Home is whenever I’m with you.

At last! I was able to go home to visit my parents for four days. Yesterday, Monday, was National Heroes Day so I booked my return flight for today, Tuesday. I was able to treat them to a movie which we do very seldom as a family. We were also able to spend some time on a local beach, nothing fancy, just your plain beach with some kubos. Mama just brought some bread, chips and soft drink. The water was not that clear also. Nevertheless, we had fun. My paper review requirement for my course this semester due tomorrow is taking a lot of my time though. I could have spent some more time with them on one of our local parks or visit some of our relatives. Hopefully, when I come home some other time I will have a more requirements-free schedule.

Today and tomorrow will most likely be a rough day for me. I need to write two paper reviews today (The Future of Supercomputing by M. Snir, GPUs: a closer look by K. Fatahalian et. al) for submission tomorrow. Add to that, I need to write some exercise CUDA C code in preparation for our class programming exercise. The faster I will be able to finish my paper reviews, the more time I will have for coding. Hopefully, I will have already finished my review of the first paper by the time our plane arrives in Manila. I am currently writing this blog post mid-flight.  

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Masters thesis and parallel computing

I am currently taking a course on Parallel Computing this semester under Dr. F. Cabarle. The course will require programming on a graphics processing unit (GPU) using CUDA C by NVIDIA. It has been a while since I have written a program in C since I have been coding in Java ever since I started working at DOST-ASTI. I need to refresh my C programming skills then for this sem, at least the minimum concepts necessary for writing CUDA applications.

We will also be required to submit reviews of all our required readings for the class. The last time I attended a class with paper review requirement was during our Advanced Computer Networks class under Dr. C. Festin. You can browse through my blog and will find some of my short reviews of the assigned readings for my networks class.

Lastly, the course will also require a project wherein the concepts of parallel computing will be applied. I have not yet decided on my topic for the project but I might work on implementing one of the algorithms in my masters thesis using DOST-ASTI’s GPU cluster.

Since I still need to simulate the algorithms in my thesis and do some revisions of my manuscript, I need to budget my time well if I want to do well in this course and at the same time finish my masters requirements this semester.

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Proof-of-Concept Requiring Service Bus Programming

Currently, our team is working on a prospect project which requires service bus programming. I am new to the concept of using a service bus for interoperability but I think it is a good way of decoupling heterogenous systems which require communication. Some key terms I am currently encountering are MuleESB, MarkLogic NoSQL Database Server, REST, SOAP, web service, PKI. We are fortunate to be provided with all the resources we need for the proof-of-concept application we are building.

Hopefully, I will be able to post some updates on service bus programming including issues which I encountered and solutions which I found for them, also the new things which I will be learning during the application development. I am also currently coming up with results for my MS thesis so I’ll be able to defend my proposal and thesis this month.

That is all for now I guess.

Best Regards,
Jeff

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MeshStream: Peer-to-Peer Video Streaming

It has been a while and a lot has happened the past semester, especially in our Advanced Computer Networks course. Peer-to-peer (P2P) overlay networks became our topic for our term mini project. I and my partner looked into the possibility of creating a P2P-based video streaming application and we were able to create a very simple proof of concept software application which uses a P2P client library and a media player library for Java for seeking, downloading, buffering and playback of pieces from other peers. We named our project as MeshStream. Mesh is for its P2P aspect and Stream is for the playback aspect. I personally am planning to further develop the concept by looking into papers about P2P-based video streaming this summer. After further planning and redesigning, we plan to offer the application to the community as an open-source application which anybody could further develop into something more useful. For the mean time, I am back to the drawing board for the redesigning of the application. Source code will be offered for forking once everything is set up and working properly through BitBucket.org. 🙂 Ciao! Excelsior! Jeff

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A Synthesis on the Paper Entitled “A Survey and Comparison of Peer-to-Peer Overlay Network Schemes” by E. K. Lua et al

Peer-to-Peer overlay networks offers features which weigh differently according to situation. As the authors mentioned in their paper, these are:

  • robust wide-area routing architecture
  • efficient search of data items
  • selection of nearby peers
  • redundant storage
  • permanence
  • hierarchical naming
  • trust and authentication
  • anonymity
  • massive scalability
  • fault tolerance

The authors also mentioned two classifications  of P2P overlay networks, namely, structured and unstructured.

On Structured P2P Overlay Networks

Structured P2P overlays take advantage of determinism to increase efficiency of queries within the network. Structured P2P networks make use of Distributed Hash Table for mapping data objects to peers within the network using key-value pairs, in which keys are mapped to unique peers. A look-up table is also maintained by each peer for keeping track of its neighboring peers all the time. Note that this requires a periodic updating of each peer’s look-up table to ensure efficiency of query propagation across the network. It is worth noting that in theory, DHT-based P2P overlays ensure a O(log N) in average query roundtrip time in hops for any data object within the network. The physical topology of the underlying network may differ from what is theoretically assumed though. This may cause in increase in latency within the overlay network which may greatly affect the performance of the applications running on the upper tier of the infrastructure. An advantage of the determinism of structured P2P overlay networks is its efficiency in locating “rare” items within the network. Unstructured networks do not scale well in locating this kind of items within the network due to flooding of query. On the other hand, unstructured networks do work well with high distribution of same items in the network.

