than you can access, and of course disks can be formatted in different ways so there will be different kernel mode drivers that support different formats. Even so, an intelligent disk controller can remap the addresses used by the kernel mode driver anyway. In short there are too many levels of possible redirection for you to be sure that your intervention is happening at the correct level.
If you are talking about Windows - which you haven't stated but which appears to assumed - then you need to be looking at storage drivers in the kernel (see https://learn.microsoft.com/en-us/windows-hardware/drivers/storage/). I think the closest you could reasonably come would be to write your own Installable File System driver (see https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/_ifsk/). This is really a 'filter' as it sits in the IO request chain and can intercept and change IO Request Packets (IRPs). Of course this would run in the kernel, not in userspace, and normally this would be written in C and I note your question is tagged for Delphi.
Your IFS Driver can sit at differnt levels in the request chain. I have used this technique to intercept calls to specific file system locations (paths / file names) and alter the IRP so as to virtualise the request - even calling back to user space from the kernel to resolve how the request should be handled. Using the provided examples implementing basic functionality with an IFS driver is not too involved because it's a filter and not a complete storgae system.
However the very nature of this approach means that another filter can also alter what you are doing in your driver.
You could look at replacing the file system driver that interfaces to the hardware, but I think that's likely to be an excessive task under the circumstances ... and as pointed out already by #fpiette the disk controller hardware can remap your request anyway.
In the days of MSDOS the access to the hardware was simpler and provided by the BIOS which could be hooked to allow the requests to be intercepted. Modern environments aren't that simple anymore. The IFS approach does allow IO to be hooked, but it does not provide the level of control you need.
EDIT regarding suggestion by the OP of using FSCTL_MOVE_FILE
For simple environment this may well do what you want, it is designed to support a defragmentation process.
However I still think there's no guarantee that this actually will do what you want.
You will note from the page you have linked to it states that it is moving one or more virtual clusters of a file from one logical cluster to another within the same volume
This is a code that's passed to the underlying storage drivers which I have referred to above. What the storage layer does is up to the storage layer and will depend on the underlying technology. With more advanced storage there's no guarantee this actually addresses the physical locations which I believe your question is asking about.
However that's entirely dependent on the underlying storage system. For some types of storage relocation by the OS may not be honoured in the same way. As an example consider an enterprise storage array that has a built in data-tiering function. Without the awareness of the OS data will be relocated within the storage based on the tiering algorithms. Also consider that there are technologies which allow data to be directly accessed (like NVMe) and that you are working with 'virtual' and 'logical' clusters, not physical locations.
However, you may well find that in a simple case, with support in the underlying drivers and no remapping done outside the OS and kernel, this does what you need.
Since you problem is to mark bad cluster, you don't need to write any program. Use the command line utility CHKDSK that Windows provides.
I an elevated command prompt (Run as administrator), run the command:
chkdsk /r c:
The check will be done on the next reboot.
Don't forget to read the documentation.
I am building framework for realtime web applications. I started to do it in Elixir, because
it is modern way how to develop application for Erlang VM. Erlang should be good if you need concurrency, fault tolerant, scalable apps (something like web server etc.). That is exactly what i need.
Question: Realtime framework always need for instance keep information about who is interested in what. This will be accomplished by using publish/subscribe pattern. So i will have 1000 clients subscribing to topic "newest-message". I need to save those clients (pid of process representing each client) somewhere to later access them if content for topic "newest-message" appears.
This is where i am confused if Erlang is really good for my framework.
ETS is probably the only option where to store shared data, but ETS is always copying everything if you save/access records. So that means copy 1000 pids always when i need to access them (instead of just iterating over some list, if i will do it for instance in c/java/python).
This will be probably great bottleneck if still copying many and many records from ETS (many clients, many subscriptions etc), i am right?
Sharing the state may be a sign of bad design. You can for example have process for each queue/topic and it will store its own list of subscribers. You send a message to that topic process and it in turn sends the message to clients. This way, you don't copy entire subscriber list.
If you need to process them in parallel, you can split the subscriber list between more processes.
The fault tolerance of Erlang is achieved, because it doesn't let you share state and you have to put more thought to the design, that will not involve state sharing, but will be efficient. This will pay off in the long run, so Erlang/Elixir is definitely good language for this kind of apps. Just look at RabbitMQ.
In my opnion, if you plan to save states like "who is interested in what" Erlang alone may not be a good idea. Of course, sometimes it is very convenient to pass everything in signals (like you'd do in Erlang), but when there is much content to store - lack of state in Erlang starts to hinder you rather than help.