Content Addressable Network (CAN) is a highly structured P2P overlay network infrastructure. CAN efficiently facilitates query routing through its mode of identifier assignment to the peers of the network. The identifier space (both for data objects and nodes) is represented by a d-dimensional coordinate space divided into sectors or zones which are assigned to peers. As common to structured P2P overlay networks, peers also keep a look-up table of neighbors to facilitate efficient routing of requests across the network. Introducing multiple d-dimensional coordinate spaces will expand the zone of specific peers thereby also allowing scalability within the network. In contrast to CAN, Chord uses a ring structure to facilitate mapping of peers to identifiers in the identifier space. Peers also maintain a lookup table termed as finger table to keep track of neighbor peers. In Chord, traversal of the network and assignment of keys to peers uses a notion of peer successor which is identified by a factor of modulo 2m from an origin peer during queries. Both CAN and Chord provides facility for handling “insertion” of new peers and “deletion” of current peers into the network. CAN handles this with splitting and joining of zones while Chord does reassignment of successor pointers. Other structured P2P overlay networks discussed by the authors are Tapestry, Pastry, and Kademlia.

Note that in each of these structured infrastructures some of the issues commonly addressed are the query request and response time, keeping track of neighbor peers to facilitate efficient propagation of requests, and joining and leaving of peers resulting to dynamic assignment of data objects within the network. The application performance benefits well from the structure of the these network infrastructures in terms of query propagation due to determinism of the assignment of identifiers in the network. The investment in computing space of structured P2P overlay networks results to gain in speed of propagation of request and response across the network.

On Unstructured P2P Overlay Networks

In contrast to structured P2P overlay networks, unstructured overlay networks do not depend on the topology of the overlay network in providing identifier names for data items and peers. In unstructured networks, there are no visualization of d-dimension zones or rings. The topology of the network evolves freely as peers join and leave the network.

Common to some infrastructures under this category is the use of super or ultra-peers. As the name suggests, these are peers with high bandwidth, large disk space, and high processing power. Gnutella protocol and FastTrack file-sharing system share this commonality. Peers publish their files list to these ultra-peers as meta-info to facilitate more efficient querying of data items. Ultra-peers act as directories wherein ordinary peers could lookup data item information, pointing to the peer/s hosting the queried file, if there are any. Queries are directed to the ultra-peers (they are capable of processing queries due to their high capacity) and are propagated using the common flooding approach.

Decentralized unstructured P2P overlay networks, like Freenet network and networks built on top of the Gnutella protocol, have the advantage of high reliability and fault-tolerance as compared to centralized ones like those built on top of the BitTorrent protocol, which has a single point of failure. On the other hand the details of the design of the BitTorrent protocol justifies the choice of centralization for more efficient file-sharing. A tracker is employed to keep track of the activities and the files available for sharing across the network. The protocol employs measures to ensure fair exchange of bits between peers. Among these are pipelining and choking.

Note that any protocol which requires caching or keeping of meta-info in some part/s of the network requires refreshing either in a periodic or aperiodic manner. In centralized networks like those built on BitTorrent, this is most likely done from all peers propagating their files lists to the central management node. This could be done either periodic (peers republishes their files lists) or in a native manner already built into the design of the protocol (refreshes are incorporated in queries and responses). This incurs overhead space cost in maintaining the list in exchange for faster request-response time. This is addressed by some protocols and systems by using high-capacity peers. Space cost is also starting to cease as an issue due to the enormous advancements in hardware research. Time cost usually still comes first as an issue as compared to space. It may vary though depending on the situation and nature of application of the overlay network.

Weight of the integrity and quality of data received by requesting peers may also vary depending on the situation. Downloaders do not really mind much usually about the quality of movie files they are receiving as long as they get a usable copy. Security, as always, remains to be a major concern in P2P file-sharing systems though. Peers are not assured of this when engaging with file-sharing systems in the Internet. They are only assured, usually, of the availability of data they are looking for.

Violation of copyright laws is also a common issue among file-sharing networks. It is desirable to incorporate in the design of these protocols the filtering of data being shared across the network. It is a difficult task to do so though due to volatility of data in the network and the frequent evolution (maybe revolution should be the more correct term) of topologies of networks. Identifiers for the classification of content could be standardized (but by whom?) but this is a far cry to solving this issue though.

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On Frenzy of Reading Books . . . Again

 

The end of year 2012 has come to me extraordinarily as I found my self getting back into the frenzy of reading books…again. I have been a long fan of the case of a boy who flies through the wind at night and dwells in an island called Neverland, never growing old and always chasing out adventure every tick of the clock. Of course that has to be Peter Pan (Hey, who does not know Peter? Kids nowadays maybe?). Add to that the great stories crafted by Tolkien, namely Lord of the Rings, The Hobbit, The Silmarilion and several other pieces, and those written by C.S. Lewis like The Lion, The Witch and the Wardrobe and his several writings on life and philosophy (and maybe faith, subtly).

 

As the end of 2012 approached I found my self reading literary books again. (Most of my readings during year 2012 has been on scientific journals, papers and books.) Every trip to the mall is synonymous to hunting books in Booksale outlets. Some past curiosities of my childhood days came to surface again. Daydreams of dragons, dwarves, elves, halflings, barbarians, vikings, wizards and several other mythical creatures of great stories once again occupied my always working mind. They became the major subjects of my book-hunting sessions in every Booksale outlets I go into. Scientific foundation books are still on my shopping list of course and for a man of science that will always be true. On the other hand, these book-hunting sessions has taken a toll on my resources like time and money without me becoming aware of it. I once went to Booksale to check some new stocks and walked out of the store six to seven books richer and more or less one-thousand five-hundred pesos poorer.

 

Half unaware, I came to start reading several classic pieces like The Pickwick Papers and Oliver Twist by Charles Dickens written during the early 1800s, Stuart Little by E. B. White also written during the 1800s, and of course The Hobbit by J. R. R. Tolkien. I also started looking for several contemporary series by R. A. Salvatore like The Legend of Drizzt (of which, Book 6: The Legacy, I have read just before Christmas ) and his other trilogies (a note, R. A. S. began writing about elves, dwarves and heroes when he got inspired by Tolkien’s The Lord of the Rings). The two books Peter and the Starcatchers and Peter and the Shadow Thieves by D. Barry and R. Pearson also caught my curiosity (and several other books by the authors like Peter and the Secret of Rundoon). In their writings the authors imaginatively told the story of how Peter Pan came to be, from an orphan who does know his family name to a flying, never-aging boy. Gladly, I also got my hands on one of Phillip Pullman‘s works, The Amber Spyglass (of which his other first two books, The Golden Compass and A Subtle Knife, are still on my hunt list) and two of J. Stroud‘s works, Heroes of the Valley and The Golem’s Eye (which is the third book of a trilogy), each of which are still on my soon-to-read list.

 

I admire story tellers, I mean those good ones of course. Not all could tickle your mind and bring it into a lullaby of imagination. Not all authors could put you into Peter Pan’s shoes and soar the night sky or into Mr. Pickwick’s suit and join your gang of gentlemen into some countryside silly adventures. I love books and enjoy reading them as much as I admire their authors. Books are like ticket to a movie house. Only, the movie plays on your mind and it takes a handful of good imagining to experience so. Reading a book is more participative, I should say, as compared to watching a movie wherein the cast and the staff already did all the imagining for you.

 

Deep inside my mind, I am thinking that, perhaps in a very subtle manner, I love reading books and good story tellers because I myself dream of becoming a good story teller at some point in time of my life…ala Bilbo Baggins.

 

Now, it is time to get back to my books…once again.

 

Excelsior! Jeff

 

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To Read is to Dream. . .

Aaaah! Christmas break is now just around the corner. For a bookworm and lover of Tolkenish readings like me, this is the season to sit back, sip up some coffee and pick up some books on my To Read list. Of course I also have my reading list of scientific papers which I need and want to look into but that is another story I suppose. There is time for everything under the sun, bids King Solomon. ^__^

In my reading list, I have the following:

  • Heroes of the Valley by Jonathan Stroud – I have already covered some five chapters or more as I remember. I got stuck when busyness in the lab and office got hold of me. I haven’t read J. Stroud’s Bartimaeus Trilogy but I am giving this a shot. I am happy so far about how the story is going.
  • The Hobbit by J. R. R. Tolkien – I have already finished reading the book and as expected Tolkien never ceases to amaze me. I would love to read it again after watching The Hobbit in the cinema. I am glad that my imagination of the dwarves and the dragon basking in the pile of gold fits well the depiction of the characters in the movie.
  • The Silmarillion by J. R. R. Tolkien – I have not finished reading this one again due to busyness. Tolkien has really wonderfully made a rich fantasy in his writings about Middle Earth and his characters that an imaginative person like me couldn’t help but to daydream.
  • The Legacy, Book VII of The Legend of Drizzt series by R. A. Salvatore – I have to postpone this one because I want to read the previous six books of this series first so I can trace citations to the other six books when reading it. So the goal now is to find a bargain of the other books! I hope I won’t get tempted to get a copy in Fullybooked. Grrrr.

These are just some of the books which I would like to enjoy reading during any of my free time. Also, I hope to have time to make reviews of these readings to record my reading experiences and to give others a viewpoint before reading them.

This Christmas, on top of my wish list is.. time. I wish to have time for my self and time to enjoy my books. ^__^

Have a Merry Christmas everyone!

Excelsior! Jeff.

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