On the other hand, you can keep a broad piece of convenience of Erlang and use it with a Java application, for example. Erlangs interface for Java enables you to connect both technologies quite easily, and at the same time you can use a Java app to store information for you (and save them somewhere, when necessary) and Erlang for the whole concurrent signaling real time part. Even better than that: you can still implement OTP with architecture like that, so you can create quite a lightweight application (because real-time logic is done by Erlang for you) being able to access stored data easily (because Java helps you here).
I am receiving SAP broadcasts, which I can normally use and play using the standalone vlc application.
I have been asked to provide a dump of the same. I have 2 questions:
I dont clearly understand what exactly dump is
How can I obtain the same?
There are multiple types of dumps, so you might first find out, what kind of dump is meant. It could be a database dump, which is similar to a backup, but usually it's a memory dump.
A memory dump or crash dump is a copy of the application including its memory at a specific point in time. Usually you want to create a dump exactly at the time an application is crashing or hanging. The dump will then be helpful to find the cause of the problem.
There are many ways to obtain a dump. First, Windows might do that for you, when it asks "Send information to Microsoft". Second, you can create it using Task Manager. Right click a process and choose "Create dump file". Third, there are many tools out there, e.g. Process Explorer or ProcDump, which all have pros and cons and serve different purposes.
To suggest a tool for your specific case, we would need more information. Exact wording might matter in this situation.
Update
In your particular case it looks like SAP means Service Advertising Protocol, which is related to the network. A broadcast is a message which is sent to everybody.
You could capture that one with Wireshark, but you would need a lot of network knowledge to get the filters set up. In this case the term "dump" probably refers to a something similar to a database dump, because SAP uses tables to store lists of services.
I don't know if it sounds crazy, but here's the scenario -
I need to print a document over the internet. My pc ClientX initiates the process using the web browser to access a ServerY on the internet and the printer is connected to a ClientZ (may be yours).
1. The document is stored on ServerY.
2. ClientZ is purely a cliet; no IIS, no print server etc.
3. I have the specific details of ClientZ, IP, Port, etc.
4. It'll be completely a server side application (and no client-side on ClientZ) with ASP.NET & C#
- so, is it possible? If yes, please give some clue. Thanks advanced.
This is kind of to big of a question for SO but basically what you need to do is
upload files to the server -- trivial
do some stuff to figure out if they are allowed to print the document -- trivial to hard depending on scope
add items to a queue for printing and associate them with a user/session -- easy
render and print the document -- trivial to hard depending on scope
notify the user that the document has been printed
handling errors
the big unknowns here are scope, if this is for a school project you probably don't have to worry about billing or queue priority in step two. If its for a commercial product billing can be a significant subsystem in its self.
the difficulty in step 4 depends directly on what formats you are going to support as many formats are going to require document specific libraries or applications. There are also security considerations here if this is a commercial product since it isn't safe to try to render all types of files.
Notifications can be easy or hard depending on how you want to do it. You can post back to the html page, but depending on how long its going to take for a job to complete it might be nice to have an email option as well.
You also need to think about errors. What is going to happen when paper or toner runs out or when someone tries to print something on A4 paper? Someone has to be notified so that jobs don't just build up.
On the server I would run just the user interaction piece on the web and have a "print daemon" running as a service to manage getting the documents printed and monitoring their status. I would use WCF to do IPC between the two.
Within the print daemon you are going to need a set of components to print different kinds of documents. I would make one assembly per type (or cluster of types) and load them into your service as plugins using MEF.
sorry this is so general, but you are asking a pretty general and difficult to answer question.
Is there an application that is capable of monitoring AND logging information (to file) about another process (in particular IIS aspnet_wp.exe) like (in periods of time):
- memory usage of process
- cpu usage
Or maybe there is another way to monitor IIS process?
Thanks Pawel
You can check Process Monitor from Microsoft.
Process Monitor is an advanced
monitoring tool for Windows that shows
real-time file system, Registry and
process/thread activity. It combines
the features of two legacy
Sysinternals utilities, Filemon and
Regmon, and adds an extensive list of
enhancements including rich and
non-destructive filtering,
comprehensive event properties such
session IDs and user names, reliable
process information, full thread
stacks with integrated symbol support
for each operation, simultaneous
logging to a file, and much more.
One choice would be Process explorer http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx
You might want to look at the ANTS Performance and Memory Profilers from Red Gate. I'm using their memory profiler to track down some memory issues as I write this.
Pretty much any monitoring system or framework that allows custom checks is capable of this.
You write your check and just put an extra line in it to post/print/put something to a file of your choice.
I for example use sensu for which I wright custom checks in ruby.
So I can easily do something like
if %x[{ping]}
ok
%x[{ print ‘all is well’ > syslog]}
end
and similar to that you can do for most other monitoring systems like Nagios etc.